Complex socio-economic, political and demographic factors have driven the increased conversion of Europe’s semi-natural grasslands to intensive pastures. This trend is particularly strong in some of the most biodiverse regions of the continent, such as Central and Eastern Europe. Intensive grazing is known to decrease species diversity and alter the composition of plant and insect communities. Comparatively little is known, however, about how intensive grazing influences plant functional traits related to pollination and the structure of plant-pollinator interactions. In traditional hay meadows and intensive pastures in Central Europe, we contrasted the taxonomic and functional group diversity and composition, the structure of plant-pollinator interactions and the roles of individual species in networks. We found mostly lower taxonomic and functional diversity of plants and insects in intensive pastures, as well as strong compositional differences among the two grassland management types. Intensive pastures were dominated by a single plant with a specialized flower structure that is only accessible to a few pollinator groups. As a result, intensive pastures have lower diversity and specificity of interactions, higher amount of resource overlap, more uniform interaction strength and lower network modularity. These findings stand in contrast to studies in which plants with more generalized flower traits dominated pastures. Our results thus highlight the importance of the functional traits of dominant species in mediating the consequences of intensive pasture management on plant-pollinator networks. These findings could further contribute to strategies aimed at mitigating the impact of intensive grazing on plant and pollinator communities.
Mid‐field woodlots play an important role in maintaining biodiversity in agricultural landscapes. However, it is not clear whether non‐linear or linear woodlots are most beneficial for wild bee conservation. We assessed the attractiveness of two common types of woodlots in an agricultural landscape in northern Poland (non‐linear and linear: 7 and 9 sites, respectively) in terms of wild bee abundance, species richness, and functional diversity. Linear habitats had higher abundance of wild bees. However, woodlot type did not affect wild bee species composition or functional trait composition. Species composition responded significantly to measures of syntaxonomic heterogeneity and landscape heterogeneity. Woodlot area, landscape context (isolation and landscape heterogeneity), and syntaxonomic heterogeneity explained most of the differences among habitats (non‐linear vs . linear) in wild bee abundance and species richness, regardless of the habitat type. The higher attractiveness of linear woodlots was due to increased food availability in the herbaceous layer in the spring–summer (June) and summer (July–August) periods. Linear woodlots have the potential to be used as tools for integrating agricultural production with biodiversity conservation and ecosystem services.
18 June 2020 in Agricultural and Forest Entomology
Semi‐natural habitats are characterized by a high diversity of wildlife. However, other areas, e.g. old fields, can also play an important role in biodiversity conservation. We assessed the species richness, abundance, and diversity of wild bees (Apiformes), including species of various functional groups in two contrasting and differently managed landscape types. For this study, we selected 15 xerothermic or sandy grasslands or extensively managed fresh meadows located in agricultural landscapes as well as 15 old fields located in wooded landscapes. The study sites differed in area, stage of succession, and management regime. We did not detect any significant differences in total species richness, abundance, and diversity of Apiformes between the two landscape types, which suggests that both semi‐natural habitats and old fields are highly attractive to bees. The two habitat types, however, differed in species composition and proportions of functional groups. We found that in wooded landscapes, eusocial, hive‐nesting, and large‐sized species increased in abundance. The collected information on the preferences of Apiformes in respect of various habitats and landscapes makes it possible to protect and restore valuable habitats through the implementation of suitable methods of management, both locally and on the scale of landscapes.
This study complements earlier research on wild bees (Apiformes) in the “Góra Gipsowa” steppe reserve and other habitats near the town of Kietrz (SW Poland), close to the Czech border. It also attempts to reassess the opinion of some researchers about the Moravian Gate as a migration route of southern species to Poland. 109 bee species were recorded at the study sites, including 10 red-listed ones; southern species accounted for 16.5% of this number. The hypothetical route of migration of thermophilous bees through the Moravian Gate to Poland was analysed and the species composition of southern species at either side of the Moravian Gate compared. The results of this study indicate that at present the Moravian Gate plays no part in the migration of southern bee species to Poland.
Earthworks, such as embankments or excavations, because of their transient nature, usually do not play any important role in biodiversity protection and promotion in urban areas. However, the results of this study show that pits playing the role of infiltration basins, which are filled with water only in some periods, can provide bees with food resources and nesting sites. They are particularly important in habitats with simplified vegetation structures, e.g., in monoculture habitats. The attractiveness of infiltration basins and ditches as habitats for bees was assessed by comparing species richness and abundance of bee communities found there with those of coniferous forests—pine monocultures (where the reservoirs were created) and clearings. The species richness and abundance of bees in clearings, infiltration ditches, and basins were higher than in forests. Simultaneously, we found that an increase in woody vegetation coverage and the level of shading in the daytime had a negative effect on bee abundance. In contrast, it was positively affected by increasing the mean radius of a belt of predominantly open habitats around sampling sites (herbaceous plants and seedlings of woody plants <60%). In this case, food resources were not a limiting factor of bee occurrence in the study area.