Factors driving bumble bee (Hymenoptera: Apidae: Bombus) and butterfly (Lepidoptera: Rhopalocera) use of sheared shrubland and young forest communities of the western Great Lakes.

In the northern Great Lakes region, the creation and maintenance of early-successional woody communities as wildlife habitat have increasingly become a conservation priority. The extent to which insect pollinators use these systems remains largely anecdotal. In summer (June-August) of 2021, we surveyed 49 early-successional sites in the western Great Lakes region treated with either shrub-shearing or silviculture (young forest) for bumble bees, butterflies, and habitat components (i.e., structural vegetation and floral resources). Hierarchical distance models predicted pollinator densities (λ^) to be, on average, λ^ = 84 bumble bees/ha and λ^ = 102 butterflies/ha. Although sheared shrubland and young forest communities supported comparable densities of bumble bees and butterflies, density was not equal across all sites. At the microhabitat scale, butterfly density and morphospecies richness were negatively associated with tall shrub cover and butterfly morphospecies richness (but not density) was driven by floral richness. Similarly, bumble bee density was positively associated with metrics of floral resources, underscoring the importance of blooming plants within these woody systems. Landscape covariates explained variation in butterfly density/richness but not bumble bee density. Ultimately, our results demonstrate that blooming plant abundance is an important driver of bumble bee and butterfly densities within these managed early-successional communities. Because early-successional woody communities are dynamic and their herbaceous openings are ephemeral, routine management would ensure that a variety of successional conditions exist on the landscape to meet the needs of bumble bees, butterflies, and potentially other insect pollinators.

Diversidade de um cerrado sensu stricto com base em modelos de abundância de espécies / Diversity of a cerrado sensu stricto based on species abundance models

Este estudo teve como objetivo avaliar a diversidade de uma comunidade lenhosa de cerrado sensu stricto no sudeste de Goiás, a partir de modelos de distribuição de abundância de espécies. Foram alocadas aleatoriamente 10 parcelas de 20 x 20 m em um trecho de 4 km2 de cerrado sensu stricto preservado, onde todos os indivíduos com DB ≥ 5 cm (diâmetro a altura da base = 30 cm do nível do solo) foram amostrados e identificados. A comunidade apresentou ajuste aos modelos de vara-quebrada (χ 2 = 37,62, P = 0,99) e normal-logarítmico (χ 2 = 2,61, P = 0,63), que refletem equilíbrio ecológico. O modelo normal-logarítmico foi o de melhor ajuste, mostrando que as espécies se distribuem ao longo de mosaicos de recursos, fato corroborado pela diferenciação na distribuição das espécies a partir de uma análise de gradientes (análise de correspondência segmentada - DCA).

This study aimed to evaluate the diversity of the woody community of a cerrado sensu stricto in southeastern of Goiás State (Brazil), through species abundance models. Ten plots of 20 x 20 m were randomly allocated in an undisturbed cerrado sensu stricto area of 4 km2, and all individuals with DSH ≥ 5 cm (diameter at soil height = 30 cm aboveground) were sampled and identified. The broken-stick (χ 2 = 37.62, P = 0.99) and lognormal (χ 2 = 2.61, P = 0.63) models fits to community, reflecting an ecological equilibrium. The lognormal model was the most adequate, showing that the species are distributed along resource patches, in agreement to the pattern found in the gradient analysis (Detrended correspondence analysis - DCA)