Belowground top-down and aboveground bottom-up effects structure multitrophic community relationships in a biodiverse forest

Abstract

Ecosystem functioning and human well-being critically depend on numerous species interactions above- and belowground. However, unraveling the structure of multitrophic interaction webs at the ecosystem level is challenging for biodiverse ecosystems. Attempts to identify major relationships between trophic levels usually rely on simplified proxies, such as species diversity. Here, we propose to consider the full information on species composition across trophic levels, using Procrustes correlation and structural equation models. We show that species composition data of a highly diverse subtropical forest―with 5,716 taxa across 25 trophic groups― reveal strong interrelationships among plants, arthropods, and microorganisms, indicating complex multitrophic interactions. We found substantial support for top-down effects of microorganisms belowground, indicating important feedbacks of microbial symbionts, pathogens, and decomposers on plant communities. In contrast, aboveground pathways were characterized by bottom-up control of plants on arthropods, including many non-trophic links. Additional analyses based on diversity patterns revealed much weaker interrelationships. Our study suggests that multitrophic communities in our forest system are structured via top-down effects of belowground biota on plants, which in turn affect aboveground arthropod communities across trophic levels. Moreover, the study shows that the consequences of species loss will be more complex than indicated by studies based solely on diversity.

Diversity of Arbuscular Mycorrhizal Fungi in Forest Ecosystems of Brazil: A Review

“…However, other studies have indicated that tree species of initial ecological sequences have a greater presence of AMF species in relation to the climax (late) sequences, especially when mycotrophic forest species are present (Zangaro et al, 2000;Uibopuu et al, 2009). In fact, microbial symbionts (AMF) have positive and important effects on plant communities (Schuldt et al, 2017).…”

Effects of Lime Application and Understory Removal on Soil Microbial Communities in Subtropical Eucalyptus L’Hér. Plantations

“…It is generally accepted that soil microbial community is controlled by the bottom-up force [38,39]. Normally, understory vegetation is considered as a minor portion of biomass in a forest ecosystem and contributes less to the bottom-up force on soil decomposers than overstory plants.…”

Multi‐trophic guilds respond differently to changing elevation in a subtropical forest

“…We used data on 24 organism groups originally compiled by Schuldt et al (2015) (see also Schuldt et al 2017). The data include producers (plants), consumers (arthropods) and microorganisms (Table 1), and were classified according to their ecology into six trophic guilds (Supplementary material Appendix 1).…”