陕西青木川国家级自然保护区脊椎动物 物种多样性现状和保护成效

野生动物资源本底是自然保护区开展生物多样性有效管理的基础。为了掌握脊椎动物资源现状和评估保护成效,在2017和2018年,利用样线法和红外相机陷阱法等方法,对陕西青木川国家级自然保护区脊椎动物资源进行了实地调查,并采用专家打分法对该保护区保护成效进行赋值评估。结果表明：（1）青木川自然保护区现已记录野生脊椎动物342种,隶属5纲32目91科233属,其中,国家I级、II级重点保护野生动物分别为10种和41种;与2002年保护区建立初期相比,增加了4目9科46属83种,其中,鸟类物种数增加最多,达55种,两栖类仅增加1种。（2）青木川镇游客总量从2009年的5万余人次/年,发展到2017年的162万人次/年,保护区外围的旅游开发对该保护区脊椎动物及栖息地均有一定的潜在影响。（3）过去30年内土地利用模式变化明显,2001年未建立保护区时,该区域农业用地面积约占总面积的33%,建立保护区后至2018年,农业用地仅占保护区总面积的1%,使得区域内脊椎动物的栖息地面积显著增加。（4）保护区的保护成效显著,主要干扰因素发生变化,表现为保护区脊椎动物物种总数明显增加,栖息地适宜性和区域完整性显著增强,主要干扰因素类型已由早期的农林牧渔活动转变为现在的外围旅游开发。     

Contribution of peeling host for epiphyte abundance in two tropical dry forests in the “El Cielo Biosphere Reserve”, Mexico

Host traits partly determine the abundance and species richness of epiphytes in tropical forests. It has been proposed that older trees with rough bark and evergreens often house more individuals and more epiphytic species than those with thin, smooth, and peeling bark, which harbor few epiphytes. We hypothesize (i) that epiphytes are more abundant and species-rich in the more shaded forest, which is related to bark roughness, and (ii) that epiphytes are distributed in the middle of the host, where microenvironmental conditions are more favorable to survival. We evaluated abundance, species richness, and vertical distribution of epiphytes in two tropical dry forests, according to the deciduousness and basal area of the trees. Moreover, we selected the most abundant epiphytes to test whether their distribution is related to a specific bark type and examine their vertical distribution in two dry forests. We distinguished a high abundance and species richness of epiphytes in the deciduous forest, although basal area and host species richness were higher in the semi-deciduous forest. In both forests, we found a positive relationship between epiphyte abundance and basal area. Higher abundance of epiphytes was related to the predominance of Tillandsia schiedeana, a drought-adapted species, in both forests. Unexpectedly, epiphytes abundantly colonized Bursera simaruba, a host with peeling bark and a very branched crown, where small individuals of T. schiedeana colonized abundantly toward the top of the crown. Our results show the importance of the tropical dry forest, particularly, B. simaruba, in maintaining epiphyte diversity in terms of T. schiedeana colonization.     

Inconsistent detection of extinction debts using different methods

The extinction debt, delayed species extinctions following landscape degradation, is a widely discussed concept. But a consensus about the prevalence of extinctions debts is hindered by a multiplicity of methods and a lack of comparisons among habitats. We applied three contrasting species–area relationship methods to test for plant community extinction debts in three habitats which had different degradation histories over the last century: calcareous grassland, heathland and woodland. These methods differ in their data requirements, with the first two using information on past and current habitat area alongside current species richness, whilst the last method also requires data on past species richness. The most data‐intensive, and hence arguably most reliable method, identified extinction debts across all habitats for specialist species, whilst the other methods did not. All methods detected an extinction debt in calcareous grassland, which had undergone the most severe degradation. We conclude that some methods failed to detect an extinction debt, particularly in habitats that have undergone moderate degradation. Data on past species numbers are required for the most reliable method; as such data are rare, extinction debts may be under‐reported.     

气候和土地利用与空间结构在影响大熊猫同域分布大中型哺乳动物物种丰富度中的相对作用

气候因子和土地利用因子是影响生物多样性分布格局的两个主要驱动因素。然而,当前关于气候因子和土地利用因子对生物多样性影响的研究主要集中在物种层面上,在群落水平上对生物多样性的影响依然知之甚少。本研究以大熊猫同域分布大中型哺乳动物为研究对象,结合物种丰富度数据、气候数据、土地利用数据以及经纬度数据,构建基于不同变量组合的多元线性模型,并通过模型拟合优度比较和方差分解等方法,探讨气候因子、土地利用因子和空间结构在影响大熊猫同域分布大中型哺乳动物物种丰富度中的相对作用。结果表明：（1）四川省大熊猫分布的五大山系内的大中型哺乳动物在属数和物种数方面差异较大。其中岷山山系的属数和物种数最高,分别为25属和28种,凉山山系的属数和物种数最低,分别为19属和20种,五大山系内排名前五的优势种分别为大熊猫、羚牛、野猪、中华斑羚、中华鬣羚;（2）大熊猫同域分布大中型哺乳动物物种丰富度在空间分布上差异较大。所有10 km×10 km栅格内的物种数在1~14之间,平均值为6.199±3.475;（3）完全模型（包含所有气候变量、土地利用变量和空间结构变量的模型,CLS）的拟合优度要好于其它6类模型,且包含土地利用变量模型的拟合优度要好于没有包含的模型;（4）气候变量、土地利用变量和空间结构变量共同解释了大熊猫同域分布大中型哺乳动物物种丰富度43.0%的空间变异,其中,土地利用变量对物种丰富度的解释率最高,单独解释率为23.2%,气候变量和空间结构变量的解释率则相对较低,单独解释率分别为6.3%和9.3%。这些研究结果说明土地利用因素是影响大熊猫同域分布大中型哺乳动物物种丰富度最为关键的驱动因素。因此,提高森林覆盖率,减少人为干扰和使用,是实现对大熊猫同域分布哺乳动物综合保护的关键。     

Can we manage fisheries with the inherent uncertainty from eDNA?

Environmental (e)DNA, as a general approach in aquatic systems, seeks to connect the presence of species' genetic material in the water and hence to infer the species' physical presence. However, fisheries managers face making decisions with risk and uncertainty when eDNA indicates a fish is present but traditional methods fail to capture the fish. In comparison with traditional methods such as nets, electrofishing and piscicides, eDNA approaches have more sources of underlying error that could give rise to false positives. This has resulted in some managers to question whether eDNA can be used to make management decisions because there is no fish in hand. As a relatively new approach, the methods and techniques have quickly evolved to improve confidence in eDNA. By evaluating an eDNA based research programmes through the pattern of the eDNA signal, assay design, experimental design, quality assurance and quality control checks, data analyses and concurrent search for fish using traditional gears, the evidence for fish presence can be evaluated to build confidence in the eDNA approach. The benefits for fisheries management from adopting an eDNA approach are numerous but include cost effectiveness, broader geographic coverage of habitat occupancy, early detection of invasive species, non-lethal stock assessments, exploration of previously inaccessible aquatic environments and discovery of new species hidden beneath the water's surface. At a time when global freshwater and marine fisheries are facing growing threats from over-harvest, pollution and climate change, we anticipate that growing confidence in eDNA will overcome the inherent uncertainty of not having a fish in hand and will empower the informed management actions necessary to protect and restore our fisheries.     

At Palmyra Atoll,the fish-community environmental DNA signal changes across habitats but not with tides

At Palmyra Atoll, the environmental DNA (eDNA) signal on tidal sand flats was associated with fish biomass density and captured 98%–100% of the expected species diversity there. Although eDNA spilled over across habitats, species associated with reef habitat contributed more eDNA to reef sites than to sand-flat sites, and species associated with sand-flat habitat contributed more eDNA to sand-flat sites than to reef sites. Tides did not disrupt the sand-flat habitat signal. At least 25 samples give a coverage >97.5% at this diverse, tropical, marine system.     

Trade-off between number and length of remote videos for rapid assessments of reef fish assemblages

Remote underwater videos are widely employed to assess the structure and composition of reef fish assemblages but the sampling effort employed on each survey differs considerably, indicating that both the number of assessments and video length could be optimized. We searched for this optimal sampling effort in remote video samples to conduct rapid assessments of community composition and discussed the relation between number of replicates and video length, and how it impacts the method's efficiency to characterize species assemblages. Remote video recordings from tropical reefs in northeastern Brazil were used to investigate how fish species richness and composition builds across time and number of assays. Videos as short as 5 min successfully recorded species richness, requiring about five repetitions to record most species that compose 80% of the total biomass. Recording species composition required even less time in these reefs, setting a minimum of 3 min with the same five videos. By comparing the detected richness per analysed time unit, we found several shorter videos recorded for more species than a few longer videos, indicating that increasing the sampling coverage in the reef area might be better than just extending the video length for rapid assessments.     

西南地区壳斗科物种丰富度和特有性分布格局模拟及其环境解释

如何准确地模拟物种宏观丰富度格局和特有性中心是生物多样性保护工作的重点,也是生物地理学的热点话题。西南地区是我国壳斗科植物最丰富的地区之一,但物种多样性格局及环境驱动机制尚不清楚。本研究基于西南地区161种壳斗科植物7258个分布点位数据,利用点格局法和物种分布模型两种方式构建了物种丰富度、加权特有性指数和校正加权特有性指数的分布格局,并采用空间自回归模型(SAR)分析上述3个多样性指数与环境因子间的关系。总体上看,物种分布模型模拟的3个指数在空间上比点格局法更为连续,但数值高低分布情况具有相似性: 两种方式模拟的物种丰富度高值区主要分布在滇南边缘、桂北部和桂西南部地区(62～89种);加权特有性指数最大值集中在滇南和桂西地区(1.77～5.02);藏东南、秦岭-大巴山、桂西南部和滇东南地区具有最高的校正加权特有性指数(0.07～0.17)。SAR模型结果显示:最干月降雨量、温度季节性变化标准差、海拔变幅和土壤有机碳含量对物种丰富度的影响均显著,最干月降雨量、温度季节性变化标准差、潜在蒸散量和海拔变幅对加权特有性有着显著影响,温度季节性变化标准差、最干月降雨量、历史温度变化、增强型植被指数变异系数和海拔变幅对校正加权特有性的影响显著;SAR模型对物种丰富度、特有性指数和加权特有性指数的拟合效果(R²=0.857、0.733、0.593)分别优于普通线性模型(R²=0.689、0.425、0.422)。综上,水分可获得性、气候季节性、生境异质性、历史气候变化和土壤状况是制约西南地区壳斗科丰富度和特有性分布的最重要因素。滇南、滇东南、桂西南、桂西、秦岭-大巴山以及藏东南地区是壳斗科物种丰富度中心或特有性中心,应受到重点关注和保护。     

中条山油松人工林下物种对群落物种丰富度分布格局的贡献

该研究以中条山油松人工林群落为研究对象,研究林下不同大小的子群落对群落物种丰富度分布格局的贡献,并确定影响该区域群落物种丰富度分布格局的关键种,为区域物种多样性保护提供理论依据。结果表明:(1)该地区林下物种频度分布格局呈明显右偏,且不同样方物种丰富度存在明显差异。(2)常见种对群落丰富度分布格局的贡献大于稀有种。(3)最常见的物种解释了整个群落物种丰富度格局的88.4%(P0.01),而最稀有物种仅解释了24.5%(P0.05),去除最稀有物种后,最常见物种可以解释剩余物种的90.8%(P0.01),而去除最常见物种后,最稀有物种仅能解释剩余物种的48.6%(P0.01)。(4)当子群落中常见种越多时,子群落与整个群落的丰富度分布格局相关性越高。(5)连翘(Forsythia suspensa)、太平花(Philadelphus pekinensis)、鞘柄菝葜(Smilax stans)、多歧沙参(Adenophora wawreana)、金花忍冬(Lonicera chrysantha)等对群落物种丰富度分布格局的贡献最大,但并非越常见的物种对群落丰富度格局贡献越大。(6)与频度较高物种的种间关联度低的物种对于群落物种的分布格局贡献较大,但此解释并不适用于稀有种。研究发现,稀有种对中条山油松人工林群落物种丰富度分布格局存在较大的贡献,所以在油松人工林物种多样性保护过程中并不能只关注常见种而忽视稀有种。     

Congruent spatial patterns of species richness and phylogenetic diversity in karst flora: Case study of Primulina (Gesneriaceae)

The karst landform in southern China is renowned for its high levels of species diversity and endemism. Globally, karst ecosystems are under threat from unsustainable anthropogenic disturbance and climate changes and are among the most threatened ecosystems worldwide. In this study, we used the typical karst endemic genus in southern China, Primulina Hance, as a model to identify areas within the karst landform with high diversity and to investigate congruence between phylogenetic and species‐based measures of diversity. Using phylogenetic information and species distribution data, we measured geographical patterns of diversity with four metrics: species richness (SR), corrected weighted endemism (CWE), phylogenetic diversity (PD), and phylogenetic endemism (PE). Our results revealed a high spatial congruence among SR, PD, and PE, with hotspot areas identified in the Nanling Mountains (i.e., north Guangdong and northeast Guangxi) and southeast Yungui Plateau (i.e., north and southwest Guangxi), whereas the hotspots of CWE are comparatively uniform throughout the geographic extent. The categorical analysis of neo‐ and paleoendemism identified a pattern of mixed neo‐ and paleoendemism in numerous grid cells, suggesting that karst areas in southern China have acted as both “museums” and “cradles” of plant evolution. Conservation gap analysis of hotspots revealed that the majority of prioritized hotspots (>90%) of the genus are outside of protected areas, therefore indicating the limited effectiveness of national nature reserves for the karst flora. Overall, our results suggest that the karst flora merits more conservation attention and SR can be an effective surrogate to capture PD in conservation planning.