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Seiichi Kanetani Mitsuteru Akiba Katsunori Nakamura Koichiro Gyokusen Akira Saito 《Journal of Forest Research》2001,6(4):307-310
The process of decline of an endangered tree species,Pinus armandii var.amamiana, was monitored on the southern slope of Mt. Hasa-dake in Yaku-shima Island from 1994 to 1998. There are 163 trees ofP. armandii var.amamiana over 1.3 m in height. They are distributed on steep ridges and rocks with a thin soil layer mostly consisting of friable
granite. During the monitoring period, 21 trees ofP. armandii var.amamiana died and the mortality rate was 12.9%. Dead trees were categorized into three types: standing, uprooted and landslide. The
uprooted- and landslide-typed dead trees were found only after a severe typhoon struck Yaku-shima Island. This suggests that
the combination of fragile site conditions and severe typhoons play an important role in the process of decline ofP. armandii var.amamiana. The standing-typed dead trees were presumed to have been killed by pine wilt disease, accounting for 71.4% of the dead trees.
However,Bursaphelenchus xylophilus, the cause of pine wilt disease, was not detected from any of the wood chips or branch samples from the standing-typed dead
trees ofP. armandii var.amamiana. This might indicate that some factor(s) other than pine wilt disease could be responsible for the standing-typed death ofP. armandii var.amamiana in natural habitats.
A part of this paper was presented at the 109th Meeting of the Japanese Forestry Society. 相似文献
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对海南岛尖峰岭热带山地雨林采伐迹地次生林及周围的保留林进行了群落调查.组建了一个基于分割线段模型的边缘效应测度公式:Y=α e0[1-(D/Dmax)](式中Y为与边缘垂直距离D处的测定指标值,e0为边缘效应强度的最大值,Dmax为边缘效应作用的最大距离,α为常数),研究了热带山地雨林群落的边缘效应,结果表明:(1)用组建的测度公式来分析热带山地雨林采伐迹地边缘的次生林及保留林的边缘效应强度及其作用距离,结果是有效和可靠的;(2)热带山地雨林采伐后形成的边缘,其效应的作用距离一般都不超过15m;(3)边缘对保留林和次生林的效应没有显著差异。 相似文献
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基于MSPA与MCR模型的资源节约型生态网络构建——以福建省东山岛为例 总被引:2,自引:0,他引:2
以福建东山岛为研究对象,采用形态学空间格局分析和景观连通指数提取连通性较好的生态源地斑块,基于最小累积阻力模型和重力模型,识别重要生态源地斑块,定量筛选廊道,构建了由19个生态源地和171条生态廊道组成的“源—廊—点”互通的海岛景观生态网络。结果表明,研究区生态网络面积共11 852.298 hm2,其中生态源地占52.76%,生态廊道占47.23%,生态踏脚石占0.01%。生态源地以林地、淡水水域为主;生态源地间的相互作用强度差异显著,总体上南高北低;生态廊道分布东南密、西北疏;生态源地与建设用地无明显冲突,廊道与建设用地冲突由南向北递减,二级廊道与建设用地冲突更加剧烈。研究结果可为东山岛生态网络构建和优化策略提供理论依据。 相似文献
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A total of 518 Gerres sp. were collected around Okinawa Island, Japan, from November 2002 to July 2005, with monthly sampling where the standard
length of females (n=218) were 56.2–147.1 mm, and males (n=149) were 62.2–139.4 mm. The maximum ages observed for females were 5+ years and males were 4+ years, estimated by transverse sectioned sagittal otoliths. Mean marginal increment indicated that opaque rings were formed
once a year during April to July. The standard length (SL; mm) — body wet weight (BW; g) relationships were described as BW=(3.26×10−5) SL2.97 and BW=(3.13×10−5) SL
2.98 for females and males, respectively, and the standard length at age described by von Bertalanffy growth function for females,
L
t=137.1(1−e−0.80[t+0.80]) and males, L
t=127.3(1−e−0.82[t+0.93]). 相似文献