Land-use effects on local biodiversity in tropical forests vary between continents

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The use of forest inventory data for placing flight-interception traps in the forest canopy

Forest canopies are an important part of forest ecosystems and comprise the majority of arthropod diversity. As tree crowns provide various microhabitats, a suitable trapping standard for canopy-dwelling arthropods is required. However, vertical trap position is often not standardized. We developed six vertical placement strategies for flight-interception traps based on information on tree height and crown base obtained from forest inventory data. Strategies differed in how crown base and height of trees were weighted in the calculations of trap height. Forest inventory data from almost 1600 plots in three regions of Germany. Were used to calculate the theoretical suitability of the strategies. The strategy to place traps at the canopy centre was predicted to result in very few trees for which placement would not be possible because trees are too short or crown base is too high, and this strategy by definition resulted in the lowest deviation of trap position from the canopy centre. The strategy Centre was tested in the field by installing three flight-interception traps each in 150 deciduous or coniferous stands of various age structures. On average, 53.8% of the traps were installed at exactly the desired height and for 86.9% of the traps the difference was <10% from the desired height. The strategy worked less well in thickets and pole woods. Overall, our results show that (1) forest inventory data are highly suitable to derive a priori trap placement strategies, even though these data are generally collected in only a small circle in each forest stand, (2) placing traps in the canopy centre largely avoids the problem of not being able to place traps at the desired height in the field, and (3) calculations of trap height should ideally be based on plot-specific data, but data from many stands of one forest type also provide a reasonable fit

Promoting Pollinating Insects in Intensive Agricultural Matrices: Field-Scale Experimental Manipulation of Hay-Meadow Mowing Regimes and Its Effects on Bees

Bees are a key component of biodiversity as they ensure a crucial ecosystem service: pollination. This ecosystem service is nowadays threatened, because bees suffer from agricultural intensification. Yet, bees rarely benefit from the measures established to promote biodiversity in farmland, such as agri-environment schemes (AES). We experimentally tested if the spatio-temporal modification of mowing regimes within extensively managed hay meadows, a widespread AES, can promote bees. We applied a randomized block design, replicated 12 times across the Swiss lowlands, that consisted of three different mowing treatments: 1) first cut not before 15 June (conventional regime for meadows within Swiss AES); 2) first cut not before 15 June, as treatment 1 but with 15% of area left uncut serving as a refuge; 3) first cut not before 15 July. Bees were collected with pan traps, twice during the vegetation season (before and after mowing). Wild bee abundance and species richness significantly increased in meadows where uncut refuges were left, in comparison to meadows without refuges: there was both an immediate (within year) and cumulative (from one year to the following) positive effect of the uncut refuge treatment. An immediate positive effect of delayed mowing was also evidenced in both wild bees and honey bees. Conventional AES could easily accommodate such a simple management prescription that promotes farmland biodiversity and is likely to enhance pollination services

Nest architecture, life cycle, and natural enemies of the neotropical leafcutting bee Megachile (Moureapis) maculata (Hymenoptera: Megachilidae) in a montane forest

Studies on the nesting biology of cavity nesting hymenoptera (bees and wasps) have stimulated many questions related to the behavior, life cycle, trophic niche, and sex ratio to better understanding of the life history of insects. Leafcutting bees are common insects, and many are important and efficient pollinators of crops and other plants.We studied the nesting biology of Megachile (Moureapis ) maculata in a montane semi-deciduous forest in Brazil using trap nests in order to improve the knowledge of aspects of the natural history of this important pollinator group. During 27 months, 87 nests were collected with an average of seven brood cells per nest. Most of the nests were in cavities of 0.9 cm in diameter (77%), and the number of brood cells ranged from 1 to 11. Absence of seasonality in nesting behavior suggests a multivoltine species. The total mortality rate was 26%, with the cuckoo bee Coelyoxis (Acrocoelioxys ) sp. being the main natural enemy attacking 15% of brood cells. The sex ratio is clearly male-biased (1:0.42). Females and their brood cells were larger than males and their brood cells, which may suggest an imbalance in the energetic cost of each sex. The success of this bee species in colonizing trap nestsmakes it an interesting potential opportunity to use this species for pollination of cultivated Asteraceae plant species, like sunflower