A rapid survey method for the estimation of density and cover in desert plant communities

Abstract. The Log-series survey method allows rapid estimates of density and cover and is applicable for studies of perennial vegetation in arid environments. An optical rangefinder is used to determine boundaries of large circular plots. Numbers of individuals of each species within a plot are assessed; this information is used to assign species to logarithmic density classes equivalent to the logarithm base 2 of actual abundances. Each species is then assigned to a logarithmic canopy cover class, equivalent to the logarithmbase 2 of average cover per individual. Log total cover per species per plot is obtained by the addition of logarithmic density and cover classes. Percent cover per species is rapidly computed by taking the antilog of the difference between log total cover per species and log total plot area.     

The role of regional and local scale predictors for plant species richness in Mediterranean forests

Abstract

Both local and regional predictors play a role in determining plant community structure and composition. Climate, soil features as well as different local history and management affect forest understorey and tree species composition, but to date their specific role is relatively unknown. Few studies have addressed the importance of these predictors, especially in the Mediterranean area, where environmental conditions and human impacts have generated heterogeneous forest communities. In this study, the relationships between environmental variables and species richness of different groups of vascular plants (vascular species, woody species and open habitat species) and bryophytes were investigated in Tuscan forests. A total of 37 environmental variables were used by generalised linear model fitting in order to find parsimonious sub-sets of environmental factors (predictors) that are able to explain species diversity patterns at the local scale. Moreover, the role of regional and local variable groups on species richness of the considered plant groups was estimated by using the variance partitioning approach. We found that local variables, such as forest management and structure, explained more variance than regional variables for total species richness, open habitat species richness and bryophyte species richness. On the other hand, regional variables (such as elevation) played a central role for woody species richness.     

Alien plant species composition and associations with anthropogenic disturbance in North American forests

A probability-based sampling scheme was used to survey plant species composition in forests of 16 states in seven geopolitical regions of the United States (California, Colorado, Minnesota, and parts of the Pacific Northwest, Southeast, Mid-Atlantic, and Northeast) in 1994. The proportion of alien species relative to the total species number and to canopy cover in the ground stratum (0–0.6 m height) was evaluated in 279 plots. Visually evident anthropogenic disturbances (e.g., artificial regeneration, logging, prescribed burning, and grazing by livestock), if any, were recorded on each plot. In each of the seven regions we quantified (1) the percentage of the number of species and total cover comprised of alien species, (2) the difference in these percentages for disturbed and undisturbed plots, and (3) the origin or native range for the alien species.The percentage of alien species ranged from approximately 4.5% (Colorado) to approximately 13.2% (California). The percentage of alien species cover ranged from approximately 1.5% in Colorado to 25% in California. In five regions, species introduced from temperate Eurasia comprised the largest proportion of alien species and cover. In the Southeast, species introduced from far eastern and subtropical Asia dominated the alien flora. In the Mid-Atlantic, the majority of alien species was Eurasian and the majority of alien species cover consisted of far eastern and subtropical Asian species.The proportion of plots in which at least one alien species was recorded was significantly higher in disturbed than undisturbed plots in the Southeast and marginally significantly higher ($p=0.053$) in the Northeast. These results are consistent with other published studies that indicate that anthropogenic disturbance affects the structure and composition of both the ground stratum and upper canopy of forest habitats. In other regions, however, no significant differences were found.     

Life-history correlates of plant invasiveness at regional and continental scales

We implemented cross‐species and independent‐contrasts multiple regression models to compare life‐history correlates of invasion success between regional and continental spatial scales among non‐native plants of eastern Australia. We focussed on three life‐history traits that represent major axes of variation in plant life history: specific leaf area (SLA), plant height and seed mass. After controlling for residence time and cross‐correlation with other life‐history traits, small seed mass was significantly and uniquely correlated with invasion success at continental and regional scales. High SLA was significantly and uniquely correlated with invasion success at the continental scale only. Plant height could not explain unique variation in invasion success at either spatial scale. Variation among spatial scales in the significance and strength of life‐history relationships with invasion success suggests that the search for predictive tools of invasion need not be fruitless, as long as predictive investigations are targeted at appropriate spatial scales.     

Probabilistic key for identifying vegetation types in the field: A new method and Android application

Quick identification of vegetation types in the field, based on species composition but not requiring time‐consuming plot sampling, is often needed for vegetation mapping, conservation assessment, teaching and other applications of vegetation classification. Here, we propose a new method that identifies the probability of belonging to the units of an established vegetation classification for vegetation stands encountered in the field. The method is based on calculating the probability that a few species observed in the field would co‐occur in a priori defined vegetation types, using the existing information on species occurrence frequency in these types. The method has been implemented in a freely available Android application called Probabilistic Vegetation Key, which makes it possible to employ it in the field using smartphones or tablets, even in the absence of internet access.     

植物种群研究中的分子标记及其应用

综述了植物种群分子生态研究中各种标记法及其应用,包括等位酶、ＡＦＬＰ、ＲＡＰＤ、ＳＳＲ及ＲＦＬＰ等方法,并根据所涉及的有关研究论述及研究工作总结比较了各种方法应用在植物种群学研究中的利弊,强调应依不同的研究目的采用不同的分子标记方法,各种标记方法对解决不同的问题在质和量上是不同的。     

若尔盖高原沙化沼泽区植物群落物种组成及其驱动因素

若尔盖高原沼泽区土壤沙化过程中植物群落的变化及其成因机制是亟待解决的区域关键科学问题之一。在若尔盖高原红原县沙化沼泽区,研究了土壤沙化梯度上植物群落种类组成、物种多样性、地上生物量的变化及其与土壤湿度、容重和孔隙度的关系。随着土壤沙化程度增加,群落特征种组替代顺序为华扁穗草(Blysmus sinocompressus)种组→高山嵩草(Kobresia pygmaea)种组→四川嵩草(K.setchwanensi)种组→黑褐穗苔草(Carex atrofusca subsp.minor)种组→粗壮嵩草(Kobresia robusta)种组;植物种数(单位样方物种丰富度和总种数)和地上生物量均表现为单峰变化格局,但植物种数峰值出现在极轻度沙化的高山嵩草群落,地上生物量峰值出现在中度沙化的四川嵩草-黑褐穗苔草群落;β多样性表现为"U"型变化格局,最高值出现在未沙化的华扁穗草群落,最低值出现在极轻度沙化的高山嵩草群落;土壤湿度对植物种多度影响最大,可解释总方差的24.8%,其次为土壤容重,可解释总方差的1.4%;沙化过程中土壤湿度是影响植物群落生态分布和种类构成的关键因素之一,尤其影响群落...     

地理来源与生物化学属性对泥炭地植物残体分解的影响

不同地理来源的泥炭地植物残体在同一环境中的分解速率一直缺乏比较研究。该研究沿纬度梯度, 选择大九湖、哈泥和满归3处泥炭地, 以三地的10种植物为分解材料, 使用分解袋包装, 埋藏于长白山哈泥泥炭地, 开展为期1年的分解实验, 研究地理来源及生物化学属性对泥炭地植物残体分解的影响。结果表明, 如不考虑物种差异, 从总体上看, 随着纬度增加, 3处泥炭地植物残体的初始氮(N)含量下降, 初始木质素含量、碳氮比(C/N)和木质素/N上升。经一年分解后残体分解速率因植物类群不同而不同, 桦木属(Betula)和薹草属(Carex)植物残体的干质量损失率均接近50%, 远大于泥炭藓属(Sphagnum)植物(约为10%)。3处来源地植物残体干质量损失率总体上无差异, 但比较同种植物残体发现, 来自中纬度泥炭地哈泥的中位泥炭藓(S. magellanicum)的干质量损失率(19%)远高于来自高纬度泥炭地满归的(9%)。制约残体分解的因素因植物类群不同而不同, 残体初始总酚/N是决定属间残体干质量损失率差异的重要指标。薹草属植物初始N含量和C/N与残体分解速率、泥炭藓属植物初始Klason木质素含量和总酚/N与残体分解速率均呈正相关关系。该研究一定程度上表明, 若以纬度降低指代气候变暖, 当前持续的气候变暖可能通过改变高纬度泥炭地的植物组成和植物的生物化学属性, 来改变植物残体分解速率, 进而影响泥炭地的碳汇功能。     

Positive trends in plant,dragonfly, and butterfly diversity of rewetted montane peatlands

Drainage and afforestation of peatlands cause extensive habitat degradation and species losses. Restoration supports peatland biodiversity by creating suitable habitat conditions, including stable high water tables. However, colonization by characteristic species can take decades or even fail. Peatland recovery is often monitored shortly after restoration, but initial trends may not continue, and results might differ among taxonomic groups. This study analyzes trends in plant, dragonfly, and butterfly diversity within 18 years after rewetting of montane peatlands in central Germany. We compared diversity and species composition of 19 restored sites with three drained peatlands and one near‐natural reference site. Restoration resulted in improved habitat conditions and benefited species diversity, but there were marked differences among taxonomic groups. Dragonflies rapidly colonized small water bodies but their diversity did not further increase in older restoration sites. Characteristic peatland vegetation recovered slowly, since it depended on a high water holding capacity that was only reached after peat started accumulating. Generally, plant diversity developed toward reference conditions albeit incompletely, even 18 years after restoration. Butterflies responded less to peatland restoration; generalists increased only temporarily and specialists could not establish. In conclusion, peatland restoration improves habitat conditions and biodiversity, while trajectories of recovery are nonlinear and incomplete after two decades. This highlights the need for long‐term monitoring and a strategic selection of indicator species for evaluation of restoration success.     

流动沙丘区和固定沙丘区丘间低地植物种间关联关系

丘间低地植物种间关联研究对揭示植物对生境变化的响应及植被演替机制具有重要意义。通过χ2检验和AC关联系数对科尔沁沙地22个不同面积的流动沙丘区和固定沙丘区丘间低地植物种间关联进行了比较分析。结果表明:在固定沙丘区,当丘间低地面积<0.5hm2时,|AC|≤0.3的种对数占所有种对数的百分比和|AC|≥0.7的种对数占所有种对数的百分比略大于流动沙丘区,当丘间低地面积>0.5hm2时,|AC|≤0.3的种对数占所有种对数的百分比显著小于流动沙丘区,|AC|≥0.7的种对数占所有种对数的百分比显著大于流动沙丘区;当面积<0.5hm2时,沙丘固定未引起丘间低地植物种间关系发生明显变化;当面积>0.5hm2时,沙丘固定导致丘间低地植物种间关系更加紧密。     

Species richness and abundance of defoliating Lepidoptera associated with Eucalyptus grandis in Brazil and their response to plant age

The present paper documents patterns of species richness and abundance in Lepidoptera associated with a Eucalyptus grandis plantation, and how these patterns relate to plant age. The large number of species collected (1385), the lack of dominant species and the absence of pest outbreaks during the survey may be related to the high level of plant diversity of the native forest reserves in the area. There was no clear pattern of seasonal variation in species richness, but there were seasonal fluctuations in abundance, with minor defoliator species prevailing in October at the start of the rainy season. Species richness and abundance of Lepidoptera were positively correlated, with both variables decreasing in older plantations. However, the greatest numbers of major outbreak species and minor eucalypt defoliators were observed in plants after the mid‐point (6 years old) of their cutting cycle (7–10 years). This may be because of a larger amount of better‐quality plant leaves after this mid‐point or the reduction in silvicultural management interventions at this period of the Eucalyptus cutting cycle. The abundance of the main outbreak species observed in the survey, Stenalcidia grosica Schaus (Geometridae), was negatively correlated with plant age. Nonetheless, the effect was weak (r = – 0.21, P = 0.03) and we were not able to find further significant correlations between plant age and abundance of the other most frequent and constant species that were collected.     

西藏珠峰－卓奥友峰普士拉地区高山稀疏植被的群落特征及小地形的影响

在西藏定日县珠穆朗玛峰-卓奥友峰附近的普士拉地区的-山坡上(海拔5176—5390m),设置13个样方。进行群落调查、小地形测定和土壤剖面调查,分析该地区高寒植被的群落特征及其与小地形的关系。13个样方(面积25—200m^2不等)中,共记载物种80个(含变种和亚种),分别隶属于47个属。出现频度较高的种有高山嵩草(Kobresia pygmaea)、矮兔耳草(Lagottes humilis)、楔叶委陵菜(Potentilla funeata)、华马先蒿(Pedicularis oederi var.sinensis)、高山委陵菜(Potentilla polyjchista)、密生雪灵芝(Arenaria densissima)等;含物种数较多的属有：虎耳草属(Saxifraga)、风毛菊属(Saussurea)、嵩草属(Kobresia)、委陵菜属(Potentilla)、龙胆属(Gentiana)、葶苈属(Draba)等。随着海拔降低,物种和属的丰富度呈现出上升的趋势在该地区,植被盖度能较好地指示生境条件。等级聚类的结果也支持了这一观点：随着植被盖度的增加,转换物种丰富度(TSR)和转换属丰富度(TGR)增加,而物种多样性指数(Shannon-Wiener指数)减小。利用物种矩阵以及海拔、坡度、坡向、土壤深度、植被盖度等环境变量进行CCA排序,结果分出4类生境类型,它们较好地反映了群落特征与地形的关系。     

城市公共绿地常见木本植物组成对鸟类群落的影响

快速城市化背景下, 城市公共绿地已经成为重要的鸟类栖息地, 其中的木本植物群落构成对鸟类群落结构有显著影响, 研究木本植物配置与鸟类多样性的关系对提升城市公共绿地作为鸟类栖息地的生态服务功能有重要的理论和应用价值。我们于2009–2010年间在上海市滨江森林公园就木本植物和鸟类群落的相互关系展开研究。样线法结合样点调查共记录到鸟类10目25科64种5,368只(次), 鸟类多度全年变化显著, 峰值分别出现在4月和11月。丰富度全年也呈现双峰型变化, 峰值出现在4月和12月。全年鸟类多样性(Simpson指数)差异显著, 10月最高, 8月最低。样方调查共记录到77种木本植物, 其中有14种(乔木9种、灌木5种)出现率超过5个样方, 定义为常见种, 其果期主要集中在9月到翌年2月, 其上常见林业致病害虫的发生盛期集中在5–11月。主成分分析显示, 常见木本植物上观察到的鸟类可划分为8个鸟类集团, Spearman秩相关检验显示秋冬季常见木本植物果期与植食性、肉食性、食虫性、杂食性等多个鸟类集团的多度均呈显著正相关。说明在秋冬季鸟类迁徙高峰期不同鸟类集团均能获得丰富的食物资源。就常见木本植物对鸟类群落的重要值进行排序, 结果显示, 大叶杨(Populus lasiocarpa)、枫杨(Pterocarya stenoptera)、香樟(Cinnamomum camphora)等乔木对鸟类重要值较高, 而灌木层对鸟类的重要性整体偏低, 说明滨江森林公园的灌木层作为鸟类栖息地的功能建设尚需加强。根据以上研究结果, 我们提出了提高上海城市公园鸟类多样性的植被配置建议。     

陆地生态系统植被氮磷化学计量研究进展

因化学功能的耦合和元素的不可替代性, 植物对N、P的需求和利用存在严格的比例。植物N、P化学计量在不同功能群、生长地区、生长季、器官之间以及环境梯度下存在明显的变化规律。多数研究从N、P浓度、N:P及N、P间异速指数等角度分析了植物化学计量变化规律, 并探讨其在全球范围内的具体数值。为增进对植物响应全球变化的理解, 该文综述了N、P化学计量的影响因素及其机理的最新研究进展, 并指出未来拟重点研究的方向。     

Twenty‐five years of plant community dynamics and invasion in New Zealand tussock grasslands

Understanding how plant communities respond to plant invasions is important both for understanding community structure and for predicting future ecosystem change. In a system undergoing intense plant invasion for 25 years, we investigated patterns of community change at a regional scale. Specifically, we sought to quantify how tussock grassland plant community structure had changed and whether changes were related to increases in plant invasion. Frequency data for all vascular plants were recorded on 124, permanent transects in tussock grasslands across the lower eastern South Island of New Zealand measured three times over a period of 25 years. Multivariate analyses of species richness were used to describe spatial and temporal patterns in the vegetation. Linear mixed‐effects models were used to relate temporal changes in community structure to the level and rate of invasion of three dominant invasive species in the genus Hieracium while accounting for relationships with other biotic and abiotic variables. There was a strong compositional gradient from exotic‐ to native‐dominated plant communities that correlated with increasing elevation. Over the 25 years, small‐scale species richness significantly decreased and then increased again; however, these changes differed in different plant communities. Exotic species frequency consistently increased on some transects and consistently declined on others. Species richness changes were correlated with the level of Hieracium invasion and abiotic factors, although the relationship with Hieracium changed from negative to positive over time. Compositional changes were not related to measured predictors. Our results suggest that observed broad‐scale fluctuations in species richness and community composition dynamics were not driven by Hieracium invasion. Given the relatively minor changes in community composition over time, we conclude that there is no evidence for widespread degradation of these grasslands over the last 25 years. However, because of continuing weed invasion, particularly at lower elevations, impacts may emerge in the longer term.     

Trait‐based analysis of decline in plant species ranges during the 20th century: a regional comparison between the UK and Estonia

Although the distribution ranges and abundance of many plant species have declined dramatically in recent decades, detailed analysis of these changes and their cause have only become possible following the publication of second‐ and third‐generation national distribution atlases. Decline can now be compared both between species and in different parts of species' ranges. We extracted data from distribution atlases to compare range persistence of 736 plant species common to both the UK and Estonia between survey periods encompassing almost the same years (1969 and 1999 in the UK and 1970 and 2004 in Estonia). We determined which traits were most closely associated with variation in species persistence, whether these were the same in each country, and the extent to which they explained differences in persistence between the countries. Mean range size declined less in Estonia than in the UK (24.3% vs. 30.3%). One‐third of species in Estonia (239) maintained >90% of their distribution range compared with one‐fifth (141) in the UK. In Estonia, 99 species lost >50% of their range compared with 127 species in the UK. Persistence was very positively related to original range in both countries. Major differences in species persistence between the studied countries were primarily determined by biogeographic (affiliation to floristic element) and ecoevolutionary (plant strategy) factors. In contrast, within‐country persistence was most strongly determined by tolerance of anthropogenic activities. Decline of species in the families Orchidaceae and Potamogetonaceae was significantly greater in the UK than in Estonia. Almost all of the 736 common and native European plant species in our study are currently declining in their range due to pressure from anthropogenic activities. Those species with low tolerance of human activity, with biotic pollination vectors and in the families referred to above are the most vulnerable, especially where human population density is high.     

Species associations and nurse plant effects in patches of high-Andean vegetation

Abstract. In high-elevation communities of the southern Andes, plant cover is low due to severe environmental conditions and vegetation occurs mostly as isolated small (< 1 m²⁾ patches. Most patches are dominated by flat cushion plants. We evaluated patterns of plant species co-occurrence and species affinity for patches with and without cushion plants and different species richness. We mapped and recorded species composition of patches occurring within two 20 m × 20 m plots at the NE slope of Cerro Chall-Huaco, Nahuel Huapi National Park, Argentina. In these plots, we identified 32 and 24 plant species, and a maximum of 15 and 12 species per patch, respectively. The community was characterized by positive associations between species. Patches in which either of the common cushion plants Mulinum leptacanthum and Oreopolus glacialis occurred sustained richer communities than patches in which they were absent. Patches dominated by different cushion plants did not differ in species composition, but species differed in their affinities for patches with different numbers of species. Because richness increased with patch size and patch size with time, differential affinities of plant species suggest that successional changes take place in the patches. Some small herbaceous species appear to act as late colonizers, mostly restricted to species-rich patches. Flat cushion plants are considered ‘nurse plants’; they strongly modify micro-environmental conditions and allow establishment and survival of associated species.     

民间植物分类系统与区域性物种多样性快速评估——以西双版纳傣族为例

生物多样性的快速流失 ,使传统分类工作在热带物种多样性评估中显出不足 ,而民间分类系统在区域性物种多样性快速评估中的作用已经引起人们的重视。前人对西双版纳傣族民间植物命名和分类系统已做过研究 ,该文在此基础上 ,探讨能否将这种知识用于区域性物种多样性快速评估。利用生物多样性快速编目、样方调查及民族植物学中民间访谈的方法 ,考察了三个傣族村寨原住民的植物识别能力。结果表明 ,傣族原住民的植物识别程度与其年龄呈显著正相关 ,中年以后识别能力趋于稳定 ,识别率高达 91 %以上。通过与长期在西双版纳地区工作的野外植物分类学家相比较 ,我们发现傣族原住民的植物识别率不低于分类学家 ,且所需时间比分类学家少。作者认为 ,民间植物分类系统可以用于局部地区的物种多样性快速评估。