Investing in ecosystem services can boost food security: UN

Investing in ecosystem services can boost food security: UN 
This new UNEP report launched during World Water Week in Stockholm, focuses on the links between ecosystems, water and food, and illustrates how resilient ecosystems can support and increase food security.


Ecosystem Services


Against the current challenges to enhance food security worldwide, the publication aims at illustrating the importance of healthy ecosystems for the provisioning of key services that contribute to food security. Such ecosystem services are water provisioning and food production. In this regard the publication will provide an overview of the linkages between ecosystems, water, and food security. The publication further will explore how to manage ecosystems for a variety of ecosystem services such as provisioning of water and food, and how to manage ecosystems in a sustainable way so they can substantially contribute to enhancing current and future food security.

Publication Date: 01.08.2011
Author(s): Sithara Atapattu, Jennie Barron, Prem Bindraban and et al

Root of the Problem

The Scientist

August 2011 » Cover Story » Features

http://the-scientist.com/2011/08/01/the-root-of-the-problem/

New research suggests that the flow of carbon through plants to underground ecosystems may be crucial to how the environment responds to climate change.

By Richard D. Bardgett | August 1, 2011

Link this Stumble Tweet this

Corbis, MICHAEL POLE

CORBIS, MICHAEL POLE

Human beings have inexorably altered the world’s ecosystems. We’ve plowed and seeded more than 40 percent of the Earth’s land surfaces, introduced alien species into new territories, poured carbon dioxide into the atmosphere, disrupted natural climate cycles, and polluted aquatic ecosystems with excessive nitrogen and other contaminants.

These far-reaching changes have spurred scores of researchers to examine the impacts of human activities on biodiversity and ecosystem functioning, and to devise management strategies that might lessen the damage. Scientists have scoured ecosystems from the ocean’s depths to the highest mountain peaks searching for signals of global change. But only recently has this attention extended under the Earth’s surface to the soil, and the linkages between plants and belowground microbial and animal communities. This realm of research is of paramount importance because the impact of human-induced disturbances on the functioning of terrestrial ecosystems is often indirect: they tend to operate via changes aboveground that cascade belowground to the hugely complex and diverse, soil-bound biological community, driving biogeochemical processes and feeding back to the whole Earth-system.

And these studies may be overturning a commonly held view of how plants help mitigate the impacts of global warming. Indeed, it is widely thought that vegetation, especially trees, will respond to increasing atmospheric CO2 concentrations by growing more vigorously, and thus help to moderate climate change by locking up more carbon in their leaves, branches, and trunks. But research into the intricate dynamics occurring just below the soil surface, where carbon, nitrogen, and other elements flow through plant roots into the soil and react with the microbial and animal communities living there—including bacteria, fungi and a host of fauna—is complicating this simplistic view. In fact, some work suggests that as plant growth increases because of elevated CO2, more carbon not only flows into the plants themselves, but also exits their roots to impact the growth and activity of soil microbes. This causes a net increase in CO2 and other greenhouse gases escaping from the soil and entering the atmosphere, thus adding to anthropogenic levels.

These insights indicate that a combined plant-microbial-soil approach can lead to a more holistic understanding of the consequences of global change—including climate change—for the health and functioning of both terrestrial ecosystems and the whole Earth-system. Most importantly, the role that plant-microbial-soil interactions, and specifically carbon transfer from roots to soil, play in governing climate change and its impact on ecosystem carbon cycling is coming to light.

Getting Down and Dirty

Soils are the Earth’s third largest carbon storage depot after oceans and fossil fuels and together with vegetation contain about 2.7 times more carbon than the atmosphere. As a result, there is much concern that climate change will enhance the decomposition of this soil-bound carbon, potentially shifting soils from being sinks to sources of atmospheric CO2, thereby accelerating climate change: the so called carbon-cycle feedback. There is also a vigorous debate about the feasibility of slowing climate change by increasing the capacity of soils to sequester carbon from the atmosphere. Recent research is revealing that both the loss and gain of carbon in soil depend heavily on the pattern of interaction between plants, microbes, and the soil itself.

Infographic: From the Ground Up
View full size JPG | PDFKEVIN HAND

Climate change impacts soil carbon in a variety of ways, both direct and indirect.1 Even a subtle uptick in global air temperatures (of approximately 1°C) can directly stimulate microbial activity, causing an increase in ecosystem respiration rates in the subarctic peatlands which cover vast tracts of northern hemisphere and harbor a large portion of the organic carbon found in the world’s soil.2Researchers monitoring an Alaskan tundra landscape also showed that permafrost thaw occurring over a span of decades has led to significant losses of soil carbon through soil respiration, despite increased plant growth and consequent ecosystem carbon input to soil, in the form of leaf litter and other plant sources.3Given that tundra soils are among the world’s largest carbon stores, these studies indicate a potentially large and long-lasting positive feedback of carbon to the global climate system.

There remains much uncertainty, however, about how soil organisms directly respond to warming. For instance, it is unclear whether short-term increases in microbial activity and carbon cycling in response to warming will be sustained when fast-cycling soil carbon pools, such as carbohydrates and amino acids, become depleted and soil communities become acclimated to living in a warmer world.4

While more work remains to be done to fully elucidate the direct effects of climate change on soil microbes and carbon cycling, understanding strong indirect effects—for example, responses mediated via plants—is perhaps even more important. Two types of mechanisms drive these processes: first, rising atmospheric CO2 indirectly impacts soil microbes by way of increased plant photosynthesis and transfer of photosynthetic carbon to soil as root exudates; and, second, long-term, climate change-induced alterations in the composition and diversity of vegetation alter the amount and quality of organic matter entering soil, affecting the activity and structure of belowground communities.

It is becoming clear that both of these indirect mechanisms—short-term, individual plant-level and long-term, community-level inputs—have significant consequences for the carbon budget of terrestrial ecosystems under conditions of climate change. With regard to short-term effects, University of Illinois graduate student John Drake and colleagues constructed a belowground carbon budget based on 12 years of measurements from the Duke Forest free-air CO2 enrichment (FACE) experiment in North Carolina, and showed that elevated CO2 concentrations caused a carbon cascade through the root-microbial-soil system in a low-fertility pine forest, altering the carbon budget of this ecosystem. Specifically, the researchers found that elevated atmospheric CO2increased the flux of carbon to roots, which in turn stimulated microbial activity and the breakdown of organic matter in the soil. Because this process also stimulated the release and turnover of nitrogen and its uptake by the trees, it set in motion a positive feedback loop that sustained enhanced rates of tree growth, which locked up even more carbon in tree biomass, but not in soil.5

In a related study at Duke Forest, Indiana University’s Richard Phillips and collaborators, investigated the mechanisms behind this carbon cascade: over a period of 3 years, elevated CO2 concentrations in the air increased the rate at which tree roots exuded carbon by 55 percent, leading to a 50 percent annual increase in soluble organic inputs to soil.6 Upping the amount of carbon oozing from plant roots drove belowground microbes to release more extracellular enzymes involved in breakdown of organic nitrogen and accelerated the turnover rate of organic nitrogen in the soil. In sum, these findings point to the importance of such indirect, plant-driven mechanisms for understanding how climate change impacts the functioning of terrestrial ecosystems.

Scientists have scoured ecosystems from the ocean’s depths to the highest mountain peaks searching for signals of global change. But only recently has this attention extended under the Earth’s surface to the soil.

Despite these reports, there is still uncertainly about how soil microbes respond to more carbon being pumped into soil in a high CO2 world. For example, while the above studies show that upping the amount of carbon entering the soil stimulated soil microbes and nitrogen cycling, other studies show a different pattern. That is, enhanced root exudation under elevated CO2can stimulate the locking up of nitrogen by microbes—termed nitrogen immobilization—which in turn limits nitrogen availability to plants, plant growth, and, ultimately, carbon transfer to soil. The reason for this discrepancy is unclear, but it is most likely due to the quality of the exudates and of other plant-derived organic matter, such as plant litter, entering soil. When the material is rich in nitrogen and hence has a low carbon-to-nitrogen ratio, microbes will use the carbon for growth and liberate the excess nitrogen that they don’t need into the soil, thereby increasing nitrogen availability to plants. Conversely, when those substrates are low in nitrogen and have a high carbon-to-nitrogen ratio, the microbes become nitrogen starved and soak up any nitrogen that is available, therefore reducing its availability to plants. This often occurs because elevated CO2 reduces the nitrogen concentrations in plant tissues, unless there is a continuing supply of nitrogen to the plants, for example through fertilizers.

More carbon coming from roots can also result in the mineralization of both recent and old soil organic carbon, making it metabolically available and leading to net carbon loss from soil through respiration.7 This mineralization can also increase the growth of mycorrhizal fungi, which can alter the release of carbon to the soil microbial community and enhance the stabilization of organic carbon by causing soil particles to aggregate.8 These studies show that forests respond to elevated CO2 in complex ways that tightly link plant-microbial-soil feedbacks fueled by inputs of root-derived carbon to soil. Moreover, they bolster the growing view that the transfer of recently fixed carbon from roots to the belowground subsystem serves as a major driver of soil food webs, and this has significant consequences for the functioning of terrestrial ecosystems adapting to climate change.

Evidence is also emerging that climate change can cause both local and regional shifts in the composition of vegetation by altering precipitation patterns and temperature regimes and by further elevating atmospheric CO2 concentrations. It’s becoming clear that such long-term shifts in composition of the plant community can affect the transfer of recent photosynthetic carbon belowground and thus affect ecosystem carbon dynamics. For example, Sue Ward and colleagues at the Lancaster Environment Centre, UK, used in situ stable carbon-isotope labeling approaches to show that removing key plant species from a dwarf-shrub heath community strongly affected belowground transfer and metabolism of recently added photosynthetic carbon.9 In particular, the removal of dwarf shrubs greatly increased community-level photosynthesis rates, the transfer of this recently assimilated carbon to soil, and its use by soil microbes, thereby speeding up rates of carbon cycling. There is growing evidence from a variety of ecosystems that plant species and functional groups—different species, such as legumes, grasses, and herbs, with similar physiological characteristics—differentially influence the uptake and transfer of carbon to soil via their exudates, suggesting that global warming-induced changes in plant community structure have the potential to alter patterns of carbon exchange. In general, however, much remains unknown about how changing the composition of plant communities can affect carbon cycling, and an important challenge will be to better understand the role of plant-soil feedbacks in modifying ecosystem carbon dynamics, especially given the extent to which climate-mediated changes in vegetation are already occurring worldwide.

Digging Deep

In all the work being done to illuminate and quantify the importance of belowground dynamics in driving the carbon cycle, the central message is similar: to better understand ecosystem functioning and its response to global change, we must consider feedbacks among plants, microbes, and soil processes. It’s clear that root carbon transfer and resulting carbon cascades through the plant-microbial-soil system play a primary role in driving carbon-cycle feedbacks and in regulating ecosystem responses to climate change.

Recent studies highlight the potential application of such understanding to land management challenges, such as enhancing soil carbon sequestration in grassland and degraded soils, which also hold potential benefits for food production and biodiversity conservation. Further study is also required to realize the potential for targeted crop-improvement strategies based on root traits that favor carbon sequestration in soil while also efficiently producing food. A new age of research and funding is needed to meet these scientific challenges and to integrate such understanding into future land-management and climate change mitigation strategies.

Soils as Sinks

A possible way to lessen the impacts of climate change is to engineer landscapes to increase the amount of carbon sequestered in soil. Mounting evidence suggests that managing grasslands may be a way to enhance soil carbon stocks, while reaping additional benefits for biodiversity conservation. For example, in model grassland systems it was recently shown that increasing plant diversity enhances CO2 assimilation by surrounding plants and belowground carbon allocation to roots and mycorrhizal fungi, which is a key mechanism driving carbon sequestration in soil.10,11 These effects, however, were due to the presence of legumes in high-diversity mixtures, rather than to diversity per se. Consistent with this, the introduction of legumes into grasslands under diversity restoration in northern England enhanced soil carbon sequestration, most likely because of increased input of carbon and nitrogen to soil and suppression of extracellular enzyme activities involved in the breakdown of organic matter.12

These findings point to the potential for using diverse grasslands with healthy plant-microbial-soil interactions to act as crucial buffers of climate change. Further research is needed to exploit this approach, especially since restoration of high-diversity grassland on degraded and formerly arable land is a key policy objective for sustainable agriculture in many parts of the world.

The mechanisms involved in plant manipulation of the carbon sequestered in soil involve myriad biotic interactions between plants, their symbionts (i.e., mycorrhizal fungi and nitrogen-fixing bacteria), and decomposers whose activities determine the rate of decomposition of organic matter and hence of carbon loss from soil. In 2008, Lancaster University’s Gerlinde De Deyn and I, along with Hans Cornelissen of the Vrije Universiteit, Amsterdam, proposed a simplified plant-trait-based framework for understanding linkages between plant communities, the microbial community, and soil carbon sequestration.13 This framework is consistent with the growing recognition that plant functional traits, such as leaf-litter nitrogen content and relative growth rate, act as major drivers of belowground nutrient and carbon cycling and can favor particular groups of soil organisms that play key roles in these processes. A recent study of grassland plant species showed that, in particular, root traits, such as biomass and nitrogen content, were strongly correlated with several soil properties, especially the biomass and composition of the surrounding microbial community and measures related to soil carbon cycling.14

The mineralization of soil organic carbon—and hence soil carbon loss—in grasslands also appears to increase with plant productivity and decrease with root nitrogen concentration. For example, Feike Dijkstra and colleagues at the University of Minnesota showed in a study of sixteen grassland plant species that increased root nitrogen concentration (e.g., in flowering plants that are not grasses and especially in legumes) slowed down the decomposition of recalcitrant soil organic matter, whereas increasing plant biomass enhanced rates of decomposition.15 But specific plant traits, such as differences in the quantity and chemical composition of root exudates, are also likely to affect the mineralization of soil carbon by altering microbial activity.15 These studies suggests that plant traits, and especially those of roots, represent tools for understanding the mechanisms behind plant-microbial-soil interactions and ecosystem functions, and for predicting how climate change-induced shifts in plant species composition will feed back to the Earth-system. Moreover, given the importance of root traits for soil microbial processes related to carbon cycling, understanding of root interactions offers potential for modification of plant communities and the root traits of crops. Perennial grain species, for example, could be bred to produce more and deeper roots, which may maximize soil carbon sequestration.16

Richard D. Bardgett is a Professor of Ecology at Lancaster University’s Lancaster Environment Centre, in the UK. His research is focused on understanding the role that linkages between plant and soil communities play in the delivery of ecosystem services, especially sequestration in soils and nutrient cycling.

References

  1. R.D. Bardgett et al., “Microbial contributions to climate change through carbon-cycle feedbacks,”ISME J, 2:805-14, 2008. 
  2. E. Dorrepaal et al., “Carbon respiration from subsurface peat accelerated by climate warming in the subarctic,” Nature, 460:616-19, 2009. 
  3. E.A.G. Schuur et al., “The effect of permafrost thaw on old carbon release and net carbon exchange from tundra,” Nature, 459:556-59, 2009. 
  4. M.A. Bradford et al., “Thermal adaptation of soil microbial respiration to elevated temperature,”Ecol Lett, 11:1316-27, 2008. 
  5. J. E. Drake et al., “Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO2,” Ecol Lett, 14: 349-57, 2011. 
  6. R.P. Philips et al., “Enhanced root exudation induces microbial feedbacks to N cycling in a pine forest under long-term CO2 fumigation,” Ecol Lett, 14:187-94, 2011. 
  7. J. Heath et al., “Rising atmospheric CO2 reduces soil carbon sequestration of root-derived soil carbon,” Science, 309:1711-13, 2005. 
  8. G.W.T Wilson et al., “Soil aggregation and carbon sequestration are tightly correlated with the abundance of arbuscular mycorrhizal fungi: results from long-term field experiments,” Ecol Lett, 12:452-61, 2009. 
  9. S.E. Ward et al., “Plant functional group identity influences short-term peatland ecosystem carbon flux: evidence from a plant removal experiment,” Funct Ecol, 23:454-62, 2009. 
  10. G.B. De Deyn et al., “Vegetation composition promotes carbon and nitrogen storage in model grassland communities of contrasting soil fertility,” J Ecol, 97:864-75, 2009. 
  11. G.B. De Deyn et al., “Plant species richness, identity and productivity differentially influence key groups of microbes in grassland soils of contrasting fertility,” Biol Lett, 7:75-78, 2011. 
  12. G. B. De Deyn et al., “Additional carbon sequestration benefits of grassland diversity restoration,” J Appl Ecol, 48: 600-08, 2011. 
  13. G.B. De Deyn et al., “Plant functional traits and soil carbon sequestration in contrasting biomes,”Ecol Lett, 11:516-31, 2008. 
  14. K.A. Orwin et al., “Linkages between plant traits and soil properties related to the functioning of temperate grassland,” J Ecol, 98:1074-83, 2010. 
  15. F.A. Dijkstra et al., “Soil processes affected by sixteen grassland species grown under different environmental conditions,” Soil Sci Soc Am J, 70:770–77, 2006. 
  16. J.D. Glover et al., “Increased food and ecosystem security via perennial grains,” Science, 328:1638-39, 2010. 

The Root of the Problem

The Scientist

August 2011 » Cover Story » Features

http://the-scientist.com/2011/08/01/the-root-of-the-problem/

New research suggests that the flow of carbon through plants to underground ecosystems may be crucial to how the environment responds to climate change.

By Richard D. Bardgett | August 1, 2011

Link this Stumble Tweet this

Corbis, MICHAEL POLE

CORBIS, MICHAEL POLE

Human beings have inexorably altered the world’s ecosystems. We’ve plowed and seeded more than 40 percent of the Earth’s land surfaces, introduced alien species into new territories, poured carbon dioxide into the atmosphere, disrupted natural climate cycles, and polluted aquatic ecosystems with excessive nitrogen and other contaminants.

These far-reaching changes have spurred scores of researchers to examine the impacts of human activities on biodiversity and ecosystem functioning, and to devise management strategies that might lessen the damage. Scientists have scoured ecosystems from the ocean’s depths to the highest mountain peaks searching for signals of global change. But only recently has this attention extended under the Earth’s surface to the soil, and the linkages between plants and belowground microbial and animal communities. This realm of research is of paramount importance because the impact of human-induced disturbances on the functioning of terrestrial ecosystems is often indirect: they tend to operate via changes aboveground that cascade belowground to the hugely complex and diverse, soil-bound biological community, driving biogeochemical processes and feeding back to the whole Earth-system.

And these studies may be overturning a commonly held view of how plants help mitigate the impacts of global warming. Indeed, it is widely thought that vegetation, especially trees, will respond to increasing atmospheric CO2 concentrations by growing more vigorously, and thus help to moderate climate change by locking up more carbon in their leaves, branches, and trunks. But research into the intricate dynamics occurring just below the soil surface, where carbon, nitrogen, and other elements flow through plant roots into the soil and react with the microbial and animal communities living there—including bacteria, fungi and a host of fauna—is complicating this simplistic view. In fact, some work suggests that as plant growth increases because of elevated CO2, more carbon not only flows into the plants themselves, but also exits their roots to impact the growth and activity of soil microbes. This causes a net increase in CO2 and other greenhouse gases escaping from the soil and entering the atmosphere, thus adding to anthropogenic levels.

These insights indicate that a combined plant-microbial-soil approach can lead to a more holistic understanding of the consequences of global change—including climate change—for the health and functioning of both terrestrial ecosystems and the whole Earth-system. Most importantly, the role that plant-microbial-soil interactions, and specifically carbon transfer from roots to soil, play in governing climate change and its impact on ecosystem carbon cycling is coming to light.

Getting Down and Dirty

Soils are the Earth’s third largest carbon storage depot after oceans and fossil fuels and together with vegetation contain about 2.7 times more carbon than the atmosphere. As a result, there is much concern that climate change will enhance the decomposition of this soil-bound carbon, potentially shifting soils from being sinks to sources of atmospheric CO2, thereby accelerating climate change: the so called carbon-cycle feedback. There is also a vigorous debate about the feasibility of slowing climate change by increasing the capacity of soils to sequester carbon from the atmosphere. Recent research is revealing that both the loss and gain of carbon in soil depend heavily on the pattern of interaction between plants, microbes, and the soil itself.

Infographic: From the Ground Up
View full size JPG | PDFKEVIN HAND

Climate change impacts soil carbon in a variety of ways, both direct and indirect.1 Even a subtle uptick in global air temperatures (of approximately 1°C) can directly stimulate microbial activity, causing an increase in ecosystem respiration rates in the subarctic peatlands which cover vast tracts of northern hemisphere and harbor a large portion of the organic carbon found in the world’s soil.2Researchers monitoring an Alaskan tundra landscape also showed that permafrost thaw occurring over a span of decades has led to significant losses of soil carbon through soil respiration, despite increased plant growth and consequent ecosystem carbon input to soil, in the form of leaf litter and other plant sources.3Given that tundra soils are among the world’s largest carbon stores, these studies indicate a potentially large and long-lasting positive feedback of carbon to the global climate system.

There remains much uncertainty, however, about how soil organisms directly respond to warming. For instance, it is unclear whether short-term increases in microbial activity and carbon cycling in response to warming will be sustained when fast-cycling soil carbon pools, such as carbohydrates and amino acids, become depleted and soil communities become acclimated to living in a warmer world.4

While more work remains to be done to fully elucidate the direct effects of climate change on soil microbes and carbon cycling, understanding strong indirect effects—for example, responses mediated via plants—is perhaps even more important. Two types of mechanisms drive these processes: first, rising atmospheric CO2 indirectly impacts soil microbes by way of increased plant photosynthesis and transfer of photosynthetic carbon to soil as root exudates; and, second, long-term, climate change-induced alterations in the composition and diversity of vegetation alter the amount and quality of organic matter entering soil, affecting the activity and structure of belowground communities.

It is becoming clear that both of these indirect mechanisms—short-term, individual plant-level and long-term, community-level inputs—have significant consequences for the carbon budget of terrestrial ecosystems under conditions of climate change. With regard to short-term effects, University of Illinois graduate student John Drake and colleagues constructed a belowground carbon budget based on 12 years of measurements from the Duke Forest free-air CO2 enrichment (FACE) experiment in North Carolina, and showed that elevated CO2 concentrations caused a carbon cascade through the root-microbial-soil system in a low-fertility pine forest, altering the carbon budget of this ecosystem. Specifically, the researchers found that elevated atmospheric CO2increased the flux of carbon to roots, which in turn stimulated microbial activity and the breakdown of organic matter in the soil. Because this process also stimulated the release and turnover of nitrogen and its uptake by the trees, it set in motion a positive feedback loop that sustained enhanced rates of tree growth, which locked up even more carbon in tree biomass, but not in soil.5

In a related study at Duke Forest, Indiana University’s Richard Phillips and collaborators, investigated the mechanisms behind this carbon cascade: over a period of 3 years, elevated CO2 concentrations in the air increased the rate at which tree roots exuded carbon by 55 percent, leading to a 50 percent annual increase in soluble organic inputs to soil.6 Upping the amount of carbon oozing from plant roots drove belowground microbes to release more extracellular enzymes involved in breakdown of organic nitrogen and accelerated the turnover rate of organic nitrogen in the soil. In sum, these findings point to the importance of such indirect, plant-driven mechanisms for understanding how climate change impacts the functioning of terrestrial ecosystems.

Scientists have scoured ecosystems from the ocean’s depths to the highest mountain peaks searching for signals of global change. But only recently has this attention extended under the Earth’s surface to the soil.

Despite these reports, there is still uncertainly about how soil microbes respond to more carbon being pumped into soil in a high CO2 world. For example, while the above studies show that upping the amount of carbon entering the soil stimulated soil microbes and nitrogen cycling, other studies show a different pattern. That is, enhanced root exudation under elevated CO2can stimulate the locking up of nitrogen by microbes—termed nitrogen immobilization—which in turn limits nitrogen availability to plants, plant growth, and, ultimately, carbon transfer to soil. The reason for this discrepancy is unclear, but it is most likely due to the quality of the exudates and of other plant-derived organic matter, such as plant litter, entering soil. When the material is rich in nitrogen and hence has a low carbon-to-nitrogen ratio, microbes will use the carbon for growth and liberate the excess nitrogen that they don’t need into the soil, thereby increasing nitrogen availability to plants. Conversely, when those substrates are low in nitrogen and have a high carbon-to-nitrogen ratio, the microbes become nitrogen starved and soak up any nitrogen that is available, therefore reducing its availability to plants. This often occurs because elevated CO2 reduces the nitrogen concentrations in plant tissues, unless there is a continuing supply of nitrogen to the plants, for example through fertilizers.

More carbon coming from roots can also result in the mineralization of both recent and old soil organic carbon, making it metabolically available and leading to net carbon loss from soil through respiration.7 This mineralization can also increase the growth of mycorrhizal fungi, which can alter the release of carbon to the soil microbial community and enhance the stabilization of organic carbon by causing soil particles to aggregate.8 These studies show that forests respond to elevated CO2 in complex ways that tightly link plant-microbial-soil feedbacks fueled by inputs of root-derived carbon to soil. Moreover, they bolster the growing view that the transfer of recently fixed carbon from roots to the belowground subsystem serves as a major driver of soil food webs, and this has significant consequences for the functioning of terrestrial ecosystems adapting to climate change.

Evidence is also emerging that climate change can cause both local and regional shifts in the composition of vegetation by altering precipitation patterns and temperature regimes and by further elevating atmospheric CO2 concentrations. It’s becoming clear that such long-term shifts in composition of the plant community can affect the transfer of recent photosynthetic carbon belowground and thus affect ecosystem carbon dynamics. For example, Sue Ward and colleagues at the Lancaster Environment Centre, UK, used in situ stable carbon-isotope labeling approaches to show that removing key plant species from a dwarf-shrub heath community strongly affected belowground transfer and metabolism of recently added photosynthetic carbon.9 In particular, the removal of dwarf shrubs greatly increased community-level photosynthesis rates, the transfer of this recently assimilated carbon to soil, and its use by soil microbes, thereby speeding up rates of carbon cycling. There is growing evidence from a variety of ecosystems that plant species and functional groups—different species, such as legumes, grasses, and herbs, with similar physiological characteristics—differentially influence the uptake and transfer of carbon to soil via their exudates, suggesting that global warming-induced changes in plant community structure have the potential to alter patterns of carbon exchange. In general, however, much remains unknown about how changing the composition of plant communities can affect carbon cycling, and an important challenge will be to better understand the role of plant-soil feedbacks in modifying ecosystem carbon dynamics, especially given the extent to which climate-mediated changes in vegetation are already occurring worldwide.

Digging Deep

In all the work being done to illuminate and quantify the importance of belowground dynamics in driving the carbon cycle, the central message is similar: to better understand ecosystem functioning and its response to global change, we must consider feedbacks among plants, microbes, and soil processes. It’s clear that root carbon transfer and resulting carbon cascades through the plant-microbial-soil system play a primary role in driving carbon-cycle feedbacks and in regulating ecosystem responses to climate change.

Recent studies highlight the potential application of such understanding to land management challenges, such as enhancing soil carbon sequestration in grassland and degraded soils, which also hold potential benefits for food production and biodiversity conservation. Further study is also required to realize the potential for targeted crop-improvement strategies based on root traits that favor carbon sequestration in soil while also efficiently producing food. A new age of research and funding is needed to meet these scientific challenges and to integrate such understanding into future land-management and climate change mitigation strategies.

Soils as Sinks

A possible way to lessen the impacts of climate change is to engineer landscapes to increase the amount of carbon sequestered in soil. Mounting evidence suggests that managing grasslands may be a way to enhance soil carbon stocks, while reaping additional benefits for biodiversity conservation. For example, in model grassland systems it was recently shown that increasing plant diversity enhances CO2 assimilation by surrounding plants and belowground carbon allocation to roots and mycorrhizal fungi, which is a key mechanism driving carbon sequestration in soil.10,11 These effects, however, were due to the presence of legumes in high-diversity mixtures, rather than to diversity per se. Consistent with this, the introduction of legumes into grasslands under diversity restoration in northern England enhanced soil carbon sequestration, most likely because of increased input of carbon and nitrogen to soil and suppression of extracellular enzyme activities involved in the breakdown of organic matter.12

These findings point to the potential for using diverse grasslands with healthy plant-microbial-soil interactions to act as crucial buffers of climate change. Further research is needed to exploit this approach, especially since restoration of high-diversity grassland on degraded and formerly arable land is a key policy objective for sustainable agriculture in many parts of the world.

The mechanisms involved in plant manipulation of the carbon sequestered in soil involve myriad biotic interactions between plants, their symbionts (i.e., mycorrhizal fungi and nitrogen-fixing bacteria), and decomposers whose activities determine the rate of decomposition of organic matter and hence of carbon loss from soil. In 2008, Lancaster University’s Gerlinde De Deyn and I, along with Hans Cornelissen of the Vrije Universiteit, Amsterdam, proposed a simplified plant-trait-based framework for understanding linkages between plant communities, the microbial community, and soil carbon sequestration.13 This framework is consistent with the growing recognition that plant functional traits, such as leaf-litter nitrogen content and relative growth rate, act as major drivers of belowground nutrient and carbon cycling and can favor particular groups of soil organisms that play key roles in these processes. A recent study of grassland plant species showed that, in particular, root traits, such as biomass and nitrogen content, were strongly correlated with several soil properties, especially the biomass and composition of the surrounding microbial community and measures related to soil carbon cycling.14

The mineralization of soil organic carbon—and hence soil carbon loss—in grasslands also appears to increase with plant productivity and decrease with root nitrogen concentration. For example, Feike Dijkstra and colleagues at the University of Minnesota showed in a study of sixteen grassland plant species that increased root nitrogen concentration (e.g., in flowering plants that are not grasses and especially in legumes) slowed down the decomposition of recalcitrant soil organic matter, whereas increasing plant biomass enhanced rates of decomposition.15 But specific plant traits, such as differences in the quantity and chemical composition of root exudates, are also likely to affect the mineralization of soil carbon by altering microbial activity.15 These studies suggests that plant traits, and especially those of roots, represent tools for understanding the mechanisms behind plant-microbial-soil interactions and ecosystem functions, and for predicting how climate change-induced shifts in plant species composition will feed back to the Earth-system. Moreover, given the importance of root traits for soil microbial processes related to carbon cycling, understanding of root interactions offers potential for modification of plant communities and the root traits of crops. Perennial grain species, for example, could be bred to produce more and deeper roots, which may maximize soil carbon sequestration.16

Richard D. Bardgett is a Professor of Ecology at Lancaster University’s Lancaster Environment Centre, in the UK. His research is focused on understanding the role that linkages between plant and soil communities play in the delivery of ecosystem services, especially sequestration in soils and nutrient cycling.

References

  1. R.D. Bardgett et al., “Microbial contributions to climate change through carbon-cycle feedbacks,”ISME J, 2:805-14, 2008. 
  2. E. Dorrepaal et al., “Carbon respiration from subsurface peat accelerated by climate warming in the subarctic,” Nature, 460:616-19, 2009. 
  3. E.A.G. Schuur et al., “The effect of permafrost thaw on old carbon release and net carbon exchange from tundra,” Nature, 459:556-59, 2009. 
  4. M.A. Bradford et al., “Thermal adaptation of soil microbial respiration to elevated temperature,”Ecol Lett, 11:1316-27, 2008. 
  5. J. E. Drake et al., “Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO2,” Ecol Lett, 14: 349-57, 2011. 
  6. R.P. Philips et al., “Enhanced root exudation induces microbial feedbacks to N cycling in a pine forest under long-term CO2 fumigation,” Ecol Lett, 14:187-94, 2011. 
  7. J. Heath et al., “Rising atmospheric CO2 reduces soil carbon sequestration of root-derived soil carbon,” Science, 309:1711-13, 2005. 
  8. G.W.T Wilson et al., “Soil aggregation and carbon sequestration are tightly correlated with the abundance of arbuscular mycorrhizal fungi: results from long-term field experiments,” Ecol Lett, 12:452-61, 2009. 
  9. S.E. Ward et al., “Plant functional group identity influences short-term peatland ecosystem carbon flux: evidence from a plant removal experiment,” Funct Ecol, 23:454-62, 2009. 
  10. G.B. De Deyn et al., “Vegetation composition promotes carbon and nitrogen storage in model grassland communities of contrasting soil fertility,” J Ecol, 97:864-75, 2009. 
  11. G.B. De Deyn et al., “Plant species richness, identity and productivity differentially influence key groups of microbes in grassland soils of contrasting fertility,” Biol Lett, 7:75-78, 2011. 
  12. G. B. De Deyn et al., “Additional carbon sequestration benefits of grassland diversity restoration,” J Appl Ecol, 48: 600-08, 2011. 
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Crops with deeper roots capture more carbon, fight drought: study

By David Fogarty, Singapore, Reuters, US, August 5, 2011 http://www.reuters.com/article/2011/08/05/us-crops-carbon-idUSTRE77412Q20110805

(Reuters) – Creating crops with deeper roots could soak up much more carbon dioxide from the air, help mankind fight global warming and lead to more drought-tolerant varieties, a British scientist says in a study.

Douglas Kell of the University of Manchester says crops can play a crucial role in tackling climate change by absorbing more of mankind’s rising greenhouse gas emissions from burning fossil fuels.

Doubling root depth to two meters would also make crops more drought resistant, improve soil structure and moisture, store more nutrients and reduce erosion, Kell says in the study published online in the Annals of Botany journal.

Plants use carbon dioxide (CO2) and sunlight to grow and carbon is stored in the roots and leaves. Deeper and more bushy roots would store more carbon underground.

Many crop varieties have root systems that don’t extend beyond one meter, limiting their access to water during drought but ensuring rapid growth above ground and bumper yields when the weather is good.

“Doubling root biomass to a nominal two meters is really the key issue, together with the longevity of the carbon they secrete and sequester below-ground,” Kell says in the study.

He said previous studies have doubted the benefits of deep roots locking away large amounts of carbon. But this was because the studies did not take soil measurements much below a meter.

“What matters is not so much what is happening now as what might be achieved with suitable breeding of plants with deep and reasonably long-lived roots. Many such plants exist, but have not been bred for agriculture,” he says.

Kell calculated that even a 2 percent increase in soil carbon down to 2 meters could lead to an extra 100 tonnes of carbon per hectare if that carbon stays in the soil for at least two years.

CARBON CALCULATOR

To underscore the potential, Kell and colleagues created a carbon calculator that allows users to see how much carbon could be locked away depending on depth and percentage of carbon uptake over the total area of global crop and grasslands.

The calculator can be found here:

Kell based the calculator on the existing estimates of the world’s soils holding 1.5 trillion tonnes of carbon — double the 750 billion tonnes in the atmosphere — and the 4.6 billion hectares of crop and grasslands.
The more carbon locked away, the more the world’s croplands could reduce or even halt the annual rise in global CO2 levels in the atmosphere, the study shows.
Carbon dioxide levels in the air have risen 40 percent to 390 parts per million (ppm) since the start of the Industrial Revolution and are growing about 2 ppm a year.
“If you add an extra 2 ppm a year and you can effectively trap that by increasing the amount of roots by an equivalent amount, you can stop the increase stone dead,” he told Reuters in an interview.
“To take about 100 ppm from the atmosphere is highly feasible and that equates to an extra 100 tonnes per hectare on average for two years,” he said.

ASSURING FOOD SECURITY IN DEVELOPING COUNTRIES: CONTINUING WITH BUSINESS AS USUAL APPROACHES IS NOT AN OPTION

Small integrated farms with off-grid renewable energy may be the perfect solution to the food and financial crisis while mitigating and adapting to climate change
sustainable energy
Dr. Mae-Wan Ho

An emerging scientific consensus that a shift to small scale sustainable agriculture and localized food systems will address most, if not all the underlying causes of deteriorating agricultural productivity as well as the conservation of natural soil and water resources while saving the climate
To substantially improve living standards, access to modern energy is also crucial. Small agro-ecological farms are known to be highly productive, and are ideally served by new renewable energies that can be generated and used on site, and in off-grid situations most often encountered in developing countries
A model that explicitly integrates sustainable farming and renewable energies in a circular economy patterned after nature could compensate, in the best case scenario, for the carbon emissions and energy consumption of the entire nation while revitalising and stimulating local economies and employment opportunities
Food crisis, global economic instability, and political unrest
Soaring food prices were a major trigger for the riots that destabilized North Africa and the Middle East, and have since spread to many other African countries [1, 2]. The UN Food Price Index hit its all-time high in February 2011, and the May 2011 average was 37 percent above a year ago [3]. This is happening as the global economy is still staggering from the 2008 financial (and food) crisis, with public debt expanding and unemployment sky high [4].
Lester Brown, venerated veteran world-watcher, says food has quickly become the hidden driver of world politics [5], and food crises are going to become increasingly common. “Scarcity is the new norm.” The world is facing increasing demand for food as population increases while food crops and land are being diverted to produce biofuels; in 2010, the United States alone turned 126 million tons of its 400 million tons corn harvest into ethanol. At the same time, the world’s ability to produce food is diminishing. Aquifers are running dry in the major food producing countries where half of the world population live. There is widespread soil erosion and desertification; and global warming temperatures and weather extremes are already reducing crop yields [6-9], hitting the most vulnerable people in sub-Saharan Africa and south Asia the hardest.
“We are now so close to the edge that a breakdown in the food system could come at any time.” Brown warns [5]. “At issue now is whether the world can go beyond focusing on the symptoms of the deteriorating food situation and instead attack the underlying causes. If we cannot produce higher crop yields with less water and conserve fertile soils, many agricultural areas will cease to be viable…..If we cannot move at wartime speed to stabilize the climate, we may not be able to avoid runaway food prices….The time to act is now — before the food crisis of 2011 becomes the new normal.”
The importance of small family farms
There is an emerging scientific consensus that a shift to small scale sustainable agriculture and localized food systems will address most, if not all the underlying causes of deteriorating agricultural productivity as well as the conservation of natural soil and water resources while saving the climate [10-13].
Small, family farming is the dominant form of agriculture in the world, especially in the developing world of Africa and Asia. Approximately 3 billion people live in rural areas in developing countries, which also include 80 percent of the poor in the developing world. Around 2.5 billion are involved in agriculture as farmers or workers, and at least 75 percent of farms in the majority of Asian and African countries are 2 ha or less [14]. As Ulrich Hoffmann points out [12], MDG (Millennium Development Goal) 1 aims at eradicating extreme hunger and poverty; and one of the most effective ways of halving both the number of hungry and poor by 2015 is to make the transition towards more sustainable forms of agriculture “that nourish the land and people and provide an opportunity for decent, financially rewarding and gender equal jobs.” It would at the same time meet health targets from MDG 3 and 6 in providing a more diverse, safe, nutritious and affordable diet (see also [10]).
Notably, small farms generally produce more per hectare than large farm; so much so that economists have long observed and debated this apparently paradoxical inverse relationship between farm size and productivity [14]. Small farms are 2 to 10 times as productive and much more profitable; and not just in the developing world [15]. A US Agricultural Census in 1992 found a sharp decline of net income from $1 400/acre to $12/acre as farm size increased from 4 to 6709 acres [16].
Small farms are associated with [14] “intensive use of household and community labour, high levels of motivation and much lower supervision and transaction costs”, which may well account for the economic advantages, but not the actual productivity. Small farms are highly productive because they are typically biodiverse systems integrating multiple crops and livestock that enable them to maximise synergetic relationships while minimizing wastes; turning wastes such as farmyard manure into fertilizer resources. In effect, they embody the circular economy of nature [10] where energy and nutrients are recycled within the ecosystem for maximum productivity and carbon sequestration both above and below ground. This ‘thermodynamics of organisms and sustainable systems’ is derived and explained in detail elsewhere [17].
The importance of renewable energy
To substantially improve living standards, sustainable farming is not enough, access to modern energy is also crucial. Lack of access to modern energy is generally recognized as the biggest obstacle to sustainable development. The International Energy Agency 2010 report on energy poverty stated [18]: “Lack of access to modern energy services is a serious hindrance to economic and social development and must be overcome if the UN Millennium Development goals (MDGs) are to be achieved.” This view is echoed in the report of the 6th Annual Meeting of the African Science Academy Development Initiative (ASADI) [19]: “Access to modern energy services, defined as electricity and clean cooking fuels, is central to a country’s development.”
Worldwide, 1.4 billion people lack access to electricity, 85 percent in rural areas, and 2.7 billion still rely on traditional biomass fuels for cooking and heating [18]. The greatest challenge is sub-Saharan Africa, where only 31 percent of the population has access to electricity, the lowest level in the world. If South Africa is excluded, the share declines to 28 percent.
There is close correlation between income levels and access to modern energy. Countries with a large proportion of the population living on an income of less than $2 per day tend to have low electrification rates and a high proportion of the population relying on traditional biomass.
The World Health Organization estimates that 1.45 million people die prematurely each year from household air pollution due to inefficient biomass combustion; a significant proportion young children. This is greater than premature deaths from malaria or tuberculosis.
Small agro-ecological farms are ideally served by new renewable energies that can be generated and used on site, and in off-grid situations most often encountered in developing countries [20, 21]. The renewable energies generated can also serve local businesses, stimulate local economies and create plenty of employment opportunities.
Off-grid renewable power systems entering mainstream worldwide
Within the past few years, off-grid power systems have entered the mainstream, driven by the ready availability of renewable energy options that can cost less than grid connections.
A UK company advertises on its website [22]: “Homes across the UK and Europe are looking at the potential benefits of supplying some, if not all their domestic power requirement from off-grid sources” for a variety of reasons: connection to the grid is too expensive, reducing energy bills, protect from power cuts and reduce greenhouse gas emissions. Solar panels, wind turbines, and small generators are suitable for most homes, and a system with a battery connected to a battery charger/inverter is the most convenient.
The UK government Office of Fair Trading has launched an investigation into the off-grid market for renewables and mainstream energy in January 2011, following energy price hikes and supply issue over the winter [23].
Examples of small scale off-grid renewables are found across Scotland [24], such as remote ferry waiting rooms on the Western Iles and the Charles Inglis Clark Memorial hut on Ben Nevis using small wind turbrines. Photovoltaic (PV) installations integrated with battery are often used where only a small amount of power is required, as for lighting, maintaining power for monitoring equipment or maintaining water treatment facilities.
However, it is in developing countries where power requirements are generally low, and where rapidly improving electronic lighting and telecommunication equipment that have low power requirements and perform reliably with little or no maintenance that off-grid renewable energy is coming to its own [21].
Three examples of large scale off-grid renewable energy use with varying degrees of success are the Grameen Shakti f or renewables of Bangladesh [25], Lighting Africa [26] and Biogas for China’s Socialist Countryside [27].
Grameen Shakti is a non-profit organization founded in 1996 to promote, develop, and supply renewable energy to the rural poor of Bangladesh. It has become one of the world’s largest and fastest growing renewable energy companies through a system of microfinancing, training of technicians (mainly women) for installation, maintenance and repair, provision of services including buy-back. It runs technology centres for training throughout the country (see [25] for details). At the end of May 2011, Grameen Shakti had installed 636 322 solar home systems, 18 046 biogas plants and 304 414 improved cooking stoves. It also trained a total of 28 932 technicians in 46 technology centres nationwide, covering all districts. Its beneficiaries are 40 000 villages and around 4 million people [28].
What began as a grassroots endeavour to provide solar light for the rural population has now attracted the backing of the World Bank. It started by training “barefoot women engineers” for installing, maintaining and repairing solar panels, lights, telephone charging, batteries and other accessories.
Lighting Africa is now a joint World Bank and International Finance Corporation programme that aims to help develop commercial off-grid lighting markets in sub-Saharan Africa as part of the World Bank Group’s wider efforts to improve access to energy [29]. It aims to provide safe, affordable, and modern off-grid lighting to 2.5 million in Africa by 2012 and to 250 million by 2030. The market for off-grid lighting products is projected to grow at 40 to 50 percent annually. In 2010 alone, the sales of solar portable lanterns that have passed Lighting Africa’s quality tests grew by 70 percent in Africa, resulting in more than 672 000 people with cleaner, safer, reliable lighting and improved energy access (see [26] for details)
Provision of biogas is an important part of China’s New Socialist Countryside programme launched in 2006 to improve the welfare of those living outside booming cities, which include the country’s 130 million migrant workers and the rural poor. China is one of the first countries in the world to use biogas technology and it has been revived in successive campaigns by the current government to provide domestic sanitation and energy off-grid and to modernize agriculture (see [27, 30] for details). The anaerobic digester producing biogas is typically combined with a greenhouse for growing vegetables and other crops with a pigsty, so that pig and human manure can be digested while carbon dioxide generated by the pigs boosts plant growth in the greenhouse. The biogas produced (typically 60 percent methane and 40 percent carbon dioxide with traces of other gases) can be used as cooking fuel and to generate electricity, while the residue is a rich fertilizer for crops. It is an example of the circular economy that has served Chinese peasants well in traditional Chinese agriculture [31]. More elaborate models include orchards and solar panels. According to the latest update from China’s Ministry of Agriculture [32], 35 million household biogas tanks have been installed by the end of 2009 in 56 500 biogas projects. This exponential growth phase that started around 2001 is set to continue, along with medium and big digesters for community and industrial use. Anaerobic digestion of organic wastes is a key renewable energy technology for a truly green circular economy off-grid that could make a real difference for improving the lives of the rural poor (See [12] for a complete list of the benefits of biogas).
Integrating sustainable farming and renewable energies in a circular economy
A model that explicitly integrates sustainable farming and renewable energies is ‘Dream Farm 2’ that operates according to circular economy principles (see final chapter in [10]). It is patterned after environmental engineer George Chan and the dyke-pond system of Pearl River Delta [31] that Chinese peasants have perfected over thousands of years, a system so productive that it supported 17 people per hectare in its heyday. An ideal Dream Farm 2 is presented in Figure 1.

Figure 1 An integrated food and energy Dream Farm 2 that optimises the sustainable use of resources and minimises wastes in accordance with the circular economy of nature
The diagram ( see attachment) is colour-coded. Pink is for energy, green for agricultural produce, blue is for water conservation and flood control, black is waste in the ordinary sense of the word, which soon gets converted into food and energy resources. Purple is for education and research into new science and technologies. This ideal Dream Farm is complete with laboratory facilities for education, as well as a restaurant to take advantage of all the fresh produce. It is a perfect setting for developing cottage industries such as food preservation, processing, wine and cheese making, bread-making, not to mention electronic workshops, battery charging, retailers of renewable energy components and electronic devices. The synergies between agriculture and industries are obvious especially in the case of food industries, as they are close to the source of production. Moreover, the organic wastes from these industries can go right back into anaerobic digestion to be converted into energy and nutrients for agriculture.
Some preliminary estimates, based on data and statistics made available by the Chinese government and academics, on the energy and carbon savings involved, are presented in Tables 1 and 2 [33].

Table 1 Green potential of organic agriculture and anaerobic digestion for China

CO2e savings (% National) Energy savings (% National)
Organic agriculture
N fertilizers saving 179.5 Mt (2.38%) 2.608 EJ (3.61%)
N2O prevented 92.7 Mt (1.23%)
Carbon sequestration 682.9 Mt (9.07%)

Total for org. agri. 955.1 Mt (12.69%) 2.608 EJ (3.61%)

Anaerobic digestion
Livestock manure ghg saving 70.3 Mt (0.09%)
methane produced 215.5 Mt (2.86%) 3.124 EJ (4.33%)
Hum manure methane 7.7 Mt (0.10%) 0.112 EJ (0.16%)
Straw methane 292.5 Mt (3.93%) 4.234 EJ (5.86%)
Total for AD 586.0 Mt (7.79%) 7.470 EJ (10.35%)
Total overall 1 491.1 Mt (20.48%) 10.078 EJ (13.96%)

Table 2 Green potential of Dream Farm 2

CO2e savings (% National) Energy savings (% National)
Organic agriculture 955.1 Mt (12.69%) 2.608 EJ (3.61%)
Anaerobic digestion 586.0 Mt (7.79%) 7.470 EJ (10.35%)
Energy savings local gen. 1 287.1 Mt (17.10%) 21.660 EJ (30.00%)
Total 2 828.2 Mt (37.58%) 31.738 EJ (43.96%)

As can be seen from Table 1, the combination of organic agriculture and anaerobic digestion in China has the potential to mitigate at least 20 percent of national greenhouse gas emissions and save 14 percent of energy consumption. If Dream Farm 2 were to be universally adopted, China would mitigate 38 percent of its greenhouse emissions, and save 44 percent of energy consumption, only counting anaerobic digestion, basically because of efficiency savings arising from the possibility of using ‘waste’ heat in combined heat and power generation, and avoiding the loss in long distance transmission of electricity. A conservative allowance of 30 percent efficiency saving (out of a maximum of about 60 percent) gives the net carbon and energy savings in Table 2, which, again, is from anaerobic digestion only. The savings could be far greater as low power consuming LED lighting and other electronic devices replace conventional high power consuming models.
With the addition of solar, wind or micro-hydroelectric as appropriate, and batteries to store and maintain a steady power supply, such farms could compensate, in the best case scenario, for the carbon emissions and energy consumption of the entire nation. Surplus energy from the farm can go to supply homes and businesses in the vicinity through a ‘mini-grid’ that could eventually link up to the national grid, if necessary or desirable. This could be a model for the natural evolution of connectivity and power sharing. At the very least, such integrated food and energy farms will give food security while playing its part along with other sectors of the circular economy in cutting its own carbon footprint. Furthermore, such small scale agro-ecological farming and local renewable power generation are much more resistant and resilient to weather extremes, and indeed to earthquakes and sabotage.

Why our food is so dependent on Oil?

Are we eating food or oil? Why our food production is so dependent on oil and what are links between the ways of production, consumption and climate change? Two interesting articles on this topic

Why Our Food is So Dependent on Oil

Eating Oil: Food Supply in a Changing_ClimateFighting Global Warming at the Farmer’s Market The Role of Local Food Systems In Reducing Greenhouse Gas Emissions

Climate change to reduce water availability, FAO warns

XINHUA

APA woman piles up wheat after harvesting at a farm in village Majra Khurd of Haryana. File photo

Climate change will make water less available to produce food crops in years to come, the United Nations Food and Agriculture Organization (FAO) said in a report issued Thursday.

River runoff and aquifer recharges will decrease in the Mediterranean, the Americas, Australia and southern Africa, it said.

Areas in Asia which depend on the melting of ice and mountain glaciers will also be affected, while areas with a lot of fluvial deltas are threatened by reduced water flow, increased salinity and rising sea levels, said the report entitled “Climate Change, Water and Food Security”.

The report also predicted an acceleration of the hydrologic cycle of the planet because high temperatures will raise the evaporation rate of the soil and sea.

“The rain will increase in the tropics and at higher altitudes, but it will decrease in areas that already have dry and semi-dry characters and are located inland on the big continents,” the report said.

Because of this, there will be a higher frequency of droughts and flooding, which will lead to an increased use of ground water and limit the water available for agriculture even more.

“The loss of glaciers, which sustain about 40 percent of the watering at world level, will finally affect the amount of available water on the surface for watering in the main producer basins,” it said.

The increase in temperature will prolong the growing season of crops in warmer regions, but reduce the harvest season elsewhere, adding to a higher rate of evaporation and a decrease in agricultural productivity, the report said.

Rural communities and the food security of the urban population are threatened, “but the poor people in rural areas are the most vulnerable, and they could be affected in a disproportionate way,” it said.

 

Mapping hotspots of climate change and food insecurity in the global tropics

Polly Ericksen, Philip Thornton, An Notenbaert, Laura Cramer, Peter Jones, Mario Herrero.

Executive Summery

This study was coordinated by the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS) to identify areas that are food insecureand vulnerable to the impacts of future climate change, across the priority regions for the CGIAR centres. The research was undertaken by a team of scientistsfrom the International Livestock Research Institute (ILRI). The study relied on maps: first, of variables that indicate the different aspects of food security(availability, access and utilization), and second, of thresholds of climate change exposure important for agricultural systems. Vulnerability was assessed usinga domain approach based upon the Intergovernmental Panel on Climate Change (IPCC) framework of vulnerability as a function of exposure, sensitivity andcoping capacity. Nine domains were identified; for each domain areas of the tropics were classified by high or low exposure, high or low sensitivity, and high orlow coping capacity.Length of growing period declines by 5% or more across a broad area of the global tropics, including heavily cropped areas of Mexico, Brazil, Southern andWest Africa, the Indo-Ganetic Plains, and Southeast Asia. This suggests that at a minimum, most of the tropics will experience a change in growing conditionsthat will require adaptation to current agricultural systems. High temperature stress (above 30:C) will be widespread in East and Southern Africa, north andsouth India, Southeast Asia, northern Latin America and Central America. Length of growing period flips to less than 120 days in a number of locations acrossthe tropics, notably in Mexico, northeast Brazil, Southern and West Africa and India. This is a critical threshold for certain crops and rangeland vegetation;hence these are important target areas for high exposure to climate change. Reliable crop growing days decrease to critical levels, below which cropping mightbecome too risky to pursue as a major livelihood strategy in a larger number of places across the global tropics, including West Africa, East Africa, and the Indo-Ganetic Plains. Much of the tropics already experiences highly variable rainfall, above the median of 21% for cropped areas. Thus any increases in thisvariability will make agriculture more precarious.In terms of food security, the net food production index is stagnant in all areas of interest, with differences between countries rather than regions. GDP percapita is low in many countries in Africa, as well as in Afghanistan, Nepal, Bangladesh, Laos and Cambodia. Poverty hotspots are West, Central and East Africa,India and Bangladesh and Southeast Asia. Africa and south Asia are clearly much more chronically food insecure regions than Latin America or China.The most vulnerable domain for most exposures is high exposure, high sensitivity and low coping capacity (HHL). Such areas are highly vulnerable to climatechange and have significant agriculture and high levels of food insecurity. Under exposure 1 (LGP decreases more than 5%), HHL is the category with the mostpeople, followed by HHH. For exposure 2 (LGP flips) HHL is very small in terms of people; most people are in the categories LHL or LHH. Exposure 3 (reliablecrop growing days – RGCP flips) has about 10 million more people in the HHL category, but again most people are in LHL or LHH. Under exposure 4 (maximumtemperature -Tmax flips), the vulnerable population more than triples relative to exposure 3. Under exposure 5 (temperature flips) again more people are inthe vulnerable categories. Under exposure 6 (rain per rainy day decrease), the most vulnerable population drops to 27.5 million, while under exposure 7 (rainper rainy day increase) 45.7 million are in the HHL category. This suggests that the choice of domain variables makes a big difference in terms of areasincluded.

 

A warming planet struggles to feed itself

Justin Gillis
http://www.hindu.com/2011/06/06/stories/2011060662511300.htm

The dun wheat field spreading out at Ravi P. Singh’s feet offered a possible clue to human destiny. Baked by a desert sun and deliberately starved of water, the plants were parched and nearly dead.

Dr. Singh, a wheat breeder, grabbed seed heads that should have been plump with the staff of life. His practiced fingers found empty husks.

“You’re not going to feed the people with that,” he said.

But then, over in Plot 88, his eyes settled on a healthier plant, one that had managed to thrive in spite of the drought, producing plump kernels of wheat. “This is beautiful!” he shouted as wheat beards rustled in the wind.

Hope in a stalk of grain: It is a hope the world needs these days, for the great agricultural system that feeds the human race is in trouble.

The rapid growth in farm output that defined the late 20th century has slowed to the point that it is failing to keep up with the demand for food, driven by population increases and rising affluence in once-poor countries.

Four staples

Consumption of the four staples that supply most human calories — wheat, rice, corn and soybeans — has outstripped production for much of the past decade, drawing once-large stockpiles down to worrisome levels. The imbalance between supply and demand has resulted in two huge spikes in international grain prices since 2007, with some grains more than doubling in cost.

Those price jumps, though felt only moderately in the West, have worsened hunger for tens of millions of poor people, destabilising politics in scores of countries.

Climate change

Now, the latest scientific research suggests that a previously discounted factor is helping to destabilise the food system: climate change.

Many of the failed harvests of the past decade were a consequence of weather disasters. Scientists believe some, though not all, of those events were caused or worsened by human-induced global warming. A rising unease about the future of the world’s food supply came through during interviews this year with more than 50 agricultural experts working in nine countries.

These experts say that in coming decades, farmers need to withstand whatever climate shocks come their way while roughly doubling the amount of food they produce to meet rising demand. And they need to do it while reducing the considerable environmental damage caused by the business of agriculture.

Sitting with a group of his fellow wheat farmers, Francisco Javier Ramos Bours voiced a suspicion. Water shortages had already arrived in recent years for growers in his region, the Yaqui Valley, which sits in the Sonoran Desert of northwestern Mexico. In his view, global climate change could well be responsible.

Farmers everywhere face rising difficulties: water shortages as well as flash floods. Their crops are afflicted by emerging pests and diseases and by blasts of heat beyond anything they remember.

Green Revolution

Decades ago, the wheat farmers in the Yaqui Valley of Mexico were the vanguard of a broad development in agriculture called the Green Revolution, which used improved crop varieties and more intensive farming methods to raise food production across much of the developing world.

When Norman E. Borlaug, a young American agronomist, began working here in the 1940s under the sponsorship of the Rockefeller Foundation, the Yaqui Valley farmers embraced him. His successes as a breeder helped farmers raise Mexico’s wheat output six-fold.

In the 1960s, Dr. Borlaug spread his approach to India and Pakistan, where mass starvation was feared. Output soared there, too.

Other countries joined the Green Revolution. Dr. Borlaug became the only agronomist ever to win the Nobel Peace Prize, in 1970, for helping to “provide bread for a hungry world.”

As he accepted the prize in Oslo, he issued a stern warning. “We may be at high tide now,” he said, “but ebb tide could soon set in if we become complacent and relax our efforts.”

As output rose, staple grains — which feed people directly or are used to produce meat, eggs, dairy products and farmed fish — became cheaper and cheaper. Poverty still prevented many people in poor countries from buying enough food, but over all, the percentage of hungry people in the world shrank.

By the late 1980s, food production seemed under control. Governments and foundations began to cut back on agricultural research, or to redirect money into the problems created by intensive farming, like environmental damage. Over a 20-year period, Western aid for agricultural development in poor countries fell by almost half, with some of the world’s most important research centres suffering mass layoffs.

Just as Dr. Borlaug had predicted, the consequences of this loss of focus began to show up in the world’s food system toward the end of the century. Output continued to rise, but because fewer innovations were reaching farmers, the growth rate slowed.

That lull occurred just as food and feed demand was starting to take off, thanks in part to rising affluence across much of Asia. And erratic weather began eating into yields. In 2007 and 2008, with grain stockpiles low, prices doubled and in some cases tripled. Whole countries began hoarding food, and panic buying ensued in some markets, notably for rice. Food riots broke out in more than 30 countries.

Farmers responded to the high prices by planting as much as possible, and healthy harvests in 2008 and 2009 helped rebuild stocks, to a degree. That factor, plus the global recession, drove prices down in 2009. But by last year, more weather-related harvest failures sent them soaring again. This year, rice supplies are adequate, but with bad weather threatening the wheat and corn crops in some areas, markets remain jittery.

Experts are starting to fear that the era of cheap food may be over. “Our mindset was surpluses,” said Dan Glickman, a former United States Secretary of Agriculture. “That has just changed overnight.”

For decades, scientists believed that the human dependence on fossil fuels, for all the problems it was expected to cause, would offer one enormous benefit.

Carbon dioxide

Carbon dioxide, the main gas released by combustion, is also the primary fuel for the growth of plants. They draw it out of the air and, using the energy from sunlight, convert the carbon into energy-dense compounds like glucose. All human and animal life runs on these compounds.

Humans have already raised the level of carbon dioxide in the atmosphere by 40 per cent since the Industrial Revolution, and are on course to double or triple it over the coming century. Studies have long suggested that the extra gas would supercharge the world’s food crops, and might be especially helpful in years when the weather is difficult. For the past decade, scientists at the University of Illinois have been putting the “CO {-2} fertilization effect” to a real-world test in the two most important crops grown in the United States — soybeans and corn.

Their work has contributed to a broader body of research suggesting that extra carbon dioxide does act as plant fertilizer, but that the benefits are less than previously believed — and probably less than needed to avert food shortages.

At the end of a dirt road in north-eastern India, nestled between two streams, lies the remote village of Samhauta. Anand Kumar Singh, a farmer there, recently related a story that he could scarcely believe himself.

Last June, he planted 10 acres of a new variety of rice. On August 23, the area was struck by a severe flood that submerged his field for 10 days. In years past, such a flood would have destroyed his crop. But the new variety sprang back to life, yielding a robust harvest.

“That was a miracle,” Mr. Singh said.

The miracle was the product of technology. “It’s the best example in agriculture,” said Julia Bailey-Serres, a researcher at the University of California, Riverside, who has done genetic work on the rice variety that Mr. Singh used. “The submergence-tolerant rice essentially sits and waits out the flood.”

The new rice variety that is exciting farmers in India is the product of another, the International Rice Research Institute in the Philippines.

Leading researchers say it is possible to create crop varieties that are more resistant to drought and flooding and that respond especially well to rising carbon dioxide. The flood-tolerant rice was created from an old strain grown in a small area of India, but decades of work were required to improve it. Money was so tight that even after the rice had been proven to survive floods for twice as long as previous varieties, distribution to farmers was not assured. Then an American charity, the Bill & Melinda Gates Foundation, stepped in with a $20 million grant to finance final development and distribution of the rice in India and other countries. It may get into a million farmers’ hands this year.

In 2008 and 2009, in the midst of the political crises set off by food prices, the world’s governments outbid one another to offer support. At a conference in L’Aquila, Italy, they pledged about $22 billion for agricultural development.

It later turned out, however, that no more than half of that was new money not previously committed to agriculture, and two years later, the extra financing has not fully materialised. “It’s a disappointment,” Mr. Gates said. ( Hari Kumar contributed reporting from Samhauta, India.)

— © New York Times News Service