赤峰市沙地油松林草本植物多样性及种间关联动态

研究了赤峰市天然沙地油松林草本植物群落物种多样性以及种间关联动态。在200m×200m的样地中,设置100个1m×1m草本样方,2009年69月份每月底调查样方内所有草本植物物种、多度、高度及盖度。分析结果表明,69月份共调查到草本植物32种,隶属于16科,24属。用多项指标进行物种多样性的测度,8月份草本植物物种数、丰富度最高。6、7月份草本植物群落的Simpson指数、Shannon-Wiener指数和均匀度指数最大,9月份最小。通过方差比率法(VR)和χ2检验的计算,对草本群落总体关联性和草本群落种间关联进行分析。结果表明,草本植物群落总体关联性在8月份为正关联,其它月份(6、7、9月份)均为负关联。69月份,草本植物群落总体关联性程度逐渐降低,由负相关逐渐变为不显著相关。群落总体相关性不显著,说明群落中物种间虽然存在一定联系,但仍然存在独立的分布格局。某一草本群落总体关联性随时间变化是在不断改变的,并不是单一的从负相关到正相关,或从相关到不相关。群落整体关联性随着生境的改变而发生变化。分析每月都出现的20个物种的种间关联,结果显示,69月份草本植物正负联结比值变动范围为0.3790.558;4个监测月份中负联结种对数均大于正联结种对数。69月份草本物种对之间的关联性也在随时间发生变化,说明随着群落内物种动态发育,群落组成在不同时期出现此消彼长的动态变化,不同物种的群落功能及相互关系也将发生改变,进而影响物种种间联结性。植物种对的正联结体现了植物利用资源的相似性和生态位的重叠性,植物种对的负联结体现了物种间的排斥性,这是长期适应不同微环境,利用不同空间资源的结果,也是生态位分离的反映。     

吉林省天然阔叶混交林生态系统多功能性及驱动因素

量化天然林生态系统的多功能性,分析不同功能间的权衡-协同关系及驱动因子,对于天然林保护及修复具有重要的意义。基于吉林省第8次森林资源清查天然阔叶混交林固定样地调查数据、土壤及气候数据,选取土壤保持、涵养水源、碳储量、气候调节、土壤肥力维持、生物多样性、生产力和木材生产8个生态系统功能来表征生态系统多功能性。利用平均值法中的最大值转换法计算多功能性指数。结果表明：（1）8个功能间权衡、协同和中性关系均存在,但以协同关系为主。生物多样性除与气候调节为权衡关系外,与其他功能均为协同关系;碳储量-木材生产协同关系最强（r=0.960,P<0.01）,气候调节-涵养水源间权衡关系最强（r=-0.934,P<0.01）;（2）吉林省天然阔叶混交林的多功能性指数在0.31-0.89之间,且生物多样性和气候调节为主导功能;（3）多功能性与驱动因子的结构方程模型确定系数为R²=0.795,多功能性的驱动因子的总路径系数依次为：林分密度指数（0.752） > 平均年龄（0.375） > 年降雨量（0.365） > 树种丰富度（0.101） > 土壤pH（0.064） > 结构多样性（-0.037） > 年均温（-0.105）,林分密度是最重要的驱动因子。结果对理解天然阔叶混交林的多功能形成及经营调控有一定的意义。     

Primary Seed Dispersal by Red Howler Monkeys and the Effect of Defecation Patterns on the Fate of Dispersed Seeds1

The effectiveness of a seed disperser depends on the quantity and quality of dispersal. The quality of dispersal depends in large part on factors that affect the post–dispersal fate of seeds, and yet this aspect of dispersal quality is rarely assessed. In the particular case of seed dispersal through endozoochory, the defecation pattern produced has the potential of affecting the fate of dispersed seeds and consequently, dispersal quality and effectiveness. In this study, I assessed the effects of dung presence and dung/seed densities on seed predation by rodents and secondary dispersal by dung beetles. In particular, I compared seed fates in clumped defecation patterns, as those produced by howler monkeys, with seed fates in scattered defecation patterns, as those produced by other frugivores. I also determined the prevalence of red howler monkeys (Alouatta seniculus) as seed dispersers at the plant community level in Central Amazonia by determining the number of species they dispersed in a 25–month period. I found that dung presence and amount affected rodent and dung beetle behavior. Seed predation rates were higher when dung was present, and when it was in higher densities. The same number of seeds was buried by dung beedes, in dumped versus scattered defecation patterns, but more seeds were buried when they were inside large dung–piles versus small piles. Seed density had no effect on rodent or dung beetle behavior. Results indicate that caution should be taken when categorizing an animal as a high or low quality seed disperser before carefully examining the factors that affect the fate of dispersed seeds. Red howler monkeys dispersed the seeds of 137 species during the study period, which is the highest yet reported number for an Alouatta species, and should thus be considered highly prevalent seed dispersers at the plant community level in Central Amazonian terra firme rain forests.     

Coexistence and divergence of tropical dry forests and savannas in southern Mexico

Aim The purpose of the study was to assess the degree of floristic differentiation between tropical dry forest (TDF) and savanna occurring in a single landscape. This comparison provides information on the responses of vegetation to the prevailing environmental conditions, while it also allows us to make inferences about large‐scale events and processes, both biogeographical and evolutionary. Our approach included three levels of analysis: (1) taxonomic, (2) morphological and (3) vegetational. Location The seasonal dry tropical landscape in the Nizanda region, Oaxaca State, southern Mexico. The landscape comprises a complex vegetation mosaic in which tropical dry forest and savannas are the most conspicuous components. Methods Comparisons between TDF and savanna were based on inventories for these communities produced after 8 years of botanical survey. At the taxonomic level, the relative representation of taxa of different hierarchical levels in each community was examined. Morphological analyses required the classification of species on each of three criteria: (1) growth form, (2) life form and (3) growth habit. Vegetation level analysis was based on the frequencies of taxa in one hundred 100‐m² composition plots with which matrices of binary data were constructed for species, genera and families. These were subjected to classification analysis with Ward's method and using Euclidean distances as the dissimilarity algorithm. Results The combined flora for both communities comprised 600 species, 375 genera and 94 families; between them they shared 31, 40 and 34 taxa, respectively. The corresponding Sørensen similarity values were 10%, 21% and 72%, respectively. Ranking genera and families according to their species richness displayed large differences between savanna and TDF. Large differences between these communities were observed for Acanthaceae, Cactaceae, Euphorbiaceae and Mimosaceae, whereas Fabaceae and Asteraceae had similar high ranks according to the species richness in the two systems. The growth form spectrum diverged between the two communities, with TDF having more trees, shrubs and climbers. Savanna was characterised by forbs and graminoid herbs. Growth habit spectra revealed a clear dominance of herbaceous and suffruticose plants in savanna, and of woody elements and epiphytes in TDF. Regarding Raunkiaer's life forms, savanna had relatively more hemicryptophytes, and TDF more phanerophytes. Classification analyses showed that savanna and TDF forest samples kept their identities, regardless of taxonomic level (species, genera and families) at which the analyses were performed. Main conclusions The TDF and savanna of Nizanda represent two floristic systems with a large degree of differentiation at all taxonomic levels and patterns of morphological attributes. This suggest that the two floristic sets have evolved independently for extended periods of time, despite their close proximity. One important implication of this floristic differentiation is the large joint contribution made by these communities to the regional flora.     

融入植被连续性因子的生态单元制图法在城市生物多样性维护中的应用

基于一个以植被结构为构建框架的生态单元分类系统,构建了融入了植被覆盖连续性因子的改良城市生态单元制图模型,并将其应用于瑞典赫尔辛堡市的绿色空间研究.使用原生林地指示种或林地连续性指示种（AWIS）鉴定长、短连续性林地的分布,对比其含有维管束植物的物种丰富度,对植被覆盖的连续性因子进行评估检验.结果表明： 长连续性林地中含有较多的AWIS;在建群种均龄大于30年的林地中,长连续性林地相对于结构相似的短连续性林地通常含有较高的生物多样性.融入植被连续性因子的生态单元制图模型是调查城市生物多样性的重要工具,通过图谱中各生态单元所含有的生物多样性信息,可对今后城市生物多样性的维护提出相应策略.     

中国森林生态系统净初级生产力时空分布及其对气候变化的响应研究综述

植被生产力是表征植被活力的关键变量,能够反映陆地生态系统的质量状况。森林净初级生产力(NPP)对气候变化的响应研究,是理解森林生态系统碳收支的基础,有助于认识气候变化与森林生态系统的相互作用机制,因而对于深刻理解陆地碳循环和全球变化均具有重要意义。目前我国已有大量针对近几十年国家和区域尺度上植被NPP时空分布的研究,其中专门针对森林生态系统NPP的研究也有不少。研究尺度多为全国范围或者片段式区域,以行政区或流域尺度最为多见。然而,这些研究总体比较分散,其中部分研究的结果、结论并不一致甚至相悖,尚缺乏异同性分析与比较,也缺乏系统性和综合性。这并不利于全面掌握我国相关研究的整体情况、了解清晰明确的研究结论以及进行更深层次的规律及原因探究,也非常影响对森林NPP的精确评估及机理认识,因而,对相关研究成果进行梳理、整合和总结非常有必要。鉴于此,本文收集了近几十年我国植被NPP研究的相关文献,依据其研究结果,系统地综述了全国及区域尺度森林生态系统NPP的时空分布规律及未来可能变化趋势,揭示出NPP与气候因子(以CO₂、温度、降水为主)的关系及对气候变化的响应情况,并指出目前...     

鹞落坪落叶阔叶林蔷薇科主要树种的空间分布格局及种间关联性

为探讨大别山森林群落的构建和演替机制, 本文基于安徽鹞落坪落叶阔叶林11.56 ha动态监测样地的定位监测资料, 采用最近邻分析和O-ring函数、Monte Carlo拟合和零模型选取的方法, 分析了落叶阔叶林蔷薇科主要树种水榆花楸(Sorbus alnifolia)、山樱花(Cerasus serrulata)和中华石楠(Photinia beauverdiana)不同年龄阶段的空间分布格局及种间关联性。结果表明: (1)在整个样地中3个树种的小树和成年树阶段都为聚集分布, 且随年龄增加聚集性减弱, 在老树阶段转为随机和均匀分布。(2)在0-50 m尺度范围内, 以完全随机模型(complete spatial randomness, CSR)为零假设时, 3个树种整体及小树都在小尺度(≤ 10 m)上呈聚集分布, 成年树与老树多为随机分布。以异质性泊松模型(heterogeneous Poisson, HP)为零假设时, 树种的聚集与生境异质性间呈负相关, 3个树种只在≤ 4 m尺度上出现聚集现象。(3) 3个树种种内各个年龄段之间在较大范围内多为负相关和无显著相关性, 同时各树种及不同年龄段之间受种间竞争和密度制约效应影响在小尺度上(≤ 10 m)多为负相关, 随尺度增加相关性减弱。综合而言, 大别山落叶阔叶林中蔷薇科植物的分布格局整体上多为聚集分布, 随树龄增加聚集性减弱, 在中大尺度上受生境异质性效应的影响显著, 在小尺度上多为负相关, 各树种内部各龄级相互之间也多为负相关。     

古田山中亚热带常绿阔叶林群落物种多样性的空间变异特征

古田山常绿阔叶林的群落组成、结构及其维持机制已有许多研究, 但该地区亚热带常绿阔叶林生物多样性空间变异特征还缺乏认识。本文以古田山24 ha大样地(划分为24个1 ha小样地)为基础, 具体分析了α多样性和β多样性在1 ha尺度上的空间变异特征。结果表明: (1)群落第一、二优势物种在各小样地之间变化不大, 但第三优势种变化较大; (2) α多样性变化中, 样地间木本植物个体数量变异最大, 物种丰富度其次, Pielou均匀度指数变异性最小; (3)物种丰富度与植株个体数量、Pielou均匀度指数没有显著的相关性, 与Shannon-Wiener指数呈显著正相关; Shannon-Wiener指数与Pielou均匀度指数呈显著正相关; (4)相邻样地间物种替代速率空间变异较大, 与物种丰富度的空间变化格局有明显差异。这些结果说明尺度对认识群落结构、探讨群落维持机制有重要作用; 由于森林群落是多尺度生态过程作用的结果, 大尺度样地可能有利于更好地揭示森林群落维持机制。     

沙地不同树种人工林土壤氮素矿化过程及其有效性

土壤氮素（N）转化是生态系统重要的生态过程之一,可作为生态恢复评价的重要指标。以位于科尔沁沙地东南缘的章古台地区草地、30年生的樟子松（Pinus sylvestris vat．mongolica）、赤松（P.densiflora）和杨树（Populus simonii）人工林为对象。采用PVC顶盖埋管法和离子交换树脂袋法研究了土壤N矿化特征及其有效性。结果表明,生长季内土壤N净矿化量表现为草地（8.06μg／g）和赤松林（9．06μg／g）低于樟子松林（18．36μg／g）和杨树林（17．88μg／g）（P〈0．05）;树脂吸附的无机N表现为草地（283．50μg／g dry resin）和杨树林（297.00μg／g dry resin）最低,樟子松林（440．10μg／g dry resin）居中,而赤松林（835．65μg/g dry resin）最高（P〈0．05）。综合分析林地土壤理化特性、矿化特征和N有效性,表明樟子松、赤松和小叶杨均可作为固沙造林选择树种,其表现为赤松〉樟子松〉小叶杨。认为深入开展生态系统N平衡研究有利于更好地评价固沙林的功能。     

森林土壤氮转化的微生物功能研究

本文研究了不同林型下土壤(A+6层和A_1层)微生物、土壤酶活性在森林土壤氮转化中的作用。结果表明不同林型下土壤具有不同的固氮作用、反硝化作用、氨化作用和硝化作用速率,即阔叶林>针阔混交林>针叶林。已经证明,固氮作用主要存在于森林土壤的A_1层,反硝化作用主要存在于A_0层。森林土壤存在2种硝化作用过程,即由自养微生物所引起的自养硝化作用过程和异养微生物所引起的异养硝化作用过程。它的存在与林型有关,某些森林土壤中这2种硝化作用过程都存在,如针阔混交林下的A_0层和A_1层。有些林型下土壤,则以异养硝化作用过程为主,如针叶林的A_0层。