Climate variability can greatly influence the effects of species on their ecological communities. A growing number of studies have demonstrated climate-induced changes in species’ trophic (feeding) effects, however changes in other types of species interactions have been less studied. To some degree, all organisms engineer their environments by altering the physical structure of ecosystems, and ecosystem engineering interactions occur when species respond to these altered environments. Ecosystem engineering interactions may respond more predictably to climate variation than trophic interactions. Relationships between climate and ecosystem engineering interactions could form when communities respond to abiotic conditions that are affected by climate and engineering simultaneously. Moreover, ecosystem engineering often outlasts the lifetime of the causal species, and greater temporal stability of engineering versus trophic effects may promote long term associations with climate, such as temporal lag effects. Here, we used a six year manipulative field experiment to test whether precipitation lag effects positively influenced the strength of a dominant vertebrates’ engineering (soil burrowing) and trophic (herbivory) effects on plant community composition. In addition, we tested for mechanisms driving plant community responses, performing a second experiment to examine whether soil moisture mediates relationships between soil engineering interactions and precipitation.
Results/Conclusions
We found that the strength of plant community composition responses to engineering were strongly and positively correlated with precipitation in the previous year (R² = 0.94), while relationships involving current precipitation or trophic interactions were nonsignificant. Plant community composition responses to engineering had greater temporal stability compared to responses to trophic effects. The lagged relationship between climate and engineering interactions arose because plant community composition diverged on and off engineered soils. In response to precipitation in the previous year, grasses increased and forbs decreased in abundance on engineered soils, while legume abundances increased off engineered soils. These plant responses were driven by changes in soil moisture, which was concurrently affected by precipitation and soil engineering. Our results suggest that climate effects on ecosystem engineering interactions may often be more predictable than those for trophic interactions. This study has important implications for ecological management, especially in the context of climate change, because management goals may be met more reliably if management efforts are focused on ecosystem engineering interactions.