Surface energy flux measurements from a sample of 10 flux network (FLUXNET) sites selected to represent a range of climate conditions and biome types were used to assess the performance of the Hadley Centre land surface model (Joint U.K. Land Environment Simulator; JULES). Because FLUXNET data are prone systematically to undermeasure surface fluxes, the model was evaluated by its ability to partition incoming radiant energy into evaporation and how such partition varies with atmospheric evaporative demand at annual, seasonal, weekly, and diurnal time scales. The model parameters from the GCM configuration were used. The overall performance was good, although weaknesses in model performance were identified that are associated with the specification of the leaf area index and plant rooting depth, and the representation of soil freezing.
A process-based model of the energy crop Miscanthus  giganteus is integrated into the global climate impact model IMOGEN, simulating the potential of large-scale Miscanthus plantation to offset fossil fuel emissions during the 21st century. This simulation produces spatially explicit, annual projections of Miscanthus yields from the present day to the year 2100 under an SRES A2 anthropogenic emissions scenario and includes the effects of climate change. IMOGEN also simulates natural vegetation and soil carbon storage throughout the 21st century. The benefit of Miscanthus cultivation (avoiding fossil fuel emissions of CO 2 ) is then compared with the cost of displacing natural vegetation (carbon emissions from vegetation and soil). The time taken for these effects to cancel out, the pay-back time, is calculated regionally. The effects of large-scale Miscanthus plantation are then integrated globally to produce an estimate of atmospheric CO 2 concentrations throughout the 21st century. Our best estimate of the pay-back time for Miscanthus plantation is 30 years. We project a maximum possible reduction in atmospheric CO 2 of 323 ppmv by the end of 21st century, with a reduction of 162 ppmv corresponding to the best estimate scenario.
Seasonal body weight changes were investigated in red and grey squirrels in spruce-dominated conifer plantations in the north of England. Annual seed food availability, particularly in the spruce plantations, varies markedly and is characterized by years with large cone crops (`mast crops') followed by several years of intermediate or low crops. The last mast crop in Kielder Forest District occurred in 1991 and we studied the two squirrel species when food availability was intermediate and low between 1992 and 1999. Neither red nor grey squirrels in the conifer plantations signi®cantly increased their body weight for the autumn or winter. The responses of red and grey squirrels to the different foraging conditions in deciduous and conifer woodlands and the accumulation of seasonal fat stores may have to be seen in the context of habitat type and the pattern and predictability of seed availability. Our ®ndings suggest that fat accumulation is likely to be less pronounced in conifer habitats where autumn and winter food supplies are more predictable, and manoeuvrability to feed on cones in the canopy is important.
SummaryThis paper describes the use of a spatially explicit population model (SEPM) to investigate the effects of different forest management strategies on a red squirrel conservation area. The study was based in woodland managed by Forest Enterprise, which manages 75 000 ha of woodlands in Northumberland, Co. Durham, Tyne and Wear, and east Cumbria. The forests contain the largest remaining red squirrel populations in northern England and the area of the study, Kidland Forest, is one of five key areas or refuges where red squirrel conservation is a priority. The SEPM integrates expert knowledge on red and grey squirrels, based on 10 years of fieldwork in the area and information from the scientific literature. We investigated the current tree species composition, distribution and proposed felling plans as well as the future restocking for Kidland Forest, an area of 2050 ha of predominantly conifer species. The assessment also included a proposed planting of 15 ha of oak and its likely consequences on grey squirrel population viability. These results were then applied to develop a forest design plan to ensure red squirrel persistence over the next rotation. Results indicated that red squirrels were at risk of extinction due to a drastic reduction in the availability of suitable habitats through clear-felling. Furthermore the proposed planting of 15 ha of oak could lead to a substantial grey squirrel population at Kidland once the trees matured and assuming that grey squirrels colonize the area. The felling profile was therefore revised, allocating a proportion of the tree crop on more wind-firm sites to long-term retentions. The approach adopted at Kidland illustrates how geographical information systems, expert knowledge on the threatened species and spatially explicit models can be integrated to assist forest managers in assessing the suitability of a site for red squirrel conservation.
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