Woody plant richness does not influence invertebrate community reassembly trajectories in a tree diversity experiment

Yeeles, Peter; Lach, Lori; Hobbs, Richard J.; Wees, Mary van; Didham, Raphaël K.

doi:10.1002/ecy.1662

Cited by 15 publications

(11 citation statements)

References 54 publications

(96 reference statements)

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“…In contrast, litter ant abundance and species richness in a young Australian tree diversity experiment were unrelated to woody plant species richness [63]. Likewise, ant abundance did not differ in an experiment comparing mahogany monocultures to mixtures of four tree species [56].…”

Section: Predatory Antsmentioning

confidence: 80%

The Influence of Tree Diversity on Natural Enemies—a Review of the “Enemies” Hypothesis in Forests

Staab

Schuldt

2020

Curr Forestry Rep

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Purpose of Review Natural enemies are an important component for forest functioning. By consuming herbivores, they can be effective top-down regulators of potential pest species. Tree mixtures are generally expected to have larger predator and parasitoid populations compared to monocultures. This assumption is based on the “enemies” hypothesis, a classical ecological concept predicting a positive relationship between plant diversity (and complexity) and natural enemies, which, in turn, should increase top-down control in more diverse environments. However, the “enemies” hypothesis has mostly been tested and supported in relatively simple agricultural ecosystems. Until recently, research in forests was sparse. We summarize the upcoming knowledge-base for forests and identify forest characteristics likely shaping relationships between tree diversity, natural enemies (abundance, species richness, diversity), and top-down control. We further identify possible implications for mixed species forestry and key knowledge gaps. Recent Findings Tree diversity (almost exclusively quantified as tree species richness) does not consistently increase enemy abundance, diversity, or result in herbivore control. Tests of the “enemies” hypothesis are largely based on aboveground natural enemies (mainly generalists) and have highly variable outcomes across taxa and study systems, sometimes even finding a decrease in predator diversity with increasing tree diversity. Recurrent effects of tree species identity and composition indicate that a closer focus on tree functional and phylogenetic diversity might help to foster a mechanistic understanding of the specific circumstances under which tree diversity can promote top-down control. Summary Our review suggests that the “enemies” hypothesis may not unambiguously apply to forests. With trees as structurally complex organisms, even low-diversity forests can maintain a high degree of habitat heterogeneity and may provide niches for many predator and parasitoid species, possibly blurring correlations between tree and natural enemy diversity. Several further factors, such as latitude, identity effects, intraguild predation, or functional and phylogenetic components of biodiversity, may confound the predictions of the “enemies” hypothesis. We identify topics needing more research to fully understand under which conditions tree diversity increases natural enemy diversity and top-down control—knowledge that will be crucial for forest management.

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Section: Predatory Antsmentioning

confidence: 80%

The Influence of Tree Diversity on Natural Enemies—a Review of the “Enemies” Hypothesis in Forests

Staab

Schuldt

2020

Curr Forestry Rep

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“…It is known that cavity-nesting Hymenoptera species compositions are distinct for forest interiors and forest edges (Oliveira et al 2017 ; da Rocha-Filho et al 2017 ) and change with forest modification (Iantas et al 2017 ; Nether et al 2019 ). Likewise, young forests can be expected to harbor different communities, sometimes even with more species compared to old-natural forests (Yeeles et al 2017 ; Araújo et al 2018 ). We found more insect species in young regrowth forest plots which was possibly related to lower sampling intensity at the natural forest plots, or inter-annual fluctuations of insect populations, or potential higher habitat heterogeneity of the experimental sites.…”

Section: Discussionmentioning

confidence: 99%

“…After forest clearance, the regrowth is typically characterized by non-forest species, but forest insects naturally disperse from surrounding forests into new forest plantations and re-establish species-rich communities within the first years of forest growth (Hilt and Fiedler 2005 ; Yeeles et al 2017 ; Araújo et al 2018 ; Hethcoat et al 2019 ). For example, comparing forest interiors to forest edges, or following forest thinning, removal and restoration, cavity-nesting bees, wasps and their natural enemies had comparable species numbers, but showed distinct community compositions (Oliveira et al 2017 ; Iantas et al 2017 ; da Rocha-Filho et al 2017 ; Araújo et al 2018 ; Nether et al 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Multi-trophic communities re-establish with canopy cover and microclimate in a subtropical forest biodiversity experiment

et al. 2021

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Plant diversity affects multi-trophic communities, but in young regrowth forests, where forest insects are in the process of re-establishment, other biotic and also abiotic factors might be more important. We studied cavity-nesting bees, wasps and their natural enemies along an experimental tree diversity gradient in subtropical South-East China. We compared insect communities of experimental young forests with communities of established natural forests nearby the experiment and tested for direct and indirect effects of tree diversity, tree basal area (a proxy of tree biomass), canopy cover and microclimate on bee and wasp community composition, abundance and species richness. Finally, we tested if the trophic levels of bees, herbivore-hunting wasps, spider-hunting wasps and their natural enemies respond similarly. Forest bee and wasp community composition re-established towards communities of the natural forest with increasing tree biomass and canopy cover. These factors directly and indirectly, via microclimatic conditions, increased the abundance of bees, wasps and their natural enemies. While bee and wasp species richness increased with abundance and both were not related to tree diversity, abundance increased directly with canopy cover, mediated by tree biomass. Abundance of natural enemies increased with host (bee and wasp) abundance irrespective of their trophic position. In conclusion, although maximizing tree diversity is an important goal of reforestation and forest conservation, rapid closure of canopies is also important for re-establishing communities of forest bees, wasps and their natural enemies.

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“…Nonetheless, with increasing diversity of an ecosystem, mixed results are often obtained. For example, some studies postulate positive relationships between plant diversity and ground beetles, while other studies show no or negative relationships ( Vehvilainen et al 2008 ; Worthen and Merriman 2013 ; Yeeles et al 2017 ; Zou et al 2019 ).…”

Section: Discussionmentioning

confidence: 99%

What shapes ground beetle assemblages in a tree species-rich subtropical forest?

Zumstein

Bruelheide

Fichtner

et al. 2021

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As woody plants provide much of the trophic basis for food webs in forests their species richness, but also stand age and numerous further variables such as vegetation structure, soil properties and elevation can shape assemblages of ground beetles (Coleoptera: Carabidae). However, the combined impact of these numerous variables on ground beetle diversity and community structure has rarely been studied simultaneously. Therefore, ground beetles were studied in 27 plots in a highly diverse and structurally heterogeneous subtropical forest ecosystem, the Gutianshan National Park (southeast China) using pitfall traps and flight interception traps. Both trapping methods collected partly overlapping species spectra. The arboreal fauna was dominated by lebiines and to a smaller extent by tiger beetles and platynines; the epigeic fauna comprised mostly representatives of the genus Carabus and numerous tribes, especially anisodactylines, pterostichines, and sphodrines. Ground beetle species richness, abundance, and biomass of the pitfall trap catches were analyzed with generalized linear mixed models (GLMMs), fitted with seven environmental variables. Four of these variables influenced the ground beetle assemblages: Canopy cover, herb cover, pH-value of the topsoil and elevation. Contrary to our expectations, woody plant species richness and stand age did not significantly affect ground beetle assemblages. Thus, ground beetles seem to respond differently to environmental variables than ants and spiders, two other predominantly predatory arthropod groups that were studied on the same plots in our study area and which showed distinct relationships with woody plant richness. Our results highlight the need to study a wider range of taxa to achieve a better understanding of how environmental changes affect species assemblages and their functioning in forest ecosystems.

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Woody plant richness does not influence invertebrate community reassembly trajectories in a tree diversity experiment

Cited by 15 publications

References 54 publications

The Influence of Tree Diversity on Natural Enemies—a Review of the “Enemies” Hypothesis in Forests

The Influence of Tree Diversity on Natural Enemies—a Review of the “Enemies” Hypothesis in Forests

Multi-trophic communities re-establish with canopy cover and microclimate in a subtropical forest biodiversity experiment

What shapes ground beetle assemblages in a tree species-rich subtropical forest?

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