Planning a red squirrel conservation area: using a spatially explicit population dynamics model to predict the impact of felling and forest design plans

Abstract

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.

Responses of small mammals to clear-cutting in temperate and boreal forests of Europe: a meta-analysis and review

“…This decline might be caused by forest harvest and resulting habitat loss (Selonen et al 2010). Red squirrels strongly rely on tree cones for food; therefore, young stands created by large-scale clear-cutting cannot support populations of squirrels until trees mature and produce seeds (Lurz et al 2003).…”

“…Gray squirrels gain competitive advantage over red squirrels in Eur J Forest Res (2014) 133:1-11 7 conifer forests with oaks mixture (Lurz et al 1995), but have lower survival in pure conifer stands (Kenward and Holm 1993;Kenward et al 1998). Therefore, not planting oak species in large pine patches has been proposed as a part of conservation policy for red squirrels (Lurz et al 2003).…”

Genetic management of the red squirrel, Sciurus vulgaris: a practical approach to regional conservation

“…Although its use has been cautioned (Coulson et al 2001), it is still supported as the most useful tool for accurately predicting future demographic change (Brook et al 2000(Brook et al , 2002. Population dynamic modeling has been used to examine the spatial distribution of red squirrels under the effects of different forest management strategies (Lurz et al 2003) and the presence of grey squirrels (Rushton et al 1997) in the UK. This work demonstrated the need to incorporate information on habitat structure to accurately model red squirrel populations, therefore Population and Habitat Viability Analysis (PHVA) was implemented in the current study.…”

Incorporating habitat distribution in wildlife disease models: conservation implications for the threat of squirrelpox on the Isle of Arran

“…We extrapolated woodland data from the forest inventory maps for 2011 (provided by the Forestry Commission Scotland (FCS) website) using GRASS Geographical Information System (GIS) (Westervelt et al, 1992) (using similar methods to Rushton et al (2000) and Lurz et al (2003)). The island was divided into a 1km × 1km grid since 1km is typically the maximum dispersal distance for red squirrels (Bosch and Lurz, 2012) and larger than the typical 150m radius of core range activity (which is based on estimates of red squirrels home range of 9ha (Tonkin, 1983;Lurz, 1995;Bosch and Lurz, 2012)).…”