Final Report Summary - BIOCOM (Biotic community attributes and ecosystem functioning: implications for predicting and mitigating global change impacts)
Drylands (arid, semi-arid and dry-subhumid areas) are important terrestrial ecosystems, covering 41% of the world’s land surface. They are of paramount importance for biodiversity, as host many endemic plant and animal species, and include about 20% of the major centers of global plant diversity and over 30% of the designated endemic bird areas. Over 38% of the human population depends on drylands for ecosystem goods and services, but as these ecosystem functions are highly dependent on rainfall and soil fertility, drylands are particularly susceptible to ongoing global environmental change and desertification processes. Because of the extent of dryland ecosystems globally, and the dependence of an important part of the world´s population on them for goods and services, it is crucial to understand how drylands may be affected by global environmental change and, more specifically, to know how the attributes of biotic communities inhabiting them will modulate ecosystem responses to it.
As part of the research activities carried out under BIOCOM, we have surveyed the structure and functioning of 236 dryland areas in 19 countries across all continents but Antarctica. We measured the richness and diversity of both perennial plants and soil microorganisms (bacteria and fungi), and a number of non-biological factors that also affect ecosystem functioning, such as climate, slope and soil texture. In addition, we analyzed soil samples from the surveyed sites to assess 14 functions provided by ecosystems that are associated with the cycling and storage of carbon, nitrogen and phosphorus. The selected functions provide key supporting and regulating ecosystem services, and changes in these can act as early warning signals of desertification.
The results of the BIOCOM global survey show that plant species' diversity may contribute to maintaining the multi-functionality (i.e. the ability of ecosystems to provide multiple ecosystem functions simultaneously) of drylands. Our findings also indicate that global drylands could maintain multi-functionality and better resist the negative effects of higher temperatures projected under climate change, if their plant biodiversity is maintained and increased. Soil bacteria and fungi are largely responsible for key ecosystem services, including soil fertility and climate regulation, yet their responses to changes in aridity are poorly understood. Using DNA-sequencing approaches, we found that increases in aridity reduce the diversity and abundance of soil bacteria and fungi in global drylands. These results suggest that increases in aridity such as those forecasted for the next decades may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services that, such as soil fertility, largely depend on microorganisms. We also found that increased aridity will reduce carbon and nitrogen in the soil, and raise phosphorus levels. Plants, however, need these elements in the right balance. If temperatures rise as currently predicted, drylands’ essential soil processes could be affected, and their productivity reduced.
Previous research has linked the positive effects of community attributes such as biodiversity to a range of ecosystem processes, including carbon storage and the accumulation of nutrients supporting soil fertility and plant growth. However, the BIOCOM survey has provided the first empirical evidence of the relationship between the ecosystem's community attributes and its functional processes at the global level, rather than in small-scale, controlled studies. Overall, the results obtained from BIOCOM have produced novel and important insights about the factors driving ecosystem functioning in global drylands, and about how these ecosystems are likely to respond to future climatic conditions.
As part of the research activities carried out under BIOCOM, we have surveyed the structure and functioning of 236 dryland areas in 19 countries across all continents but Antarctica. We measured the richness and diversity of both perennial plants and soil microorganisms (bacteria and fungi), and a number of non-biological factors that also affect ecosystem functioning, such as climate, slope and soil texture. In addition, we analyzed soil samples from the surveyed sites to assess 14 functions provided by ecosystems that are associated with the cycling and storage of carbon, nitrogen and phosphorus. The selected functions provide key supporting and regulating ecosystem services, and changes in these can act as early warning signals of desertification.
The results of the BIOCOM global survey show that plant species' diversity may contribute to maintaining the multi-functionality (i.e. the ability of ecosystems to provide multiple ecosystem functions simultaneously) of drylands. Our findings also indicate that global drylands could maintain multi-functionality and better resist the negative effects of higher temperatures projected under climate change, if their plant biodiversity is maintained and increased. Soil bacteria and fungi are largely responsible for key ecosystem services, including soil fertility and climate regulation, yet their responses to changes in aridity are poorly understood. Using DNA-sequencing approaches, we found that increases in aridity reduce the diversity and abundance of soil bacteria and fungi in global drylands. These results suggest that increases in aridity such as those forecasted for the next decades may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services that, such as soil fertility, largely depend on microorganisms. We also found that increased aridity will reduce carbon and nitrogen in the soil, and raise phosphorus levels. Plants, however, need these elements in the right balance. If temperatures rise as currently predicted, drylands’ essential soil processes could be affected, and their productivity reduced.
Previous research has linked the positive effects of community attributes such as biodiversity to a range of ecosystem processes, including carbon storage and the accumulation of nutrients supporting soil fertility and plant growth. However, the BIOCOM survey has provided the first empirical evidence of the relationship between the ecosystem's community attributes and its functional processes at the global level, rather than in small-scale, controlled studies. Overall, the results obtained from BIOCOM have produced novel and important insights about the factors driving ecosystem functioning in global drylands, and about how these ecosystems are likely to respond to future climatic conditions.