Photosynthesis–nitrogen relationships in species at different altitudes on Mount Kinabalu, Malaysia

In situ photosynthetic nitrogen-use efficiency (PNUE, photosynthetic capacity per unit leaf nitrogen) was investigated in species that commonly distributed at different altitudes (600–3700m above sea level) on Mount Kinabalu. Photosynthetic nitrogen-use efficiency was lower in species at higher altitudes, with a mean PNUE at 3700m being one-third as large as that at 600m. This difference in PNUE was larger than that explained by the biochemical response to lower air pressures only. Across altitudes a negative correlation between ¹³C abundance (¹³C) and PNUE was found. Species at higher altitudes tended to have higher ¹³C, suggesting that they had a lower conductance for CO₂ diffusion from the air to chloroplasts. The lower conductance might be responsible for the lower PNUE in species at higher altitudes. Although leaf nitrogen content per unit area tended to be higher at higher altitudes, it did not seem to contribute to increasing photosynthetic rates. Thus, the idea that a higher nitrogen content at higher altitudes is a compensation for a lower PNUE was not supported. In contrast to the large difference in PNUE among altitudes, PNUE tended to converge within a narrow range among species growing at the same altitude.     

Early succession on lahars spawned by Mount St. Helens

The effects of isolation on primary succession are poorly documented. I monitored vegetation recovery on two Mount St. Helens lahars (mud flows) with different degrees of isolation using contiguous plots. Seventeen years after the eruption, species richness was stable, but cover continued to increase. That isolation affects community structure was confirmed in several ways. The dominance hierarchies of the lahars differed sharply. Detrended correspondence analysis on Lahar I showed a trend related to distance from an adjacent woodland, whereas vegetation on Lahar II was relatively homogeneous. Spectra of growth forms and dispersal types also differed. Lahar I was dominated by species with modest dispersal ability, while Lahar II was dominated by species with better dispersal. Variation between plots should decline through time, a prediction confirmed on Lahar II. Lahar I remained heterogeneous despite having developed significantly higher cover. Here, the increasing distance from the forest has prevented plots from becoming more homogeneous. At this stage of early primary succession, neither lahar is converging towards the species composition of adjacent vegetation. This study shows that isolation and differential dispersal ability combine to determine initial vegetation structure. Stochastic effects resulting from dispersal limitations may resist the more deterministic effects of competition that could lead to floristic convergence.     

新疆托木尔峰黄土地层中蜗牛化石组合及其意义(腹足纲:肺螺亚纲:柄眼目)

本文记述了采自新疆托木尔峰黄土地层中的蜗牛化石,经鉴定有１２种和１待定种,隶属于６科７属。依据现生蜗牛的生活习性,栖息环境及地理分布相比较,划分蜗牛化石２个组合,即琥珀螺Ｓｕｃｉｎｅａ属组合和华蜗牛Ｃａｔｈａｉｃａ属组合及其所反映的生态环境,讨论了新疆托木尔峰黄土地层形成时期的生物气候环境。     

Limits to convergence of vegetation during early primary succession

Questions: Primary succession, measured by changes in species composition, is slow, usually forcing a chronose‐quence approach. A unique data set is used to explore spatial and temporal changes in vegetation structure after a 1980 volcanic eruption. On the basis of data from a transect of 20 permanent plots with an altitudinal range of 250 m sampled through 2005, two questions are asked: Do changes along the transect recapitulate succession? Do plots converge to similar composition over time? Location: A ridge between 1218 and 1468 m on Mount St. Helens, Washington, USA. Methods: Repeat sampling of plots for species cover along a 1‐km transect. Floristic changes were characterized by techniques including DCA, clustering and similarity. Results: Species richness and cover increased with time at rates that decreased with increasing elevation. The establishment of Lupinus lepidus accelerated the rate of succession and may control its trajectory. Diversity (H) at first increased with richness, then declined as dominance hierarchies developed. Primary succession was characterized by overlapping phases of species assembly (richness), vegetation maturation (diversity peaks, cover expands) and inhibition (diversity declines). Each plot passed through several community classes, but by 2005, only four classes persisted. Succession trajectories (measured by DCA) became shorter with elevation. Similarity between groups of plots defined by their classification in 2005 did not increase with time. Similarity within plot groups converged slightly at the lower elevations. Despite similarities between temporal and spatial trends in composition, trajectories of higher plots do not recapitulate those of lower plots, apparently because Lupinus was not an early colonist. Any vegetation convergence has been limited to plots that are in close proximity.     

本溪关门山国家森林公园游客行为特征

研究游客行为特征对于旅游资源的开发、管理以及旅游目的地的可持续发展具有重要的作用。以本溪关门山国家森林公园为研究对象,通过问卷调查的方法对游客的人口统计学特征、地域结构特征、一般行为特征、消费特征及感知特征进行了研究。结果表明:关门山国家森林公园的游客以较高学历的男性中青年为主;客源主要来自本省辽宁,并以沈阳、本溪和大连的游客为主,客源地理集中度指数为35.71;旅游的主要目的是观赏枫叶,出游时间大部分集中在每年"十一"黄金周期间,且半数以上为当日往返的短程游览者;游客偏好与家人一起出游的旅行方式,所选择的交通工具主要为自驾车和旅游专车;游客的消费结构不平衡,主要集中于景区门票和交通费,占总消费的56.7%;游客对景区的喜好度依次为龙门峡景区月台子景区小黄山景区夹砬子景区鸣翠谷景区。总的来说,游客满意度较高,有89.1%的游客愿意重游此地,游客最不满意的地方主要表现在景区卫生方面。基于调查研究结果,对关门山国家森林公园的开发建设和可持续发展提供了相关建议。     

深圳马峦山华南紫萁群落及其物种多样性特征研究

对深圳马峦山地区华南紫萁占优势的植物群落进行研究,结果表明：华南紫萁群落中共有维管植物48科69属82种,种类组成具有明显的南亚热带性质;年龄结构显示群落的主要优势种属于稳定型种群,群落总体处于稳定状态;群落的频度指数规律为A＞B＜C＞D＞E,与RaunKiaer频度定律、海南岛山地雨林优势种群的频度规律等不相符合;华南紫萁种群树高和个体数百分比显示,种群高度0.3~0.7 m植株占比例较大,种群处于旺盛发展期;物种多样性指数为SP＝16.42,SW＝4.56,均匀度指数为E＝0.33,E′＝0.83,群落物种多样性指数和均匀度指数均较高,接近典型南亚热带常绿阔叶林顶极群落类型。本研究揭示了华南紫萁野外生存状态,为该种的保护和利用提供了基础资料。     

五台山林区典型人工林群落物种多样性研究

对山西五台山林区4种典型人工林群落物种多样性特征进行了定量研究,结果表明: 1 4种人工林群落灌木层和草本层的Simpson指数 D 和Shannon-Wienner指数 H′ 差异不显著,物种丰富度指数和均匀度指数 Jsw 差异显著,均匀度指数 Ea 差异极显著,草本层发育明显好于灌木层; 2 各人工群落尚处于演替初期阶段,林下植被发育常以禾本科阳生性植物为主; 3 对4种人工林群落灌草层物种多样性显著性检验结果显示,在灌草层物种多样性特征上,油松林与桦木林、山杨林多样性差异显著 P<0.05 ,其它群落差异不显著.山杨林物种多样性程度较高,油松林最差; 4 不同人工林群落物种总体多样性特征分析表明,桦木和山杨人工林群落总体α多样性与油松林差异显著,且多样性较大,阔叶林更有利于林下植被的发育和更新; 5 对人工生态系统物种多样性研究是退耕还林、天然林保护等生态环境工程的延伸,对于植被恢复后的生物学效果评价有重要意义.     

A comparison of estimates of relative abundance from a weakly structured mass‐participation bird atlas survey and a robustly designed monitoring scheme

Estimates of population size are frequently used in conservation. Volunteer‐conducted surveys are often the only source of information available, but their reliability is unclear. We compare data from a weakly structured national bird atlas collected by volunteer surveyors free to choose where and when to visit with data from an independent suite of monitoring surveys that used a stratified sampling design. We focus on the Mount Lofty Ranges, South Australia, a region that has lost most of its native vegetation. Both datasets comprise several thousand 20‐min 2‐ha searches carried out between 1999 and 2007. The atlas dataset reported more species, and covered habitats more comprehensively, but showed greater variability in the temporal and spatial distribution of survey effort. However, after we restricted the atlas dataset to native eucalypt woodlands, reporting rates from the two schemes were very strongly correlated. The structured surveys tended to record more species that are normally detected by call and the unstructured surveys recorded more species using edges and open habitats. Minimum population estimates from the two datasets agreed very well. The strength of concordance depended on whether overflying birds were included, highlighting the importance of distinguishing such records in future surveys. We conclude that appropriate calibration using selected regional surveys, including surveys to estimate absolute densities, can enable volunteer‐collected and weakly structured atlas data to be used to generate robust occupancy and minimum population estimates for many species at a regional scale.     

Prey spectra of two swarm-raiding army ant species in East Africa

Although swarm-raiding army ants are considered keystone predators in tropical forest ecosystems, information on the prey spectra of most species is based on anecdotal reports and not on systematic studies with extensive sampling. We analysed prey samples of 18 colonies of the two afrotropical species Dorylus ( Anomma ) molestus and Dorylus ( Anomma ) wilverthi (4289 prey items in total) to examine the prey composition variation within and between species and to determine the best methodology to obtain reliable prey spectrum estimates for a given species, site and season. Variation in prey composition was substantial for D. molestus even within a single site and season, with the biomass proportion of the most important prey type differing by a factor of 12. Conclusions from studies using small samples sizes may thus be misleading. We demonstrate that the method of assessing prey spectra in terms of relative prey item numbers often produces biased results, and therefore recommend relative prey biomass as the more useful parameter. The near absence of earthworms, which always constituted a substantial part of the D. molestus prey, in the diet of D. wilverthi is interpreted to result from subtle differences in swarm-raiding behaviour between these two species, but could alternatively also be due to low availability. Similar studies recording prey composition as biomass proportions and analysing large samples sizes from many colonies are needed to understand the effect of army ant swarm raids on invertebrate communities in afrotropical forests.     

江西九连山自然保护区昆虫区系分析

据对有较详细分布资料的1312种昆虫的分析,该区的昆虫区组成以东洋界成员为主体计817种,占总数的62．27％,说明本区昆虫属于东洋界范畴,按中国动物区划分析表明,华中,华南,西南三区的昆虫亲缘关系最为密切,阐述了182种昆虫在我国东部地区分布的南北限。