首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 578 毫秒
1.
To better understand the potentials of the soil seed banks in facilitating succession towards a more natural forest of native tree species, we quantified the size and composition of the soil seed banks in established plantations in South China. The seed banks were from four typical 22-year-old plantations, i.e., legume, mixed-conifer, mixed-native, and Eucalyptus overstory species. Species diversity in the seed banks was low, and the vegetation species differed from those found in the seed bank in each plantation. A total of 1211 seedlings belonging to eight species emerged in a seedling germination assay, among which Cyrtococcum patens was most abundant. All species detected were shrubs and herbs, and no viable indigenous tree seeds were found in soil samples. Size and species composition of the seed banks might be related to the overstory species compositions of the established plantations. The seed bank density in soils was highest in the mixed-conifer plantation followed by Eucalyptus, mixed-native, and legume plantations. Species richness among the seed banks of plantations was ranked as follows: Eucalyptus > mixed-conifer > mixed-native = legume. The results indicated that the soil seed banks of the current plantations are ineffective in regenerating the former communities after human disturbances. Particularly, the absence of indigenous tree species seeds in the seed banks would limit regeneration and probably contribute to arrested succession at the pioneer community stage. It would appear from these data that the soil seed banks under the current plantations should not be considered as a useful tool leading the succession to more natural stages. Introduction of target indigenous species by artificial seeding or seedling planting should be considered to accelerate forest regeneration.  相似文献   

2.
Human-induced forest edges are common in many forest landscapes throughout the world. Forest management requires an understanding of their ecological consequences. This study addressed the responses of three ecological groups (non-forest species, secondary forest species and primary forest species) in edge soil seed banks and edge understory vegetation, and explored the relationship between the invasion of non-forest species in edge understory vegetation and the accumulation of their seeds in edge soil seed banks. The soil seed banks and understory vegetation were sampled along transects established at the edges of a continuous subtropical evergreen broad-leaved forest tract (Lithocarpus xylocarpus forest) bordering anthropogenic grasslands and three tropical seasonal rain forest fragments (Shorea wantianshuea forest) bordering fallows. Species composition in both soil seed banks and understory vegetation showed great difference among edge sites. In soil seed banks, the dominance (relative abundance and relative richness) of each ecological group did not change significantly along the edge to interior gradient. In understory vegetation, the invasion of non-forest species concentrated on the first several meters along the edge to interior gradient. The dominance of secondary forest species decreased with distance from the edge, while the dominance of primary forest species increased with distance from the edge. In forest edge zones, the invasion of a majority of non-forest species in understory vegetation lags behind the accumulation of their seeds in soil seed banks. Forest edges do not act as a good barrier for the penetration of non-forest species seeds. The lack of non-forest species in understory vegetation must then be due to conditions that are not appropriate for their establishment. Therefore, to prevent germination and survival of non-forest species further into the forest, management should focus on maintaining interior forest conditions.  相似文献   

3.
Natural forests have been increasingly replaced by artificial plantations around the world. Some research results suggest that artificial plantations can promote natural regeneration. The efforts in establishing protective forests in Hong Kong over the last 50 years after the Second World War have resulted in many exotic tree plantations which are ideal sites for the study of natural regeneration. This study looked at the seed rain and understorey woody plant diversity in three Lophostemon confertus plantations (25–40 years old) in Hong Kong. All the plantations were > 1 km from the nearest seed sources. Two of the plantations had a seed rain comparable in density and diversity to unplanted grasslands, and the understorey plant diversity was also low and dominated by shrubs. The other site had a higher and more diverse seed rain, as well as higher understorey stem density, but both the seed rain and the understorey were dominated by the shrub Psychotria asiatica. The poor seed rain at two sites and the rarity of potential canopy tree species in both the seed rain and understory regeneration at all sites suggest that planting exotic monocultures does not promote succession. Enrichment planting will be needed to restore forest diversity.  相似文献   

4.
2006～2007年采用种子萌发法,对香格里拉亚高山不同退化森林群落的土壤种子密度、丰富度,物种组成及地上植被组成开展了调查研究。结果表明:(1)亚高山土壤种子库中共有42个种子植物,种子密度为471～891粒/m2;(2)退化林地种子库中的物种密度依次为重度退化>极度退化>中度退化>轻度退化>未退化,物种丰富度依次为轻度退化>未退化>极度退化>中度退化>重度退化;(3)多年生草本植物在5类群落中均占绝对优势,只在未退化林地中发现木本植物;(4)土壤种子库及地上植被在物种组成上具有较小的Jaccard相似系数;(5)11月份物种数量及种子密度比4月份及7月份高;(6)0～5 cm表土种子库中具有较高的物种数量及种子密度;(7)种子扩散、地上植物的无性繁殖及人工造林是恢复香格里拉亚高山退化植被的有效途径。  相似文献   

5.
We estimated the potential of plantation forests for the restoration of the original plant community. We compared the understory vegetation in hinoki (Chamaecyparis obtusa [Sieb. et Zucc.] Endlicher) plantations at the understory re-initiation stage and in adjacent natural forests. To estimate the effect of the original natural forests on the understory species composition of plantation forests, we established study sites in five types of natural forests (mature evergreen broadleaf, mature deciduous broadleaf, mature evergreen coniferous, immature deciduous broadleaf warm-temperate, and immature deciduous broadleaf cool-temperate) and nearby plantation forests. The understory vegetation of the plantation forests had a higher species richness, a higher proportion of early-seral species, and a higher proportion of herb or fern species than the natural forests. The differences between natural and plantation forests varied according to the species composition of the natural forests. The composition of the understory vegetation of the plantations at the understory re-initiation stage was similar to that of the immature deciduous forests. The characteristics of immature, disturbed forests remained in the understory vegetation of the hinoki forests. No great loss of species was observed. Our findings suggest that most of the original forest species still survive in the understory of the plantation forests. These forests have the potential to follow the successional pathway to broadleaf or mixed forests via thinning or clear-cutting without planting.  相似文献   

6.

Introduction

The logging of several spruce plantations is planned for the next years in the Eifel National Park (Western Germany). To understand the ecological mechanisms of spontaneous forest regeneration that follows these impacts, it is crucial to investigate the species composition and functional diversity of the buried germinable seeds in those stands.

Methods

We analysed the soil seed bank by germination method and characterised germination dynamics and distribution of seedlings throughout the samples according to a sigmoid model and cumulative curves, respectively. To compare the proportions of functional and syntaxonomical groups between seed bank and aboveground vegetation, we applied the Fisher??s exact test. Additionally, we described the spatial distribution of the species in the seed bank according to semivariograms.

Results

The studied seed bank reached a density of about 5,300 seed?m?2. Most of the species detected in the seed bank are related to open vegetation, forest fringes and early successional stages of forest regeneration. In spite of a low floristic similarity between seed bank and aboveground vegetation, the functional and syntaxonomical composition is very similar. Further studies considering the distribution of seeds in the soil and the changes of the seed bank composition during the regeneration process are required.  相似文献   

7.
We investigated characteristics (scales and composition) of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring. We also surveyed the vegetation communities at the eight study sites to explore the role of soil seed banks in vegetation restoration. The storage capacity of soil seed banks at the eight sites ranked from 766.26 to 2461.92 seeds·m -2 . A total of 23 plant species were found in soil seed banks, of which 63 80% of seeds were herbs in various soil layers and 60% of seeds were located in the soil layer at 0 5cm depth. Biodiversity indices indicated clear differences in species diversity of soil seed banks among different plant communities. The species composition of aboveground vegetation showed low similarity with that based on soil seed banks. In the above- ground plant community, the afforestation tree species showed high importance values. The plant species originating from soil seed banks represented natural regeneration, which also showed relatively high importance values. This study suggests that in the rocky mountain region of Beijing the soil seed banks played a key role in the transformation from pure plantation forest to near-natural forest, promoting natural ecological processes, and the role of the seed banks in vegetation restoration was important to the improvement of ecological restoration methods.  相似文献   

8.
Senbeta  Feyera  Teketay  Demel  Näslund  Bert-Åke 《New Forests》2002,24(2):131-145
Regeneration of native woody species was studied in the plantations and the adjacent natural forest at Munessa-Shashemene Forest Project Area, Ethiopia. The aim of the study was to test the hypothesis that tree plantations foster regeneration of native woody species. A total of 60 plots, having 10 × 10 m area each, were studied in monoculture plantations of 4 exotic species (Cupressus lusitanica, Eucalyptus globulus, E. saligna, Pinus patula) and an adjacent natural forest. Ages of the plantations ranged between 9 and 28 years. Soil seed bank analysis was also undertaken from soil samples collected in each of the 60 plots to examine the similarity between the soil seed flora and aboveground vegetation. A total of 56 naturally regenerated woody species were recorded beneath all plantation stands with densities ranging between 2300 and 18650 individuals / ha in different stands. There was a significant difference among plantation stands with regard to understorey density (standard deviation: 4836 ± 1341). Vegetation diversity was assessed through analyses of floristic composition, species richness and abundance. Generally, seedling populations were the most abundant components of the regeneration in most of the plantation stands, forming 68 % of the total regeneration count in all stands. A total of 77 plant species represented by 44 herbs, 13 woody species, 8 grasses and 12 unidentified species were recorded in the soil seed bank from all stands. Similarity between the soil seed bank and aboveground flora was very low implying that the role of soil seed banks is negligible rather dispersal plays an important role in the process of regeneration. These results support the concept that forest plantations can foster the regeneration of native woody species, thereby increasing biological diversity, provided that there are seed sources in the vicinity of the plantations.  相似文献   

9.
The objective of this study was to compare the variation in the soil seed banks and the aboveground vegetation in relation to three habitats, i.e., swamp forests, grassland and sand dunes within the Sundarbans mangrove forests of Bangladesh. We collected vegetation data (species and their percentage cover) by using quadrat sampling: 10 m × 10 m for swamp forests and 5 m × 5 m for grassland and sand dunes. We estimated the density of viable seeds of species in the seed bank by counting germinants from soil cores in a germination chamber. Species richness and composition of both aboveground vegetation and the soil seed banks differed significantly among habitats. We identified a total of 23 species from the soil seed bank. Of these, two were true mangrove species and the remaining were non-mangrove species, including halophytic grasses, herbs and mangrove associate species. Our results confirm that mangrove species do not possess a persistent soil seed bank. The presence of high-density non-mangrove and associated mangrove species in the soil seed bank implies that after frequent catastrophic disturbances which limit incoming propagules from adjacent forest stand, large canopy gaps can easily become invaded by non-mangrove and mangrove associate species. This would result in the formation of a cover of non-mangrove species and cryptic ecological degradation in mangrove habitats. We suggest that forest managers should actively consider gap plantations with mangrove species in the large canopy gaps created after catastrophic disturbances to counteract the invasion of non-mangrove species and cryptic ecological degradation.  相似文献   

10.
选择四川省沐川县凉风坳亚热带次生常绿阔叶林为研究对象,在2004年5月、2004年12月和2005年5月对其林下土壤种子库、种子雨以及种子天然萌发状况等方面进行系统调查及分析研究。结果显示,种子下落前后土壤种子库储量,变动为643.2～889.2粒.m-2,物种和种子密度多年生草本物种均占优势。天然林土壤种子库Shannon-Wiener指数均在2004年5月最大,2004年12月次之,2005年5月最小;Simpson指数却和Shannon-Wiener指数H＇的变化趋势相反;Pielou均匀度指数在2004年12月有所降低,此后又升高。种子均呈明显垂直分布,其中0～2 cm土层种子数量最多,其次是枯枝落叶层,其数量随着土层加深而降低。土壤种子库年输入活力种子142.3粒.m-2,年输出活力种子268.9粒.m-2,动物取食是造成种子损失的主要原因。对照人工林土壤种子库物种和密度均低于天然林地;种子库与地上植被物种相似性系数,人工林较高,而天然次生常绿阔叶林较低。  相似文献   

11.
以普文热带北缘季风气候的地带性植被山地雨林为中心 ,通过调查与其生态相关的次生林类型和人为控制的人工林 ,分析比较了它们的种类组成、群落结构、群落生态特征和生态系列关系。还分析了山地雨林在当地群落中的生态位置及其动态变化 ;同时 ,探讨了各群落之间的演替关系和恢复山地雨林的途径  相似文献   

12.
The establishment of invasive plant populations is controlled by seed input, survival in the soil seed bank, and effects of soil surface disturbance on emergence, growth, and survival. We studied the invasive vine Celastrus orbiculatus Thunb. (Oriental bittersweet) to determine if seedlings in forest understory germinate from the seed bank or from seed rain. We also conducted a greenhouse experiment to investigate the role of leaf litter mass and physical texture on seedling survival, growth, and allocation. In the understory of an invaded mixed hardwood forest, we measured seed input, seedling emergence with seed rain, and seedling emergence without seed rain. Mean seed rain was 168 seeds m−2: mean seedling emergence was 107 m−2, and there was a strong correlation between seed rain and seedling emergence. The ratio of seedlings to seed input (0.61) was close to the seed viability (0.66) leaving very few seeds to enter the seed bank. Seed bank germination under field conditions was low (1 seedling m−2). Soil cores were incubated in a greenhouse to determine seed bank viability, and germination from these soil cores did not occur. To determine how litter affects seedling establishment and growth, we measured seedling emergence and biomass allocation in a greenhouse experiment. Seeds were placed below intact and fragmented deciduous leaf litter in amounts ranging from zero to the equivalent of 16 Mg ha−1. Seedling emergence was not affected by fragmented litter, but decreased to <20% as intact litter increased to 16 Mg ha−1. Increasing litter resulted in greater allocation to hypocotyl and less to cotyledon and radicle, and this effect was greater in intact litter. C. orbiculatus seedlings achieve emergence through forest floor litter through plasticity in allocation to hypocotyl growth. The low survival of C. orbiculatus in the seed bank suggests that eradication of seedling advance regeneration and adult plants prior to seed rain may be an effective control strategy. However, the intact forest floor litter of an undisturbed forest will not prevent seedling establishment.  相似文献   

13.
马尾松人工林是我国南方主要的单一树种人工林之一。采用以空间代替时间方法,阐明该单一造林树种人工林林下群落结构在发育过程中的变化规律,为该人工林群落的植被生态改良提供依据和参考。湖南省衡山县紫巾山国有林场内不同林龄阶段马尾松人工林群落内调查有植物108种,隶属56科91属。檵木(Loropetalumchinensis)、白栎(Quercus fabri)、赤楠(Radix Syzygii)、栀子(Gardenia jasminoides)以及茅草(Imperata cylin-drica)、芒(Schizachyrium scoparium)、淡竹叶(Lophatherum gracile)和狗脊蕨(Woodwardia japonica)等在整个群落中有较大优势。整个群落及其各垂直层次的各多样性指数值在中熟林(15a)以下表现有很大波动性,中熟林(15a)之后群落开始出现新的野生乔木物种,同时整个群落及各垂直群落层次的丰富度指数,Simpson多样性指数,Shannon-Wiener多样性指数和Pielou均匀度指数的变化均开始趋向于稳定。在整个林下群落的演变过程中老熟林(25a)和中幼林(5a)群落间物种相似性最低(Sm为0.158),β多样性最大,体现出中幼林(5a)的群落结构最不稳定。  相似文献   

14.
Hybrid poplar plantations are increasing worldwide and are often accused of impoverishing bird communities. We conducted 124 bird point counts in a landscape where plantations, semi-natural forests and farmland occupied similar surface areas. As expected, birds occurred at higher densities in areas dominated by forests than dominated by plantations, mostly due to the scarcity of late-successional forest birds in plantations. Contrary to expectations, bird communities were the poorest in farmland dominated areas and the most specialised in areas dominated by young plantations. Indeed, many grassland species, including some of conservation concern in Europe, frequently used young plantations. However, plantations have probably depleted grassland bird communities by fragmenting open areas, while playing a limited positive role on forest species. Total length of unpaved roads had a positive effect on community specialisation index, while total length of paved roads and mean forest/plantation patch size played no role. Bird density increased with the development of the understory vegetation in mature poplar plantations. We conclude that poplar should not be planted at the expense of areas of high conservation value; in other cases, they may increase the overall diversity of bird communities. At the plantation scale, we advocate stopping understory removal as soon as possible and maintaining old trees and hedgerows alongside or within plantations to provide suitable breeding habitats for bird species that may be foraging in the plantations.  相似文献   

15.
缙云山常绿阔叶林种子雨组成及其时空动态   总被引：1，自引：0，他引：1  
【目的】分析缙云山常绿阔叶林种子雨组成及其时空动态,为常绿阔叶林种子生态学大尺度和长时序的研究提供数据支持,并为受损常绿阔叶林近自然恢复过程中的种源收集和种子撒播提供参考信息。【方法】 2014-01—2016-12,收集缙云山常绿阔叶林1 hm 2标准地中172个种子收集框内的种子,鉴定物种并计数,风干后称质量。根据果实类型及种子特征并结合野外实地观察,确定每个物种种子(果实)的散布方式。【结果】 3年间共收集到成熟种子36 298粒,种子雨密度为140.69粒·m -2 a -1;种子分属于19科21属27种,占群落木本植物物种总数的36.49%;种子雨具有明显的季节动态,在秋季出现高峰,其中有17个物种在干季(1—4和10—12月)成熟并散布,6个物种在湿季(5—9月)成熟并散布,4个物种在干、湿季均有散布;种子雨密度年际变异系数为0.36~1.73,空间变异系数为1.54~15.20。【结论】缙云山种子雨产量在常绿阔叶林中处于较低水平;优势种对群落种子雨产量贡献较大,种子雨物种组成与群落物种组成相似性较低;群落水平种子雨具有明显的季节动态,且存在很大的年际变异和空间变异,反映出亚热带常绿阔叶林种子雨时空动态的典型特征。在区域植被近自然恢复中的种子采集和撒播环节,应当充分参照不同物种的种子雨掉落的时空动态。  相似文献   

16.
三种人工林的结构特征及林分改造对策   总被引：1，自引：0，他引：1  
对广东省大岭山桉树、马尾松、马占相思三种人工林进行样方调查,分析了林分结构特征并提出林分改造对策。三种人工林的立木密度分别为1 268,2 232,1 524株/hm2,随着径级的增大,立木数减少。群落种群的频度级分布均为A〉B〉C〉D=E=0。垂直结构明显,层间植物种类多,林下植被丰富。除草本层外乔木层、灌木层和层间植物这三个的Shannon-Weiner多样性指数和均匀度比较接近,而且和自然条件下的广东亚热常绿阔叶林的群落组成结构基本相符。林分结构特征表明三种人工林受到的人为干扰少,林分改造效果较明显,从演替的角度看,这三种林分有向南亚热带常绿阔叶林发展的趋势。  相似文献   

17.
R. Scot Duncan 《New Forests》2006,31(2):131-150
The management of successional forests has become an increasingly important tool for tropical forest restoration on disturbed lands. Successful management depends on understanding factors governing tree recruitment during succession. Recruits can be on-site propagules surviving disturbance (e.g. saplings) or seeds arriving after disturbance. Among disturbed sites, the importance of seed arrival from off-site should increase as availability of on-site propagules declines. This study examines how seed arrival from off-site seemed to influence natural forest regrowth on logged plantations in Uganda. Specifically, the effect of seed arrival from mammals (determined directly) and birds (determined inferentially) was estimated in two plantations with high and three plantations with low quantities of saplings surviving logging. In both plantation types, first-year recruitment seemed to originate from on-site (seed bank and sprouts from damaged trees) and off-site sources (seed-dispersing birds). Recruitment declined 2–3 years after logging in all plantations despite high densities of seed-dispersing birds. Recruitment was generally greater in plantations with low initial quantities of on-site propagules, and by 4–6 years forest structure was similar between plantation types. Recruitment was dominated by bird-dispersed species, rather than mammal- or wind-dispersed species. Taken together, these results illustrate that disturbed areas with low initial on-site propagule availability have much potential for forest regrowth.  相似文献   

18.
Seed limitation of desired indigenous species has constrained the succession of established plantations from an early successional stage, to more natural forests in South China. Because of its low cost and time-saving advantages, direct seeding has been considered a useful method in forest regeneration. To improve our understanding of whether and how direct seeding can lead to the establishment of indigenous tree species, we carried out an experiment in four typical plantations (eucalyptus, mixed-native, mixed-legume, mixed-conifer) and a shrubland in South China. We also tested the effect of understory vegetation and litter removal on seedling establishment and growth. Seeds of three indigenous tree species (Castanopsis chinensis, Cryptocarya chinensis, and Psychotria rubra) were sown with understory vegetation and litter either retained or removed. Seedling emergence, survival, and growth were recorded for 21 months. We found that conditions that favored seedling emergence often differed from those that favored seedling survival. While the removal of understory vegetation and litter did not influence the final seedling establishments for all the three introduced species, growth of Psychotria rubra was influenced at several sites. Seed mass was positively correlated with seedling emergence and subsequent growth. The large-seeded Castanopsis chinensis showed higher emergence and growth than the intermediate-seeded Cryptocarya chinensis or the small-seeded Psychotria rubra. Seedlings of Castanopsis chinensis grew better in plant communities with high understory light penetration and high soil exchangeable potassium. Growth of P. rubra seedlings decreased significantly with soil hydrolyzed nitrogen. In conclusion, direct seeding can be useful for the establishment of indigenous tree species into plantations and shrubland. Optimizing early seedling establishment and growth will require the selection of suitable native species for improving seedling establishment in different plantations. Additionally, understory vegetation and litter and fertilizer should be properly managed to enhance the establishment of certain indigenous tree species.  相似文献   

19.
Domestic livestock grazing and firewood extraction are chronic and pervasive disturbances in dry secondary forest that reduce diversity and modify composition. Exclosure of such disturbances may allow the reestablishment of original diversity. To investigate potential vegetation recovery following 30 years of perturbation, seed rain was evaluated monthly during 3 years in 96 0.78 m2 seed traps located in eight exclosures established in 2006 in a species-poor secondary dry forest in central Mexico. Twelve additional seed traps were located outside the exclosures in 2010 for comparison purposes. Baseline diversity of seed sources (trees, ?5 cm DBH) was recorded to compare standing tree composition with seed rain. Also, baseline diversity of potential primary (birds) and secondary (ants) dispersal vectors were registered to infer current plant-animal interactions. Total seed rain over 3 years within the exclosures comprised 180,375 seeds from 61 woody species, an average of 1.12 seeds/m2/month. Half of these species (31) and 95% of the seeds falling within the exclosures belonged to trees typical of perturbed sites. Sixty percent of all recorded seeds belonged to an early-successional, bird-dispersed shrub (Hamelia patens Jacq., Rubiaceae). Seed rain at one non-excluded plot was dominated by the wind-dispersed early-successional tree Heliocarpus sp. (Tiliaceae). Richness and seed density increased significantly in the second year of exclusion; however, by the third year, richness remained constant while seed density decreased. Seed rain was richer and more abundant during the dry season and was dominated by wind-dispersed species. Phenology, successional status and the dispersal modes of woody species explained most variance in richness and seed density of seed rain in early-successional dry forest. Seeds of early-successional species were dispersed in equal measure by abiotic and biotic vectors, whereas biotic vectors dispersed a higher density of late-successional seeds. The amount and timing of fall of abiotically dispersed seeds of the three most abundant species in the standing tree community may prolong their current domination of the landscape. However, even when richness in the seed rain within exclosures remained constant through time, composition was gradually shifting towards animal-dispersed species which may start a positive feedback producing an increase in animal visitation and a further increase of richness.  相似文献   

20.
Much research effort is being devoted to developing forest management practices with limited impacts on biodiversity. While the impact of poplar Populus sp. plantations on biodiversity is relatively well-known at the landscape scale, the impact of alternative management practices at the plantation scale has received much less attention. Yet biodiversity is likely to be impacted by the choice of the poplar clone, stem density at plantation, type and duration of the understory control, and age at which the poplars are harvested. In this study, we investigated the impact of these factors on herbaceous plant communities with data from plant surveys conducted in 85 young (2–5 years) and 96 mature (11–17 years) hybrid poplar high-forest plantations in northern France. On average, ruderal or generalist plants contributed to 40.5% of the plot species richness; tall herbs (60.2%), forest (26%) and meadow plants (13.8%) contributed to the remaining 59.5% more specialised species. Soil moisture and soil nitrogen were major determinants of plant communities: wet soils were favourable to tall herbs, while meadow and forest species preferred moist soils; a significantly lower diversity of the three species groups was reported in the nutrient richer soils (in mature plantations only for forest plants). Mean species richness decreased with plantation age except for forest species. Plant communities in young plantations showed little differences in composition according to the type of understory control (chemical, mechanical or both). The development of a shrubby layer in mature plantations was restricted to the drier soils and was detrimental to both meadow plants and tall herb species. Effects of previous land use on forest and tall herb species were found only in young plantations, suggesting a rapid reset of plant communities for these two groups. This may not be the case for meadow species as the influence of previous land use was significant in mature plantations only. Finally, clone type and stem density at plantation had no significant impact on plant communities. Adjusting age at which the poplars are harvested seems the only effective way to drive plant communities in high-forest poplar plantations: delaying poplar harvest (probably beyond 15–20 years) would benefit forest plants, while advancing poplar harvest (about 10 years) would benefit tall herbs, especially in wet soil conditions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号