Using landscape suitability models to reconcile conservation planning for two key forest predators     

William J. Zielinski  Carlos Carroll 《Biological conservation》2006,133(4):409-430

Protection of area-limited species is an important component of plans to conserve biodiversity, but the habitat needs of such species can be different and important habitats may not align with existing reserves. We used empirically derived landscape suitability models for the spotted owl and the fisher to evaluate the overlap in habitat suitability for these two old forest-associated predators in an area of northern California affected by the Northwest Forest Plan (NWFP), a bioregional conservation plan. The area includes designated Wilderness areas and new reserves (Late-Successional Reserves, LSRs) established under the NWFP. We used the site selection algorithm MARXAN to identify priority habitat areas for each species, and for both combined, and to compare these areas with reserves. Sites were selected under two constraints, to achieve a threshold proportion of total habitat value and to select new areas equal to the total current area in existing reserves. The rank correlation between predicted value for the two species was low (0.11), because areas of highest predicted habitat value were more widely distributed for the owl. This difference also meant that the sites selected to optimize habitat value were more aggregated for fishers than owls, resulting in greater overlap of owl habitat and current reserves. To capture 25%, 50% and 75% of total habitat value for the owl required 14.0%, 29.2%, and 47.3% of the planning units, respectively; capturing the same for the fisher required only 5.3%, 13.5%, and 27.2%. A combined owl-fisher scenario resulted in areas that overlapped only ∼50% of existing reserves. The current location of LSRs may not be the best solution to maintaining well-connected habitats for these area-limited species in northwestern California. Whether LSRs are a better solution to protecting the diversity of other lesser-known taxa (i.e., salamanders and mollusks) is the subject of related work.  相似文献   

Extirpation and reintroduction of fishers (Martes pennanti) in Oregon: implications for their conservation in the Pacific states     

Keith B Aubry  Jeffrey C Lewis 《Biological conservation》2003,114(1):79-90

Prior to extensive European settlement, the fisher (Martes pennanti) occupied most coniferous forest habitats in Washington, Oregon, and California. Human activities since that time have resulted in the apparent extirpation of fishers throughout much of their historical range in the Pacific states. Fisher extirpations in California and Washington have been documented previously, but no comprehensive assessments of the distribution of fishers in Oregon, the history of their translocation into Oregon, or the conservation of fishers in the Pacific states have been conducted. Our objectives are to (1) review historical information on potential causes for fisher population losses in Oregon, (2) document the history of their translocation into Oregon, (3) describe the distribution of fishers in Oregon relative to those translocations and determine if any were successful, and (4) discuss the implications of our findings for the conservation of fishers in the Pacific states. Our results show that extant populations of fishers in Oregon are restricted to two disjunct and genetically isolated populations in the southwestern portion of the state: one in the southern Cascade Range and one in the northern Siskiyou Mountains. In addition, historical changes in the distribution of fisher occurrence records in Oregon and geographic variation in the genetic composition and size of fishers occurring in southwestern Oregon, show that the population in the southern Cascade Range is reintroduced and is descended from fishers that were translocated to Oregon from British Columbia and Minnesota. The loss of fisher populations from central and northern Oregon and throughout Washington has resulted in the isolation of extant populations in Oregon by >650 km from those occurring in southern British Columbia. Our results demonstrate that the historical continuity in fisher distribution that once provided for genetic interchange among fisher populations in the Pacific states no longer exists.  相似文献   

残余寿命熵的有限性     

胡必锦  雷鸣 《西南大学学报(自然科学版)》2007,29(9):25-28

从Jensen不等式出发,设计了一个不同于Rao M等的证明残余寿命熵的有限性的方案,整个证明过程简明扼要．另外,考查了依赖一个单参数的分布类的残余寿命熵的有限性问题,并得到残余寿命熵关于参数的变化率可由Fisher信息控制的结果．  相似文献   

Using occupancy and population models to assess habitat conservation opportunities for an isolated carnivore population     

Wayne Spencer  Heather Rustigian-Romsos  James Strittholt  Robert Scheller  William Zielinski  Richard Truex 《Biological conservation》2011,(2):788-803

An isolated population of the fisher (Martes pennanti) in the southern Sierra Nevada, California, is threatened by small size and habitat alteration from wildfires, fuels management, and other factors. We assessed the population’s status and conservation options for its habitat using a spatially explicit population model coupled with a fisher probability of occurrence model. The fisher occurrence model was selected from a family of generalized additive models (GAM) generated using numerous environmental variables and fisher detection–nondetection data collected at 228 survey arrays sampled repeatedly during 2002–2006. The selected GAM accounted for 69% of the Akaike weight using total above-ground biomass of trees, latitude-adjusted elevation, and annual precipitation averaged over a 5 km² moving window. We estimated equilibrium population sizes (or carrying capacities) within currently occupied areas, and identified likely population source, sink, and expansion areas, by simulating population processes for 20 years using different demographic rates, dispersal distances, and territory sizes. The population model assumed that demographic parameters of fishers scale in proportion to habitat quality as indexed by the calculated probability of fisher occurrence. Based on the most defensible range of parameter values, we estimate fisher carrying capacity at ∼125–250 adults in currently occupied areas. Population expansion into potential habitat in and north of Yosemite National Park has potential to increase population size, but this potential for expansion is predicted to be highly sensitive to mortality rates, which may be elevated in the northern portion of the occupied range by human influences, including roadkill and diseases carried by domestic cats and dogs.  相似文献   

桉树枝瘿姬小蜂危害及不同诱导方式对桉树挥发物释放的影响     

张华峰  陈顺立  康文通  汤行昊  方晓敏  欧文胜 《福建林学院学报》2013,(2):170-175

采用动态顶空吸附法和气相色谱—质谱分析法,分析了4种处理下桉树释放的挥发物组成和相对含量,以及萜烯类化合物时序变化。结果表明,不同处理的桉树植株释放出的挥发物的种类和相对含量存在显著差异。经桉树枝瘿姬小蜂危害诱导后,桉树挥发物的种类与健康植株相比较有显著的增加,且相对含量有明显变化。虫害与机械损伤处理诱导释放出的挥发物的种类和含量存在差异,但与喷施茉莉酸甲酯处理的相比较,有10种挥发物是相同的,且相对含量基本相近。不同诱导处理后,大部分萜烯类化合物在诱导后1-3 d大量释放,5-7 d后释放量逐渐减少。由此可见,不同诱导方式对桉树释放挥发物的种类和含量,以及萜烯类化合物的时序变化有较大影响。  相似文献   

桉树枝瘿姬小蜂空间分布格局     

吴耀军  常明山  李德伟  黄华艳  邹东霞 《广西林业科学》2013,(4):300-303

桉树枝瘿姬小蜂（Leptocybe invasa Fisher＆La Salle）是近年来发现的一种重要的检疫性有害生物.为了研究该虫在桉树林内的空间分布格局,2011年6月在广西北海对桉树无性系DH201-2上的虫瘿和成虫进行了详细的调查研究,应用扩散系数等7种指标对其空间分布进行了测定.结果表明：该虫在桉树林中分布格局为聚集分布,叶脉、叶柄、茎上的虫瘿和成虫的聚集原因是依靠环境因素决定的,柄脉上虫瘿的聚集主要是其本身的聚集习性和环境因素共同作用引起.在此基础上,建立该虫林间理论抽样数公式,给出了不同虫口密度以及不同误差要求的最适抽样数.  相似文献   

补充营养材料和温度对桉树枝瘿姬小蜂寿命的影响   总被引：2，自引：0，他引：2  

陈磊  金启安  韦曼丽  刘慧清  彭正强 《热带作物学报》2011,32(2):302-304

室内试验结果表明,补充营养材料和温度对桉树枝瘿姬小蜂雌蜂存活时间具有显著影响。25℃条件下,无补充营养材料时,雌蜂的存活时间仅为(3.07±1.7)d,而清水、桉树嫩枝及花粉水均不能延长其寿命,但蜂蜜水能显著延长成虫存活时间至7 d以上,且不同蜜源(杂花蜂蜜/桉树花蜂蜜)种类间无显著差异。此外,温度18～33℃范围内,随着温度的上升,桉树枝瘿姬小蜂雌虫存活时间先延长后缩短,21℃时,存活时间最长,可达8 d。  相似文献   

3S技术在桉树枝瘿姬小蜂监测预警中的应用前景     

韦春义 《福建林业科技》2010,37(4)

通过分析3S技术及其在森林病虫害预警中的应用现状,结合桉树枝瘿姬小蜂(Leptocybe invasaFisher et 1.aSalle)的发生危害特点,综述3S技术在桉树枝瘿姬小蜂监测预警中的应用前景。  相似文献   

我国桉树枝瘿姬小蜂研究现状   总被引：4，自引：0，他引：4  

常润磊  周旭东 《桉树科技》2010,(1):75-78

桉树枝瘿姬小蜂是严重危害桉属植物的枝叶害虫。本文从生物学特性、发生规律与危害、调查与收集、风险评估和防治与管理介绍了该蜂在我国的研究现状。  相似文献   

桉树枝瘿姬小蜂在尾巨桉幼林扩散为害研究     

方小玉  江洁  梁一萍  蒋虎  洪明  马文志 《广西热带农业》2011,(5)

在崇左市江州区以零星分布在林中的已受桉树枝瘿姬小蜂(Leptocybe invasa Fisher&La Salle)严重为害的巨园桉(Eucalyptus grandis×E.tereticornis)DH201-2植株作为虫源株,研究其产生的桉树枝瘿姬小蜂对由尾巨桉(Eucalyptus urophylla×E.grandis)DH32-29组成的幼林自然扩散为害情况。结果表明:以虫源株为中心约100 m2范围内尾巨桉DH32-29平均受害株率69.6%,平均有虫瘿株率51.9%,受害植株中平均枝条受害率20.4%,平均有虫瘿枝率1.9%。根据受害植株中有虫瘿枝率,巨园桉DH201-2虫源株所产生的桉树枝瘿姬小蜂对尾巨桉DH32-29扩散为害程度为轻度。  相似文献