陕西不同林区栓皮栎种群空间分布格局及动态的比较研究

在陕西黄龙山区、秦岭北坡和巴山北坡设置 1 0× 1 0 m2 样方 98个 ,应用相邻格子法进行每木调查获得野外资料 ,采用离散分布理论拟合检验、t检验和聚集强度测定的方法 ,对栓皮栎种群空间分布格局及动态进行了对比研究。结果表明 :1栓皮栎种群在黄龙山区为奈曼 A型分布 ,秦岭北坡和巴山北坡为负二项分布 ;聚集强度 ,秦岭北坡 >黄龙山区 >巴山北坡。 2在秦岭和巴山北坡中低海拔地区 ,种群为负二项分布 ,随海拔升高 ,秦岭北坡趋向随机分布 ,巴山北坡趋向均匀分布 ;两地种群聚集强度随海拔升高呈“低 -高 -低”的变化格局。3秦岭北坡 1～ 1 0年生种群的聚集度最大 ,随着年龄增加 ,聚集强度逐渐下降 ;而黄龙山区和巴山北坡种群的聚集强度随年龄增加而增强。栓皮栎种群生物学和生态学特性与环境因素共同作用是种群分布格局形成的主要因素 ,人为干扰对分布格局具有重要影响。根据环境条件和种群动态规律实行不同的经营方式是实现栓皮栎林持续利用的根本性措施     

秦岭地区大熊猫种群空间利用消长状态以及道路影响研究

研究大熊猫种群空间利用的消长动态及其干扰因素对识别大熊猫潜在生境、保护大熊猫种群可持续增长具有重要的现实意义。本文收集了第三次和第四次秦岭大熊猫种群及栖息地调查数据,借助地理信息系统空间分析工具,对比分析了大熊猫种群的空间利用变化格局,并探究了道路干扰对大熊猫种群空间利用格局的影响。结果显示：（1）2000-2012年间,佛坪、长青核心密集区大熊猫种群空间利用密度西北方向增加,东南方向减少,即黄柏塬保护区呈增加趋势,而佛坪、观音山和周至保护区交界处呈减少趋势。其中,局部高密度区面积减少,但整体空间利用面积增大,并呈向外围扩散趋势。种群空间利用密度最大增长达3.05痕迹点/ km²,最大减小密度达2.71痕迹点/km²。（2）距国道、省道和县道2000 m以内种群空间利用密度增幅上升,距乡村道路2000 m外种群空间利用密度变化减小,且距高速公路3500 m大熊猫种群空间利用密度由减转增。深入探讨大熊猫种群空间利用格局可为建设优良栖息地和潜在栖息地提供参考,其结论将有助于优化道路选址和保护区规划,缓解人为活动和野生动物之间的冲突。     

刀切法估计动物种群扩散型指数

一、引言研究动物种群空间格局,无论在生态学理论还是应用上都具有重要意义。用扩散型指数研究种群空间格局不受格局类型的限制,能反映空间格局的连续统(Continuum).长期以来,对扩散型指数的数值估计,大多采用矩法或最大似然法,由于扩散型指数的统计分布一般都比较复杂,而非正态,因而用建立在正态分布基础上的矩估计或最大似然估     

塔里木河上游天然胡杨林种群空间分布格局与动态研究

以新疆塔里木河上游阿瓦提县天然胡杨林为研究对象,采用相邻格子法进行实地调查,应用方差/均值比率法和5种聚集度指标研究了塔里木河上游天然胡杨林主要种群的空间分布格局与动态特征.结果显示:胡杨群落中除草本西北天冬种群空间分布格局呈随机分布外,其它主要种群均呈聚集分布;拟合检验表明,胡杨、灰叶胡杨种群为聚集分布.种群空间分布动态分析表明,灰叶胡杨在小树、中树与大树阶段均为聚集分布;胡杨种群在小树与中树阶段为聚集分布,但聚集强度减弱,到大树阶段为随机分布.研究表明,物种分布格局主要与物种本身的生物生态学特性和生境有关.     

扩散生态学及其意义

扩散研究是生态学研究中的一个热点领域 ,而扩散生态学则是生物学领域一门新的分支学科。本文综述了扩散生态学研究的一些基本理论问题 ,包括扩散的定义、扩散生态学的研究内容及其与生物学其它分支学科的关系 ,并阐述了研究扩散的重要意义。扩散生态学的研究内容十分广泛 ,既涉及所有生物 (从微生物到脊椎动物 )的生态学 (如复合种群、群落、生态系统多样性、复杂性和稳定性 )和进化 (如种化 )等理论问题 ,又涉及物种保护、生物多样性保育、有害生物 (包括外来物种 )的控制、流行病防范、环境保护和人口管理等应用问题。因此 ,研究生物的扩散具有十分重要的理论和实践意义。     

百山祖北坡常绿阔叶林多脉青冈种群结构和分布格局

本研究应用理论分布模型和5个聚集强度指标,研究百山祖北坡中山常绿阔叶林多脉青冈种群分布格局。结果表明：多脉青冈种群结构呈基部和中部宽、顶部窄的形状,龄级完整,属于稳定型,但存在波动性;从整个种群和不同发育阶段来看,多脉青冈的分布格局主要呈聚集分布,且随年龄增长,聚集度逐渐降低,呈现扩散趋势,到大树期为随机分布。种群自身生物学特性、种群生境以及环境资源等综合因素影响多脉青冈的年龄结构和分布格局。     

太白山巴山冷杉林主要树种与开花秦岭箭竹的空间点格局分析

采用单变量和双变量O-ring函数对太白山大熊猫栖息地巴山冷杉林主要树种的空间分布格局、种间关联性及其与林下开花箭竹的空间关联性进行了多尺度分析.结果表明: 巴山冷杉林中,巴山冷杉数量最多,但种群结构衰退,白桦种群相对年轻,种群结构稳定,红桦种群也呈衰退趋势;3个主要树种在小尺度上呈聚集分布,随尺度增加,逐渐表现为随机分布.3个树种的空间关联性主要表现在小尺度范围内,随尺度增加,空间分布格局逐渐表现为不关联;巴山冷杉和白桦与开花秦岭箭竹在大、中尺度内呈现正相关,而红桦与开花秦岭箭竹在大、中尺度上表现出负相关.大熊猫栖息地内乔木和林下秦岭箭竹共同推动森林的动态演替和发展,进而影响秦岭大熊猫栖息地的环境变化.     

祁连山北坡高寒草地狼毒种群格局

在祁连山北坡高寒退化草地,采用空间序列代替时间序列与点格局相结合的分析方法,研究了小尺度上狼毒种群的组成特征和分布格局.结果表明:伴随狼毒分盖度的增加,狼毒植株数总体上呈现先增大后减小的分布规律;幼株分布格局由随机分布向聚集分布过渡,聚集强度表现出先增强后减弱的规律,成株分布格局基本表现为随机分布;狼毒分盖度较低时,不同大小级狼毒种群在0～100 cm尺度上均表现为随机分布,狼毒分盖度较高时,随着种群的发育,分布格局由聚集分布向随机分布过渡.种群的分布格局与种群的扩散阶段存在密切的关系,狼毒种群通过斑块合并、斑块吞并以及竞争作用和协同作用的相互转化实现种群的扩散.     

GIS在野生动物空间分布格局研究中的应用

地理信息系统(GIS)在绘制动物分布图、确定物种丰富度、预测动物的空间分布格局、建立物种分布数据库等方面都有极大的应用价值。本文介绍了GIS技术在野生动物空间分布格局研究中的应用,并探讨了今后GIS技术在野生动物生态学领域的应用前景。     

复合种群中扩散的研究进展

复合种群理论是近年来景观生态学和保护生物学研究的热点之一,但有关复合种群的野外试验研究大多集中在面积和隔离度等方面,对影响复合种群动态因子的具体报道较少。事实上,复合种群的影响因子还有很多,如连通性、扩散和生境质量等。本文就复合种群中扩散进行了综述,主要包括以下的几个方面:(1)扩散的影响因子。生境质量、斑块连通性和种群自身密度等;(2)扩散方向与测定。扩散的方向是有选择的,在其方向的测定中微卫星标记(microsatellitemarker)得到了较广泛的应用;(3)扩散距离与测定。扩散的距离除受到物种自身特性的影响外,还受到踏脚石等生境因素的影响;(4)扩散对复合种群的影响。扩散受到复合种群空间结构以及生境质量等自身条件的影响,同时又反作用于复合种群的动态变化,在以后物种保护工作中必须加以重视。     

Characterizing the spatial distribution of giant pandas (Ailuropoda melanoleuca) in fragmented forest landscapes

Aim To examine the effects of forest fragmentation on the distribution of the entire wild giant panda (Ailuropoda melanoleuca) population, and to propose a modelling approach for monitoring the spatial distribution and habitat of pandas at the landscape scale using Moderate Resolution Imaging Spectro‐radiometer (MODIS) enhanced vegetation index (EVI) time‐series data. Location Five mountain ranges in south‐western China (Qinling, Minshan, Qionglai, Xiangling and Liangshan). Methods Giant panda pseudo‐absence data were generated from data on panda occurrences obtained from the third national giant panda survey. To quantify the fragmentation of forests, 26 fragmentation metrics were derived from 16‐day composite MODIS 250‐m EVI multi‐temporal data and eight of these metrics were selected following factor analysis. The differences between panda presence and panda absence were examined by applying significance testing. A forward stepwise logistic regression was then applied to explore the relationship between panda distribution and forest fragmentation. Results Forest patch size, edge density and patch aggregation were found to have significant roles in determining the distribution of pandas. Patches of dense forest occupied by giant pandas were significantly larger, closer together and more contiguous than patches where giant pandas were not recorded. Forest fragmentation is least in the Qinling Mountains, while the Xiangling and Liangshan regions have most fragmentation. Using the selected landscape metrics, the logistic regression model predicted the distribution of giant pandas with an overall accuracy of 72.5% (κ = 0.45). However, when a knowledge‐based control for elevation and slope was applied to the regression, the overall accuracy of the model improved to 77.6% (κ = 0.55). Main conclusions Giant pandas appear sensitive to patch size and isolation effects associated with fragmentation of dense forest, implying that the design of effective conservation areas for wild giant pandas must include large and dense forest patches that are adjacent to other similar patches. The approach developed here is applicable for analysing the spatial distribution of the giant panda from multi‐temporal MODIS 250‐m EVI data and landscape metrics at the landscape scale.     

Molecular analysis of dispersal in giant pandas

Although dispersal in the giant panda (Ailuropoda melanoleuca) is a demographic mechanism which can potentially counteract the negative effect of habitat fragmentation, little is known about dispersal in this species because of difficulties in observing individuals. Using data from faecal microsatellite genotyping, we compared the spatial distribution of giant pandas in two populations and the proximity of relatives in one key population to infer their dispersal pattern. We conclude that giant pandas exhibit female-biased dispersal because: (i) vAIc (variance of assignment index) for females was significantly larger than for males, suggesting that females comprise both 'local' and 'foreign' genotypes; (ii) the average spatial distance of related female dyads was significantly larger than that of males; (iii) larger r (relatedness), F(ST) (genetic variance among populations) and mAIc (mean of assignment index) values were found in males using the software FSTAT, although the differences were not significant; (iv) males set up territories neighbouring to their birth place; (v) significant population structure using microsatellites with a concomitant lack of mitochondrial structure was found in a previous study, possibly indicating more extensive female dispersal; and (vi) female-biased dispersal was strongly supported by evidence from concomitant ecological studies. Considering previous ecological data and life-history characteristics of the giant panda, female-biased dispersal is most likely to be due to competition for birth dens among females, inbreeding avoidance and enhancing inclusive fitness among related males.     

区域自然保护区群规划——以秦岭山系为例

自然保护区群的构建对于优化我国自然保护区空间布局、提高自然保护区的保护效果具有重要意义。以大熊猫为主要研究对象,以秦岭山系为研究区域,以生境评价与通达性分析为主要研究方法,探讨了自然保护区群合理布局与功能区优化的程序、内容与方法。研究表明,目前秦岭山系已建与筹建的大熊猫自然保护区17个,自然保护区群初步形成,保护了50%的大熊猫生境,但东部的3个自然保护区尚未全部相连,且整个自然保护区核心区被隔离为20部分,大大影响了自然保护区效果的发挥。为优化自然保护区的布局,建议新建湑水河与锦鸡梁两个自然保护区,以大熊猫居群为基本单位将核心区调整为4个,并且通过3个连接区的建设加强各大熊猫居群的连通性,以促进大熊猫种群间的交流与迁徙。研究结果可为秦岭山系自然保护区建设提供思路与依据,对其它地区自然保护区群的建立及全国自然保护区网络的优化也具有借鉴意义。     

Impacts of temperature on giant panda habitat in the north Minshan Mountains

Understanding the impacts of meteorological factors on giant pandas is necessary for future conservation measures in response to global climate change. We integrated temperature data with three main habitat parameters (elevation, vegetation type, and bamboo species) to evaluate the influence of climate change on giant panda habitat in the northern Minshan Mountains using a habitat assessment model. Our study shows that temperature (relative importance = 25.1%) was the second most important variable influencing giant panda habitat excepting the elevation. There was a significant negative correlation between temperature and panda presence (ρ = −0.133, P < 0.05), and the temperature range preferred by giant pandas within the study area was 18–21°C, followed by 15–17°C and 22–24°C. The overall suitability of giant panda habitats will increase by 2.7%, however, it showed a opposite variation patterns between the eastern and northwestern region of the study area. Suitable and subsuitable habitats in the northwestern region of the study area, which is characterized by higher elevation and latitude, will increase by 18007.8 hm² (9.8% habitat suitability), while the eastern region will suffer a decrease of 9543.5 hm² (7.1% habitat suitability). Our results suggest that increasing areas of suitable giant panda habitat will support future giant panda expansion, and food shortage and insufficient living space will not arise as problems in the northwest Minshan Mountains, which means that giant pandas can adapt to climate change, and therefore may be resilient to climate change. Thus, for the safety and survival of giant pandas in the Baishuijiang Reserve, we propose strengthening the giant panda monitoring program in the west and improving the integrity of habitats to promote population dispersal with adjacent populations in the east.     

Hopes and challenges for giant panda conservation under climate change in the Qinling Mountains of China

One way that climate change will impact animal distributions is by altering habitat suitability and habitat fragmentation. Understanding the impacts of climate change on currently threatened species is of immediate importance because complex conservation planning will be required. Here, we mapped changes to the distribution, suitability, and fragmentation of giant panda habitat under climate change and quantified the direction and elevation of habitat shift and fragmentation patterns. These data were used to develop a series of new conservation strategies for the giant panda. Qinling Mountains, Shaanxi, China. Data from the most recent giant panda census, habitat factors, anthropogenic disturbance, climate variables, and climate predictions for the year 2050 (averaged across four general circulation models) were used to project giant panda habitat in Maxent. Differences in habitat patches were compared between now and 2050. While climate change will cause a 9.1% increase in suitable habitat and 9% reduction in subsuitable habitat by 2050, no significant net variation in the proportion of suitable and subsuitable habitat was found. However, a distinct climate change‐induced habitat shift of 11 km eastward by 2050 is predicted firstly. Climate change will reduce the fragmentation of suitable habitat at high elevations and exacerbate the fragmentation of subsuitable habitat below 1,900 m above sea level. Reduced fragmentation at higher elevations and worsening fragmentation at lower elevations have the potential to cause overcrowding of giant pandas at higher altitudes, further exacerbating habitat shortage in the central Qinling Mountains. The habitat shift to the east due to climate change may provide new areas for giant pandas but poses severe challenges for future conservation.     

Synergistic effects of anthropogenic disturbances on giant pandas

Livestock grazing and the collection of bamboo shoots are the main threats to giant panda (Ailuropoda melanoleuca) habitat in the Liangshan Mountains in China. It is important to clarify the effect of these disturbances to the giant panda to formulate targeted management policies. Based on species distribution models and daily activity models, we investigated the effects of livestock grazing and bamboo shoot collection on giant pandas from May 2021 to July 2022. Our results indicated the giant panda's suitable habitat in the reserve covered 51.83 km² (15.02% of the reserve area). Grazing and bamboo shoot collection led to losses of 19.08 km² and 7.68 km² of suitable habitat, respectively. Together, the 2 activities resulted in a loss of 28.35 km² of suitable habitat, which was more than half of the area of panda habitat. The areas of suitable habitat for giant pandas significantly overlapped with the areas affected by both disturbances. Giant pandas did not show significant differences in daily activity rhythms under a single disturbance, but the daily activity rhythms of giant pandas differed when we compared the area combining the 2 disturbances with the undisturbed area. Our study reveals that the anthropogenic disturbances in the reserve have varying effects on the suitable habitat range and daily activity rhythm of giant pandas and evidence of a synergistic effect. Therefore, when formulating relevant conservation policies, it is important to fully evaluate the extent and characteristics of anthropogenic disturbances in shaping the population distribution and habitat preferences of the giant panda and other wildlife to enhance the efficacy of conservation management practices.     

TAS2R20 variants confer dietary adaptation to high‐quercitrin bamboo leaves in Qinling giant pandas

Sensitivity to bitter tastes provides animals with an important means of interacting with their environment and thus, influences their dietary preferences. Genetic variants encoding functionally distinct receptor types contribute to variation in bitter taste sensitivity. Our previous study showed that two nonsynonymous sites, A52V and Q296H, in the TAS2R20 gene are directionally selected in giant pandas from the Qinling Mountains, which are speculated to be the causative base‐pair changes of Qinling pandas for the higher preference for bamboo leaves in comparison with other pandas. Here, we used functional expression in engineered cells to identify agonists of pTAS2R20 (i.e., giant panda's TAS2R20) and interrogated the differences in perception in the in vitro responses of pTAS2R20 variants to the agonists. Our results show that pTAS2R20 is specifically activated by quercitrin and that pTAS2R20 variants exhibit differences in the sensitivity of their response to the agonist. Compared with pTAS2R20 in pandas from other areas, the receptor variant with A52V and Q296H, which is most commonly found in Qinling pandas, confers a significantly decreased sensitivity to quercitrin. We subsequently quantified the quercitrin content of the leaves of bamboo distributed in the Qinling Mountains, which was found to be significantly higher than that of the leaves of bamboo from panda habitats in other areas. Our results suggest that the decreased sensitivity to quercitrin in Qinling pandas results in higher‐quercitrin‐containing bamboo leaves to be tasting less bitter to them and thus, influences their dietary preference. This study illustrates the genetic adaptation of Qinling pandas to their environments and provides a fine example of the functional effects of directional selection in the giant panda.     

Integrating population size analysis into habitat suitability assessment: implications for giant panda conservation in the Minshan Mountains,China

Compared to conventional approaches, the integration of population size analysis with habitat suitability assessment on a large scale can provide more evidence to explain the mechanisms of habitat isolation and fragmentation, and thus make regional conservation plans. In this paper, we analyzed the habitat suitability for giant pandas in the Minshan Mountains, China, using the ecological-niche factor analysis (ENFA) method, and then evaluated the current conservation status of this endangered species. The results showed that (1) giant pandas were distributed in a narrow altitudinal range in which vegetation cover was dominated by coniferous forest, mixed coniferous and deciduous broadleaf forest, and deciduous broadleaf forest with scattered bamboo understory, and (2) roads and human settlements had strong negative effects on the panda habitat selection. According to habitat analysis, the total habitat area of giant panda in the Minshan Mountains was 953,173 ha, which was fragmented into 12 habitat units by major roads, rivers, and human settlements. The habitat of the mid-Minshan was less fragmentized, but was seriously fragmented in the north. The panda population size estimation showed that 676 individuals inhabited the study area, and 94.53% of them were in the mid-Minshan, but small panda populations less than 30 individuals inhabited the isolated and fragmented habitat patches in the north. The nature reserves in the Minshan Mountains have formed three conservation groups, which covered 41.26% of panda habitat and protected 70.71% of panda population of the study area, but there still exists two conservation gaps, and the connectivity among these reserves is still weak. Due to habitat isolation and extensive human disturbances, giant pandas in the north (i.e., Diebu, Zhouqu, and Wudou) are facing threats of local extinction. In order to protect pandas and their habitats in this area, some effective conservation approaches, such as establishing new reserves in gap areas, creating corridors among patches, and seasonally controlling traffic flux in key roads, should be implemented in the future to link these isolated habitats together.     

Inbreeding and inbreeding avoidance in wild giant pandas

Inbreeding can have negative consequences on population and individual fitness, which could be counteracted by inbreeding avoidance mechanisms. However, the inbreeding risk and inbreeding avoidance mechanisms in endangered species are less studied. The giant panda, a solitary and threatened species, lives in many small populations and suffers from habitat fragmentation, which may aggravate the risk of inbreeding. Here, we performed long‐term observations of reproductive behaviour, sampling of mother–cub pairs and large‐scale genetic analyses on wild giant pandas. Moderate levels of inbreeding were found in 21.1% of mating pairs, 9.1% of parent pairs and 7.7% of panda cubs, but no high‐level inbreeding occurred. More significant levels of inbreeding may be avoided passively by female‐biased natal dispersal rather than by breeding dispersal or active relatedness‐based mate choice mechanisms. The level of inbreeding in giant pandas is greater than expected for a solitary mammal and thus warrants concern for potential inbreeding depression, particularly in small populations isolated by continuing habitat fragmentation, which will reduce female dispersal and increase the risk of inbreeding.