Bee pollinator functional responses and functional effects in restored tropical forests

Abstract

Wild pollinators are necessary for ensuring plant reproduction, not only among crop fields but also remnant and restored ecosystems. Restoration activities should, therefore, lead to wild pollinator recovery, and thus be monitored to evaluate effects on pollinator diversity and functionality. We assessed bee pollinator functional responses in restoration plantings by creating functional groups (traits: body size, nesting location, sociality, and foraging strategy), comparing their abundance and diversity to that of other habitats (i.e., conserved and degraded primary forest fragments, anthropogenic wetlands, and sugarcane fields), and testing for an effect of source habitat (i.e., primary forest fragments) isolation. We analyzed functional effects on pollen transportation by identifying the pollen grains attached on the bodies of bees; creating plant functional groups with the identified species (traits: habit, successional class, geographic origin, and pollination mode); comparing their frequency, diversity, and interaction network structure among habitats; and searching for key interactions in network modules. In general, the abundance and diversity of bee communities and the frequency and diversity of the interacting plant species in restoration plantings were lower than those in primary forest fragments but higher than those in anthropogenic wetlands and sugarcane fields, suggesting that restoration plantings better enhance bee community recovery and functionality than other disturbed habitats. The interacting bees and plants were also negatively affected by habitat isolation, demonstrating the importance of primary forest fragments to supply bee populations to restored sites. The structure of interaction networks was little affected by habitat change and isolation, but the composition and diversity of functional groups varied significantly. There were more effects on larger bee species with more restricted nesting and floral requirements, and the woody species with which they interact most frequently. We identified key functional groups of bee pollinators that deserve priority for conservation because they play an important role in the pollen transportation of some the most relevant species in remnant forests and restoration plantings and also respond more negatively to habitat disturbances. Restoration efforts should include provisioning of nesting resources and management and conservation of primary forest remnant fragments that represent source habitats for them.

Landscape Simplification Modifies Trap-Nesting Bee and Wasp Communities in the Subtropics

“…The composition in each land use is likely dependent on the traits of bee and wasp assemblages in our study system such as body size, foraging distance, resource use, and life history strategies such as parasitism (e.g., [16,28,[55][56][57][58]). For example, the three bee and four wasp species that accounted for most dissimilarity between land uses (A. adelaidae, M. mystacaena, M. simplex, Fabriogenia sp.…”

“…Similarly, wasp diversity, abundance, and activity in fields can decrease with increasing distance to, or between patches of natural vegetation [10,12]. However, not all bee and wasp taxa are affected by landscape simplification in the same way, with traits such as nesting strategy (above-or below-ground) or sociality largely determining responses [15][16][17][18][19]. Furthermore, most research on bee and wasp responses to landscape simplification has been conducted in temperate regions of North America, Europe, and South America (see meta-analyses by [11,[20][21][22]).…”

“…Within forests, bee and wasp diversity has been found to increase with canopy cover and fragment size in Australia [17,27], Colombia [28], and Mexico [29]. However, the longest tropical studies (two years), both in Brazil, show conflicting results with landscape simplification such as both increased [6] and decreased bee abundance [16]. This highlights the need for more long-term studies in tropical regions to understand the effects of landscape simplification.…”

Figure 3 from: Mazón M, López X, Romero O (2020) Hymenoptera functional groups’ shifts in disturbance gradients at Andean forests in Southern Ecuador. Journal of Hymenoptera Research 80: 1-15. https://doi.org/10.3897/jhr.80.60345

“…Bees are abundant in Andes even above 2500 masl (Gonzalez and Engel 2004), and at least 51 bee species have been recorded from Southern Ecuador (Rasmussen 2004). Since one of the main factors limiting bee nesting is high humidity (Michener 2007;Reyes-Novelo et al 2009), the season when sampling was done may have influenced these results. Furthermore, Malaise traps may not be the most appropriate sampling method for bees.…”

Reintroduced grazers and prescribed fire effects on beetle assemblage structure and function in restored grasslands

“…In particular, insect communities may represent the majority of animal species diversity in a restored habitat and they support critical functions as predators, prey, decomposers, pollinators, seed dispersers, ecosystem engineers, and other roles (Weisser and Siemann 2008). Nonetheless, insects are often overlooked in ecological restoration planning and assessment, although attention to pollinator communities has increased (Wodika and Baer 2015, Griffin et al 2017, Tonietto et al 2017, Luong et al 2019, Montoya‐Pfeiffer et al 2019). A more complete understanding of functional restoration will require ecologists to examine insect community responses to restoration and management activities.…”