Cross-scale effects of land use on the functional composition of herbivorous insect communities

Landscape Ecology - Insect herbivores comprise the majority of macroinvertebrate communities of temperate grasslands and act as drivers for important ecosystem functions. Landscape- and local-level...     

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.     

Effects of functional groups and species richness on biomass constituents relevant for combustion: results from a grassland diversity experiment

Grassland biomass has been identified as a potential energy source. The combustion of mature and fibrous biomass, as occurs in extensive grasslands managed with low cutting frequencies, is one possible conversion technique. This study tested the relationship between plant diversity and biomass constituents relevant for combustion, as they determine energy content, energy yield and emission and corrosion risks. The biomass from a biodiversity experiment, with a species richness (SR) gradient of 1–60 species from Central European mesophilic grasslands divided into four functional groups (grasses, legumes, small and tall herbs), was harvested twice a year (in 2008 and 2009). The higher heating value (HHV) was estimated from carbon, hydrogen and oxygen contents to give insight into the energy potential of the species mixtures. The potential risk of emission and corrosion was assessed by analysing ash content, potassium, calcium, magnesium, nitrogen, sulphur and chloride content. HHV was independent of SR, and the overall mean was 18·13 MJ kg^?1 DM. Biomass and gross energy (GE) yield were positively affected by SR. The presence of legumes in a mixture resulted in increased HHV, biomass yield and GE, irrespective of the level of SR. Annual GE varied between 59 (average of monocultures) and 152 GJ ha^?1 year^?1 (mixture of sixty species). The concentration of ash‐forming elements was generally high, suggesting a pre‐treatment of the biomass prior to combustion. Emission‐ and corrosion‐related constituents were clearly affected by the different functional groups, and sulphur and nitrogen both declined with SR. The results of this study show that high SR in experimental grassland communities is beneficial for the energy output and that legumes play a key role for the energy potential. However, identifying a functional group as being solely beneficial or disadvantageous for fuel quality was difficult.     

La Campana,a new national park in central Chile

La Campana, a new Chilean national park, includes examples of all the major biotic communities of central Chile: Nothofagus forest, hygrophilous forest, sclerophyll forest, matorral, bamboo thicket, succulent scrub, high altitude communities, and palm forest. Although the exact boundaries have yet to be determined, the park includes approximately 15,000 ha, and lies less than 75 km from both Santiago and Valparaiso. The unique natural features of the park are discussed and the current movement to support its development are described.     

Present and historical landscape structure shapes current species richness in Central European grasslands

Landscape Ecology - Current diversity and species composition of ecological communities can often not exclusively be explained by present land use and landscape structure. Historical land use may...