Michele E. Taylor

Air and soil microclimates of deciduous woodland compared to an open site

Forest microclimate has been monitored continuously for more than 3 yr at two sites in deciduous woodland at Wytham Woods, Oxford, UK. Automatic weather stations provided hourly data for wind speed, photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and, in particular, temperature at different heights above the ground and at different depths in the soil. These data were compared with values from an open site at the same location. Air temperatures could be up to 3°C lower under the canopy than at the open site under sunny conditions in summer, but the differences averaged 0.6 and 0.9°C during the summer months and barely differed over winter. Effects of forest cover on soil temperatures were much greater and under the woodland they neither fell below 0°C nor rose above 20°C even at 5 mm depth, in contrast to temperatures under bare earth and grass. The temperature of a grass tussock at the soil surface under the canopy was intermediate between soil and air temperature; in comparison to grassland plants at an open site it experienced a much smaller range of temperatures. The differences between both soil and air temperature under the canopy and in the open were significantly correlated with solar radiation, presence or absence of canopy leaves and wind speed. Soil water content had no significant effect on soil temperature, partly because thermal diffusivity was relatively insensitive to it and partly because soil heat flux was small. Seasonal changes in canopy leaf cover caused a large peak of PAR under the canopy in spring prior to bud burst in trees and a much smaller one in the autumn after leaf fall. Wind speed under the canopy was also affected by the presence of leaves and was proportionally lower in summer and autumn than winter and spring.

Drought stress differentially affects leaf-mining species

Abstract 1. The impact of climate change on phytophages is difficult to predict, due in part to variation between species in their responses to factors such as drought stress. Here, the hypothesis that several species within the leaf‐mining feeding guild will respond in a consistent way to changes in rainfall patterns is tested, using a manipulative field experiment.

Factors Affecting Soil Fauna Feeding Activity in a Fragmented Lowland Temperate Deciduous Woodland

British temperate broadleaf woodlands have been widely fragmented since the advent of modern agriculture and development. As a result, a higher proportion of woodland area is now subject to edge effects which can alter the efficiency of ecosystem functions. These areas are particularly sensitive to drought. Decomposition of detritus and nutrient cycling are driven by soil microbe and fauna coactivity. The bait lamina assay was used to assess soil fauna trophic activity in the upper soil horizons at five sites in Wytham Woods, Oxfordshire: two edge, two intermediate and one core site. Faunal trophic activity was highest in the core of the woodland, and lowest at the edge, which was correlated with a decreasing soil moisture gradient. The efficiency of the assay was tested using four different bait flavours: standardised, ash (Fraxinus excelsior L.), oak (Quercus robur L.), and sycamore (Acer pseudoplatanus L.). The standardised bait proved the most efficient flavour in terms of feeding activity. This study suggests that decomposition and nutrient cycling may be compromised in many of the UKs small, fragmented woodlands in the event of drought or climate change.