Climate change
Climate change is often referred to as one of the biggest threats to biodiversity . In this meta-analysis, despite the general decline in soil fauna biodiversity, climate change was not the greatest threat. However, a more nuanced view may be needed. Based on aboveground organisms, it might be expected that temperature changes would result in a decline in biodiversity . However, our results further reinforce the hypothesis that soils can buffer the impacts of temperature change (also found in ). Indeed, the observed decline was due to clear negative effects of reduced water availability, which has previously been shown in other meta-analyses to be a strong driver of soil biodiversity . This is cause for concern, as areas of climate change-induced drought are increasing . Thus, it is likely that the detrimental impact of drought, as well as depleted soil fauna community will result in reduced ecosystem function and services in those areas , thus human populations in those areas may experience two-fold impacts.
Although we categorised drought as a pulse stressor and expected less impact on soil biodiversity than changes in temperature and gas, it was impossible to determine and quantitatively compare the strength or duration of the drought manipulations (relative to the normal levels) across the different studies with the information available. If the drought manipulations were too severe (too extreme or too long), there is the potential for the buffering capacity of the soil to be significantly reduced , resulting in biodiversity loss. In a similar vein, the temperature manipulations may also not be an appropriate length to be considered a press stressor. found that longer climate-change treatments resulted in more significant effects, although in their study, the effect was positive.
Considering the length of the treatment application using an alternative modelling structure, may provide further insights. However, often temperature changes occur simultaneously with water-regime changes, and previous studies have demonstrated that if soil water is available for soil organisms, the effects of other stressors, such as temperature increases, can be buffered against . Thus, it would be prudent to consider the synergistic effects of many of the stressors simultaneously (discussed further below), to fully understand the most detrimental components of climate change for soil biodiversity.