‘Relationships between relationships’ in forest stands: intercepts and exponents analyses

Relationships between diameter at breast height(dbh) versus stand density, and tree height versus dbh(height curve) were explored with the aim to find if there were functional links between correspondent parameters of the relationships, exponents and intercepts of their power functions. A geometric model of a forest stand using a conic approximation suggested that there should be interrelations between correspondent exponents and intercepts of the relationships. It is equivalent to a type of ‘relationship between relationships’ that might exist in a forest stand undergoing self-thinning, and means that parameters of one relationship may be predicted from parameters of another. The predictions of the model were tested with data on forest stand structure from published databases that involved a number of trees species and site quality levels. It was found that the correspondent exponents and intercepts may be directly recalculated from one another for the simplest case when the total stem surface area was independent of stand density. For cases where total stem surface area changes with the drop of density, it is possible to develop a generalization of the model in which the interrelationships between correspondent parameters(exponents and intercepts) may be still established.     

Nighttime transpiration of Populus euphratica during different phenophases

Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains limited Accordingly, we measured sap flow velocity of Populus euphratica using the heat ratio method between 2012 and2014. Nocturnal stem sap flow was separated into nighttime and stem refilling using the ‘‘forecasted refilling'method. Nighttime transpiration was observed for each phenophase. The highest value was during the full foliation period but lowest during leaf expansion and defoliation periods. The contribution of nighttime transpiration to daytime transpiration was an average of 15% but this was comparatively higher during the defoliation period. Relationships between nighttime transpiration, vapor pressure deficits, and air temperatures were more closely associated than with wind speed in all phenophases. Moreover, we found that nighttime transpiration linearly correlated to vapour pressure deficit during the first and the full foliation periods, but nighttime transpiration showed exponential correlations to air temperatures during the same phenophases. Additionally, environmental drivers of transpiration were significantly different between nighttime and daytime(P \ 0.05). Driving forces behind nighttime transpiration were characterized by many factors, and integrated impacts between these multiple environmental factors were complex. Future studies should focus on these integrated impacts on nighttime transpiration, and the physiological mechanisms of nighttime transpiration should be investigated, given that this could also influence its occurrence and magnitude during different phenophases.     

The Impact of Cane Supply on Rattan Trade in China

Rattan-related products from China are popular and well known in international market, but China is facing shortage of rattan cane supply, and extinction of some rattan species. The big gap between demand and supply of rattan canes in China market is urgent to be bridged. This paper makes a brief introduction on rattan in the world and analyzes the rattan trade in China. The loss of habitats, overexploitation and inadequate replenishment of rattan result in a depleting resource and there are many challenges and technical issues needed to be dealt with. The forest policies should not only state broad desires but also commit governments to undertake adequate and appropriate measures to protect and develop the resource on a sustainable basis.     

Relationships between native tree species and soil properties in the indigenous forest fragments of the Eastern Arc Mountains of the Taita Hills,Kenya

The relationship between soil properties and spatial distribution of native woody species was studied in three Taita Hills forest fragments which, although degraded, are ranked among 34 biodiversity hotspots of the world due to their high biodiversity of both plant and animal species. This relationship was assessed by using Spearman correlation and principal component analyses (PCA). The results of these analyses should be useful in instituting forest restoration programs that are crucial for the forests. Both the soil and vegetation studied were sampled from 17 subplots in the natural forest fragments of Ngangao (120 ha), Chawia (86 ha) and Mbololo (185 ha). The soil variables measured were: pH, texture, soil nutrients of C, N, Ca, P, K, Mg and Na. In total 36 native tree species from 13 families were identified from the three forest fragments. Ordination results show that axis 1 accounted for 35% and axis 2 for 25% of the total variation in species composition, indicating that the structure of vegetation is related to two major environmental gradients. The correlation analyses of species and soil properties showed that Na and clay particles were the most important determinants of species distribution; pH and soil variables such as C, N, Ca and P also played minor roles. Unexpectedly, some species (e.g. Psychotria petitii) showed positive relationships with Na attributed to possible substitution for K. Relationships with P were both positive (e.g. Craibia zimmermannii) and negative (e.g. Albizia gummifera) with some species, attributable to pH levels. An ANOVA for soil variables showed that there were differences in the Ca content in Mbololo (due to the parent material) and P in Ngangao where a special relationship was observed between some of the species. The presence of gaps accounted for the distribution of seedlings but not for the saplings, whose distribution responded more to factors similar to those to which mature trees respond. Soil-species relationships that were established may be utilized along with soil analyses when choosing native species for restoration.     

Composition and characteristics of natural secondary forests in Shenzhen,South China

The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversity level. According to succession process of subtropical forest and ecological characteristics of dominant species, the authors speculate that five communities are at different stages. Sinosideroxylon community dominated by heliophilous evergreen broad-leaved tree (Sinosideroxylon wightianum) and conifer tree (Pinus massoniana) is at the third stage. Itea Acronychia community dominated by two evergreen broad-leaved heliophytes (Itea chinensis and Acronychia pedunculata) is at the fourth stage. The others, i.e., Schefflera,Sterculia and Cleistocalyx Sterculia community are at the fifth stage where some mesophytes are dominant but heliophytes have a weighed percentage of importance value. Due to succession stage and different forest management and conservation models, the species diversity of five communities is significantly lower than that of Endospermum community in Hong Kong. The values of Shannon-Wiener index and Pielous evenness index of five communities are 2.04-2.953 and 64.2%-74% respectively, but those of the Endospermum community are 4.74 and 79％ respectively. The current situation of these communities suggests that the necessary measures should be taken to protect and restore the communities.     

Competition effects in an afrotemperate forest

Background： Information about competition responses is mainly available for monospecific stands or mixed stands with a small number of species. Studies on complex multi-species and highly structured forest ecosystems are scarce. Accordingly, the objective of this study was to quantify competition effects and analyse competition responses in a species-diverse afrotemperate forest in South Africa, based on an observational study with mapped tree positions and long-term diameter increment records. Methods： The sensitivity to competition was analysed for individual species and involved the calculation of the slope of the linear relation between the value of a competition index （CI） and diameter growth as a measure of sensitivity. In a next step different competition indices were combined and tree diameters were grouped in three classes as surrogates for canopy status and ontogenetic stage. Results： Five competition indices were found to be effective in showing sensitivity to competition for a number of canopy and sub-canopy species. Significant linear regressions were fitted for 18 of a total of 25 species. Species reactions varied significantly in their sensitivity to the different CIs. The indices were classified as belonging to two groups, those that responded more to local crowding and those that are more sensitive to overtopping, which revealed species-specific sensitivities to both factors. The analysis based on diameter classes revealed that species clearly changed their sensitivity to crowding or overtopping depending on diameter. Canopy and sub-canopy species showed distinct differences in their reactions. Conclusions： The application of multiple CIs brought novel insights relating to the dynamics of afrotemperate forests. The response patterns to different competition indices that focus on crowding and overtopping are varied and tree diameter dependent, indicating that oversimplified assumptions are not warranted in the interpretation of Cl- growth relations.     

Variations in bark thickness and sapwood density of <Emphasis Type="Italic">Calophyllum inophyllum</Emphasis> provenances in Australia and in Sri Lanka

Sapwood density and bark thickness of Calophyllum inophyllum L. (a multipurpose durable timber species) were studied in various locations in Northern Australia and in Sri Lanka. Measurements were taken non-destructively by using core sampling and bark gauge. From each provenance, 4-15 mature trees having girth at breast height over bark (GBHOB) at 100-150 cm were selected on the basis of the population size. Significant (p<0.05) hemispheric and provenance variations in bark thickness were found. Variations in the bark thickness are influenced by environmental variables. Variations in sapwood density were less pronounced compared to that of bark thickness. Variations in sapwood density are likely to be governed by genotypic variations.     

Effects of wheeled cable skidder on rut formation in skid trail — a case study in Hyrcanian forest

The impact of skidding operations on forest soils can be divided into three major categories: soil profile disturbance, soil compaction, and soil puddling and rutting. The present study was designed as a factorial experiment in the Kheyrud Forest with a Timberjack cable skidder to evaluate the influences of number of machine passes and soil moisture of skid trails on rutting over a fine-grained soil, and to quantify these effects. The effects of soil moisture of 20% 30%, 30% 40% and 40% 50% and different levels of compaction were studied. Compaction treatments were applied using different numbers of skidding passes (1, 5, 10, 15, 20, 25, 30 times). Result shows that an increase in the number of machine passes could increase rut depth, but the majority of rutting was occurred after the initial few machine passes. Also rut depth at soil moisture of 40% 50% was higher than rut depths at soil moisture of 30% 40% and 20% 30%. The average rut depth in soil with 20% 30%, 30% 40% and 40% 50% moisture was 17, 22 and 35 cm, respectively. Rut depths were increased significantly with soil moisture and number of machine passes. It is suggested that skidding operations should be planned when soil conditions are dry in order to minimize rutting., but if skidding must be done under wet conditions, the operations should be stopped when machine traffic could create deep ruts.     

Relationships between Artemisia ordosica communities and environmental factors following sand-dune stabilization in the Mu Us desert,northwest China

Artemisia ordosica is an excellent sand-fixing shrub for sand stabilization in northwestern China. Sand dune stabilization, a critically important process, leads changes in abiotic factors, such as soil structure and nutrient contents. However, the effects of factors on an A.ordosica community following sand stabilization remain unclear. In this study, we used canonical correspondence analysis(CCA) to examine the relationships between A.ordosica communities and environmental factors at three habitats: semi-fixed dune(SF), fixed dune with low-coverage biological soil crust(F), and fixed dune with highcoverage biological soil crust(FC) in Mu Us desert. The mean height and coverage of plants increased with sand stabilization, while species diversity and richness increased initially and then reduced significantly. Correlation analysis and CCA revealed that slope, soil organic carbon, and nutrient contents, proportion of fine soil particles, soil moisture, and thickness of biological soil crust were allhighly correlated with vegetation characteristics. These environmental factors could explain 40.42 % of the vegetation–environment relationships at the three habitats. The distribution of plant species was positively related to soil moisture in the SF dune. Soil moisture, soil nutrient, and fine-particle contents mainly affected plants distribution in the F dune. In the FC dune, distribution of plant species was positively and negatively correlated with the thickness of biological soil crust and soil moisture at a depth0–20 cm, respectively. The dominance value of typical steppe species increased significantly following sand-dune stabilization and relations between species and samples in CCA ordination bi-plots showed that perennial grasses could invade the A. ordosica community on FC, indicating A. ordosica communities had a tendency to change into typical steppe vegetation with the further fixation. We conclude that the significant differentiation not only occurred in community characteristics, but also in the relationships between vegetation and environmental factors among the three stages of dune fixation. So, restoration of degraded dune ecosystems should be based on habitat conditions and ecological needs.     

Community ecology and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracts,Bangladesh

We investigated the floristic composition, woody species diversity and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracks, Bangladesh. We recorded 25 families, 37 genera, 40 species and 1771 woody individuals in a 0.09 ha plot. Euphorbiaceae and Moraceae were the most speciesrich families, and Castanopsis, Ficus and Terminalia were the most species-rich genera. Bursera serrata Wall. ex Colebr. was the dominant species in terms of highest importance value(13%). Trema orientalis(L.)Bl was typically a light demanding species as it appeared in the top canopy with only one individual having the seventh highest IV, but had no regeneration. The expected maximum number of species(Smax) was 140,indicating that many species may invade the forest as the Smax is greater than the recorded total number of species. The nature of the disappearance and appearance of species in the present forest reflects instability of floristic composition. The values of Shannon's index H ′ and Pielou's index J ′(evenness) were 3.36 bit and 0.63, respectively. These values show moderately high species diversity as compared to other subtropical forests in the tropics. In addition, a sample area of 200 m2 in this forest would be sufficient for measuring the diversity indices H ′ and J ′,whereas the trend of J ′may indicate the rate of equality of individuals among the different species decreased with increasing area. The distribution pattern for the total stand was completely random. However, the dominant species showed aggregate distribution for small areas, but random distribution for large areas. The spatial association between species showed that the strongest positive interspecific association occurred between Streblus asper Lour. and Castanea indica Roxb.(ω =0.51). As a whole, most species were weakly associated with each other,of which 58% species associations were completely negative. The result of cluster analysis showed that species pairs were spatially independent at all or most small clusters; stands of species from all clusters are mosaics of complete habitat and pioneer habitat. All patches in this forest community have similar habitat and regeneration niches, which could be a phenomenon for a young growth forest. Thus, the existence of habitat and regeneration niches may be an important factor in the maintenance of diversity in this forest.     

旋花科植物ITS序列分析

通过提取白色圆叶牵牛基因组的DNA及紫色重瓣圆叶牵牛的DNA,对其内转录间隔区(ITS)序列进行PCR扩增和序列测定.采用BLAST方法,将测序结果在GenBank中进行同源搜索,采用邻接距离矩阵法构建了与其亲缘关系接近的旋花科14个种基于ITS序列的系统发育树,并分析了它们的亲缘关系.结果表明,原牵牛属和番薯属的亲缘关系较近,打碗花属、旋花属与番薯属为旋花科两大亲缘关系较远的类群;疑似新种的紫色重瓣圆叶牵牛并非一个新种,而是属于圆叶牵牛种下分类水平的变种或变型.     

狭口蛙属分子系统发育研究

基于线粒体基因序列(12S rRNA和16S rRNA)的联合分析,采用贝叶斯法和最大似然法分别构建了狭口蛙属9个物种的系统发育树,结果表明,(1)狭口蛙属为单系类群;(2)四川狭口蛙和多疣狭口蛙先聚为一支,后与北方狭口蛙聚为单系;(3)狭口蛙属分为印度-斯里兰卡支系,中国西南-东北支系和中国南部-东南亚支系等3个地理居群。     

松属线粒体基因序列变异研究

本研究利用ＰＣＲ和ＰＣＲ产物直接序列分析技术,获得了分属于松属（Ｐｉｎｕｓ）两个亚属Ｐｉｎｕｓ和Ｓｔｒｏｂｕｓ１２个松树种ｃｏｘＩ、ａｔｐ６和ｏｒｆ２５三个线粒体基因ＤＮＡ片段的序列。发现ｃｏｘＩ基因的ＤＮＡ序列在属内没有任何变异,但ａｔｐ６和ｏｒｆ２５在两个亚属间和亚属内出现了较多的碱基置换。这说明尽管裸子植物线粒体基因有较多的ＲＮＡ编辑（ＲＮＡｅｄｉｔｉｎｇ）存在,可促进ＤＮＡ序列的变异,但促进程度因不同基因而异。依据ａｔｐ６和ｏｒｆ２５所做的系统进化树不仅与分类结果一致,而且进一步表明了亚属内种间的亲缘关系。尽管线粒体基因序列变异比叶绿体和核ＤＮＡ变异小,线粒体基因编码序列变异仍适于研究裸子植物亚属甚至组间的系统进化关系。     

基于28S rDNA分析板栗和杉木上针叶小爪螨物种分化原因

【目的】我国经济林树种板栗和杉木上的重要害螨一直被认为是同一种螨——针叶小爪螨,但针叶小爪螨的山东板栗种群和浙江杉木种群间存在生殖隔离,且生殖隔离并非由地理隔离和能调控寄主生殖的内共生菌引起,似乎二者已分化为2个独立的种。本研究目的是明确其成种原因,丰富物种形成理论。【方法】从之前做杂交试验时所采集的针叶小爪螨板栗和杉木种群中各随机取3头雌成螨,提取单头雌成螨的总DNA,使用根据其他小爪螨28S rDNA两端保守序列设计的引物扩增28S rDNA,扩增产物纯化后测序。比较2种群的28S rDNA序列,并基于28S rDNA序列构建小爪螨属系统发育树,结合已有研究分析两种群分化原因。【结果】每个种群的3个个体的28S rDNA序列完全一致,无种群内变异。2种群的28S rDNA序列一致性为98. 3%,遗传距离为1. 7%。在基于28S rDNA序列构建的小爪螨属系统发育树上,浙江杉木种群与采自日本的日本柳杉上的本岛小爪螨亲缘关系最近,山东板栗种群与采自日本的日本栗上的栗小爪螨的亲缘关系最近。【结论】板栗和杉木上的叶螨并非由同一种叶螨因适应不同寄主植物分化而成,很可能是2个独立的物种。     

Integrating functional diversity into tropical forest plantation designs to study ecosystem processes

? The elucidation of relationships between biodiversity and ecosystem processes has been limited by the definition of metrics of biodiversity and their integration into experimental design. Functional trait screening can strengthen the performance of these designs.

? We suggest the use of Rao’s quadratic entropy to measure both functional diversity and phylogenetic diversity of species mixtures proposed for an experimental design, and demonstrate how they can provide complementary information.

? We also present an index assessing the statistical performance of these independent variables in different experimental designs. Measurement of independent variables as continuous vs. discrete variables reduces statistical performance, but improves the model by quantifying species differences masked by group assignments.

? To illustrate these advances, we present an example from a tropical forest tree community in which we screened 38 species for nine functional traits. The proposed TropiDEP design is based on the relative orthogonality of two multivariate trait axes defined using principal component analysis.

? We propose that independent variables describing functional diversity might be grouped to calculate independent variables describing suites of different traits with potentially different effects on particular ecosystem processes. In other systems these axes may differ from those reported here, yet the methods of analysis integrating functional and phylogenetic diversity into experimental design could be universal.

     

利用核糖体小亚基RNA序列探讨四种腹毛目纤毛虫的系统进化

以四个在环境监测中比较有代表性的纤毛虫属－游仆虫属、尾柱虫属、棘尾虫属和伪角毛虫属纤毛虫(Euplotes, Urostyla, Stylonychia, Pseudokeronopsis)为材料,对其16s小亚基核糖体RNA(16s－like Small Subunit rRNA,SSrRNA)基因进行序列测定,并与其他种腹毛目纤毛虫相比较,以美国赭虫(Blepharisma americanum)为外群构建系统进化树.结果显示:游仆虫属最先从腹毛目纤毛虫中分化出来,尾柱虫属(Urostyla)与全列虫属(Holosticha)纤毛虫亲缘关系较近.贻贝棘尾虫(Stylonychia mytilus)和浮萍棘尾虫(Stylonychia lenmae)是姊妹种,在外观上及其相似,但可以用构建进化树的方法从分子角度加以区分.从构建的进化树拓扑结构上可知,红色伪角毛虫与全列虫科种类的亲缘关系较近,与尾柱虫科种类的亲缘关系较远.     

利用16S rDNA基因序列进行害竹飞虱(半翅目:飞虱科)的分子鉴定

采用DNA测序技术测定了中国飞虱科5属10种15个地理种群的线粒体16S rDNA基因长约480 bp片段的序列,分析了其序列组成及变异特征.所获序列中,A+T约占77.5％,其中,190个核苷酸位点发生了变异(约占39.6％).利用MEGA 4.0软件计算遗传距离,外群与内群的遗传距离平均值(0.317)最高,内群各属间和各属内遗传距离平均值(分别为0.209和0.132)次之,而种内不同地理种群间的遗传距离平均值(0.013)最低.构建了10种飞虱科昆虫的MP和NJ分子系统树,结果显示:各属飞虱基本上形成单系群;各种飞虱各自不同地理种群均聚为一支,构成一单系群,可以很好的区分不同种类的飞虱.上述结果与形态学研究结果非常吻合.     

河北省葡萄座腔菌科菌物系统分类研究

【目的】葡萄座腔菌科菌物是引起众多经济及生态造林树种枝干溃疡、枝枯类病害的病原生物,在世界各地均有广泛的分布。本研究对河北省内,与经济林木病害相关的葡萄座腔菌科菌物进行系统分类研究,目的在于揭示该科菌物在特定地区的地理分布特征,明确该类菌物所致树木枝干溃疡、枝枯类病害的寄主植物范围,为河北省树木溃疡、枝枯类病害的控制提供理论依据。【方法】在对河北省树木溃疡类病害系统调查的基础上,本研究根据菌物无性型及有性型的形态学特征、rDNA-ITS序列特征对包括河北省石家庄在内的8个市(县、区)25个不同地点的葡萄座腔菌科菌物进行分类鉴定和系统分类。【结果】共获得葡萄座腔菌科菌物5种73株,分别属于Botryosphaeria dothidea、B.stevensii、B.obtusa、B.sarmentorum和Phyllosticta citrichinaensis。其中B.dothidea为河北省葡萄座腔菌科优势菌物种,占全部检出菌物菌株总数的77%。葡萄座腔菌科菌物侵染杨树、柳树、苹果、核桃等28种植物,其中包括大叶黄杨、构树、火炬树、连翘、花椒和刺梅等6种新寄主植物。【结论】B.dothidea不仅危害杨树等传统寄主,而且危害花椒等新寄主植物以及入侵树种火炬树,是危害河北省树木健康生长的最为重要、分布最为广泛的枝干病原菌物,有必要对其溃疡致病性分化和种群遗传分化进行深入分析。来自柿树、花椒等寄主的10个具有Dothiorella型分生孢子的菌株形成单系类群,提示这些菌株可能是与B.sarmentorum和B.iberica不同的一个系统发育学新种。     

Logging and livestock influence the abundance of common mammal species in Mediterranean forested environments

Forest and livestock management puts pressure on forests and the wildlife they support. Although many species may be negatively affected by these human activities, the abundance of other species may be promoted, although this has perhaps received less attention in livestock, logging, and conservation management plans. Wild boar and red fox, two common mammals distributed throughout Europe, occupy a wide variety of Mediterranean environments. Little is known about how increases in logging and livestock management have changed their status. This work models the response of wild boar and red fox to these pressures in the human-altered Mediterranean forest landscapes of the central Iberian Peninsula (NHR), where the predominant land uses in the last hundred years have focused on livestock and logging (thinning and selective cutting). We collapsed land use and habitat structure variables into independent habitat vectors using principle component analysis (PCA) and then used a general linear model (GLM) to explain the relationships between red fox and wild boar abundance and the independent habitat vectors observed in human-altered forests. Livestock and logging activity was positively correlated with wild boar abundance, and negatively correlated with red fox abundance, although red fox tolerated open scrubland that had been logged. Red fox abundance remained negatively correlated with the same variables when boar abundance was added as an environmental predictor in the model, but some additional variance was explained, demonstrating the need to include indirect interspecific relationships in the habitat-species models. The combined effects of wild boar, logging and livestock are indirectly important factors which modify habitat structure and negatively affect red fox. Therefore, common mammal species are influenced by livestock and logging in different ways which necessarily may be taken into account in management and conservation decisions in Mediterranean human-altered forests.