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1.
Nitrogen (N) has great ecological importance, but the biogeographic pattern across forest biomes in China has only recently been explored. Here we conducted a systematic census of leaf C and N following the same protocol to explore the variations of leaf traits, and their possible responses to plant functional types (PFTs) and environmental factors. Results showed that leaf traits varied substantially across biomes, and the relationships of PFTs to climatic factors were stronger than those of PFTs versus soil nutrient proxies, indicating that plant species composition might be a better predictor of plant species distribution with climate than leaf traits. Soil nutrient proxies explained more variation of leaf traits than climate, which demonstrates that leaf traits reflect important aspects of plant responses to soil nutrients. Importantly, partial general linear models analyses found that PFTs showed the greatest direct influence for leaf traits, and climate and soil affected leaf traits mainly through the change in plant species composition rather than having direct impacts. Hence, we concluded that leaf traits were largely controlled by PFTs rather than climate or soil at the biome scale. The results favored the species composition hypothesis, indicating that leaf nutrient concentration is mainly determined by PFTs.  相似文献   

2.
不同植被类型蛾类及植物相似性分析   总被引：1，自引：1，他引：0  
对紫金山不同植被类型植物种类及蛾类群落结构、时空动态进行了调查,运用jaccard相似性分析方法对不同植被类型植物种类、蛾类种的相似性进行了分析,并在植物及蛾类的相似性之间进行了分析探讨。结果表明：紫金山植物种类丰富,植物分布特别是草本植物分布对环境有较强的依赖性。蛾类种亦丰富,有蛾类28科494种,各植被类型植物种类与蛾类种、数量呈正相关,生态环境及植物群落的差异是导致紫金山蛾类群落结构差别的主要因素;紫金山蛾类多食性种较多。紫金山针阔混交林和阔叶林、针阔混交林和针叶林亲缘关系较近,验证了紫金山针阔混交林是由针叶林衰退的基础上自然演替或是人工干预发展而成的,最后将演替成含有常绿成份的落叶阔叶林,各植被类型处于演替的不同阶段,竹林受人为干扰最大。  相似文献   

3.
干扰对天然红松林植物多样性的影响   总被引：18，自引：2，他引：18  
罗菊春  王庆锁 《林业科学》1997,33(6):498-503
对长白山林区受不同程度干扰（择伐）的红松林与红松林被皆伐后形成白桦次生林的植物多样性进行了研究，结果表明，白桦群落及其下木层的多样性高于各类型的红松林。不同类型的红松林中，以轻度干扰的红松原始群落及其立木层和草本层的多样性最大，这是群落长期演容、物种适应的结果。白哗群落处于演替的第二阶段，群落中侵入了较多的耐荫树种，加之林内光照条件好，故而有发达的下木层，致使树种的多样性很高。本文还分析了多样性与均匀度及生境条件的关系。  相似文献   

4.
Although wildfires are occurring frequently in the pine–oak forests in the Sierra Madre Oriental (northeastern Mexico), data on post-fire succession and forest structure are still rare. Our objectives were to (1) assess the changes in woody plant species composition after fire and to (2) to relate successional patterns to environmental variability. Based on their fire history 23 plots were selected in the Parque Ecológico Chipinque (PECH). Changes in forest structure across the chronosequence of burned stands were deduced from density, height and diameter measurements of trees and shrubs (>5 cm in diameter) in all plots of 1000 m2. Differences in woody plant species composition among the plots were evaluated using Shannon evenness measure and the Whittaker's measure and by Hierarchical cluster analysis and Detrended Correspondence Analysis. Hierarchical cluster analysis showed a high similarity among all recently burned plots, independed of the aspect. Multivariate analysis showed that local environmental factors, including time since fire, continue to structure species composition. Oak species (mainly Quercus rysophylla) resprouted successfully after fire and dominated young post-fire stands. Pine species (Pinus pseudotrobus and Pinus teocote) only appeared 18 years after fire and were the dominating species in mature stands (62 years after fire). In contrast, woody plant species composition in older stands tended also to be influenced by factors such as aspect and by the potential solar radiation (PSR) during the growing season. The results demonstrate that in the PECH, natural regeneration is sufficient and woody plant species composition will be similar to pre-fire conditions after 60 years of succession. We conclude that the park managers should consider incorporating natural disturbance regimes into their management practices.  相似文献   

5.
Effects of gaps on regeneration of woody plants: a meta-analysis   总被引：1，自引：0，他引：1  
Forest gaps, openings in the canopy caused by death of one or more trees, have a profound effect on forest regeneration and drive the forest growth cycle. It is therefore necessary to understand the effects of forest gaps on regeneration for modern forest management. In order to provide a quantitative assessment of the effects of forest gaps on regen-eration of woody plants, we conducted this review of gap effects on woody plant regeneration on the basis of 527 observations from 42 indi-vidual papers, and reported the results of these data in a meta-analysis. Overall, densities of regenerated woody plants were significantly greater （359%） in forest gaps than on the closed-canopy forest floor. The regen-eration density in gaps of plantation forests was significantly greater （P＆lt;0.05） than that of natural forest because the regeneration in gaps of plan-tation forests was improved by both gap effects and experimental meas-ures. Similarly, in comparison to natural gaps, regeneration was better enhanced in artificial gaps. Regeneration density exhibited a significantly positive correlation with gap size, but a negative correlation with gap age because the gap size decreased with increasing gap age. Shade tolerance of woody plants affected regeneration density in gaps and understory. Average regeneration density of shade-tolerant species exhibited a sig-nificantly positive response to gaps but densities remained lower in total than those of intermediate and shade-intolerant species. Gap effects on regeneration decreased in response to increasing temperature and pre-cipitation because of the limiting effects of lower temperature and moisture on woody plant regeneration. In summary, forest gaps enhance woody plant regeneration, and the effects of gaps varied by forest type, gap characteristics, environmental factors and plant traits. The results of this meta-analysis are useful for better understanding the effects and roles of gaps on forest regeneration and forest management.  相似文献   

6.
以上海市佘山国家森林公园主要森林植被类型的群落学调查资料为基础,通过应用群落相似性和物种多样性测度方法进行计算分析,对该区域的主要森林群落类型、植物多样性特征及其演替趋势进行了分析研究。结果表明:佘山国家森林公园主要由白栎林、毛竹林、香樟林、朴树-榉树林、朴树-刺槐林、梧桐林和枫香-刺槐林等7种森林类型组成; 现有森林植被的植物多样性明显低于邻近的浙江地区,其树种组成也明显偏重于落叶树种,以榆科植物、壳斗科栎类树种为主,而常绿树种则只有香樟、苦槠、毛竹、女贞等少数几个建群种;从森林演替趋势看,未来上海佘山地区的森林主要为三大类:以白栎为主的地带性森林群落,毛竹林和以樟科、榆科、木犀科等科树种组成的常绿、落叶混交林。  相似文献   

7.
High Andean cloud forests are home to a diversity of unique wildlife and are important providers of ecosystem services to people in the Andean regions. The extent of these cloud forests has been widely reduced through conversion to pasture for livestock, which threatens the forests’ ability to support biodiversity and provide ecosystem services. This paper explores whether impacts on woody plant biodiversity and four ecosystem properties (woody plant species richness, juvenile timber tree abundance, soil organic matter content and soil moisture) from converting forest to pasture can be mitigated if some woody forest vegetation is maintained within pastures. Woody vegetation in pastures was found to conserve those woody plant species that are more tolerant to exposure and grazing, but conservation of the high montane cloud forest community required areas of forest from which livestock were restricted. The sampled sites clustered according to woody plant species cover; these clusters represented a gradient from pasture with patches of shrubs to mature forest. Clusters differed in both woody plant species richness and number of juvenile timber trees whereas soil organic matter and soil moisture were observed to be similar among all clusters. This suggests that the different habitats may have some equivalent ecosystem properties. We conclude that the presence of woody vegetation in pastures may reduce some of the impacts of converting forest to pasture, but should not be considered a substitute for protecting large areas of forest, which are essential for maintaining woody plant species diversity in high Andean cloud forest.  相似文献   

8.
对小兴安岭伊春林区5个林业局的40块标准地阔叶次生林的群落结构和树种多样性进行了调查分析的结果表明:试验区样地共有木本植物12科17属22种。木本植物丰富度13~20种,其中演替层主林层更新层,树种重要值最大为山杨,其次为糠椴和水曲柳;林层多样性指数演替层主林层更新层;试验区多样性指数五营桃山新青翠峦上甘岭;均匀度指数主林层演替层更新层;试验区多样性指数五营翠峦桃山上甘岭新青。整体上树种组成复杂多样,软阔叶树种较多,硬阔叶次之,针叶树种不到5%,硬阔的更替趋势较明显。  相似文献   

9.
森林粗木质残体研究综述   总被引：2，自引：0，他引：2  
森林粗死木残体（coarse woody debris,CWD）是指所有地上和地下小头直径≥2．5cm的枯立木（snag）、倒木（Log）、树桩（Stump）、大枯枝（Large Branch）、小枯枝（Twig）、连接在活树上的枯死小树枝（Suspended Twig）等的总称。该文综述了近几十年CWD的研究成果,总结了CWD的概念及其在碳氮循环、生物多样性维护等方面的生态功能,CWD的贮量和养分动态。大量的研究证明,CWD对森林生态系统具有重要的生态功能,但它的蓄积量、空间分布以及它的生态意义因所研究的森林生态系统植被林型而异。另外,CWD还受诸多生物学和非生物学因子的影响,研究各因子与CWD的关系对于保持CWD的生态功能也是十分必要的。  相似文献   

10.
一个世纪来黑龙江省森林景观动态研究   总被引：1，自引：0，他引：1  
With the help of GIS tool of ARC/INFO,ARCVIEW and FRAGSTATS,the map of forest resource distribution of Heilongjiang Province was analyzed in 1896,1949 and 1981.Using total area,mean patch size,patch density,coefficient of patch size variation,mean patch fractal dimension and mean shape index,we studied the change of forest landscape pattem and the change of each patch types in this region.As a result,the total area of forest landscape and mean patch size decreased sharply,the quantity and density of patches increased,the juxtaposition of patches weakened,the shape of patch tended to become regular,and the border of patch simplified.All these showed that the forest landscape of this area tended to fragment gradually,and the fragment of Korean pine forest is the severest.the diversity of whole forest landscape and the eveness of landscape types distribution reduced gradually.Human impact,instead of climate change and forest community succession,is the most important reason for such dramatic chages.  相似文献   

11.
地带性木本植物群落功能型的水热分布格局   总被引：3，自引：0，他引：3  
王国宏 《林业科学》2002,38(1):15-23
植物功能型是对环境条件做出相似的反应和对关键生态学过程具有相似影响的植物组合。不同功能型植物对生态系统过程的作用不同 ,通过植物功能型的分析对揭示生态系统功能至关重要。甘肃省境内 5种地带性木本植物群落 (亚热带常绿落叶阔叶林、暖温带落叶阔叶林、温带针阔混交林、寒温性针叶林和荒漠旱生灌木群落 )依据植物体的高度、叶片的生长对策及果实类型可划分出 2 3种功能型。其分布格局与水热因子的相关分析表明 :1)湿热的生境利于乔木、大灌木、藤木、寄生植物和常绿植物及翅果、坚果、核果、果、颖果类植物的发育 ,干冷生境利于灌木、小灌木和落叶植物以及蒴果类植物的发育。 2 )干果类和肉果类的成因可能与植物生长环境中水分供应状况密切相关 ,即潮湿的生境利于肉果类植物的发育 ,干旱的生境有利于干果类 (如胞果 )的发育。 3)研究区域地带性木本植物群落物种丰富度和功能型的丰富度格局主要受制于水分梯度影响 ,而良好的水热组合可孕育木本植物群落最丰富的果实类型。  相似文献   

12.
Using plant community analysis methods, we analyzed the floristic characteristics, species composition, community structure, population structure, and spatial distribution patterns of a Betula dahurica forest on the “1238” mountain of Badaling in Beijing, China. The results show that: 1) There are 33 plant species in the B. dahurica community, including 18 woody plant spe- cies. The B. dahurica forest is a monodominant community with 75.9% dominance. 2) Based on diameter at breast height (DBH) size class distribution, the population structure of B. dahurica and Acer mono—two heliophyllous and pioneer tree species—is cascade-type, with both in an increasing stage. The population structure of Tilia mandshurica and T. mongolica, two shade-tolerant tree species, is inverse-J type, and they have more young seedling individuals and regenerate more stably. They are associated species of the pioneer tree species. The population structure of Quercus mongolica, as the associated species of climax species in the community, is sporadic, and its regeneration is fluctuating and random. Fraxinus rhynchophylla is a shade-tolerant tree species which has a unibar population structure and climax characteristics of pioneer tree species. The relative frequency of young seedlings reached 0.4. 3) The dominant species B. dahurica is still in an increasing stage, and the regeneration of other species is steady or partly influences the community, putting the community in the pioneer species stage. From the population structure and distribution frequency of F. rhynchophylla, the B. dahurica forest will approach to a climax state in the future.  相似文献   

13.
Lianas (woody vines) are an important component of tropical forests, with a strong impact on forest dynamics, but their responses during forest succession have received relatively little attention. Here, we present an analysis of the changes in stem density, biomass, and species richness of lianas and self-supporting plants during tropical forest succession. We surveyed lianas ≥0.5 cm diameter at breast height (dbh) and self-supporting plants ≥2.5 cm dbh in 0.1 ha inventory plots in a chronosequence of 30 sites in northeastern Costa Rica, 23 sites on abandoned pastures 10–44 years of age, and seven sites in old-growth forest. Stem density of self-supporting plants showed no predictable chronosequence trend, but liana stem density declined significantly with forest age. Aboveground biomass of self-supporting vegetation increased rapidly during succession, with forests 31–44 years exhibiting higher levels of biomass than old-growth forests. Liana biomass accumulated more slowly, with the highest levels in old-growth sites. Species richness of self-supporting vegetation increased significantly during succession, but species richness of lianas showed no change or a slight decline with forest age, depending on the method of assessment. The differences between tree and liana responses during succession stem from the unique physiology and life history traits of lianas.  相似文献   

14.
热带次生林面积巨大且在热带森林资源中的作用越来越重要,因而拥有巨大的经营潜力和生态功能。次生林演替过程中的主要研究成果如下：土壤贮存的种子对次生林的再生非常重要,光投射的强度增加和温度提高将刺激种子萌芽,而残余植被群落强烈影响次生林种子的散布,食种子动物影响次生林的成林;次生林群落植物种类数量一般随演替的进程而增加;随着演替的进程,次生林内阳生树种趋于衰亡,耐荫树种不断增加;次生林的树种数量能接近原生林水平的时间过程更随着林分种类、过去土地的利用强度和利用种类,以及环境条件的不同而异;在一定环境中,人工林树种通过人工林树种改变光、温度和土壤表层的湿度,能够促进发芽和种子生长,改善林地和林下植被的状况,从而加速次生林演替。大多数食草动物喜欢在次生林中取食,因为次生林中先锋树种很少或没有机械和化学保护,且林内许多树种产生大量可食用的果实;环境和火对次生林演替有一定影响;在早期的演替过程中,更多的生物量分配到资源需求旺盛的组织（如叶和细根）,在演替晚期阶段,更多的生物量则分配到结构组织中（如木质部和根端）。次生林在15至20年内能迅速积累生物量,然后积累逐渐减慢;次生林被砍伐或火烧后,森林土壤的结构被破坏,导致土壤有机质和氮减少。  相似文献   

15.
为揭示不同森林植被类型鳞翅目蛾类昆虫群落的结构状态和功能,评价不同植物群落的生态稳定性,于2007～2008年对紫金山主要植被类型蛾类昆虫种类、种群密度、分布及发生规律进行了调查;对不同植被类型、不同季节、整体时间动态的蛾类昆虫进行了多样性方面的分析研究.结果表明:紫金山共有蛾类13总科28科355属494种,阔叶林蛾...  相似文献   

16.
Improvement cutting, which decreases tree density by cutting and thinning while leaving logging residues, has been practiced on Okinawa Island since the 1970s and changes not only the vegetation composition but also the amount and composition of woody debris on the forest floor. To quantitatively compare the effect of improvement cutting with the effects of woody debris and vegetation on the community structure of aphyllophoraceous fungi, we conducted a field survey of vegetation composition, the amount and composition of woody debris, and the aphyllophoraceous fungi flora on Okinawa Island in December 2006. We established 3 plots in forest stands without logging and 13 plots in a forest that had undergone improvement cutting from 1 to 22 years before our field survey. The number and volume of woody debris tended to be highest soon after improvement cutting. We recorded 1,172 fungal samples belonging to 81 species in four orders. Fungal species richness was correlated with the composition of the woody debris. Fungal species composition in forest plots 1 year after improvement cutting differed from most of the other logged forests. Variation partitioning revealed that the effects of improvement cutting explained 14.1 % of the total variation in fungal species composition, and that differences in woody debris and vegetation not related to improvement cutting explained 40.4 %. Changes in the composition of woody debris caused by improvement cutting explained at most 2.7 % of the variation. This suggests that improvement cutting does not have a strong effect on fungal community structure, but woody debris does.  相似文献   

17.
Forest recovery on disturbed areas is of special significance in the Ecuadorian Andes, where deforestation is a serious problem. Natural diachronic succession was evaluated on three large plots or sites, differing in their land use and vegetation composition, one is dominated by grass species on an abandoned pasture (Pasture site), the other two are post-fire vegetation dominated by bracken (Bracken site) and various shrubs (Shrub site). Additionally, we assessed the effectiveness of manual removal of competitive herbaceous species to accelerate forest recovery. Monitoring was done in 2003, 2005 and 2007 on 48 subplots of 116 m2 each recording species richness and woody-species density. Results showed that the Pasture site demonstrated a competitive effect of exotic grasses on woody species recruitment with much lower species recruitment and density, suggesting serious inhibition of natural forest regeneration and an unclear successional trajectory. The Bracken and Shrub sites became significantly similar floristically and there is evidence for a marked facilitation of woody plant recruitment correlated with light availability on the ground. Both sites showed characteristics of classic succession, with Shrub showing a higher species richness and density while late-successional species are poorly represented on the Bracken site. However, NMDS ordination using species density showed that the two trajectories may not be converging towards a common “final state”. Manual weeding was ineffective for accelerating forest recovery. These results suggest that the main limiting factor for the recruitment of woody species on the Pasture site is strong grass competition and must be addressed before seed availability, while seed availability seems to be the constraining factor for Bracken and Shrub site development, thus direct seeding or planting may be effective in accelerating forest recovery.  相似文献   

18.
Dry afromontane forests are among the most poorly managed and endangered ecosystems.Therefore,we assessed the composition,diversity,and conservation status of woody plant species of the Debre Libanos church forests and surrounding forest lands in Oromiya Regional National State,central Ethiopia in 62 nested circular sample plots spaced 200 m apart along two transect lines.Large circular plots 314 m~2 were used to sample trees with DBH of at least 10 cm,and subplots of 28.26 m~2 were laid in each main plot were used to assess saplings and shrubs;a small subplot of 3.14 m~2 was used to assess seedlings.In total,70 woody plant species belonging to 62 genera and 43 families were recorded.Of these,59,28 and 32 were in the church,government and private forest types,respectively.The most dominant families were Fabaceae and Verbenaceae,each represented by five species.In the forests considered,trees accounted for 61%,and shrubs with diameter at breast height(DBH) of 1-10 cm accounted for ca.33%.Among growth forms of woody species,shrubs and seedlings,followed by trees constituted much of the density of woody species in all the three ownership types of forests.The church forest had the most species(59) and highest Shannon(3.12) and Simpson(0.92) species diversity indices,and the government and private forests had a nearly similar total number of species and Shannon and Simpson species diversity indices.Most of the species with higher importance value indices(IVI) were indigenous in origin within the church forest(Juniperus procera=82),government forest(J.procera=66) and private forest(Acacia abyssinica=84).The composition,diversity,and population structure of woody species in the church forest were significantly higher than in the other forest lands.However,interventions of the government and private sectors to conserve forest systems in the areas,particularly the government-owned forest and specific species such as Olea europaea need active enrichment plantings due to their limited natural regeneration.Without improved management interventions,livelihood income diversification and ecosystem services obtained from the forest will not be sustainable.  相似文献   

19.
The herbaceous understory forms the richest stratum in temperate broadleaved forests in terms of plant diversity. Understanding the process of understory succession is thus of critical importance for the development of management guidelines for biodiversity restoration in post-agricultural plantation forests.We studied effects of stand age, forest fragmentation, and soil and canopy conditions on species richness and abundance of four species groups in the understory of post-arable oak plantations in southern Sweden: herbaceous forest specialists, habitat generalists and open-land species, and woody species.The group of forest specialists may approach the richness of continuously forested sites after 60-80 years in non-fragmented plantations, but many forest species were sensitive to habitat fragmentation. Open-land species richness decreased during succession, while the richness of woody species and of generalists remained stable, and was not affected by fragmentation. Abundance of generalists gradually decreased in non-fragmented plantations, probably due to competition from colonizing forest specialists. Soil pH in post-arable stands remained consistently higher than in continuously forested stands, which maintained differences in species composition. The development of a shrub layer seemed to imply a competitive advantage for forest specialists compared to generalist species.For successful recovery of a rich understory, we suggest that post-arable plantations should be established on loamy soils of intermediate to high pH proximate to older forest with source populations, and that a continuous overstory canopy cover of 70-80% is maintained by regular light thinnings and promotion of a shrub layer.  相似文献   

20.
The spatial distribution of tree juveniles in relation to light environments may reflect species differences in growth, survival, and functional traits and will shape the nature of forest regeneration. Long-term field experiments are important to evaluate this issue because of the potentially very long juvenile period in trees. Here, we combine a 10-year seedling survival–growth data with the results of community ordination and multivariate analyses of functional traits to ask how observed juvenile light guilds are related to species functional traits and seedling performance. We transplanted seedlings at a standardized height of 11 cm into the shaded understory and quantified their growth and survival for 10-years. Using the community-wide stem distribution data, we categorized 33 species including the focal 11 species to understory vs. gap/edge guilds. Then, we determined differences between the two guilds in seedling survival, growth, as well as seed size, adult height, and a series of leaf traits, including toughness and chemical traits (fiber, protein, phenolics, tannins, alkaloids, saponins). Among the 11 non-pioneer species whose seedlings were planted into the understory, there was no significant difference in 10-year survival between light guilds, but species in gap/edge guild tended to achieve greater height than species in the understory guild. The leaf chemical traits of 33 species did not differ between the two juvenile light guilds, but gap/edge species had smaller seeds, taller adults, and tougher leaves than understory species. We used logistic regression as a complementary approach to assess the extent to which plant traits varied between light guilds and the most parsimonious model based on AICc ranking included only leaf toughness and had an Akaike weight of 0.52. In addition, across the 11 species planted as seedlings, these traits were not significantly related to survivorship or growth over 10 years. A Principle Components Analysis illustrated associations among traits. We conclude that light guilds in terms of juvenile stem distribution could not be explained by long-term field performance of post-establishment seedlings alone. Earlier seedling stage or later sapling stage may be more important in differentiation of light guilds. For the species examined difference in growth rates could be linked to seed size and adult stature, but not to the adult leaf chemical traits considered. These results suggest the importance of examining ontogenetic shifts and relationships among functional traits for a better understanding of regeneration strategies of tropical trees.  相似文献   

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