高寒草甸植物群落多样性及土壤因子对坡向的响应

坡向是山地的重要地形因子之一,是导致植物群落物种多样性和结构特征产生差异的间接环境因子,它通过改变光照、温度、水分和土壤养分等生态因子而对生物多样性、植物生长发育、生产力以及生态系统功能等产生重要影响.本文研究了青藏高原高寒草甸不同坡向上的植物群落物种多样性变化特点及与环境因子的关系.结果表明:阳坡-阴坡生境梯度上,土壤含水量的变化趋势为阴坡＞半阴半阳坡＞阳坡,土壤温度和光照度的变化趋势为阳坡＞半阴半阳坡＞阴坡,土壤养分含量除了全氮和有机碳为阴坡＞阳坡＞半阴半阳坡外,其他养分总体呈现阴坡＞半阴半阳坡＞阳坡.阳坡-阴坡生境梯度上植物群落物种多样性的变化趋势为:阴坡＞半阴半阳坡＞阳坡,阳坡的主要功能群是禾草类,而阴坡则是杂草类.相关分析表明,在阴阳坡微生境梯度上,光、热、水、土均影响了物种多样性的变化,而其中土壤含水量是引起这种变化的主要因素.     

恢复方式和地形对晋西黄土区退耕林分物种多样性的影响

运用样带样方调查法,对比不同恢复方式和地形条件下退耕林分的物种多样性,以期为晋西黄土区植被恢复效果评价和经营管理提供参考.结果表明: 恢复方式对退耕林分物种多样性具有显著影响.自然恢复林物种数为刺槐人工林的 1.6倍,Shannon 指数大于刺槐人工林,Pielou 指数小于刺槐人工林.物种多样性受坡位影响显著,各指数均表现为沟底>沟坡>梁峁坡>梁峁顶;坡向对退耕林分物种多样性影响不显著,各指数均表现为阴坡>阳坡.物种多样性受地形和恢复方式综合作用影响显著,在自然恢复林阴坡沟底处最高,物种均匀度在刺槐人工林阴坡沟底处最高.从提高物种多样性角度,黄土区植被恢复在遵循适地适树原则的同时,应参照自然恢复林分,在不同地形部位采用不同的造林设计.     

坡向和坡位对四川夹金山灌丛群落结构与物种多样性特征的影响

研究不同坡向、坡位夹金山灌丛群落结构和物种多样性特征。结果表明: 在 24 个样地中,共有维管植物 186 种,隶属于 50 科 127 属。其中,灌木层有 32 种,隶属于 14 科 22 属,阴坡下坡位物种数最多;草本层有 154 种,隶属于 43 科 109 属,阴坡物种数最少。灌木层的平均高度表现为阳坡>半阳坡>阴坡,平均密度则相反;草本层平均高度表现为阴坡>半阳坡>阳坡,平均密度无显著变化。坡位仅对阳坡草本层平均高度有显著影响,灌木层物种多样性在阴坡较高,草本层物种多样性在阳坡下坡位和阴坡中坡位较高。坡向对灌木层和草本层 Shannon多样性指数、Simpson优势度指数、物种丰富度指数、Pielou均匀度指数影响显著(除草本层 Simpson 指数),坡位对灌木层和草本层物种多样性指数均无显著影响,坡向和坡位的交互作用对草本层物种多样性的影响大于灌木层。冗余分析(RDA)表明,物种多样性不仅与坡向正弦值、坡向余弦值相关,也与群落结构特征相关性较大。     

昆嵛山老杨坟阳坡与阴坡半天然植被植物群落生态学特性的初步研究

本文对昆嵛山老杨坟阳坡与阴坡半天然植被植物群落的上层（乔木层）和下层（灌木层）的物种优势度、多样性指数、群落的均匀度、相似性指数以及群落的最小面积进行了分析。昆嵛山老杨坟半天然植物群落上层的最小面积应为３００ｍ２,下层应为２２５ｍ２。阳坡与阴坡植物群落的上层和下层优势种的分布格局存在一定差异;乔木层的物种多样性指数,阴坡大于阳坡,灌木层阳坡大于阴坡,但二者的差异水平不显著;两群落乔木层的均匀度指数存在显著差异。阳坡与阴坡植物群落乔木层的相似性指数低于灌木层,并且以相对盖度和相对优势度（相对重要值）为基础统计所得到的群落相似性指数更好地反映了群落间乔木层在结构和功能上的差异。     

砒砂岩区不同立地类型人工沙棘林下草本物种多样性环境解释

砒砂岩区是黄土高原区水土流失最为严重的地区之一。砒砂岩区沙棘人工林有良好的水土保持功能,沙棘林下草本植物是该人工林生物多样性的重要组成部分。目的是探明砒砂岩区人工沙棘林下草本物种多样性与环境的关系,依据生境条件的差异,沙棘林被划分为7个类型。野外调查记录了各类型所处的地形条件,采用样方法调查了每个样地草本的生物多样性,并取土样测定其养分和水分状况。采用Patrick指数、Pielou指数、Shannon指数、Simpson指数对砒砂岩区不同立地类型人工沙棘林下草本植物进行了物种多样性分析,并通过CCA、PCCA方法研究了物种分布与环境的关系。结果表明:(1)砒砂岩区不同立地类型人工沙棘林下草本层优势种不同,阴坡混交林物种数最多为23种,阳坡混交林Pielou指数最高为0.89,阴坡纯林和混交林Shannon指数均为最高,Simpson指数没有明显差异。(2)影响砒砂岩区人工沙棘林下草本物种的分布的环境因子顺序为地形因子土壤因子灌木层因子,其中坡向、坡度、土壤含水量、土层厚度、郁闭度、混交结构所占解释量较大。本研究可为当地沙棘人工林生物多样性保护和植被建设提供基础数据。     

山西岚县皇姑梁小流域人工植物群落生态

应用双向指示种分析法（TWINSPAN）和除趋势对应分析（DCA）等数量分析方法,对山西岚县皇姑梁小流域人工植物群落生态关系进行研究,将该人工植被划分为12个群丛,分别位于不同的海拔高度和坡向。分类结果很好地反映了人工植物群落类型及优势种的分布与环境因子的关系,并在DCA二维排序图上得到了较好的验证。DCA排序轴反映了群落土壤含水量、坡向、海拔高度、人工植被恢复时间和物种多样性的梯度变化,表明土壤含水量、坡向、海拔高度、物种类型及其配置模式是影响人工植物群落分布和变化的主要环境因子,不同物种配置模式对群落演替和物种多样性变化有重要影响,油松＋华北落叶松．沙棘、小叶杨＋油松、油松-沙棘、油松-柠条锦鸡儿等组成的乔灌混交林的物种多样性高于柠条锦鸡儿灌木纯林,并且油松＋华北落叶松-沙棘混交林的物种多样性高于小叶杨＋油松混交林,混交林的生态恢复效果优于纯林,并且对该小流域的生态恢复作用明显。华北落叶松适合在该小流域海拔较高的梁坡顶、半阳坡、半阴坡和阴坡生长,小叶杨适合在其海拔较低的沟底、半阳坡和半阴坡生长,而油松、沙棘、柠条锦鸡儿的生态适应性强,可在其不同海拔和坡向生长。人工植物群落的演替进程,遵循地带性植物群落演替规律。随着群落演替,野生植物不断侵入,油松、华北落叶松、小叶杨等人工林郁闭度增加,沙棘、柠条锦鸡儿等逐渐退化,油松、华北落叶松、小叶杨等出现枯枝、死株现象,这是自然稀疏的结果,亟待加强管理。     

文冠果种群繁殖方式及其在种群更新中的作用

以黄土高原丘陵区文冠果天然种群为研究对象,通过样地调查,分析了不同生境文冠果种群的有性和无性繁殖方式及其在种群更新中的地位.结果表明：不同坡向文冠果种群均能进行有性繁殖和无性繁殖,在阳坡、半阴坡生境,文冠果以有性繁殖为主,实生苗数量和占据空间的能力均大于萌生苗,有性繁殖在这2个生境中对种群的更新贡献较大;在半阳坡生境,文冠果以无性繁殖为主,萌生苗数量和占据空间的能力均大于实生苗,无性繁殖对种群更新的贡献较大.在相同生境条件下,文冠果幼苗生长状况均表现为萌生苗＞实生苗.同一起源的文冠果幼苗生长状况均表现为阳坡＞半阳坡＞半阴坡.2种繁殖的瓶颈期在实生苗的种子-幼苗阶段和萌生苗的幼树-成株阶段.黄土丘陵区文冠果种群在新生境定居下来的过程中,首先以实生苗入侵,当水分、光照、养分条件较好时,文冠果又以无性繁殖方式迅速占领空间,繁衍后代.     

不同坡向人工油松林生长状况与林下物种多样性分析

采用野外调查的方法,研究了绥德地区28年生不同坡向人工油松林林木个体生长、植物种类、相似系数和林下物种多样性特征,以明确坡向对人工油松林生长和群落结构的影响.结果显示,(1)阴坡油松的胸径、树高、冠高和冠幅均显著大于阳坡;(2)阴坡与阳坡林下分别有植物21和19种,共有种11种.群落相似系数为55%,说明坡向对人工油松林林下物种组成影响较大.(3)阴坡物种丰富度指数、均匀度指数和多样性指数均表现为草本层＞灌木层;而阳坡的Shannon-Wiener指数和Pielou指数(Jsw)则与阴坡相反,为灌木层＞草本层;群落总体多样性表现为丰富度指数和多样性指数均是阴坡稍大于阳坡,而均匀度指数表现为阳坡稍大于阴坡.研究表明,绥德地区人工油松林的生长状况阴坡显著优于阳坡,但与陕北南部地区人工油松林相比,该地区人工油松林林木生长各项指标还是较低,群落结构配置不合理.     

高寒草甸不同生境类型植物群落的α及β多样性研究

用比较样地法调查了青藏高原东缘高寒草甸不同生境 阴坡、滩地、阳坡 植物群落的α及β多样性特征.结果表明?1各种α多样性指数均显示高寒草甸不同生境植物群落多样性顺序为?阴坡>滩地>阳坡.2各种α多样性指数之间均呈正相关,高寒草甸植物群落多样性更多地受均匀度的影响.3在高寒草甸,用物种盖度和地上生物量作为测定指标计算的群落α多样性所得的结果优于用株数作为测定指标计算的结果.4当生境由阴坡向滩地、由滩地向阳坡变化时,β多样性表现出由低到高,再由高到低的趋势,这表明在土壤湿度和日照时间适中时环境异质性大,物种替代速率比较快,β多样性较高.     

生境因子对岩质边坡生态恢复过程中植被多样性的影响

通过对舟山市已生态恢复的岩质边坡进行植物群落调查,记录了36个不同生境条件下边坡样地中的植物种及生境因子,计算了4个植物物种多样性指数,利用广义线性混合模型分析了生境因子与边坡植被多样性交化的关系,以揭示生境因子对岩质边坡生态恢复植被的影响.结果表明:从1 a到7 a的岩质边坡生态恢复过程中,坡位对边坡植被多样性的影响最显著(P＜0.05),不同坡位的Shannon-Wiener指数、Margalef指数、物种丰富度差异明显,其变化呈现一致的趋势为下坡＞中坡＞上坡;坡向与Margalef指数显著相关(P＜0.05),从阳坡、半阳坡、半阴坡到阴坡,植被多样性呈总体上升趋势;随着边坡恢复年限的延长,边坡植被多样性逐渐增加,但没有表现出统计学意义上的差异(P＞0.05);坡度、海拔、土壤厚度对边坡植被多样性的变化无明显影响(P＞0.05);Pielou均匀度指数与各个生境因子均无显著关系,在边坡植被恢复过程中基本保持稳定的状态.因此,坡位、坡向是影响岩质边坡生态恢复过程中植被多样性最重要的因子;Margalef丰富度指数和Shannon-Wiener多样性指数是岩质边坡生态恢复过程中植物群落变化的主要指示因子.     

亚高寒草甸植物群落的中性理论验证

 该文以物种组成较为复杂的青藏高原东部亚高寒草甸为背景,结合最新的群落中性理论,以解释亚高寒草甸草本植物群落的物种分布格局和生物多样性的维持机制。通过对阴坡、阳坡和滩地3个生境进行随机取样调查,用中性模型对所得多样性数据进行拟合,并分别应用置信区间检验、拟合优度检验和多样性指数检验3种方法对拟合效果进行检验。研究结果表明,在拟合优度检验中,3个生境中中性理论预测和实际物种多度分布之间没有显著差异(p>0.05);实际观测值基本全部落入模型预测分布的95%的置信区间之内（仅滩地草本植物群落的63个物种中的1个以及阴坡草本植物群落75个物种中的2个偏离95%的置信区间）;对群落多样性的预测也和实际观测没有显著差异,其中丰富度预测拟合得最好(0.49相似文献   

坡向对暗紫贝母生长和繁殖特征的影响

在青藏高原东部的牛牛山和卡卡山,在其东、南、西、北4个坡面各设置一个海拔相同(3800m)的样地,每个样地中随机选择30株同龄级的暗紫贝母植株作为研究对象,然后比较各坡面的生态因子以及暗紫贝母的生长和繁殖特征。结果表明:1融雪时间、气温、土壤含水量在南北坡面间有显著的差异,但土壤p H在各坡面间无明显差异。2开始生长期、始花期和盛花期等物候阶段都是北坡最迟,南坡最早,而枯黄期在各坡面间无显著差异。3单叶面积、比叶面积和植株株高以北坡最大,南坡最小。4鳞茎生物量以南坡最大,北坡最小,东、西坡面的值介于南、北坡之间。5单粒果实的生物量在各坡面之间无明显的差异,果实生物量在地上部分中所占的比例以南坡最大,北坡最小。6单粒果实平均种子数以北坡最多,南坡最少;而种子千粒重则以南坡最重,北坡最轻。可见,坡面对暗紫贝母的生长和繁殖特征有显著的影响,尤其是在南北坡面之间大多数性状差异显著。     

冬季清凉峰山区小麂和野猪的生境选择及差异

从2005 年11 月5 日至2006 年1 月21 日,为了评估小麂和野猪的生境选择及其差异,我们在浙江清凉峰国家级自然保护区核心区共设置了248 个样方群。研究发现,两者都选择平缓坡的灌丛植被、草本密度小、离住宅较近和离隐蔽物距离适中的生境,表现了它们的生境选择有一定的重叠性。但是它们也表现出生境选择的一些差异,小麂选择乔木密度适中、灌丛密度大和郁闭度适中的生境,而野猪选择乔木密度小的生境,随机地使用各类灌丛密度和郁闭度的生境。小麂还选择北坡、离水源距离较远的生境,野猪只是随机地使用不同的坡向和离水源距离的生境。分析两者共存的机制,我们发现小麂采取隐藏策略而野猪采取逃跑策略来避敌和利用资源,即它们之间存在与反捕食策略相关的生境选择差异。
     

子午岭天然林与人工林群落特征比较研究

采用标准样地调查法对比研究了黄土高原子午岭地区人工刺槐林、人工油松林与天然林山杨林、白桦林与辽东栎林的群落特征。结果表明,人工林与天然演替森林（山杨林与自桦林）均具有较丰富的物种组成,为62种左右,而天然顶极森林（辽东栎林）的物种数量则相对较少,为48种。人工林与天然林空间层次分化明显,而且还有一定数量的层间藤本植物。从群落结构的空间格局来看,人工油松林与天然林乔木层与灌木层发育较好,但人工刺槐林的草本层发育较好。人工林的植物多样性主要体现在草本层,而天然林乔木层与灌木层也具有相对较高的多样性。以天然辽东栎林为参照,群落物种组成相似性的比较结果表明,人工刺槐林与天然林的相似性较低,其相似性指数（IS）为19．4,而人工油松林与天然林的相似性则较高,IS值为43．4,甚至高于天然白桦林（33．3）与山杨林（42．9）。因此,相比较而言,油松比刺槐更适合作为黄土高原子午岭地区的人工造林树种。     

Taxonomic and functional β-diversity of ants along tree plantation chronosequences differ between contrasting biomes

The replacement of natural by anthropogenic habitat changes biological communities in any biome. Variations in environmental conditions along the chronosequence of tree plantations may act as a gradient of environmental filtering where the gain or loss of species occurs. It is expected that environmental filtering increases with the decrease in environmental similarity between the plantations and the natural habitat. Young tree plantations are structurally more similar to grasslands than to mature plantations, which in turn are structurally more similar to subtropical forest than young plantations. This study compares patterns of beta diversity across exotic pine plantation chronosequences in contrasting biomes. We predict that taxonomic and functional beta diversity between plantation and the natural habitat assemblages increase with plantation age in grasslands and decrease in the subtropical forest. We sampled epigean ants and measured environmental variables at 54 plantations of different ages and natural habitats in grassland and forest biomes in Argentina. Taxonomic and functional beta diversity between natural habitat and pine plantations were estimated through dissimilarity indexes of turnover and nestedness. To assess the response of beta diversity estimators to plantation age we performed general linear and non-linear models. Results revealed opposite beta diversity patterns between biomes along the plantation cycle. Turnover increased and nestedness decreased with declining environmental similarity between pine plantations and the natural habitats; changes in the identity of the species were coupled to changes in their functional characteristics. Thus, a given environmental gradient may produce different diversity patterns depending on the regional species pool. Forestry practices that generate environmental conditions similar to natural environments could help to conserve species from the natural habitat.     

Increasing topographic influence on vegetation structure during primary succession

Mount Pinatubo, Philippines (15.14°N, 120.35°E) erupted violently in 1991 to initiate significant primary succession. Aspect, the direction faced by a slope, affects patterns of vegetation at higher latitudes, but such effects remain unreported in the wet tropics. Therefore, we monitored species composition and cover in established plots during 2006, 2010, and 2013 to characterize how aspect affected primary succession. We used redundancy analysis (RDA) to assess vegetation change in response to time and environmental factors. Vegetation cover increased from 153 to 245% on north-facing slopes, and from 174 to 230% in south-facing slopes while species richness and diversity indices also increased. From 38 to 63% of the species were restricted to one aspect, depending on the year of study. Redundancy analysis demonstrated that aspect strongly affected species composition and that its effects persist. Fabaceae was concentrated on south-facing slopes, which suggested that aspect effects might be accentuated due to enhanced soil nitrogen. Vines, grasses, and forbs, all typical of habitats with greater insolation, were more abundant on south aspects, while trees and ferns were more common on the north aspects. This is the first survey of vegetation dynamics using permanent plots on new volcanic surfaces in this region. Aspect differences produced distinct insolation and moisture patterns that enhanced habitat diversity and altered species composition. This effect has not been noted in monsoon forests. Aspect may continue to initiate divergence in succession trajectories as soils and vertical canopy structure develop differentially in response to differential dominance.     

Do ridge habitats contribute to pteridophyte diversity in tropical montane forests? A case study from southeastern Ecuador

We address the question to which degree ridge habitats in tropical montane forests contribute to overall plant diversity by analysing patterns of pteridophyte (i.e. lycophytes and ferns) assemblages on ridges and slopes in three montane forest sites near Podocarpus National Park, Ecuador. The analyses, which involved 158 pteridophyte species (110 terrestrial, 96 epiphytic, 48 both) from 28 plots of 20 m × 20 m (or an equivalent of 400 m²), showed that more species were typical of one of the three study sites than of one of the two habitats (ridge/slope). As found in previous studies, alpha diversity on ridges was lower than on slopes, accounted for by the absence of numerous species that are found on slopes. Pteridophyte assemblages on ridges were more similar across study sites than those on slopes. Thus, unlike the structurally comparable (i.e. stunted, open) Amazonian forests, the studied montane ridge forests harbour fairly homogenous pteridophytes assemblages with very few specialised species. Our study implies that slope forests are of higher conservation priority for pteridophytes in the study region than ridge habitats. However, comparative studies are needed because other geographical regions and other groups of organisms may not share this pattern. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Post-fire diversity patterns in two subassociations of Californian coastal sage scrub

Abstract. Coastal sage scrub exhibits floristically dissimilar subassociations on opposing aspects in the Santa Monica Mountains of southern California. Southward-facing (Venturan I) and northward-facing (Ventaran II) subassociations were sampled at two scales (1 m² and 625 m²) each spring for five years following a fire. Mature (10- and 28 yr-old) sites of these subassociation types were also sampled in the study area. The subshrub and herbaceous components that were most prevalent on northerly slopes following the first post-burn year contributed the most cover for all ages examined. Aspect-related differences in species richness were most apparent at the smaller sampling scale where they were equal the first post-burn year and varied inversely thereafter. At this scale, richness values were two times higher on older north-facing sites, largely due to the herbaceous component. South-facing sites displayed progressive decreases in equitability through time. This pattern reflects gradual reduction in overall species richness combined with progressive site domination by fewer species, as manifested by increasing dominance concentration values. By contrast equitability on north-facing sites fluctuated little through time, though dominance concentration tended to decrease. Higher richness, equitability, and overall cover with time after burning on north-facing sites is associated with the relatively mesic habitats upon which this subassociation develops. Post-burn patterns of species richness and stratal differentiation on south-facing slopes are consistent with those reported for other mediterranean-type shrublands, i.e. peak richness was attained the first two years following a fire with subsequent decrease to a constant level.     

Neotropical moth assemblages degrade due to oil palm expansion

Oil palm is one of the most rapidly expanding crops throughout the tropics, yet little is known about its impacts on Neotropical invertebrate biodiversity. Responses of insect assemblages to land conversion may substantially vary among taxa. We assessed geometrid and arctiine moth assemblages in a Costa Rican human dominated landscape, where oil palm plantations are now the second most common land cover. Moths were sampled during 6 months with automatic traps in the interior and margin of old-growth forests, young secondary forests and oil palm plantations in a 30 km² area. Our results show that richness and diversity of both taxa were severely reduced in oil palm compared to all other habitats. Geometrid abundance was highest in forest interiors and lowest in oil palm, while arctiine numbers did not differ between habitats. Dominance was highest in oil palm plantations, where one arctiine species and one geometrid species accounted for over 40% of total abundance in each of their respective taxa. Species composition was distinct in oil palm and forest interior sites, and depicted a gradient of habitat disturbance in ordination space that was strongly related to vegetation diversity and structure. This study demonstrates that oil palm plantations are not a suitable habitat for these moth taxa. Whilst some arctiine species seem adapted to disturbed habitats, geometrids were more dependent on old-growth forests, showing higher bioindicator potential. In the face of accelerated oil palm expansion, conservation strategies should focus on protecting old-growth forest remnants, as well as increasing species diversity and structural complexity of degraded habitats.     

黄土高原典型小流域综合治理的水文生态效应

从流域产流规律及水土保持措施改变引起的土壤水分状况和流域蒸散发的变化等方面评价了黄土丘陵沟壑区泉家沟流域水土保持措施变化对流域水分生态环境的影响.结果表明:水土保持与生态建设过程改变了土地利用结构,对小流域水环境变迁具有很大的影响作用,主要表现在:减少地表径流量,径流模数1996～2000年平均较1980～1985年减少了36.1%;不同治理措施土壤水分状况不同,灌木林地、人工草地和乔木林地均存在深度和厚度不等的土壤"干层";不同地貌部位土壤储水差异很大,阴坡的水分环境优于阳坡,沟底优于峁顶,缓坡优于陡坡;林草措施对流域总蒸散量起着决定性作用,1991～1995年流域林草地面积达到最大,总蒸散量也达到最大,与治理初期相比,总蒸散量累计增加了56.3 mm.