Abstract
The most recent climate models unequivocally predict a strong drying trend for the southwestern USA within the next century. Soil nematodes are a highly important component of desert ecosystem functioning, but rely on water films for movement. However, it is currently poorly understood how different trophic groups of nematodes respond to chronic presses as well as short‐lived pulses of altered water availability, especially in arid systems where such changes are expected to have the greatest impact. The aim of this study was to assess the effects of both instantaneous and long‐term variation in water availability on desert soil nematode trophic groups. We hypothesized that nematode abundance would respond positively to both short‐ and long‐term increases in moisture. Based on the ecology of the different trophic groups we further made predictions about their relative rates of response. We increased or decreased precipitation from ambient levels in the Chihuahuan Desert for four consecutive years and sampled soil nematodes after two, three and four years. We tested the effects of altered precipitation treatments through time as well as gravimetric soil moisture at the time of sampling on the abundance of the different nematode trophic groups. In contrast to our hypotheses, the abundances of most nematode trophic groups were unaffected by the amount of precipitation, even after four years of altered precipitation. Plant‐parasitic nematodes from low moisture soils were the only group that reacted positively to increased precipitation from the third year onwards. Trophic groups responded differently to soil moisture, with bacterivores decreasing with increasing moisture and omnivores showing a positive relationship that diminished over time. We show that in general, these desert nematodes were not limited by precipitation, and were highly resilient to decreases therein. However, when also considering the effects of soil moisture, some more complex patterns and differences among trophic groups emerged. We discuss potential mechanisms explaining these observations and contrast our findings with those from other ecosystems around the world. We conclude that deserts harbor nematode communities that seem more resilient to altered water availability than other ecosystems.
Highlights
An unprecedented combination of global change drivers and their associated disturbances is likely to push many ecosystems beyond the limits of their resilience within the current century (IPCC 2007)
Climate models predict an increase in precipitation in many regions of the United States (IPCC 2007), the southwestern states are predicted to become drier within the century (Seager et al 2007), with an increase in the duration and intensity of droughts and number of dry days and a decrease in the occurrence of wet extremes (Cayan et al 2010, Singh et al 2013)
To test the above hypotheses, we investigated the abundance of different trophic groups of nematodes collected during three consecutive years from experimental plots at the Jornada Long Term Ecological Research site (LTER) that had experienced reduced, ambient or increased amounts of incoming precipitation
Summary
An unprecedented combination of global change drivers and their associated disturbances is likely to push many ecosystems beyond the limits of their resilience within the current century (IPCC 2007). Both the area affected by drought as well as the frequency of heavy precipitation events are predicted to increase (IPCC 2007). A recent meta-analysis (Blankinship et al 2011) has shown that soil biota are in general more sensitive to changes in precipitation than to CO2 or temperature (see Ayres et al 2008), suggesting that altered precipitation regimes may have significant impacts belowground. It is necessary to understand how this functionally important component of the ecosystem will react to the future reduction in water availability and to assess whether the system is resilient to the effects of increased drought
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
