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1.
Timothy J. S. Whitfeld Jesse R. Lasky Kipiro Damas Gibson Sosanika Kenneth Molem Rebecca A. Montgomery 《Biotropica》2014,46(5):538-548
Much of the world's tropical forests have been affected by anthropogenic disturbance. These forests are important biodiversity reservoirs whose diversity, structure and function must be characterized across the successional sequence. We examined changes in structure and diversity along a successional gradient in the lowlands of New Guinea. To do this, we measured and identified all stems ≥5 cm diameter in 19 0.25 ha plots ranging in age from 3 to >50 yr since disturbance. We also measured plant functional traits related to establishment, performance, and competitive ability. In addition, we examined change in forest structure, composition, species diversity, and functional diversity through succession. By using rarefaction to estimate functional diversity, we compared changes in functional diversity while controlling for associated differences in stem and species density. Basal area and species density increased with stand age while stem density was highest in intermediate secondary forests. Species composition differed strongly between mature and secondary forests. As forests increased in basal area, community‐weighted mean wood density and foliar carbon increased, whereas specific leaf area and proportion of stems with exudate decreased. Foliar nitrogen peaked in medium‐aged forests. Functional diversity was highest in mature forests, even after accounting for differences in stem and species diversity. Our study represents one of the first attempts to document successional changes in New Guinea's lowland forest. We found robust evidence that as succession proceeds, communities occupy a greater range of functional trait space even after controlling for stem and species density. High functional diversity is important for ecological resiliency in the face of global change. 相似文献
2.
The first few years of tropical forest restoration can be expensive, especially when applied to expansive areas. In light of this, passive restoration has been recommended as a considerably cheaper or even free alternative. There are, however, both direct and indirect costs associated with passive restoration. First, the longer recovery time that is typically required in passive restoration can be perceived as project failure, especially when compared with nearby active restoration efforts. In the worst‐case scenario, this can lead to the premature termination of a project by a landowner who would like to see more rapid or visible results. Second, passive restoration may be viewed as land abandonment, and in developing nations where land tenure is not always strictly enforced this may invite unanticipated uses, such as ranchers who may unintentionally or intentionally allow livestock to take advantage of the “unused” forage grass, thus setting back recovery efforts. Lastly, passive restoration does have direct financial costs, including material costs for establishing fences and repairing them, and labor costs for site vigilance. These upfront investments may need to be made repeatedly in passive restoration efforts, and for a longer time period than for an active restoration project. Both the direct and indirect costs should be considered prior to choosing passive restoration as a strategy in a particular restoration project. 相似文献
3.
The \"Initial Floristic Composition\" hypothesis is applied to secondary tropical rain forest succession in abandoned agricultural fields with light previous land-use and close to seed sources. This hypothesis predicts that both pioneer and shade-tolerant species colonize a site directly after abandonment, and as the canopy closes, the recruitment of pioneers sharply declines, while recruitment of shade-tolerant species continues. It also predicts higher mortality among pioneers. Consequently, recruited and dead trees are expected to differ in species composition, with highest species richness for the recruits. During 18 mo, we monitored recruitment and mortality of trees with height ≥ 1.5 m in eight plots in abandoned cornfields with initial fallow age of 1–5 yr, in SE Mexico. Shade-tolerant species established in the first years of succession, albeit in low numbers. As predicted, recruited and dead trees differed in species richness and composition, and in shade-tolerant frequency. In contrast to our expectations, over 50 percent of recruits were from pioneer species, as high stand-level mortality opened new opportunities for continued pioneer colonization. Species turnover starts very early in succession but is not always a gradual and continuous process, complicating prevailing succession models. The strong spatial and temporal variability of succession emphasizes the need to monitor these dynamics in permanent plots across a range of initial stand ages, with multiple plots in a given age class. 相似文献
4.
Exotic tree plantations may serve as catalysts for native forest regeneration in agriculturally degraded landscapes. In 2001, we evaluated plant species regeneration in the understory of a 7‐year‐old experimental Eucalyptus saligna forest in Hawaii approximately 1 year after the cessation of 5 years of herbicide. These forests were organized in a 2 × 2–factorial design of planting density (1 × 1– or 3 × 3–m spacing) and fertilization (unfertilized control and regular fertilization), which resulted in varying resource availabilities. We found that understory biomass was highest under high light conditions, regardless of fertilization treatment, whereas species richness was lowest under fertilized 1 × 1–m plots. The understory was dominated by species exotic to Hawaii. The most common tree species, the noxious weed Citharexylum caudatum, was particularly successful because high light–saturated photosynthesis rates and a low light compensation point allowed for high growth and survival under both light conditions. To assess longer‐term recruitment patterns, we resurveyed a portion of this site in 2006 and also surveyed five Eucalyptus plantations in this region of Hawaii that differed in age (5–23 years), species (E. saligna, E. grandis, E. cloeziana, E. microcorys), and management (experimental, industrial, nonindustrial stewardship); all were established on previous agricultural sites within approximately 3 km of native‐dominated forest. Again, very few native species were present in any of the stands, indicating that within certain landscapes and for native species with certain life history traits, exotic plantations may be ineffective nursery ecosystems for the regeneration of native species. 相似文献
5.
Secondary forests constitute a substantial proportion of tropical forestlands. These forests occur on both public and private lands and different underlying environmental variables and management regimes may affect post‐abandonment successional processes and resultant forest structure and biodiversity. We examined whether differences in ownership led to differences in forest structure, tree diversity, and tree species composition across a gradient of soil fertility and forest age. We collected soil samples and surveyed all trees in 82 public and 66 private 0.1‐ha forest plots arrayed across forest age and soil gradients in Guanacaste, Costa Rica. We found that soil fertility appeared to drive the spatial structure of public vs. private ownership; public conservation lands appeared to be non‐randomly located on areas of lower soil fertility. On private lands, areas of crops/pasture appeared to be non‐randomly located on higher soil fertility areas while forests occupied areas of lower soil fertility. We found that forest structure and tree species diversity did not differ significantly between public and private ownership. However, public and private forests differed in tree species composition: 11 percent were more prevalent in public forest and 7 percent were more prevalent in private forest. Swietenia macrophylla, Cedrela odorata, and Astronium graveolens were more prevalent in public forests likely because public forests provide stronger protection for these highly prized timber species. Guazuma ulmifolia was the most abundant tree in private forests likely because this species is widely consumed and dispersed by cattle. Furthermore, some compositional differences appear to result from soil fertility differences due to non‐random placement of public and private land holdings with respect to soil fertility. Land ownership creates a distinctive species composition signature that is likely the result of differences in soil fertility and management between the ownership types. Both biophysical and social variables should be considered to advance understanding of tropical secondary forest structure and biodiversity. 相似文献
6.
Catarina C. Jakovac André B. Junqueira Renato Crouzeilles Marielos Peña-Claros Rita C. G. Mesquita Frans Bongers 《Biological reviews of the Cambridge Philosophical Society》2021,96(4):1114-1134
Secondary forests are increasingly important components of human-modified landscapes in the tropics. Successional pathways, however, can vary enormously across and within landscapes, with divergent regrowth rates, vegetation structure and species composition. While climatic and edaphic conditions drive variations across regions, land-use history plays a central role in driving alternative successional pathways within human-modified landscapes. How land use affects succession depends on its intensity, spatial extent, frequency, duration and management practices, and is mediated by a complex combination of mechanisms acting on different ecosystem components and at different spatial and temporal scales. We review the literature aiming to provide a comprehensive understanding of the mechanisms underlying the long-lasting effects of land use on tropical forest succession and to discuss its implications for forest restoration. We organize it following a framework based on the hierarchical model of succession and ecological filtering theory. This review shows that our knowledge is mostly derived from studies in Neotropical forests regenerating after abandonment of shifting cultivation or pasture systems. Vegetation is the ecological component assessed most often. Little is known regarding how the recovery of belowground processes and microbiota communities is affected by previous land-use history. In published studies, land-use history has been mostly characterized by type, without discrimination of intensity, extent, duration or frequency. We compile and discuss the metrics used to describe land-use history, aiming to facilitate future studies. The literature shows that (i) species availability to succession is affected by transformations in the landscape that affect dispersal, and by management practices and seed predation, which affect the composition and diversity of propagules on site. Once a species successfully reaches an abandoned field, its establishment and performance are dependent on resistance to management practices, tolerance to (modified) soil conditions, herbivory, competition with weeds and invasive species, and facilitation by remnant trees. (ii) Structural and compositional divergences at early stages of succession remain for decades, suggesting that early communities play an important role in governing further ecosystem functioning and processes during succession. Management interventions at early stages could help enhance recovery rates and manipulate successional pathways. (iii) The combination of local and landscape conditions defines the limitations to succession and therefore the potential for natural regeneration to restore ecosystem properties effectively. The knowledge summarized here could enable the identification of conditions in which natural regeneration could efficiently promote forest restoration, and where specific management practices are required to foster succession. Finally, characterization of the landscape context and previous land-use history is essential to understand the limitations to succession and therefore to define cost-effective restoration strategies. Advancing knowledge on these two aspects is key for finding generalizable relations that will increase the predictability of succession and the efficiency of forest restoration under different landscape contexts. 相似文献
7.
秦岭山地典型次生林木本植物幼苗更新特征 总被引：6，自引：0，他引：6
采用样方法调查了秦岭山地5种典型次生林--油松林、锐齿栎林、红桦林、云杉林和华山松林幼苗的更新特征.结果表明: 不同次生林木本植物幼苗物种分化明显,除锐齿栎林和华山松林外,其余次生林幼苗物种相似性系数均较低;油松林和锐齿栎林木本植物幼苗数量、物种丰富度指数、Simpson优势度指数及均匀度指数均较高,红桦林均最低;云杉林和华山松林幼苗数量及物种多样性指数基本一致.不同次生林幼苗和幼树所占比例存在明显差异,除红桦林幼树数量的比例较大外,其余林分幼苗的比例较大,为云杉林＞油松林＞锐齿栎林＞华山松林.不同林分幼苗萌生比例差异明显,为华山松林＞云杉林＞红桦林＞锐齿栎林＞油松林.锐齿栎林和油松林乔木幼苗比例最高,分别占木本幼苗总种数的68%和51.4%,群落处于演替中期,持续更新能力较强;云杉林、华山松林乔木幼苗比例分别为40%和15%,处于演替后期,更新能力较差;而红桦林中幼苗很难发育成幼树,持续更新能力欠缺. 相似文献
8.
Wang Xian-pu arrd Hu Shun-shi 《植物学报(英文版)》1984,26(3)
The mixed evergreen and deciduons broadleaf forest on yeIlow-brown soil mountain belongs to climax vegetation type in humid subtropics. Analysis of its phytocoenological features shows that its physiognomy is characterized by leathery and herbaceous, simpie-leaved, microphyllous and mesophyllous types of evergreen broadleaf phanerophytes and deciduous broadleaf phanerophytes. As the structure of the community, from the aerial top to the forest floor, there are three distinct layers, namely, the tree layer, the shrub layer and the herbaceous layer. Moreover, the tree layer can be subdivided into three sublayers. Synusia structure is considerably complex, and there are different dominant synusia in each layer. The epiphytes and liana are not as abundant as that of seasonal rain forest. Floristic composition of the community is dominanted by endamic chinese subtropical plant species and East Asian elements. This condition indicates that it can be considered as a special vegetational type of humid chinese subtropics. Analysis of population in the community shows that most of the edificators have different age groups indicating normal reproduction of saplings and seedlings. This means that the habitat is suitable for their growth and reproduction during a certain duration of time. The community will be able to maintain its relative stable status. However, such a forest area is not large, and it is necessary to be protected intensively. Many kinds of rare plants in this forest, for example, Fagus lucida, Fagus longipetiolata, Cyclobalanopsis multinervis, Pseudosassafras tsumu, Manglietia fordiana, Manglietia chingii, Michelia maudiae, Castanopsis lamontii, Schima argentea, Pterostyrax leveillei etc. are worth mentioning. 相似文献
9.
The natural forest of Masha was studied to determine the species composition and population structure of woody species in the area. A total of 130 plant species belonging 61 families were recorded, in which family Acanthaceae was represented by 11 species followed by Rubiaceae (10) and Asteraceae (9). The composition and population structure of woody species, with diameter at breast height (DBH) >2.5 cm and height >2 m, and their regeneration were assessed in 65 sample plots of 400 m2 each. The density for trees and shrubs with DBH >2.5 cm was 1681 ind.ha?1, and the basal area of the study area was 142.6 m2 ha?1. Four community types were recognized. This forest is of international and national conservation importance given its high biodiversity. Managing the remaining forest would be an appropriate option for sustainable management of biodiversity. 相似文献
10.
Tinde van Andel 《Biodiversity and Conservation》2001,10(10):1645-1682
The adequate protection and sustainable management of a tropical rain forest requires a good knowledge of its biodiversity. Although considerable parts of Guyana's North-West District have been allocated as logging concessions, little has been published on the forest types present in this region. The present paper reviews the floristic composition, vegetation structure, and diversity of well-drained mixed and secondary forests in northwest Guyana. Trees, shrubs, lianas, herbs and hemi-epiphytes were inventoried in four hectare plots: two in primary forests, one in a 20-year-old secondary forest and one in a 60-year-old secondary forest. The primary forests largely corresponded with the Eschweilera–Licania association described by Fanshawe, although there were substantial variations in the floristic composition and densities of dominant species. The late-succession forest contained the highest number species and was not yet dominated by Lecythidaceae and Chrysobalanaceae. There is a need for updating the existing vegetation maps of northwest Guyana, as they were based on limited information. Large-scale forest inventories may provide a fair indication of species dominance and forest composition, but do not give a reliable insight in floristic diversity. Although previous reports predicted a general low diversity for the North-West District, the forests plots of this research were among the most diverse studied in Guyana so far. These results will hopefully influence the planning of protected areas in Guyana. 相似文献
11.
We compared early plant succession in four abandoned pastures of differing age since abandonment and a nearby secondary forest site in northwestern Ecuador. Two “Open” pastures had no tree canopy covering, and two “Guava” pastures had a well-developed canopy cover of Psidium guajava. No site had been seeded with pasture grasses. All pastures were compared in a chronological sequence; two were monitored for 18 months. Species richness was consistently higher in Guava sites than in Open sites and it continued to increase over time, whereas it remained static in Open sites. Species richness was highest in secondary forest. Recruitment of tree saplings in Guava sites was lower than in secondary forest; however, it was nearly absent in Open sites. The seed bank contained predominantly herbaceous species at all sites, and was highly dissimilar to aboveground vegetation. Dominance-diversity curves for Guava sites showed a more equitable distribution of species that increased over time. In contrast, dominance-diversity curves for Open sites were static and indicated dominance by a few aggressive species. Soil characteristics among sites were variable; however, a principal components analysis on soils isolated the older Open site from all others. The older Open site had the lowest species richness and was dominated by Baccharis trinervis, an aggressive shrub species. The site appears to be in a state of arrested succession and some form of restorative intervention may be necessary to initiate succession toward a forested condition. Succession in Guava sites appears headed toward secondary forest, whereas it does not in Open sites. 相似文献
12.
13.
西双版纳片断热带雨林植物区系成分及变化趋势 总被引：15，自引：0，他引：15
本文以西双版纳地区的6个“龙山”片断热带雨林的植物物种多样性编目为基础,通过与同样类型的原始热带雨林的比较,探讨了片断热带雨林植物区系成分的变化。随着热带雨林的片断化,森林边缘效应和人为干扰加剧,阳性先锋植物和藤本植物等的侵入,导致这些先锋植物和藤本植物所属的科属在群落中的种数增多,优势度增大。而一些含喜荫湿的荫生植物、群落顶极树种及附生植物较多的科属则在群落中的种数减小了,优势度下降。在植物属的地理成分构成上,片断热带雨林中全热带分布和热带亚洲—热带非洲分布成分比例相对增高,而热带亚洲成分相对减少。在种的地理成分构成上,片断热带雨林中广域分布种比例相对增高,显示了与属的地理成分类似的变化。这也是森林片断化后,由于边缘效应和林内生境在一定程度上干暖化,喜光的先锋成分增多,而先锋成分大多为一些广域分布属种所致。 相似文献
14.
CARL R. GOSPER COLIN J. YATES SUZANNE M. PROBER BLAIR C. PARSONS 《Austral ecology》2012,37(2):164-174
Mallee‐heath and mallee communities occur in a mosaic across large areas of south‐western Australia, in topographically subdued and fire‐prone landscapes. Consequently, it could be expected that these communities would have historically experienced similar fire regimes, and would respond similarly to variation in aspects of the fire regime. We studied the response of mallee‐heath and mallee to time since the last fire, measuring species density, species–area relationships, diversity indices and vegetation structure. Floristic responses to time since fire accorded with the initial floristic composition model of plant succession, with declining species density and Shannon diversity with age in mallee‐heath. Mallee‐heath exhibited structural senescence when > approximately 45–55 years since fire, with increasing standing dead vegetation, bare ground and stagnating or declining size in sprouting Eucalyptus spp. Mallee showed no such evidence of senescence, and indeed continued to increase in stature beyond the mean fire interval but without the compositional change required to provide support for the relay floristic model of plant succession. These results indicate that mallee‐heath is a fire maintained community and as such is reliant upon periodic burning to maintain diversity and vigour. Mallee, in contrast, is modified but not maintained by fire (at least over the period of time since fire examined) and hence is less susceptible to fire interval effects. Indeed, structural attributes likely to be significant for fauna habitat and carbon sequestration continue to develop in mallee unburnt for 55 years or more. Different responses to time since fire will create challenges for management, particularly in fragmented landscapes where fire potentially interacts with other threatening processes. 相似文献
15.
Secondary forest habitats are increasingly recognized for their potential to conserve biodiversity in the tropics. However, the development of faunal assemblages in secondary forest systems varies according to habitat quality and species‐specific traits. In this study, we predicted that the recovery of bird assemblages is dependent on secondary forest age and level of isolation, the forest stratum examined, and the species’ traits of feeding guild and body mass. This study was undertaken in secondary forests in central Panama; spanning a chronosequence of 60‐, 90‐, and 120‐year‐old forests, and in neighboring old‐growth forest. To give equal attention to all forest strata, we employed a novel method that paired simultaneous surveys in canopy and understory. This survey method provides a more nuanced picture than ground‐based studies, which are biased toward understory assemblages. Bird reassembly varied according to both habitat age and isolation, although it was challenging to separate these effects, as the older sites were also more isolated than the younger sites. In combination, habitat age and isolation impacted understory birds more than canopy‐dwelling birds. Proportions of dietary guilds did not vary with habitat age, but were significantly different between strata. Body mass distributions were similar across forest ages for small‐bodied birds, but older forest supported more large‐bodied birds, probably due to control of poaching at these sites. Canopy assemblages were characterized by higher species richness, and greater variation in both dietary breadth and body mass, relative to understory assemblages. The results highlight that secondary forests may offer critical refugia for many bird species, particularly specialist canopy‐dwellers. However, understory bird species may be less able to adapt to novel and isolated habitats and should be the focus of conservation efforts encouraging bird colonization of secondary forests. 相似文献
16.
广西酸性土地区亚热带落叶阔叶林的群落学特点及其合理利用的方向 总被引：5，自引：2，他引：5
亚热带落叶阔叶林在大多数情况下是常绿阔叶林或山地常绿落叶阔叶混交林遭受破坏以后发展起来的一个演替阶段。本文对其群落外貌、结构、种类组成和演替进行了比较详尽的分析,充分论证了上述的结论。组成这个类型的建群种多是阳性速生树种,木材的用途广泛,应该加以利用,任意砍伐烧垦和改种其它针叶树种都是不妥当的。一般可待其达到成熟龄时予以择伐利用,并促使群落向常绿阔叶林的方向发展。 相似文献
17.
The rehabilitation of disturbed ecosystems through ecological succession should lead to the recovery of indigenous biological assemblages typical of a region. However, rehabilitation may give rise to unusual successional pathways and lead to atypical assemblages. We compared millipede assemblages along a chronosequence of habitats developing in response to a post‐mining coastal dune forest rehabilitation program with those developing spontaneously in the same area. Our comparison suggests that active rehabilitation mimics and even surpasses spontaneous successional development. On both chronosequences, the total number of species, as well as the mean density, diversity, and species richness increased, and dominance decreased, with habitat regeneration age. Moreover, the similarity of millipede assemblages on the two chronosequences to those on three sets of reference sites (mature forests) increased with regeneration age, but this recovery of community composition occurred faster on the rehabilitating chronosequence than on the spontaneously regenerating chronosequence. This suggests that successional processes are leading to a recovery of the predisturbed state, but factors like protection from further disturbances, which occur on the spontaneously regenerating chronosequence, is probably important to ensure success. The distance between a regenerating site and a colonization source area apparently affects the direction of community recovery—assemblages on the rehabilitating chronosequence converged faster onto assemblages on closer reference sites than onto those on reference sites farther away. 相似文献
18.
广西的南桦林和西桦林及其演替趋向 总被引：3，自引：0，他引：3
在亚热带地区,当常绿阔叶林或山地常绿落叶阔叶混交林被砍伐后,桦木常常迅速侵入并发展成林,构成亚热带落叶阔叶林的一种重要类型,在自然发展过程中,它们又将向原来的森林类型恢复和演变。本文重点介绍了广西南桦林和西桦林的一些群落类型及其演替替向、期待发挥它们在林业建设中应有的作用。 相似文献
19.
Lack of seed dispersal can be an important obstacle to natural regeneration (NR) of degraded pastures in the humid tropics. Tree plantations can facilitate secondary forest succession by attracting seed dispersal agents from nearby forests. We studied seed rain and seed dispersal agents in 12–13 years old pure and mixed native tree plantations at La Selva Biological Station, Costa Rica from July to December 2004. Plantations of Balizia elegans (5,522), Dipteryx panamensis (2,263), and Jacaranda copaia (2,091) had the greatest total seed abundance; treatments with the least total seed abundance were Calophyllum brasiliense (56), nonplanted abandoned pasture control 2 (353), Mixed Species 2 (389), and control 1 (836). Plantations of J. copaia and Hyeronima alchorneoides had the greatest seed species richness density, whereas the lowest seed species richness was found in the control treatments. The NR plots had more seeds dispersed by wind, whereas in the plantations, the most important dispersal agents were birds and mammals. The most abundant seeds were those of Miconia spp. (14,492), Psychotria bracheata (2,252), and the Poaceae family (1,346), all species from early successional stages. Plantations of native species are effective in attracting seed dispersal agents and thus facilitating regeneration of degraded pasturelands in the region. 相似文献
20.
拟赤杨林是亚热带落叶阔叶林的一个群落类型 ,属于常绿阔叶林演替系列的一个演替阶段 ,主要见于东部中亚热带地区海拔 1 30 0m以下的红壤和黄壤山地山坡中下部环境比较湿润的地方 ,本文研究划分出 3个群丛纲和 1 3个群丛。它向常绿阔叶林恢复的演替趋向 ,从 1 3个群丛之间的群落外貌 ,结构和种类组成变化的分析可以得到充分的证明。 相似文献