A geostatistical approach to spatial density distributions of sika deer ( Cervus nippon )
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ORIGINAL ARTICLE
A geostatistical approach to spatial density distributions of sika deer (Cervus nippon) Hiroshi Kondoh • Toru Koizumi • Koichi Ikeda
Received: 7 September 2010 / Accepted: 15 October 2011 / Published online: 18 November 2011 The Japanese Forest Society and Springer 2011
Abstract Sika deer (Cervus nippon) cause serious damage to trees in Japanese forests. Browsing, bark stripping, and tree abrasion with antlers account for 50% of total wildlife damage over the past decade. The extent of forest damage depends on deer population density. We determined the spatial distribution of sika deer population density on Mt. Hiko (Fukuoka Prefecture, southwestern Japan). We also investigated changes in population density distribution over time. Determinants of population density were examined, with particular emphasis on the hunting cull. Deer densities in 1999 and 2004 were estimated by fecal pellet counts at 86 sites. We used kriging, a geostatistical technique that is a component of geographic information systems, to interpolate site-specific point data over large areas of landscape. Mapping procedures showed that high-density (C30.0 deer km-2) and low-density sections of landscape (B10.0 deer km-2) decreased in areal extent between 1999 and 2004. Contractions of high-density sections were attributable to intensive hunting. In lowdensity landscape sections, reduced hunting pressure allowed increased persistence of adult animals whose high fecundity led to population growth and higher deer densities. Landscape tracts with medium deer densities
H. Kondoh (&) Kyushu Research Center, Forestry and Forest Products Research Institute, Kurokami 4-11-16, Kumamoto 860-0862, Japan e-mail: [email protected] T. Koizumi Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba 305-8687, Japan K. Ikeda Fukuoka Prefecture Forest Research and Technology Center, Toyota 1438-2, Yamamoto, Kurume, Fukuoka 839-0827, Japan
(10.0–30.0 deer km-2) expanded, adding further difficulties to the task of wildlife management. Given the scale of the problems caused by deer, it is clear that reliable estimates of population size across space and time are essential components of the wildlife manager’s toolbox. Keywords Hunting Landscape Sika deer Spatial distribution Wildlife population
Introduction Annual reports on the state of Japanese forests and forestry show that damage by sika deer (Cervus nippon) through browsing, stripping bark, abrading of trees with antlers, and other activities accounts for 50% of the total damage caused by wildlife in the past decade (Forest Agency of Japan 2006). Deer damage occurs widely across the country (Li et al. 1996; Hareyama 1998; Japan Wildlife Research Center 1998; Tokida 1998; Ueyama 1998; Oi and Suzuki 2001; Murakami and Koizumi 2003; Murakami et al. 2004) and is a major factor in declining enthusiasm for reforestation among landowners (Sakai 2000). After partial amendment of the Wildlife Protection and Hunting Law in 1999, prefectural governments introduced a new policy e
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