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Banbury, United Kingdom

Bebber D.P.,Earthwatch Institute | Watkinson S.C.,University of Oxford | Boddy L.,University of Cardiff | Darrah P.R.,University of Oxford
Oecologia | Year: 2011

Anthropogenic nitrogen (N) deposition affects many natural processes, including forest litter decomposition. Saprotrophic fungi are the only organisms capable of completely decomposing lignocellulosic (woody) litter in temperate ecosystems, and therefore the responses of fungi to N deposition are critical in understanding the effects of global change on the forest carbon cycle. Plant litter decomposition under elevated N has been intensively studied, with varying results. The complexity of forest floor biota and variability in litter quality have obscured N-elevation effects on decomposers. Field experiments often utilize standardized substrates and N-levels, but few studies have controlled the decay organisms. Decomposition of beech (Fagus sylvatica) blocks inoculated with two cord-forming basidiomycete fungi, Hypholoma fasciculare and Phanerochaete velutina, was compared experimentally under realistic levels of simulated N deposition at Wytham Wood, Oxfordshire, UK. Mass loss was greater with P. velutina than with H. fasciculare, and with N treatment than in the control. Decomposition was accompanied by growth of the fungal mycelium and increasing N concentration in the remaining wood. We attribute the N effect on wood decay to the response of cord-forming wood decay fungi to N availability. Previous studies demonstrated the capacity of these fungi to scavenge and import N to decaying wood via a translocating network of mycelium. This study shows that small increases in N availability can increase wood decomposition by these organisms. Dead wood is an important carbon store and habitat. The responses of wood decomposers to anthropogenic N deposition should be considered in models of forest carbon dynamics. © 2011 Springer-Verlag. Source

Crockatt M.E.,Earthwatch Institute
Fungal Biology Reviews | Year: 2012

Fungi are vital within forest ecosystems through their mycorrhizal relationships with trees, and as the main agents of wood decomposition and thus carbon and nutrient cycling. Globally, forests are becoming increasingly fragmented, creating forest patches that are isolated, reduced in area, and exposed at edges. Edges are often ecologically distinct from the forest interior due to their exposure to the matrix habitat. This exposure can result in altered microclimatic conditions and flows of biotic and abiotic materials such as spores or inorganic nitrogen, respectively.Although fungi are known to be affected by microclimate and nitrogen deposition, knowledge of forest edge effects on fungi is extremely limited; however, a consideration of the factors known to regulate fungal activity in combination with known biotic and abiotic edge effects implies that forest edges are likely to strongly influence fungi. These include responses of fungi to the altered microclimate and nitrogen levels at forest edges, at both the individual and community level; interactions with plants and animals that have been influenced by edges; above-belowground feedback between mycorrhizal fungi and host trees. The small body of existing research focuses on fruit body presence and distribution; fungal biomass and community composition in soil have been touched upon. Positive, negative and neutral edge responses have been found, the majority of studies finding a significant effect on some of the parameters measured. Generally, abundance of fruit bodies and biomass in the soil is lower at the forest edge.Understanding how fungi respond to edges is essential to a more complete knowledge of carbon and nitrogen cycling in forest edges, influence of mycorrhizal species on vegetation, and conservation of rare fungi. As edges become increasingly dominant landscape features it is vital to investigate processes within them, to understand ecosystem function at a landscape scale. © 2012 The British Mycological Society. Source

Slade E.M.,University of Oxford | Slade E.M.,University of Helsinki | Merckx T.,University of Oxford | Merckx T.,Catholic University of Louvain | And 5 more authors.
Ecology | Year: 2013

How best to manage forest patches, mitigate the consequences of forest fragmentation, and enable landscape permeability are key questions facing conservation scientists and managers. Many temperate forests have become increasingly fragmented, resulting in reduced interior forest habitat, increased edge habitats, and reduced connectivity. Using a citizen science landscape-scale mark-release-recapture study on 87 macro-moth species, we investigated how both life-history traits and landscape characteristics predicted macro-moth responses to forest fragmentation. Wingspan, wing shape, adult feeding, and larval feeding guild predicted macro-moth mobility, although the predictive power of wingspan and wing shape depended on the species' affinity to the forest. Solitary trees and small fragments functioned as "stepping stones," especially when their landscape connectivity was increased, by being positioned within hedgerows or within a favorable matrix. Mobile forest specialists were most affected by forest fragmentation: despite their high intrinsic dispersal capability, these species were confined mostly to the largest of the forest patches due to their strong affinity for the forest habitat, and were also heavily dependent on forest connectivity in order to cross the agricultural matrix. Forest fragments need to be larger than five hectares and to have interior forest more than 100 m from the edge in order to sustain populations of forest specialists. Our study provides new insights into the movement patterns of a functionally important insect group, with implications for the landscape-scale management of forest patches within agricultural landscapes. © 2013 by the Ecological Society of America. Source

Riutta T.,University of Oxford | Slade E.M.,University of Oxford | Bebber D.P.,Earthwatch Institute | Taylor M.E.,UK Center for Ecology and Hydrology | And 4 more authors.
Soil Biology and Biochemistry | Year: 2012

Forest ecosystems have been widely fragmented by human land use. Fragmentation induces significant microclimatic and biological differences at the forest edge relative to the forest interior. Increased exposure to solar radiation and wind at forest edges reduces soil moisture, which in turn affects leaf litter decomposition. We investigate the effect of forest fragmentation, soil moisture, soil macrofauna and litter quality on leaf litter decomposition to test the hypothesis that decomposition will be slower at a forest edge relative to the interior and that this effect is driven by lower soil moisture at the forest edge. Experimental plots were established at Wytham Woods, UK, and an experimental watering treatment was applied in plots at the forest edge and interior. Decomposition rate was measured using litter bags of two different mesh sizes, to include or exclude invertebrate macrofauna, and containing leaf litter of two tree species: easily decomposing ash (. Fraxinus excelsior L.) and recalcitrant oak (. Quercus robur L.). The decomposition rate was moisture-limited at both sites. However, the soil was moister and decomposition for both species was faster in the forest interior than at the edge. The presence of macrofauna accelerated the decomposition rate regardless of moisture conditions, and was particularly important in the decomposition of the recalcitrant oak. However, there was no effect of the watering treatment on macrofauna species richness and abundance. This study demonstrates the effect of forest fragmentation on an important ecosystem process, providing new insights into the interacting effects of moisture conditions, litter quality, forest edge and soil macrofauna. © 2012 Elsevier Ltd. Source

Crockatt M.E.,Earthwatch Institute | Crockatt M.E.,University of Oxford | Bebber D.P.,University of Exeter
Global Change Biology | Year: 2015

Forests around the world are increasingly fragmented, and edge effects on forest microclimates have the potential to affect ecosystem functions such as carbon and nutrient cycling. Edges tend to be drier and warmer due to the effects of insolation, wind, and evapotranspiration and these gradients can penetrate hundreds of metres into the forest. Litter decomposition is a key component of the carbon cycle, which is largely controlled by saprotrophic fungi that respond to variation in temperature and moisture. However, the impact of forest fragmentation on litter decay is poorly understood. Here, we investigate edge effects on the decay of wood in a temperate forest using an experimental approach, whereby mass loss in wood blocks placed along 100 m transects from the forest edge to core was monitored over 2 years. Decomposition rate increased with distance from the edge, and was correlated with increasing humidity and moisture content of the decaying wood, such that the decay constant at 100 m was nearly twice that at the edge. Mean air temperature decreased slightly with distance from the edge. The variation in decay constant due to edge effects was larger than that expected from any reasonable estimates of climatic variation, based on a published regional model. We modelled the influence of edge effects on the decay constant at the landscape scale using functions for forest area within different distances from edge across the UK. We found that taking edge effects into account would decrease the decay rate by nearly one quarter, compared with estimates that assumed no edge effect. © 2014 John Wiley & Sons Ltd. Source

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