Qinfeng Guo, Songlin Fei, Kevin M. Potter, Andrew M. Liebhold, Jun Wen
Understanding the relationship between tree diversity and pest invasions is of critical importance both to the theoretical understanding of invasion ecology and to the development of effective pest management practices to mitigate the enormous damages caused by nonnative pests. However, evidence of facilitation and dilution remains elusive, especially in natural ecosystems at large scales. Using a unique large dataset encompassing 130,210 forest plots with county-level pest occurrence dataset across the United States, we show that tree-pest diversity relationships are hump-shaped. Both facilitation and dilution appear to coexist, but their relative strength varies with overall native tree diversity. Our findings provide insight into the interaction between facilitation and dilution, which are critical for understanding the invasions of forests by nonnative pests.