Predator Assemblage Structure and Temporal Variability of Species Richness and Abundance in Forests of High Tree Diversity

Abstract

Predators significantly affect ecosystem functions, but our understanding of to what extent findings can be transferred from experiments and low‐diversity systems to highly diverse, natural ecosystems is limited. With a particular threat of biodiversity loss at higher trophic levels, however, knowledge of spatial and temporal patterns in predator assemblages and their interrelations with lower trophic levels is essential for assessing effects of trophic interactions and advancing biodiversity conservation in these ecosystems. We analyzed spatial and temporal variability of spider assemblages in tree species‐rich subtropical forests in China, across 27 study plots varying in woody plant diversity and stand age. Despite effects of woody plant richness on spider assemblage structure, neither habitat specificity nor temporal variability of spider richness and abundance were influenced. Rather, variability increased with forest age, probably related to successional changes in spider assemblages. Our results indicate that woody plant richness and theory predicting increasing predator diversity with increasing plant diversity do not necessarily play a major role for spatial and temporal dynamics of predator assemblages in such plant species‐rich forests. Diversity effects on biotic or abiotic habitat conditions might be less pronounced across our gradient from medium to high plant diversity than in previously studied less diverse systems, and bottom‐up effects might level out at high plant diversity. Instead, our study highlights the importance of overall (diversity‐independent) environmental heterogeneity in shaping spider assemblages and, as indicated by a high species turnover between plots, as a crucial factor for biodiversity conservation at a regional scale in these subtropical forests.

Conserving landscape structure – conclusions from partitioning of spider diversity in southern Atlantic forests of Brazil

“…Positive effects of woody plant species richness were only detected on the rarefied number of spider guilds. Interestingly, variability in species richness and abundance increased with forest age and Schuldt et al (2012) relate this to successional changes in spider assemblages, in contrast to our observations. Not the number, but the diversity of guilds was observed to differ between the stages in our study (Raub et al 2014b).…”

Patterns of functional diversity of two trophic groups after canopy thinning in an abandoned coppice

“…This relationship implies that after canopy thinning high light availability favoured larger-sized plant species. We can conclude that vegetation structure complexity is also an important factor positively influencing species richness (Schuldt et al 2012, McDonald 2015). It was demonstrated that species number may be related to foliage height diversity and cover (Roth 1976).…”

“…Indeed, the CCA model revealed that spider functional diversity showed the same trend as understory vegetation. In addition, we assumed that the greater variability of functional groups of spiders on the thinned sites could be caused by the increased spatial and temporal heterogeneity of physical conditions, including the vegetation structure (Southwood 1977, 1988, Schuldt et al 2012, Mori et al 2015). The hypothesis predicting higher spatial heterogeneity after canopy thinning can be partially supported by our results.…”

Negative Correlation between Ant and Spider Abundances in the Canopy of a Bornean Tropical Rain Forest

“…Spiders also are well‐represented in tropical rain forests (Russell‐Smith & Stork , Pfeiffer , Schuldt et al . ) and function as predators influencing various arthropod populations in the community (Finke & Denno ). The presence of ants and spiders likely affects resource use by their prey; therefore, elucidating their spatial distributions is key to understanding the arthropod community structure in tropical rain forest canopies.…”

“…Ants have varied ecological roles (e.g., Wielgoss et al 2014), including as predators, and many ant species impose significant pressure on arthropod species in forest ecosystems (Cole et al 1992, Holway 1998, Yanoviak & Kaspari 2000, Floren et al 2002). Spiders also are well-represented in tropical rain forests (Russell-Smith & Stork 1995, Pfeiffer 1996, Schuldt et al 2012 and function as predators influencing various arthropod populations in the community (Finke & Denno 2004). The presence of ants and spiders likely affects resource use by their prey; therefore, elucidating their spatial distributions is key to understanding the arthropod community structure in tropical rain forest canopies.…”