丹霞地貌沟谷生态效应

以广东省丹霞山为研究实例,探讨丹霞地貌特殊的沟谷生态效应.结果表明,丹霞地貌的特殊沟谷生态效应体现在以下两个方面:第一是丹霞地貌演变过程中形成了众多石峰隆起和沟谷凹陷,特殊的地貌环境使得沟谷中的生态因子与其它非丹霞地貌开阔区域产生差异,小气候相对封闭,水湿条件极好,为喜高温高湿的热带物种提供了较好的生存环境;沟谷所处位置的地理环境,如四周崖壁的光滑程度会影响到太阳光反射到沟谷的光强,这些都会对沟谷中的温湿度产生影响.第二是丹霞地貌特殊的生态条件,为沟谷地带孕育出一批热带性较强的分类群提供了可能,与相近纬度的诸多植被相比,丹霞地貌植物区系热带性明显增强,热带分布区类型所占比重比同纬度区域要大10%以上,大多数沟谷中热带性物种分布现象比较明显,藤本分布较多,蕨类植物也较丰富,耐水湿的植物区系发育良好;这实际上造成了植物水平分布上的移位,使中亚热带区域中分布有南亚热带甚至热带区域的物种,出现了由于其特殊的沟谷地貌效应而形成的与其地貌条件保持协调和平衡的演替顶级群落类型,称为地貌顶级群落.     

丹霞地貌山顶生态效应

首次探讨了丹霞地貌山顶生态效应现象,揭示特殊的地貌、形态所产生的特殊生态现象.测定广东省丹霞山宝珠峰和海螺峰的山顶的生态因子特征、群落结构特征和物种生态型特征,并与山脚的群落与种群以及相近非丹霞地貌区作比较.结果表明,山顶的平均温度高于山脚沟谷,平均湿度小于山脚沟谷,群落物种数和物种多样性均小于山脚沟谷.相比山顶而言,山脚沟谷的植物有很强的热带性.这些特征都有别于一般非丹霞地貌山地.另外,在山顶和山脚调查的几个种群在叶面积、比叶面积、树皮、枝下高和冠幅等方面,均出现了生态型的差异.讨论了丹霞地貌山顶对生态型研究、岛屿理论研究和适应性进化研究的科学意义.     

Ecological effect on the hilltop of Danxia Landform

The hilltop ecological effect of Danxia Landform generated by the distinct physiognomy and topography was investigated. The characteristic differences in ecological factors, community structure and species ecotype between hilltop and foot gulch and those of adjacent non-Danxia Landform were determined. The results showed that the mean daily temperature on the hilltop was higher than that at the foot gulch. But the average relative humidity and community diversity on the hilltop were lower than those at the foot gulch. In contrast to those on the hilltop, plants at the foot gulch showed stronger tropical character. All of the characteristics above were different from those in other landforms. In addition, ecotypic differentiations in leaf area, specific leaf area, bark, height under branch and crown width were found in the studied species between the hilltop and the foot gulch. Moreover, the hilltop of Danxia Landform was thought to be of significance in the scientific research of ecotype, island biogeography and adaptive evolution. Further studies are needed in order to better understand the universality of ecological effect on the hilltop of Danxia Landform.     

论丹霞地貌区生态演替特征及其科学价值

论述了丹霞地貌区生态演替的特征及其科学价值.认为植被演替由于时间漫长、过程复杂而对其研究具极大的难度,时空互代成为演替研究的重要手段,而这需要有完整的空间序列.丹霞地貌区存在着完整的原生演替与次生演替系列.典型丹霞地貌的山顶为原生演替的矮灌木林和乔木林,周围斜坡仍然受季节性降水侵蚀、风化、重力崩塌等作用,原生演替不断从裸露的岩石开始,故形成原生演替早期的苔藓、草本群落,随着岩石的进一步风化和苔藓、地衣等植物的作用,土壤层增厚,将原生演替继续往前推进.特殊的地质地貌过程使之不断有新的崩塌,从裸露的岩石开始的新的原生演替,如此形成不同时间系列的原生演替阶段.丹霞地貌区也存在着完整的次生演替系列,同时存在演替先锋林、演替过渡林和演替基本稳定林.这两个演替系列提供了一个非常难得的理想场所,使得生态学工作者在一个地点就可以观察到一个完整的植被演替系列.其研究可为该区域植被的经营管理和保护措施提供必要的依据.作为生态恢复参照系,对区域的植被生态恢复具有重要的指导意义.＃     

Characteristics and scientific values of ecological succession in Danxia Landform of China

The characteristics and scientific values of ecological succession in Danxia Landform of China were discussed. It was known that research on vegetation succession was quite difficult for its long-term and intricate process. Space-time substitution is an important method to study the succession, while it needs intact spatial succession series. In Danxia Landform, there are such primary and secondary succession series. On the hilltops, there are typical low shrubberies and arboreal forests of primary succession. The surrounding slopes are subjected to seasonal rainfall erosion, weathering action, gravitational collapse and so on. The primary succession constantly starts from bare rocks, and then moss and herbal communities of early primary succession are formed. With further weathering of rocks and effects of moss and lichen, soil layers are getting thicker and thicker, which pushes primary succession ahead. New collapses are ceaselessly induced by the special geological geomorphological process, and then a new primary succession starts from bare rocks. Thus, different stages of primary succession are formed in Danxia Landform. In addition, the secondary succession series exist in Danxia Landform, including the pioneer forests, transitional forests and steady forests. Danxia Landform provides ideal sites for vegetation succession study. The relative studies would be helpful for the vegetation management and protection in this area. As ecological restoration reference, it is also meaningful for the vegetation restoration.     

Species richness in tropical fresh waters of Australia

General ecological expectations about the relationship between latitude and species richness are that at low latitudes (the tropics) species richness is greater than at higher latitudes (temperate and polar regions). Recent work suggests that this may not be the case for several habitat types and biological groups in Australia. Results are conflicting: on present evidence (admittedly sparse) it appears that in Australian tropical fresh waters species richness is generally depressed in zooplankton and littoral microfaunal communities, but not in macroinvertebrate communities in typical streams and in fish communities (and perhaps also in amphibian and reptile communities). The situation is indeterminate for tropical phytoplankton and macrophyte communities.     

Vegetative Community Compositional Gradients of Tropical Hardwood Hammocks along the Florida Keys

Tropical hardwood hammocks, among the rarest and most threatened vegetative communities in the United States, occur throughout the 225-km Florida Keys archipelago as it extends toward the Caribbean from the southeast tip of peninsular Florida. Compounding their critical conservation status, tropical hardwood hammocks and the dynamics that support their peculiar species diversity in the region are poorly understood. The goal of this study was to explore the dynamics of the species compositional gradient of the hammocks along the Florida Keys, and to identify significant ecological units within the gradient. The primary data for this research were assembled from the Institute for Regional Conservation's floristic database of South Florida. We were able to extract presence/absence data for 295 species from comprehensive surveys of 23 study sites. Nonmetric multidimensional scaling was used to deconstruct the compositional trends into a reduced ordination space. Cluster analysis was subsequently used to identify discrete ecological units. Additionally, we used vector fitting to interpret the significant correlated ancillary variables. Our main results were three well-fitted nonmetric multidimensional scaling axes with three nonoverlapping ecological units. Of the ancillary variables, latitude, longitude, percent composition from biogeographical regions, richness, and area were correlated to the nonmetric multidimensional scaling results. These results increase our understanding of the community structure of the hammocks along the Florida Keys, and can contribute to increasing our ability to adequately protect and restore tropical hardwood hammocks and other similar tropical dry forest communities throughout the Caribbean.     

Comparative analysis of the floristic richness of alpine communities in the Caucasus and the Central Alps

Abstract. Species richness of selected alpine plant communities in the Teberda Biosphere Reserve (Northwestern Caucasus) and the Davos area (Central Alps) was compared in series of plots from 0.0025 to 100 m². Communities developing under similar ecological conditions and with similar syntaxonomic positions were compared in order to estimate the role of recent environment versus regional historical factors in determining plant community structure and diversity. The floristic richness of the Caucasian and Alpic fens was very similar. The Grasslands and Meadows were quite similar as to floristic richness for plots > 25 cm × 25 cm, but the Caucasian communities had fewer species in smaller plots. The Lichen heath at Teberda was richer than the Caricetum curvulae cetrarietosum for all plot sizes, except the two smallest ones. On the other hand, the plots of the Salix Snowbed community were richer in species than the Caucasian snowbeds for all plot sizes. The Rhododendron Shrubland plots were very similar as to floristic richness in larger plots (4 — 100 m²). Generally, most Alpic communities near Davos were richer in species at small plot sizes than the corresponding communities from Teberda. Caucasian communities were floristically less similar to each other — and thus more discrete — than the Alpic ones. The possible role of different factors controlling floristic richness of the communities is discussed. Our results suggest that recent ecological conditions have a big influence on local floristic diversity and may lead to high similarities between ecologically similar communities from different regions. In addition, the general floristic richness of a regions as well as island effects should be taken into account.     

广东优势群落甜槠林多样性研究

采用每木调查法,对广东粤北石门台和粤中象头山地区甜槠（Castanopsis eyrie（Champ.） Tutch.）林样方内胸径≥ 1 cm的乔、灌木进行测量,记录其种名、胸径、高度和在样方中的坐标位置等指标,对群落的植物组成、区系成分、优势种及物种多样性进行分析。结果显示：石门台样地有维管植物112种,隶属36科54属;象头山样地有维管植物109种,隶属36科59属。两个群落均具有明显的热带向亚热带过渡的性质。其中,石门台样地与华东、华中地区联系紧密;象头山样地则与中国台湾、日本的岛屿联系更多。比较两个地区的群落特征发现,他们的相似性较高,物种多样性指数接近,纬度并不是决定群落植物多样性高低的因素,小环境、群落演替进程及人为因素对群落植物多样性的影响更大。     

广东优势群落甜槠林多样性研究

采用每木调查法,对广东粤北石门台和粤中象头山地区甜槠( Castanopsis eyrie (Champ.) Tutch.)林样方内胸径≥ 1 cm的乔、灌木进行测量,记录其种名、胸径、高度和在样方中的坐标位置等指标,对群落的植物组成、区系成分、优势种及物种多样性进行分析。结果显示:石门台样地有维管植物112种,隶属36科54属;象头山样地有维管植物109种,隶属36科59属。两个群落均具有明显的热带向亚热带过渡的性质。其中,石门台样地与华东、华中地区联系紧密;象头山样地则与中国台湾、日本的岛屿联系更多。比较两个地区的群落特征发现,他们的相似性较高,物种多样性指数接近,纬度并不是决定群落植物多样性高低的因素,小环境、群落演替进程及人为因素对群落植物多样性的影响更大。     

Potential warm-stage microrefugia for alpine plants: Feedback between geomorphological and biological processes

During interglacial stages, microrefugia are sites that support locally favorable climates within larger areas with unfavorable warmer climates. Despite recent theoretical representations of microrefugia, an appropriate ecological characterization is still lacking, mostly for warm periods. Across mountain/alpine areas, cold-adapted plant species could adopt different strategies to manage the effects of climate warming: (A) migration toward higher elevations and summits; (B) in situ resilience of communities and species populations within microrefugia; and C) adaptation and evolution by genetic differentiation. This review aims to distinguish and characterize from an ecological perspective glacial, nival, periglacial and composite landforms and deposits that may function as potential microrefugia during interglacial warm periods.We conducted a literature screening related to the geomorphological processes and landforms associated with vegetation and plant communities in alpine/mountain environments of Europe. They include glacial deposits rock glaciers, debris-covered glaciers, composite cones and channels. In Alpine regions, geomorphologic niches that constantly maintain cold-air pooling and temperature inversions are the main candidates for microrefugia. Within such microrefugia, microhabitat diversity modulates the responses of plants to disturbances caused by geomorphologic processes and supports their aptitude for surviving under extreme conditions on unstable surfaces in isolated patches. Currently, European marginal mountain chains may be considered as examples of macrorefugia where relict boreo-alpine species persist within peculiar geomorphological niches that act as microrefugia.This review contributes to identifying potential warm-stage microrefugia areas across alpine and mountain regions and determining certain landforms that play or may play such role under global-change scenarios. The occurrence of warm-stage microrefugia within these locations may be of great importance for the modeling of future distributions of species and assessing the risk of extinction for alpine species. Microrefugia may have important implications in micro-evolutionary processes that occur across alternating climatic phases.     

Untangling latitudinal richness gradients at higher taxonomic levels: familial perspectives on the diversity of New World bat communities

Aims (i) To describe at the level of local communities latitudinal gradients in the species richness of different families of New World bats and to explore the generality of such gradients. (ii) To characterize the relative effects of changes in the richness of each family to the richness of entire communities. (iii) To determine differences in the rate and direction of latitudinal gradients in species richness within families. (iv) To evaluate how differences among families regarding latitudinal gradients in species richness influence the latitudinal gradient in species richness of entire communities. Location Continental New World ranging from the northern continental United States (Iowa, 42° N) to eastern Paraguay (Canindeyú, 24° S). Methods Data on the species composition of communities came from 32 intensively sampled sites. Analyses focused on species richness of five of nine New World bat families. Multivariate analysis of variance and discriminant function analysis determined and described differences among temperate, subtropical, and tropical climatic zones regarding the species richness of bat families. Simple linear regression described latitudinal gradients in species richness of families. Path analysis was used to describe: (i) the direct effect of latitude on species richness of communities, (ii) the indirect effects of latitude on the species richness of communities through its effect on the species richness of each family, (iii) the relative effects of latitude on the species richness of bat families, and (iv) the relative contribution of each family to variation in the species richness of communities. Results Highly significant differences among climatic zones existed primarily because of a difference between the temperate zone and the tropical and subtropical zones combined. This difference was associated with the high number of vespertilionids in the temperate zone and the high number of phyllostomids in the tropical and subtropical zones. Latitudinal gradients in species richness were contingent on phylogeny. Although only three of the five families exhibited significant gradients, all families except for the Vespertilionidae exhibited indistinguishable increases in species richness with decreases in latitude. The Emballonuridae, Phyllostomidae and Vespertilionidae exhibited significant latitudinal gradients whereby the former two families exhibited the classical increase in species richness with decreasing latitude and the latter family exhibited the opposite pattern. Variation in species richness of all families contributed significantly to variation in the species richness of entire communities. Nonetheless, the Phyllostomidae made a significantly stronger contribution to changes in species richness of communities than did all other families. Much of the latitudinal gradient in species richness of communities could be accounted for by the effects of latitude on the species richness of constituent families. Main conclusions Ecological and evolutionary differences among higher taxonomic units, particularly those differences involving life‐history traits, predispose taxa to exhibit different patterns of diversity along environmental gradients. This may be particularly true along extensive gradients such as latitude. Nonetheless, species rich taxa, by virtue of their greater absolute rates of change, can dominate and therefore define the pattern of diversity at a higher taxonomic level and eclipse differences among less represented taxa in their response to environmental gradients. This is true not only with respect to how bats drive the latitudinal gradient in species richness for all mammals, but also for how the Phyllostomidae drives the latitudinal gradient for all bats in the New World. Better understanding of the mechanistic basis of latitudinal gradients of diversity may come from comparing and contrasting patterns across lower taxonomic levels of a higher taxon and by identifying key ecological and evolutionary traits that are associated with such differences.     

红树林放线菌研究进展

红树林是生长在热带和亚热带海岸潮间带的一种独特植物群落,构成陆地与海洋间的过渡,具有水分高、盐分高、耐缺氧等特征的特殊生态系统及很高的生物多样性,是筛选和发现放线菌新物种和药用生物活性次级代谢产物的宝贵资源。在物种鉴定方面,放线菌分类学是目前红树林放线菌物种鉴定的重要手段。本文综述了红树林放线菌物种鉴定主要方法、红树林放线菌生态环境和物种分布特征、生物学活性及其次级代谢产物等,并展望了该领域研究与发展的重要问题与趋势。     

Seeds tend to disperse further in the tropics

Despite the importance of seed dispersal in a plant's life cycle, global patterns in seed dispersal distance have seldom been studied. This paper presents the first geographically and taxonomically broad quantification of the latitudinal gradient in seed dispersal distance. Although there is substantial variation in the seed dispersal distances of different species at a given latitude, seeds disperse on average more than an order of magnitude further at the equator than towards the poles. This pattern is partially explained by plant life‐history traits that simultaneously associate with seed dispersal distance and latitude, including dispersal mode and plant height. The extended seed shadow of tropical plants could increase the distance between conspecific individuals. This could facilitate species coexistence and contribute to the maintenance of high plant diversity in tropical communities. The latitudinal gradient in dispersal distance also has implications for species’ persistence in the face of habitat fragmentation and climate change.     

Vegetation dynamics of coastal sand dunes near Malindi, Kenya

This study describes the composition, structure and distribution of coastal dune vegetation near Malindi, Kenya. The vegetation was made up of 156 plant species. Sixty families were recorded with Gramineae (seventeen species) and Papilionaceae (sixteen species) being the most widely represented. Fifteen plant communities were described in the different geomorphologic units. The plant communities exhibited a distinct zonal distribution. Halopyrum mucronatum and Ipomoea pes‐caprae plant communities were common in the unstable geomorphologic units. Cordia somaliensis and Pluchea dioscoridis plant communities were common in the more stable geomorphologic units. Most of the plants in the more stable geomorphologic units were shrubs and trees. Succulent herbs were identified in the slacks and the drowned valley, which have moist and damp environments.     

陆地植物群落物种多样性的梯度变化特征

研究陆地植物落物种多样性随环境因子及群落演替梯度的变化特征是揭示生物多样性与生态因子相互关系的重要方面,根据近期国内外的文献,综述了这方面的研究进展。随纬度的降低,通常物咱多样性随中,随不分梯度的变化,物种多样性的变化有６种趋势;随海拔高的变化,物处多样性有５种模式;随土壤养分梯度的变化,表现出不同的规律;演替过程中物种多样生的变化趋势相似。关于植物群落物种多样性梯度格局的机制有多种假说,但仍需进     

Seed dispersal spectra: a comparison of temperate plant communities

Abstract. We compare the dispersal spectra of diaspores from varied plant communities in Australia, New Zealand, and North America, assigning dispersal mode to each diaspore type on the basis of apparent morphological adaptations. Species with ballistic and external dispersal modes were uncommon in most communities we surveyed. Ant dispersal was also rather uncommon, except in some Australian sclerophyll vegetation types. The frequency of vertebrate dispersal ranged up to 60% of the flora, the highest frequencies occurring in New Zealand forests. Wind dispersal ranged as high as 70% of the flora, with the highest values in Alaska, but usually comprised 10–30% of the flora. Many species in most communities had diaspores with no special morphological device for dispersal. Physiognomically similar vegetation types indifferentbiogeographic regions usually had somewhat dissimilar dispersal spectra. The frequency of dispersal by vertebrates often increased and the frequency of species with no special dispersal device decreased along gradients of increasing vertical diversity of vegetation structure. Elevation and moisture gradients also exhibited shifts in dispersal spectra. Within Australia, vertebrate- and wind-dispersal increased in frequency along a soil-fertility gradient, and dispersal by ants and by no special device decreased. Habitat breadths (across plant communities) and microhabitat breadths (within communities) for species of each major dispersal type did not show consistent differences, in general. Ant-dispersed species often had lower cover-values than other species in several Australian vegetation types. We discuss the ecological bases of these differences in dispersal spectra in terms of the availability of dispersal agents, seed size, and other ecological constraints. Seed size is suggested to be one ecological factor that is probably of general relevance to the evolution of dispersal syndromes.     

Thermal adaptation and diversity in tropical ecosystems: evidence from cicadas (Hemiptera, Cicadidae)

The latitudinal gradient in species diversity is a central problem in ecology. Expeditions covering approximately 16°54' of longitude and 21°4' of latitude and eight Argentine phytogeographic regions provided thermal adaptation data for 64 species of cicadas. We test whether species diversity relates to the diversity of thermal environments within a habitat. There are general patterns of the thermal response values decreasing in cooler floristic provinces and decreasing maximum potential temperature within a habitat except in tropical forest ecosystems. Vertical stratification of the plant communities leads to stratification in species using specific layers of the habitat. There is a decrease in thermal tolerances in species from the understory communities in comparison to middle level or canopy fauna. The understory Herrera umbraphila Sanborn & Heath is the first diurnally active cicada identified as a thermoconforming species. The body temperature for activity in H. umbraphila is less than and significantly different from active body temperatures of all other studied species regardless of habitat affiliation. These data suggest that variability in thermal niches within the heterogeneous plant community of the tropical forest environments permits species diversification as species adapt their physiology to function more efficiently at temperatures different from their potential competitors.     

基于地理探测器的丹霞梧桐空间分布与生境因子的相关性

丹霞梧桐是中国丹霞地貌的特有种,识别影响其分布的主要环境驱动因子,可为保护丹霞梧桐及其生境提供科学依据。本研究以广东南雄丹霞梧桐县级自然保护区与广东丹霞山旅游风景区(核心景区)为研究区,运用地理探测器分析丹霞梧桐空间分布与两地生境因子的相关性(用q值衡量),分析要素包括地理要素(地貌形态成因类型、土壤亚类、高程、坡度、坡向)和气候要素(年均降水、年日照时数、年均相对湿度、年均风速)。结果表明: 影响丹霞梧桐空间分布的主要生境因子为土壤亚类、年日照时数、地貌形态成因类型。其中,丹霞梧桐生境的各因子相关性分析中,土壤亚类、年日照时数和地貌形态成因类型的q值大于所有因子q值的均值,具有较强相关性;丹霞梧桐生境因子的两两组合中,地貌形态成因类型∩年日照时数和土壤亚类∩年日照时数的交互作用表现为双因子增强且q值大于所有组合q值的均值,具有较强相关性;丹霞梧桐空间分布相关性的生态探测中,与其他各因子相比,土壤亚类、年日照时数以及地貌形态成因类型的q值具有显著差异。丹霞梧桐的空间分布主要与土壤亚类、地貌形态成因类型、年日照时数存在显著相关性,同时也表明,地理探测器为植被生境因子分析、预测物种分布等研究提供了有益的方法探索。     

The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts

Climate-driven changes in biotic interactions can profoundly alter ecological communities, particularly when they impact foundation species. In marine systems, changes in herbivory and the consequent loss of dominant habitat forming species can result in dramatic community phase shifts, such as from coral to macroalgal dominance when tropical fish herbivory decreases, and from algal forests to ‘barrens’ when temperate urchin grazing increases. Here, we propose a novel phase-shift away from macroalgal dominance caused by tropical herbivores extending their range into temperate regions. We argue that this phase shift is facilitated by poleward-flowing boundary currents that are creating ocean warming hotspots around the globe, enabling the range expansion of tropical species and increasing their grazing rates in temperate areas. Overgrazing of temperate macroalgae by tropical herbivorous fishes has already occurred in Japan and the Mediterranean. Emerging evidence suggests similar phenomena are occurring in other temperate regions, with increasing occurrence of tropical fishes on temperate reefs.