气候变化对邛崃山系大熊猫主食竹和栖息地分布的影响

气候变化对生物多样性的影响,特别是珍稀濒危物种的影响是当前的研究热点。全球气候变化对大熊猫的影响一直受到广泛关注。根据野外调查的大熊猫活动痕迹点、竹类分布点和主食竹扩散距离数据,采用Maxent模型,利用植被、地形、气候等因素,在RCP8.5下分析了2050年和2070年邛崃山系大熊猫主食竹分布及栖息地变化趋势。结果显示:(1)未来大熊猫适宜生境及主食竹气候适宜区面积均有所减少,到2070年分别减少37.2%和4.7%;(2)未来主食竹分布范围总体向高海拔扩展,但面积持续减少,到2070年分布面积比当前减少8.3%;(3)大熊猫栖息地未来有向高海拔扩张的趋势,在低海拔地区退缩明显,到2070年较当前减少27.2%;但到2070年大熊猫栖息地面积加上非栖息地有主食竹分布的面积,较现有大熊猫栖息地面积大1.5%;(4)受气候变化影响较严重的区域是邛崃山系南部以及低海拔地区,其余区域所受影响相对较小;(5)未来需要加强对受气候变化影响严重区域的监测与保护,特别是邛崃山系中部的大熊猫集中分布区。     

武功山地区种子植物区系研究

通过多次野外调查及资料整理,对武功山地区种子植物科、属、种的组成及区系特征进行了调查分析,为该区植物资源的保护以及植物分区提供理论依据。结果表明:(1)武功山地区共有种子植物166科、814属、2 079种,分别占江西省种子植物科、属、种总数的72.81%、61.11%、50.46%,其中裸子植物有7科、15属、19种,分别占江西裸子植物总数的77.78%、65.21%、54.28%。(2)武功山地区科包含12个分布区类型,热带成分占优势(70科,占57.96%),温带成分丰富(46科,38.65%);属包含14个分布区类型,热带成分略占优势(368属,49.40%),温带成分增加(354属,47.53%);种包含14个分布类型,热带分布性626种(31.04%),温带分布性663种(32.87%),温带成分略占优势;武功山地区植物成分具有热带向温带过渡的特点,并且热带和温带成分相互交融、渗透。(3)武功山地区种子植物具有单种和少种的科属较多,具有起源古老的特点,其中单种属有414属,占总属数的50.86%。中国特有成分有4科、23属、728种。(4)与相邻的15个代表性区系比较表明,武功山地区种类较为丰富,聚类分析表明该区系与黄山、庐山、武夷山、井冈山等地区的关系很密切,与秦岭、西双版纳和高黎贡山的区系关系最疏远。     

Coping with the cold: minimum temperatures and thermal tolerances dominate the ecology of mountain ants

1. Ants (Hymenoptera: Formicidae) are often cited as highly thermophilic and this has led to a range of studies investigating their thermal tolerances. It is unknown, however, if the geographic distribution of ant thermal tolerance conforms to the two major macropyhsiological rules that have been found in other taxa: Janzen's and Brett's rules. In addition, there is a paucity of data on how the lower thermal tolerances of ants are able to influence behaviour. 2. These two knowledge gaps were addressed here by sampling ants across a 1500 m elevational gradient in southern Africa and estimating the upper (CTmax) and lower (CTmin) thermal tolerances of 31 and 28 species, respectively. Ant abundances and soil temperatures were also recorded across the gradient over 6 years. 3. It was found that the average CTmin of the ants declined with elevation along with environmental temperatures. It was also found that the correlation between abundance and local temperature depended on the ant species' CTmin. The activity of species with a low CTmin was not constrained by temperature, whereas those with a high CTmin were limited by low temperatures. 4. For the first time, evidence is provided here that the thermal tolerances of ants are consistent with two major macrophysiological rules: Brett's rule and Janzen's rule. A mechanistic link between physiology, behaviour and the environment is also shown, which highlights that the ability of ants to deal with the cold may be a key, but often overlooked, factor allowing multiple ant species to succeed within an environment.     

Mechanisms driving understory evergreen herb distributions across slope aspects: as derived from landscape position

In the Northern Hemisphere, the surface of south-facing slopes orients toward the sun and thus receives a greater duration and intensity of solar irradiation, resulting in a relatively warmer, drier microclimate and seasonal environmental extremes. This creates potentially detrimental conditions for evergreen plants which must endure the full gamut of conditions. I hypothesize that (1) increased southerly aspect will correlate negatively with evergreen understory plant distributions; (2) derived environmental variables (summer and winter light and heat load) will predict variance in evergreen distributions as well as topographic position (aspect, slope, and elevation) and (3) winter light will best predict evergreen understory plant distributions. In order to test these hypotheses, survey data were collected characterizing 10 evergreen understory herb distributions (presence, abundance, and reproduction) as well as the corresponding topographical information across north- and south-facing slopes in the North Carolina mountains and Georgia piedmont. The best predictive models were selected using AIC, and Bayesian hierarchical generalized linear models were used to estimate the strength of the retained coefficients. As predicted, evergreen understory herbs occurred and reproduced less on south-facing than north-facing slopes, though slope and elevation also had robust predictive power, and both discriminated well between evergreen species. While the landscape variables explained where the plants occurred, winter light and heat load provided the best explanation why they were there. Evergreen plants likely are limited on south-facing slopes by low soil moisture combined with high temperatures in summer and high irradiance combined with lower temperatures in winter. The robust negative response of the understory evergreen herbs to increased winter light also suggested that the winter rather than the summer (or growing season) environment provided the best predictive power for understory evergreen distributions, which has substantive implications for predicting responses to global climate change.     

Global patterns of genetic variation in plant species along vertical and horizontal gradients on mountains

Aim To understand global patterns of genetic variation in plant species on mountains and to consider the significance of mountains for the genetic structure and evolution of plant species. Location Global. Methods We review published studies. Results Genetic diversity within populations can vary along altitudinal gradients in one of four patterns. Eleven of 42 cited studies (26% of the total) found that populations at intermediate altitudes have greater diversity than populations at lower and higher altitudes. This is because the geographically central populations are under optimal environmental conditions, whereas the peripheral populations are in suboptimal situations. The second pattern, indicating that higher populations have less diversity than lower populations, was found in eight studies (19%). The third pattern, indicating that lower populations have lower diversity than higher populations, was found in 10 studies (24%). In 12 studies (29%), the intrapopulation genetic variation was found to be unaffected by altitude. Evidence of altitudinal differentiation was found in more than half of these studies, based on measurements of a range of variables including genome size, number of chromosomes or a range of loci using molecular markers. Furthermore, great variation has been found in phenotypes among populations at different altitudes in situ and in common garden experiments, even in cases where there was no associated variation in molecular composition. Mountains can be genetic barriers for species that are distributed at low elevations, but they can also provide pathways for species that occupy high‐elevation habitats. [Correction added after publication 9 October 2007: ‘less diversity’ changed to ‘greater diversity’ in the second sentence of the Results section of the Abstract] Main conclusions Genetic diversity within populations can vary along altitudinal gradients as a result of several factors. The results highlight the importance of phenotypic examinations in detecting altitudinal differences. The influence of mountain ridges on genetic differentiation varies depending, inter alia, on the elevation at which the species occurs. Based on these findings, zoning by altitudes or ridges would be helpful for the conservation of tree populations with the onset of global warming.     

大兴安岭兴安落叶松(Larix gmelinii)天然林分级木转换特征

通过调查样地,作树干解析,分析了不同结构兴安落叶松天然林分级木（优势木、平均木和被压木）转换特征。研究表明：（1）不同结构的兴安落叶松天然林分级木转换年龄、方向和转换率均不同。兴安落叶松分级木转换率29.4%。分级木中,优势木、平均木和被压木转换率分别35.3%、41.2%、11.8%。分级木转换中,优势木与平均木相互转换比例较高,优势木转平均木占83.3%,平均木转优势木占85.7%;优势木向被压木转换比例仅为16.7%;被压木不能转换成优势木,只能转换成平均木,被压木中无转换占88.2%,在森林经营和抚育采伐中应考虑伐除这些被压木。（2）在林分年龄36～65a范围内,随着林分年龄增大,其转换率呈增加趋势。林分年龄30～39a、50～59a和60～69a时,其转换率分别0、33.3%和46.7%。（3）随着林分密度增加,分级木转换率呈增高趋势。当林分密度小于2500株.hm^-2时,主要于优势木与平均木间转换。当林分密度大于2500株.hm^-2时,才出现其它分级木与被压木相互转换现象。（4）不同林型分级木转换率和转换方向不同。草类-落叶松和杜香-落叶松林分级木转换率分别50%和9.5%。（5）不同水平格局林分分级木转换率不同。聚集分布和随机分布时,其转换率分别61.1%和13.3%。     

天山北坡不同环境条件下雪岭云杉(Picea schrenkiana)林限土壤属性

为了研究干旱区天山北坡中山带长达1000余公里的单建群种山地针叶林的空间分布原因,选择精河、玛纳斯、阜康和巴里坤中山带作为四种不同的环境条件,通过对不同环境条件雪岭云杉(Picea schrenkiana)上、下限土壤的采样与分析,探讨土壤因素对天山北坡中山带雪岭云杉分布的控制作用.雪岭云杉在天山北坡的连续分布主要是水热组合条件和土壤因素相互作用的结果,上、下限土壤属性变化与环境条件变化间存在着紧密的联系,表现为降雨量丰富的玛纳斯林区土壤肥力较高,但CaCO3含量较低,而降雨量较小的巴里坤和精河林区土壤肥力较差,但CaCO3含量较高.虽然长达1000余公里的雪岭云杉中山带环境条件差异较大,但其土壤属性变化均在雪岭云杉发育所需土壤条件的允许范围之内,这主要是受土壤成土母质、不同海拔高度的降雨量、地形、局地环流等因素的共同影响.     

Hillslope Nutrient Dynamics Following Upland Riparian Vegetation Disturbance

We investigated the effects of removing near-stream Rhododendron and of the natural blowdown of canopy trees on nutrient export to streams in the southern Appalachians. Transects were instrumented on adjacent hillslopes in a first-order watershed at the Coweeta Hydrologic Laboratory (35°03′N, 83°25′W). Dissolved organic carbon (DOC), K⁺, Na⁺, Ca²⁺, Mg²⁺, NO₃ ⁻-N, NH₄ ⁺-N, PO₄ ³⁻-P, and SO₄ ²⁻ were measured for 2 years prior to disturbance. In August 1995, riparian Rhododendron on one hillslope was cut, removing 30% of total woody biomass. In October 1995, Hurricane Opal uprooted nine canopy trees on the other hillslope, downing 81% of the total woody biomass. Over the 3 years following the disturbance, soilwater concentrations of NO₃ ⁻-N tripled on the cut hillslope. There were also small changes in soilwater DOC, SO₄ ²⁻, Ca²⁺, and Mg²⁺. However, no significant changes occurred in groundwater nutrient concentrations following Rhododendron removal. In contrast, soilwater NO₃ ⁻-N on the storm-affected hillslope showed persistent 500-fold increases, groundwater NO₃ ⁻-N increased four fold, and streamwater NO₃ ⁻-N doubled. Significant changes also occurred in soilwater pH, DOC, SO₄ ²⁻, Ca²⁺, and Mg²⁺. There were no significant changes in microbial immobilization of soil nutrients or water outflow on the storm-affected hillslope. Our results suggest that Rhododendron thickets play a relatively minor role in controlling nutrient export to headwater streams. They further suggest that nutrient uptake by canopy trees is a key control on NO₃ ⁻-N export in upland riparian zones, and that disruption of the root–soil connection in canopy trees via uprooting promotes significant nutrient loss to streams. Received 30 January 2001; accepted 25 July 2002.     

The content of total sulphur and sulphur forms in birch (Betula pendula Roth) leaves in the air-polluted Krusne hory mountains

In leaves of birch (Betula pendula Roth), changes in the content of total sulphur and its inorganic and organic forms were determined in relation to the decreasing air-pollution load (SO₂) in the air-polluted Krusne hory mountains and the Decin sandstone highlands in 1995, 1998, 2001 and 2004. Results have shown that birch is able to use considerable amounts of sulphur taken through leaves from air-pollution load. Birch responds fast to changes in air-pollution load by fall in the content of total and inorganic forms of sulphur in leaves.     

Ecological niche modeling of the sympatric giant and red pandas on a mountain-range scale

Habitat use and separation between the two sympatric species, the giant panda and the red panda, have been primary causes of coexistence at the fine scale. In this paper, we addressed the question of coexistence between species in space. By Ecological Niche Factor Analysis, we calculated species-specific habitat requirements, built habitat suitability maps and examined interspecific differences in spatial niche parameters. According to the ENFA scores, suitable habitats in the giant and red panda are surrounded by high-altitude, and are rich in conifer forest. Compared with the giant panda, however, the red panda rather preferred sparse forests, and normally colonized far from village and road. Despite similar narrow niche breadth for both pandas, difference of niche overlap indices implied that the width of environmental niche of red pandas almost completely encompasses that of the giant panda. We, therefore, suggest that differences in use of ecological niche variables may contribute to coexistence of the sympatric species in space. Based on highly suitable locations of the sympatric species maps, most official reserves appear to be poorly located or are too small, and new reserves are recommended to be established in the central part of core habitats in the Liangshan Mountains.