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1.
Three main succession lines are found to occur on poor sandy soils in a blown drift sand landscape in the Netherlands. Site factors – organic matter, parent material, soil moisture regime and relief – were determined. Site types, specific combinations of these site factors, are defined. For five site types succession was studied. The primary criterion for separating succession lines and for delineating the successional stages, was the site factor organic matter and the second criterion, groundwater level. Influence of organic matter on succession was significant on site types with a buried podzol. Species composition on these site types indicated richer sites than the species composition on the site types without a buried podzol. Groundwater level of about 1m with gleyzone was critical for species requiring moist sites. Within a succession line vegetation stages are characterized and the potential forest type is presumed. The stages were related to humus form and soil development. Litter of dominant species was suggested to be the main criterion for the humus form. Initial and older vegetation stages were linked to development of soil horizons. The defined site types, their soil development and relationships with the succession lines clarify spatial and temporal structure and diversity of vegetation, and herewith is the basic information for clarifying the heterogeneity and potential biodiversity of this blown drift sand landscape.  相似文献   

2.
《新西兰生态学杂志》2011,33(2):164-176
Species composition patterns and vegetation?environment relationships were quantified for montane volcanic outcrops on Banks Peninsula. The flora of these habitat islands comprises 346 vascular plant species including 82 exotic species and 52 species that are nationally rare, regionally rare, or regional endemics. Both MDS ordination analysis and TWINSPAN results illustrated the high compositional and environmental heterogeneity across the outcrops. Multi-dimensional scaling revealed that primary environmental factors related to community composition comprise both regional-scale gradients of altitude and outcrop-scale gradients of slope steepness, soil pH, area available to plants, maximum vegetation height, and the percentage of the surrounding vegetation that is forest. Accordingly, TWINSPAN separated four outcrop communities that occur on steeper slopes, have less fertile soils and tend not to face north from three outcrop communities that have shallower slopes, more fertile soils and tend to face north. Types in the first group are more likely to be bordered by forest or taller shrublands, whereas those in the second group occur on outcrops primarily bordered by grasslands and support more exotic species. Within these broader groups, communities differ in their altitude and the size, soil depth and shading of the outcrops on which they occur. We describe the vegetation of the seven communities; this ranges from predominance of stunted trees and taller statured species such as Podocarpus hallii and Phormium cookianum to vegetation of shrubby species such as Heliohebe lavaudiana and Hebe strictissima, to short vegetation of native woodland and grassland species such as Polystichum vestitum and Rytidosperma corinum, to exotic pasture of clovers and exotic grasses. The percentage of species on an outcrop face that are exotic is well modelled by site factors, with exotics increasing as the surrounding matrix becomes more disturbed, slopes become more gentle, the percentage of shade on the outcrop decreases, and soil fertility increases. In contrast, nearby disturbance has little influence on the percentage or number of species that are rare on an outcrop face; rather rare species richness is more strongly related to outcrop area and lack of shade, echoing patterns observed for rare outcrop species elsewhere in the world. These results highlight the importance of considering the high compositional heterogeneity among outcrops and the influence of disturbance to surrounding ecosystems in guiding conservation planning.  相似文献   

3.
Abstract. The Vava'u island group, Tonga, comprises ca. 60 limestone islands on a single submarine platform overlain with rich soils derived from tephra deposits from nearby volcanic islands. The island group has moderate topographic relief (215 m) and is characterized by plateaus and steep cliffs. Humans settled in Tonga ca. 3000 yr ago and have exploited the flatter terrain for agriculture since that time. We conducted the first survey of forest composition in Vava'u, sampling remnant patches of late-successional forest as well as stands in various stages of secondary succession following agricultural abandonment. Plant species composition did not vary greatly with elevation over this short gradient, in contrast with patterns found on‘Eua, a higher island in Tonga. The most significant environmental gradient affecting species composition was coastal or maritime influence. However, the greatest variation in species composition and structure appeared to be related to species turnover during secondary succession, and we hypothesize a sequence of species replacements. Secondary forest begins to resemble late-successional forest in 30–50 yr in terms of structure and native species richness and therefore is of significant conservation value.  相似文献   

4.
峨眉冷杉林森林类型的研究   总被引:8,自引:1,他引:7       下载免费PDF全文
峨眉冷杉林分布于东亚两大植物亚区的交壤地带,但植物种类以中国—日本成分为主,组成我国亚热带湿润常绿阔叶林区西部边缘的山地暗针叶林类型。林区气候高湿多雨,相适应的森林类型的特征特性多不同于其以西的高山峡谷区。 文中分析了此类森林的林层结构、径级结构和年龄结构,表明为多世代的异龄性的单层纯林。根据群落外貌划分为三个林型组和六个林型,论及各林型间生产力的差异,并着重于动态观察,认为演替的途径、阶段和速度与林型本身特性有关,与采伐方式也很密切,但相对稳定的林型遭破坏后任其顺行发展,均能恢复为原来的林型。鉴于此类森林成熟过熟林多,病朽严重,而林区气候优越,植被恢复迅速,在确保水源涵养和生态环境的前提下,森林资源合理利用仍属必要,关键在于提高经营水平,应根据各林型特点和演替规律合理采伐,使可更新资源能永续利用。  相似文献   

5.
Detailed information about interspecific spatial associations among tropical tree species is scarce, and hence the ecological importance of those associations may have been underestimated. However, they can play a role in community assembly and species diversity maintenance. This study investigated the spatial dependence between pairs of species. First, the spatial associations (spatial attraction and spatial repulsion) that arose between species were examined. Second, different sizes of trees were considered in order to evaluate whether the spatial relationships between species are constant or vary during the lifetime of individuals. Third, the consistency of those spatial associations with the species-habitat associations found in previous studies was assessed. Two different tropical ecosystems were investigated: a montane cloud forest and a lowland moist forest. The results showed that spatial associations among species exist, and these vary among life stages and species. The rarity of negative spatial interactions suggested that exclusive competition was not common in the studied forests. On the other hand, positive interactions were common, and the results of this study strongly suggested that habitat associations were not the only cause of spatial attraction among species. If this is true, habitat associations and density dependence are not the only mechanisms that explain species distribution and diversity; other ecological interactions, such as facilitation among species, may also play a role. These spatial associations could be important in the assembly of tropical tree communities and forest succession, and should be taken into account in future studies.  相似文献   

6.
Leaf flushing during the dry season: the paradox of Asian monsoon forests   总被引:3,自引:0,他引:3  
Aim Most deciduous species of dry monsoon forests in Thailand and India form new leaves 1–2 months before the first monsoon rains, during the hottest and driest part of the year around the spring equinox. Here we identify the proximate causes of this characteristic and counterintuitive ‘spring‐flushing’ of monsoon forest trees. Location Trees of 20 species were observed in semi‐deciduous dry monsoon forests of northern Thailand with a 5–6‐month‐long severe dry season and annual rainfall of 800–1500 mm. They were growing on dry ridges (dipterocarp–oak forest) or in moist gullies (mixed deciduous–evergreen forest) at 680–750 m altitude near Chiang Mai and in a dry lowland stand of Shorea siamensis in Uthai Thani province. Methods Two novel methods were developed to analyse temporal and spatial variation in vegetative dry‐season phenology indicative of differences in root access to subsoil water reserves. Results Evergreen and leaf exchanging species at cool, moist sites leafed soon after partial leaf shedding in January–February. Drought‐resistant dipterocarp species were evergreen at moist sites, deciduous at dry sites, and trees leafed soon after leaf shedding whenever subsoil water was available. Synchronous spring flushing of deciduous species around the spring equinox, as induced by increasing daylength, was common in Thailand's dipterocarp–oak forest and appears to be prevalent in Indian dry monsoon forests of the Deccan peninsula with its deep, water‐storing soils. Main conclusions In all observed species leafing during the dry season relied on subsoil water reserves, which buffer trees against prolonged climatic drought. Implicitly, rainfall periodicity, i.e. climate, is not the principal determinant of vegetative tree phenology. The establishment of new foliage before the summer rains is likely to optimize photosynthetic gain in dry monsoon forests with a relatively short, wet growing season.  相似文献   

7.
We studied soil nematode communities from the surface of granite flatrock outcrops in the eastern Piedmont region of the United States. The thin soils that develop here experience high light intensity and extreme fluctuations in temperature and moisture and host unique plant communities. We collected soils from outcrop microsites in Virginia (VA) and North Carolina (NC) in various stages of succession (Primitive, Minimal, and Mature) and compared soil properties and nematode communities to those of adjacent forest soils. Nematodes were present in most outcrop soils, with densities comparable to forest soils (P > 0.05). Nematode communities in Mature and Minimal soils had lower species richness than forest soils (P < 0.05) and contained more bacterial-feeders and fewer fungal-feeders (P < 0.05). Primitive soils contained either no nematodes (NC) or only a single species (Mesodorylaimus sp., VA). Nematode communities were similar between Mature and Minimal soils, according to trophic group representation, MI, PPI, EI, SI, and CI (P > 0.05). Forest soils had a higher PPI value (P < 0.05), but otherwise community indices were similar to outcrop soils (P > 0.05). Outcrop nematode communities failed to group together in a Bray-Curtis cluster analysis, indicating higher variability in community structure than the Forest soils, which did cluster together. A high proportion of the nematodes were extracted from outcrop soils in coiled form (33-89%), indicating that they used anhydrobiosis to persist in this unique environment.  相似文献   

8.
In the Rio Ranchería watershed of the Sierra Nevada de Santa Marta, between 500 and 1500 m, savanna vegetation is interspersed with moist forests. The savannas are composed of native savanna grasses like Aristida adscensionis L., Arundinella sp., Panicum olyroides Kunth, and Schyzachyrium microstachyum (Desv.) Roseng., Arrill & Izag and the African Melinis minutiflora P. Beauv. There is also Curatella americana L. and Byrsonima crassifolia (L.) H.B.K., two typical tree species of the neotropical savannas. Although moist forest patches occur more often on lower slopes and narrow valley bottoms, they can also be found on mid- and upper-slopes and less often on ridges. Thus, these forest patches are not gallery forests as are found throughout the neotropics, but the result of deforestation and fractionation of a continuous forest. A comparison of soil profiles between the savannas and remnant forest patches on the same slope, showed the disappearance of the A and B horizons (approx. 50 cm) under savanna vegetation. The sharp difference between the savanna and forest soils at the Rio Ranchería does not appear to be due to a change in soil water status along a toposequence or differences in the underlying bedrock. We hypothesize that the savannas of the Rio Ranchería watershed, are the result of deforestation and land practices on infertile soils derived from granite. The savannization process was likely initiated by Amerindians by means of the frequent use of fire or clearing lands for the cultivation of maize. The introduction of cattle by Spaniards (c. 1530) and the frequent use of fire to maintain grazing fields, contributed to further degradation of the habitat. While some tropical landscapes recovered their forest cover when human pressure was removed approximately 500 years ago, areas such as the Rio Ranchería watershed have suffered permanent damage. The savannas of this region are likely to remain unless fire is suppressed and soil restoration practices implemented.  相似文献   

9.
采石场废弃地的生态重建研究进展   总被引:11,自引:0,他引:11  
杨振意  薛立  许建新 《生态学报》2012,32(16):5264-5274
采石场的开采严重破坏了植被和土壤,形成了大量的裸露岩石斜坡,造成宏观景观支离破碎和极端的环境条件,限制了植物的生长。由于自然恢复所需时间长久,人工恢复被广泛应用于采石场废弃地的生态重建。自然演替过程是采石场生态重建的理论基础,自然演替理论可以为人工恢复措施提供指导。植物群落演替的早期阶段,非生物因素起主要作用,随着演替的推移,生物因素的重要性增强。邻近自然植被的土壤和繁殖体通过外力的扩散,对恢复起重要作用。除了非生物和其他的限制,先到达恢复地的物种竞争能力的变化能决定了演替过程。演替过程中的干扰因素往往成为演替重要的驱动力。裸露岩石斜坡的物理稳定性对植被恢复有重要影响,有机废物的使用和施肥可以影响恢复演替的方向和生物多样性。播种一定的植物能够改变恢复演替方向,加速演替过程。乡土物种适应了当地气候,能够促进演替。随着修复时间的延长,土壤有机质含量,植被覆盖度和物种丰富度不断增加,土壤微生物生物量随之增加。开展不同地区采石场植物种类的选育、研究乡土物种的功能特性、土壤微生物群落和酶的变化、植被演替过程的定位研究、植物种间的竞争关系、自然演替和人工恢复的比较研究、探索经济高效的采石场生态重建方法是未来的研究方向。  相似文献   

10.
The aim of this study was to find out which tree species can establish in spontaneously developed forests (SDFs) on mesic stands and how many tree seedlings are present there. The influence of different factors was examined and an attempt made to find out if there are some general trends true for groups of species typical for different stages of succession or with different types of distribution. All tree seedlings present in 48 permanent plots were counted (100 m2). The following factors were tested: altitude, slope and exposition, distance from the nearest forest, age and species composition of tree layer, species composition of herb layer, light conditions and soil reaction. The species composition was dependent on altitude and soil reaction. There were surprisingly high numbers of seedlings (in average 145 tree seedlings per 100 m2) and species (in average 5) present in SDFs. Not only species common in the area were found, but also uncommon species were present there, although in low numbers. Nonspecific species are the best colonisers of SDFs, and the anemochorous trees are better colonisers than zoochorous ones. The establishment of different tree species is influenced by different factors. The SDFs most probably shift toward forest with a number of species in the tree layer. The dominant species tend to be spruce and maple, but species typical for early stages of succession will be common in these growths.  相似文献   

11.
Throughout Brazilian Amazonia anthropogenic soils that are the product of pre-Columbian settlements are called Terra Preta de índio (Indian Dark Earths, TPI). These soils are dramatically different from surrounding soils due to long-term human activity, but there is little information about how secondary forest succession is affected by these differences. We tested if community structure (density, richness and basal area), floristic composition and domesticated species’ richness and density were similar between TPI and non-anthropogenic soils (NAS) in 52 25 × 10 m secondary forest plots in different successional stages near three traditional communities along the middle Madeira River, Central Amazonia. We sampled 858 woody individuals on TPI (77 domesticated) and 1095 on NAS (27 domesticated); 550 understory palms on TPI (169 domesticated) and 778 on NAS (123 domesticated). We found 179 species on TPI (10 domesticated), 190 on NAS (8 domesticated), and 74 (25%) in both environments. Although community structure on TPI and NAS was fairly similar, they showed significantly distinctive floristic compositions, both for woody individuals and understory palms. The density and richness of domesticated species was significantly higher on TPI than on NAS for woody individuals, but not for palms. The intimate long-term association of TPI with human activity has lead to the formation of distinct secondary forests and has favored the concentration of domesticated populations of crop species. Hence, secondary forests on anthropogenic soils concentrate agrobiodiversity, offering advantages for in situ conservation of genetic resources, and are unique ecosystems that should be considered in conservation efforts.  相似文献   

12.
Relatively little information exists on neotropical secondary rain forests that have progressed beyond the pioneer stages of succession, or on the potential of natural regeneration to restore forest on large areas. We determined the structural and floristic characteristics (10 cm dbh) of a 30‐year‐old secondary forest developing on a 32.5 ha pasture on hilly terrain, abandoned after use of moderate intensity. Ten 0.24 ha sample plots covered the range of site conditions. The forest was dominated by long‐lived pioneer tree species; overall, the majority of species (70%) was vertebrate dispersed but the majority of individuals (52%) was of wind‐dispersed species. Tree species, including the dominants, were a mixture of those present in old‐growth and adventives colonizing from agricultural land. The forest was very heterogeneous. Vochysia ferruginea‐dominated stands characterized slopes with soils of high exchangeable acidity, while the adventive Cordia alliodora dominated sites with gentler topography and soils of lower acidity. Structural differences between the two forest types were slight, but Cordia forest had significantly greater species diversity and absolute and relative abundances of vertebrate‐dispersed tree species than Vochysia forest, which had significantly greater absolute and relative abundances of wind‐dispersed tree species. These latter differences between forest types, as well as the wide structural variation of the forest as a whole, were probably largely due to spatial and temporal variation in seed rains, some of it linked to the characteristics of the dominant species. Rain forest restoration on large pastures may depend greatly on wind dispersal and adventive tree species, and techniques for silvicultural diagnosis must be developed as a basis for the management of heterogeneous successional stands. Studies of early colonization of pastures should be expanded to focus on the causes of heterogeneity in older forests.  相似文献   

13.
The BRIND model, a computer model of the high altitude forests in the Brindabella Range near Canberra (Australian Capital Territory), is documented and the results of a series of tests on the model are provided. The BRIND model simulates a 1/12 ha forest stand by computing the growth of each individual tree in the stand. It considers establishment and death of trees on a tree-by-tree basis using stochastic functions. The model also simulates the effects of prescribed fire and wildfire on the forests. The model presently is restricted to southeasterly facing slopes (moist, sheltered situations) above 850 m in altitude. The BRIND model is tested in four ways: (1) A single example simulation (for 500years) is inspected for agreement with stand dynamics in wet sclerophyll forests. (2) By varying wildfire frequency, the model is used to develop a succession diagram for forests in the alpine ash (E. delegatensis) zone of the Brindabella Range. This diagram is considered in terms of the successional patterns described for this ecological zone. (3) By subjecting the model to different climatic conditions and wildfire frequencies, a simulated altitude zonation is developed. This simulated pattern of forest types is compared with the extant forest types in the Brindabella Range. (4) The model is tested on its ability to duplicate basal area, stocking density, and average diameters for different age stands found in an independent data set. The model was found to simulate patterns of vegetation that resemble those of the forests of the Brindabella Range in both space and time. The successional pattern was found to be complex and to differ from classic theories of succession originating with Clements. Potential model applications are discussed  相似文献   

14.
The scaling relationship between leaf dry mass and leaf surface area has important implications for understanding the ability of plants to harvest sunlight and grow. Whether and how the scaling relationships vary across environmental gradients are poorly understood. We analyzed the scaling relationships between leaf mass and leaf area of 121 vascular plant species along an altitudinal gradient in a subtropical monsoon forest. The slopes increased significantly with altitude, it varied from less than 1 at low altitude to more than 1 at high altitude. This means that plants growing at high altitude allocate proportionately more biomass to support tissues in larger leaves and less in smaller leaves, whereas the reverse is true at low altitude. This pattern can be explained by different leaf strategies in response to environmental pressure and constrains.  相似文献   

15.
Humus formation and the elemental composition of macromolecules of humic acids of automorphic Siberian soils (gray forest soils, chernozems, and chestnut soils) have been considered in comparison with those of the analogous soils of the European part of Russia. It has been found that an increase in the continentality of climate leads to significant changes in the structure of humic acids in soils of similar origin in the meridional direction.  相似文献   

16.
The seedling stage is generally the most important bottleneck for the successful regeneration of trees in forests. The traits of seedlings, particularly biomass allocation and root traits, are more easily quantified than the traits of adults. In this study, we tested the hypothesis that seedling traits vary and trade‐off tracking the changing environment during secondary succession. We measured the major morphological traits of 27 dominant species and the major environmental factors in a chronosequence (30‐yr‐old fallow, 60‐yr‐old fallow, and old growth forest) after shifting cultivation in a tropical lowland rain forest on Hainan Island, China. The 30‐yr‐old fallow had higher light and nutrient availability, and the older forests had higher soil water content. Redundancy analysis based on species abundance and environmental factors revealed groups of seedlings that dominate in different stages of succession. Seedlings in different stages of succession had different strategies of biomass allocation for harvesting resources that varied in availability. Species characteristic of younger forest had higher allocation to roots and higher specific leaf area, while species characteristic of older forest had higher allocation to leaves. Our study suggests that the variations and trade‐offs in the major functional traits of tree seedlings among successional classes may reflect changes in environmental conditions during succession.  相似文献   

17.
Pekka Hello 《Ecography》1985,8(2):120-132
Breeding bird communities in five stages of secondary forest succession were studied in northeastern Finland in 1980–82. Three groups of communities were distinguished: open land, brush phase and forest communities, dominated by Motacilla alba and Oenanthe oenanthe, Phylloscopus trochilus and Anthus trivialis, Phylloscopus trochilus and Fringilla montifringilla , respectively.
Pair density, number of species, biomass of adult birds and species diversity increased in the course of succession, none of these, however, monotonously. Average bird weight showed a decreasing trend although the variation was considerable. The degree of specialization in communities (measured by ratios derived from numbers of species, genera and families) increased in the course of succession with the exception that the initial stage had relatively high values. Species nesting and feeding in trees and shrubs increased in numbers during forest regeneration whereas species nesting and feeding on the ground showed the opposite trend. The proportions of hole-nesting and sedentary species increased with increasing forest age.
The initial stages of forest succession in the north are occupied by specialized open habitat species breeding originally on open bogs and shores. These communities thus clearly differ from those predicted from the general theory of succession, which postulates that the pioneer stages of succession are dominated by habitat generalists and that these communities should have relatively low values of community diversity.  相似文献   

18.
Zonation of forest vegetation and soils of Mount Cameroon,West Africa   总被引:1,自引:0,他引:1  
Mount Cameroon is an active volcano in a wet part of West Africa. The forest vegetation and associated soils on its southern slopes were studied in 1989, 1991 and 1995 in coupled 0.25 ha plots at altitudes of 180, 600, 1,100, 1,800 and 2,180 m. All lianas and trees >10 cm dbh were enumerated and their structural features quantified. The forests were of large stature throughout. The strangling Schefflera species made a substantial contribution to the very high basal areas at 1,800 m. The associated soils were dominated by andisols derived from volcanic ash that showed a distinct increase with altitude in soil organic matter and total N attributed to lower temperatures. Soil pH, exchangeable K+, Ca2+, Mg2+, effective cation-exchange capacity and percentage base saturation showed very marked increases explained by the influence of recent volcanic ashfalls. Available N and P showed less distinct trends with altitude. Although there is a large decrease in tree species richness with altitude, forest stand growth (as compared on a basal area basis) does not appear to be limited by soil fertility or temperature. The forest line (altitude treeline and extensive gaps below it) appear to be controlled by periodic volcanic activity, ashfalls and lava flows, which can destroy existing forest through soil burial and fire effects and inhibit regrowth on bare lava flows and deep deposits of volcanic ash.  相似文献   

19.
麦积山风景区不同生境类型蝶类的多样性   总被引:2,自引:0,他引:2  
刘艳梅  杨航宇 《昆虫知识》2008,45(3):465-469
于2003~2004年对麦积山地区不同生境类型中蝴蝶多样性进行调查研究。依据海拔高度、气候、土壤和植被的不同将该地区的蝴蝶生境划分为3种类型:林缘山地、森林林地、裸岩。共收集蝴蝶3950只,隶属8科43属64种。计算了3种生境类型中蝶类物种丰富度、相似性系数、多样性指数。其中,蝴蝶物种丰富度由大到小为森林林地(8·8359)>林缘山地(6·1442)>裸岩(1·4711),物种多样性指数由大到小为森林林地(H'=1·4068)>裸岩(H'=0·9746)>林缘山地(H'=0·9201);森林林地和林缘山地的相似性系数最高(0·2221),其次是林缘山地和裸岩(0·0869),森林林地和裸岩相似性系数最低(0·0656)。  相似文献   

20.
Effective wildlife management requires an understanding of how individuals select environmental factors, although few studies assess how habitat selection may differ over time or between sexes. During the post-breeding period (15 May to 1 Sep), we tracked 146 male American woodcock (Scolopax minor) in Rhode Island, USA, from 2010–2021 to assess how habitat selection varied over time, and 17 females and 51 males during the final 2 years of the study to document sex-specific differences in habitat selection. Males generally had smaller home ranges (35.0 ± 10.7 [margin of error] ha) and preferred habitat mosaics that consisted of forested wetlands, young forest patches, areas of deciduous forest, moist soils with gentle slopes, and riparian corridors. We detected subtle differences between sexes in selection for wetland young forest, upland young forest, percent slope, distance to upland young forest, distance to streams, and distance to moist soils. During 2020–2021, females tended to have larger home ranges (78.7 ± 46.4 ha) than males (35.0 ± 10.7 ha) and more strongly selected sites closer to riparian corridors, while males selected areas that were closer to upland young forest with flatter slopes than the available surrounding landscape. Such sex-specific differences in habitat selection may be related to males and females prospecting for potential breeding sites during this post-breeding period for the following spring. We used the top-ranked habitat selection models for males and females to produce a spatially explicit state-wide map that identifies low-to-high likelihood of use areas that can be used to guide forest management decisions in southern New England to maximize benefits for American woodcock.  相似文献   

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