Nearby rainforest promotes coffee pollination by increasing spatio-temporal stability in bee species richness

Natural tropical forests are highly diverse and are known to contribute to forest-based services such as pollination of nearby crops. Landscape changes cause spatial and temporal bee community changes, but consequences how the community changes affect pollination is not well analyzed. This paper addresses the effects of rainforest distance and on site flower resources in agro-forests on spatial and temporal variation in pollinator communities and the consequences for coffee pollination.     

Abandonement of coffee agroforests increases insect abundance and diversity

Shade coffee including many tree species is known to support generally high biodiversity. Due to low coffee prices on the world market, many farmers have abandoned their farms, thereby creating a new ecosystem type, which has attracted increasing interest for biodiversity conservation. Here we used pyrethrum knockdown samples to compare the arthropod community on coffee plants of six traditionally managed coffee agroforests with those of six abandoned coffee agroforests in coastal Ecuador. We investigated eight randomly selected coffee shrubs per site, six of them inside and two at the edge. All arthropods were identified to orders and beetles to morphospecies. We additionally sampled the vegetation to test for vegetation-mediated effects on the arthropod community. The number of arthropod individuals was higher in abandoned than managed coffee, driven by the abundance of Arachnida, Blattaria, and Heteroptera, and higher in the edge than in the centre of the abandoned agroforests. Higher arthropod abundance appeared to be closely related to arthropod diversity, as shown for beetles (r = 0.79, n = 96). Contrary to expectations, predator-prey ratios in managed agroforests was as high as in the abandoned ones. In conclusion, abandonment of coffee agroforests greatly encourages arthropod communities, in particular in the habitat edges, and therefore, should be considered in landscape management for conservation.     

Herbivore and pollinator responses to grassland management intensity along experimental changes in plant species richness

Agricultural intensification is a major driver of global environmental change. Disentangling the relative impact of losses in plant species richness and intensified management on higher trophic level organisms is important for conservation recommendations.We established different management regimes along an experimental gradient of plant species richness within “The Jena-Experiment” in Germany and quantified herbivory as well as grasshoppers and pollinators. Herbivory, grasshopper density and species richness and frequency of flower visiting pollinators were recorded two times in each of four subplots of altogether 80 plots differing in plant species richness. Each of the four subplots was subject to four different levels of fertilizer application and mowing to simulate very low, low, high and very high land use intensity.Fertilization and mowing significantly affected plant–herbivore interactions but plant species richness had no discernible effect. Grasshoppers were most abundant at high intensity subplots (3.1 individuals per m²) and least abundant on very low intensity subplots (1.3 individuals per m²). Leaf damage caused by herbivores was highest in even the very high intensity subplots (3.7%) with four mowing events per year and high amounts of fertilizer application and lowest on subplots with a low management intensity (2.4%) comprising two mowing events per year but no fertilizer application. In contrast, pollinators benefited most from lower management intensities, with only one or two mowing events and no fertilizer addition. In addition, higher numbers of flowering plant species and increased blossom cover was associated with enhanced pollinator species richness and flower visitation.Our results indicate that even in grasslands with high plant species richness, mowing and fertilization are more important drivers of herbivory and flower visitation by pollinators. Management with no more than two cuts per year and without fertilizer application in our grasslands balanced the ecosystem functions of increased pollination and decreased herbivory.     

The contribution of non-managed social bees to coffee production: new economic insights based on farm-scale yield data

Fruit set and quality of highland coffee (Coffea arabica) have been experimentally shown to be higher with bee-mediated or manual pollen supplementation than with autonomous self-pollination. Based on extrapolation from these small-scale experiments, very substantial monetary values for the pollination service have recently been suggested. However, previous research has not included direct measurement of coffee yield at a farm level in relation to pollinator activity, testing if pollinators are not only limiting fruit set and quality, but also coffee yield and farm profit. The extrapolations from small-scale experiments may be subject to error, because resource reallocation during fruit development, associated with enhanced pollination, was neglected, and many studies were restricted to a single coffee farm, limiting the validity of extrapolation. Here, we investigate the relationship between coffee yield and the community of coffee flower-visiting bees on 21 farms in Ecuador, where coffee is grown under tree shade. Our data show, for the first time on a farm-scale, that coffee yield was positively related to the density of non-managed, social flower-visiting bees per coffee shrub, but not to the number of inflorescences per shrub. Our data revealed that a fourfold increase in bee density was associated with an 80% increase in yield and an 800% increase in net revenues. Consequently, in our study higher yield associated with increased pollination generated higher revenues per hectare, so that farm profit was higher when bees were abundant.     

Responses of small mammals to land restoration after mining

Context

Land degradation from mining influences biodiversity and ecosystem functioning. However, comparative studies using small mammal functional groups within rehabilitated mining sites are missing, despite their significant ecological contributions.

Objectives

We investigated the recovery of small mammals according to their trophic guild and terrestriality in restored mining sites and analyzed whether they were influenced by restoration scheme (active or passive), restoration time, mineral type, body mass and invasive species. We were especially interested in whether functional groups showed different recovery patterns across time.

Methods

We classified small mammals into functional groups according to trophic levels distinguishing carnivores, herbivores and omnivores, and according to their terrestriality categorized as above ground-dwelling (AGD) and fossorial and/or ground-dwelling individuals (FGD). We studied small mammal recovery globally following restoration of mining sites based on a meta-analysis using effect sizes. Influences of environmental variables were investigated with linear mixed models using effect sizes as response variable.

Results

We did not find significant differences for restoration scheme and time but we did for mineral type, body mass and invasive species in terms of population (abundance) recovery. Trajectories of functional group recoveries differed: FGD and herbivores quickly recovered after mining activities stopped, but declined later, whereas AGD, carnivores and omnivores recovered within the first few years or decades.

Conclusions

Our results highlight the different vulnerability of functional groups, and the importance of considering this in conservation interventions.