Early successional systems support nematode community resistance to drought stress

Variable rainfall is expected to increase with climate change and will lead to more drought stress. The impact of drought on nematode resistance within agricultural systems that vary in management is unknown. Free-living nematodes can serve as bioindicators of climatic stress because they are sensitive to disturbance and span the r-K strategist continuum. Here we aim to 1) understand how management intensity impacts the resistance of nematode communities to drought and 2) assess how the immediate alleviation of drought impacts nematode communities in contrasting agroecosystems. This study utilized the W.K. Kellogg Biological Station Long-Term Ecological Research trial where three rainfall manipulations were induced (drought, variable, and control) in two land uses (an early successional and a no-till annual row-crop). Sampling for nematode communities was conducted prior to drought implementation (pre-drought), six weeks after drought was induced (peak-drought), and one day after re-wetting (post-drought). There was little shift in nematode community structure or distribution along an r-K strategist continuum at peak-drought in the early successional land use. In the no-till land use, fungivore r-strategist nematode abundances declined with drought stress, indicating overall less resistance to drought. Similar patterns persisted post-drought, whereby nematodes within the early successional land use remained unchanged, while nematodes within the no-till land use were slower to shift in response to alleviation. This study demonstrates that early successional land uses are valuable for fostering nematode communities that are resistant to drought. Moreover, drought stress impacts nematode community dynamics, which has implications for ecosystem functioning.