Biomass estimation models and allocation patterns of 14 shrub species in Mountain Luya,Shanxi, China

Aims Shrub species have evolved specific strategies to regulate biomass allocation among various organs or between above- and belowground biomass and shrub biomass model is an important approach to estimate biomass allocation among different shrub species. This study was designed to establish the optimal estimation models for each organ (leaf, stem, and root), aboveground and total biomass of 14 common shrub species in Mountain Luya, Shanxi Province, China. Furthermore, we explored biomass allocation characteristics of these shrub species by using the index of leaf biomass fraction (leaf to total biomass), stem biomass fraction (stem to total biomass), root biomass fraction (root to total biomass), and root to shoot mass ratio (R/S) (belowground to aboveground biomass).
Methods We used plant height, basal diameter, canopy diameter and their combination as variables to establish the optimal biomass estimation models for each shrub species. In addition, we used the ratios of leaf, stem, root to total biomass, and belowground to aboveground biomass to explore the difference of biomass allocation patterns of 14 shrub species.
Important findings Most of biomass estimation models could be well expressed by the exponential and linear functions. Biomass for shorter shrub species with more stems could be better estimated by canopy area; biomass for taller shrub species with less stems could be better estimated by the sum of the square of total base diameter multiply stem height; and biomass for the rest shrub species could be better estimated by canopy volume. The averaged value for these shrub species was 0.61, 0.17, 0.48, and 0.35 for R/S, leaf biomass fraction, stem biomass fraction, and root biomass fraction, respectively. Except for leaf biomass fraction, R/S, stem biomass fraction, and root biomass fraction for shrubs with thorn was significantly greater than that for shrubs without thorn.     

Latitudinal comparison of altitudinal changes in forest structure,leaf-type,and species richness in humid monsoon Asia

A new template for mountain vegetation zonation along latitudinal gradients is proposed for examining geographical pattern of various forest attributes in humid monsoon Asia. The contrasting temperature regime in tropical and temperate mountains, i.e., the former is a non-seasonal, temperature-sum controlled environment, and the latter is a seasonal, low temperature limiting environment, leads to different altitudinal patterns of tree height distribution and species richness. In the tropical mountains, both tree height and species richness decrease steeply, and the tree height often stepwise. The decline of tree height and species diversity in the temperate mountains is far less pronounced except near the forest limit. Both trends are explained by their temperature regime.     

SaudiVeg ecoinformatics: Aims,current status and perspectives

During the last decade many electronic databases of vegetation plots were established in many countries around the world. These databases contain valuable phytosociological information assisting both governmental and NGO (Non-governmental organizations) agencies to formulate strategies and on-ground plans to manage and protect nature resources. This paper provides an account on aims, current status and perspectives of building of a vegetation database for the Central Region (Najd) of Saudi Arabia – the founding element of the Saudi Vegetation Database (SVD). The data stored by the database are sample plots (vegetation relevés) collected according to the field techniques of the Braun-Blanquet approach (lists of taxa accompanied by semi-quantitative cover assessment), and are accompanied by general vegetation characteristics such as vegetation layering and cover, information on life-form of the recorded species, geographical coordinates, altitude, soil typology, topography and many more. More than 2900 vegetation-plot records (relevés) have so far been collected in the Najd region; of these more than 2000 have already been stored using the Turboveg database platform. These field records cover many habitats such as depressions, wadis (dry river beds), agricultural lands, sand dunes, sabkhas, and ruderal habitats. The ecological information collected in the database is currently the largest set of vegetation data collated into a database in the Middle East. These data are of great importance for biodiversity studies in Saudi Arabia, since the region is recording a loss of biodiversity at a fast rate due to environmental problems such as global warming and land-use changes. We envisage that this database would catalyze further data collection on vegetation of the entire Arabian Peninsula, and shall serve as one of the most important datasets for classification and mapping of the vegetation of the Kingdom of Saudi Arabia.     

基于空间生态集合覆盖模型的自学习禁忌搜索算法在保护区空间选址中的应用——以戴云山为例

自然保护区规划是保护生物多样性的有效方式.传统保护区规划方法只能识别物种保护的重点区域,无法科学确定保护区的适宜面积.地块选择方法基于数学模型,从规划区域中选择部分地块组成自然保护区,保护特定物种或生态系统,是缓解生态保护与开发利用矛盾的重要手段.现有地块选择法未考虑各单元生态差异,且最优化算法存在计算效率的瓶颈.本文首先构建适用于森林生态系统的生态值赋分评价体系,据此计算戴云山生态值并绘制其分布图;然后,结合生态值建立生态集合覆盖模型(ESCP),并基于ESCP嵌入空间紧凑性提出空间生态集合覆盖模型(SSCP);最后,利用寻优性能良好的自学习禁忌搜索算法(STS)搜索各保护目标下的近似最优选址方案,给出福建省戴云山现有建成区优化方案.结果表明: 戴云山生态值计算结果在空间分布上存在明显差异;ESCP比原集合覆盖模型(SCP)能产生生态值更高的选址方案;SSCP在ESCP基础上对生态值较高区域有聚集作用,且周长权重越大,聚集效果越明显;建议现保护区可向外拓展136 km²,并将西北向分布长苞铁杉的地块纳入保护区范围.研究结果为实现戴云山保护区可持续发展及土地资源优化配置提供了优化方案,也可为我国森林生态系统类型的自然保护区设计提供新思路.     

In and out: Effects of shoot- vs. rooted-presence sampling methods on plant diversity measures in mountain grasslands

Plant diversity measures (e.g., alpha- and beta-diversity) provide the basis for a number of ecological indication and monitoring methods. These measures are based on species counts in sampling units (plots or quadrats). However, there are two alternative conventions for defining a vascular plant species as “present” in a plot, i.e. “shoot presence” (a species is recorded if the vertical projection of any above-ground part falls within the plot) and “rooted presence” (a species is recorded only when an individual is rooted inside the plot). Very few studies addressed the effects of the two sampling conventions on species richness and diversity indices. We sampled mountain dry grasslands in Italy across different plot sizes and vegetation types to assess how large is the difference in alpha- and beta-diversity values and in sample-based rarefaction curves between the two methods. We found that the difference is greatly dependent on plot size, being more relevant, both in absolute and percentage values, at smaller grain; it is also dependent on habitat type, being larger in shallow-soil communities, as they have a sparser vegetation structure and host life-form types with a larger lateral spread. At fine spatial scales (<1 m²) the difference is large enough to bias statistical inference, and we conclude that at such scales one should not attempt to compare plant diversity indices if they were not obtained with the same sampling convention.     

Spatial variation of species diversity across scales in an old-growth temperate forest of China

Species richness and abundance are the two most important diversity variables. Species abundance is additive when aggregated across spatial scale, whereas species richness is non-additive. This study analyzes the effect of spatial scale and site on species abundance and richness in a 25-ha temperate forest plot in the Changbai Mountains, northeastern China. The result shows that species abundance and richness are not only dependent on spatial scales, but also dependent on site. Species abundance responds linearly to changes of spatial scale with no intersection in different sites of the study area. However, although species richness also increases with the increase of spatial scale, there are some intersections for the different sites, suggesting that a species-rich site does not always have a high value if the spatial scale is changed. In all, with respect to additive variables, it is relatively easy to extrapolate them from one spatial scale to another spatial scale, as they and the spatial scale usually form a linear relationship. In contrast, non-additive variables are difficult to extrapolate across spatial scales, because they often respond nonlinearly to spatial scale changes. In order to extrapolate these non-additive variables across spatial scales, it is necessary to estimate the relationships between them and spatial scales. As a result, extrapolation of information among spatial scales may be possible, but very difficult, especially for non-additive variables. Because the 25-ha Changbai plot is very small compared to the extent of the world temperate forests, and the vegetation is a relatively uniform type, more such studies in other ecosystems are needed before theories and generalization about scaling effects can be formulated.     

五台山南台旅游活动对山地草甸优势种群格局的影响

利用双项轨迹方差法,对五台山南台不同距离带上紫羊茅、珠芽蓼和北方嵩草的格局进行了研究.结果表明:(1)3个种群在第一带上格局强度很弱,在第五带上格局差异最明显.不同种群在第二、第四带上因旅游活动和种间竞争而表现出不同的格局规律.(2)近距离处,旅游干扰大,尽管紫羊茅是优势种,但它和其他种群一样都表现出斑块化的现象.随着距离的增加,旅游干扰减小,种间竞争激烈,紫羊茅的优势减小,北方嵩草的优势上升,珠芽蓼徘徊不前,种群格局各具特色.远距离处,北方嵩草斑块稳定,规模大,紫羊茅的斑块数量少,规模较小.珠芽蓼没有表现出明显的规律性,这可能与其本身的生理生态有关.     

云雾山自然保护区优势植物种群分布格局的分形特征

对宁夏云雾山草原自然保护区植物种群分布格局的分形计盒维数进行了研究。结果表明：本氏针茅、铁杆蒿和百里香是该区的优势种。3种优势种的计盒维数在1．7左右，表明它们具有较大的空间占据能力。但是它们的计盒维数最大值出现的时间不同，本氏针茅、百里香计盒维数最大值出现存封育20a的样地中，铁杆蒿出现在封育25a的样地中。