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1.
胡慧  杨雨  包维楷  刘鑫  李芳兰 《植物生态学报》2020,44(10):1028-1039
干旱区植被斑块状分布格局引起的微生境差异对植被更新影响显著。气候变化和人类活动扰动下, 干旱区生态系统微生境多样化, 急需揭示乡土植物定植对不同微生境斑块变化的响应及其种间差异性, 并采用微生境调控技术促进退化生态系统植被恢复。该研究选择岷江干旱河谷区自然分布的灌木、半灌木和裸地微生境斑块, 采用移栽鞍叶羊蹄甲(Bauhinia brachycarpa)幼苗的试验方法, 揭示微生境变化对幼苗定植的影响; 进一步以极端退化的道路边坡为案例, 通过6种乡土植物种子直播试验探讨微生境调控技术及其对乡土植物幼苗定植的促进作用。结果显示, 在自然生态系统中, 裸地斑块上幼苗保存率和生物量显著大于植被斑块, 表明裸地微生境有利于幼苗定植; 养分添加仅对裸地斑块中幼苗生物量积累有促进作用。在裸地斑块中, 叶片生物量所占的比例和比叶面积较小, 相反根和茎生物量所占的比例较大。道路边坡上植被恢复试验结果显示, 6种乡土植物均能较好地适应土石混杂的边坡生境, 多数物种出苗率大于60%; 灌木幼苗保存率大于75%, 并且形成镶嵌式乡土灌草群落结构。地表覆盖和养分添加提高了边坡上种子出苗率和幼苗保存率, 促进了幼苗定植和结构稳定。该研究提供了有效促进工程边坡上乡土植物定植的方法, 可为干旱、半干旱生态系统退化荒坡和工程破坏地乡土植被恢复提供理论依据和技术指导。  相似文献   

2.
选取青藏高原三江源区"黑土滩"型退化草地上建植的人工草地为研究对象,对不同建植年限人工草地植物群落及其各功能群的物种组成、平均高度、盖度和地上生物量及植物多样性等进行实地调查和对比分析,探讨"黑土滩型"退化草地在人工恢复过程中植物群落组成和多样性变化,以期回答人工恢复的草地植物群落何时才能接近天然草地、人工恢复的时间阈值应为多长等问题,从而为三江源区"黑土滩"型退化草地的恢复重建提供科学的理论指导。研究结果表明:草地恢复前5年内,禾本科植物的数量大量增加,植物群落的高度增加了847.6%,植物群落盖度增加了134.5%;不同恢复年限的草地植物群落的多样性指数都有相似的变化趋势,恢复8年后植物群落组成达到阶段性的稳定状态,在恢复时间达16—18年后,逐渐向更稳定的状态转化;恢复18年的草地与天然草地植物群落的Jaccard及Sorensen相似度指数分别为0.596、0.747,Cody差异度指数为9.5。由此可见,建植人工草地的方式恢复退化草地,可在建植8年后达较好的恢复效果;恢复时间达16年以上的人工草地采取适度的调控措施,有利于其向天然草地恢复演替;建植18年的人工草地物种组成情况与天然草地最接近,但仍有差异。因此,"黑土滩"型退化草地的人工促进恢复,到未退化的状态至少需要18年以上。  相似文献   

3.
不同演替阶段的群落中植物幼苗建植特性以及幼苗建植时所处的环境都会有所不同.这些差异可能会导致种子萌发率与物种多度之间的关系随着群落的演替阶段而发生改变.目前关于不同类型群落中以及同一类型群落的不同演替阶段物种多度和种子萌发能力之间的关系的研究较少.本研究以全面收集的青藏高原东缘3种常见次生植被(鼢鼠土丘群落、人工草地群落和弃耕地群落)中植物种子为基础,沿着群落演替梯度来探明种子萌发和物种多度之间的关系.通过对结果的线性回归分析发现:在鼢鼠土丘群落和人工草地群落中,种子萌发率和物种多度之间无显著相关性;而在弃耕地群落中,种子萌发率和物种多度之间的关系有随着群落的演替呈现由正相关向负相关转变的趋势.  相似文献   

4.
以不同退化程度和采用不同恢复措施的垂穗披碱草人工草地为对象,通过野外调查和室内分析相结合的方法研究了各类草地垂穗披碱草克隆种群相关表型特征的差异,结果表明,随着人工草地建植年限的延长,草地退化渐趋严重,垂穗披碱草克隆种群相关表型参数显著降低.相比较而言,封育可以提高种群的有性繁殖能力,但施肥和补播措施可以显著提高垂穗披碱草种群的克隆生长,其株高、分株数以及株丛数显著增加,而有性繁殖能力相对降低.因此,针对藏北高原以垂穗披碱草为最主要建群种或单优种群的退化草地恢复,施肥和补播应为最有效措施.  相似文献   

5.
泥炭藓繁殖体移植是影响泥炭地植被恢复的重要因素之一,不同移植方式的效果往往缺乏比较研究。选取长白山区白江河退化泥炭地为研究地,以自然生境的丘间种喙叶泥炭藓(Sphagnum flexuosum)和藓丘种中位泥炭藓(S.magellanicum)(后者耐旱能力较强)为实验材料,通过野外移植实验,研究水位提升与不同泥炭藓繁殖体移植方式对退化泥炭地植被恢复的影响。数据分析显示:水位条件显著影响了喙叶泥炭藓和中位泥炭藓的建植,随着水位上升,地表湿度增加,两种泥炭藓的盖度均呈明显的上升趋势;移植方式的变化短期内对泥炭藓的建植作用并不明显,但在移植2个月后,移植方式对喙叶泥炭藓表现出显著影响,即耐旱能力较强的中位泥炭藓置于上层时,喙叶泥炭藓盖度最高;水位和移植方式不存在交互作用,即在低水位条件下,中位泥炭藓置于上层的移植方式也未能提升泥炭藓的建植盖度。研究表明,水位提升是泥炭地植被恢复的十分有效的手段,因物种间存在对水分保持的差异,采用合理植物繁殖体移植方式,将会明显提升植被恢复的成效。  相似文献   

6.
补充限制基于生态位理论, 从种子萌发、幼苗存活和生长、繁殖体扩散等生活史阶段的种群统计特征及环境因素(土壤水分、养分、凋落物等)着手, 探讨种群的更新问题。种源限制和微生境限制是补充限制理论研究的核心内容, 但是哪个更为重要并没有统一的结论。种源限制与种子生产、土壤种子库和地下芽库中的繁殖体数量不足有关。其中, 气候的年际波动、土壤种子库寿命和动物的捕食都会影响种子生产在种群更新中的作用; 土壤种子库常被视为种群更新的保险库, 与地上种子雨共同促进种群更新, 但是, 如果土壤里种子具有较高的死亡率和休眠率, 将会降低种子库的作用; 地下芽库及其产生的无性分株对于种群更新的意义更多地体现在干扰后种群更强的恢复能力上。扩散限制是种群更新中的普遍现象, 与种子产量、散布能力、传播媒介、幼苗密度等因素有关。微生境限制主要表现为水分、养分、凋落物等非生物因素以及竞争、捕食等生物因素对种子的活力、萌发性、幼苗的存活力、物质分配等过程的影响, 其重要性随着植物生活史阶段而发生变化。未来需要进行综合的、长期的实验, 并应着重加强种源限制及相关生态过程的进化与生态相结合的机理性研究, 从而更深刻地认识和理解种群更新问题, 建立更为综合、系统的种群更新理论体系。  相似文献   

7.
关于开花植物花序内变异原因的研究有很多,而关于花序内资源分配的位置效应产生影响的研究并不常见。通过对青藏高原高寒草甸退化草地一种花序轴基向发育的优势毒杂草黄帚橐吾(Ligularia virgaurea)的野外调查和方差分析发现,其种子生产存在显著的位置效应。结实率和种子平均重表现出顶部头状花序基部头状花序的变化趋势,胚珠平均数则基部顶部,而中部种子平均数最多。通过室内萌发实验和野外盆栽实验研究了位置效应对幼苗建植能力的影响,发现基部种子的萌发开始时间比顶部种子早,萌发率和出苗率在部位间的差异不显著,而部位间幼苗存活率表现一致;幼苗的根冠比和光合速率表现出顶部基部的变化趋势,而幼苗总生物量的差异不显著,这些幼苗特性在两种肥力条件下表现一致,这说明不同花序部位种子的差异是该种植物所固有的特征,且部位间种子的萌发和幼苗生长对策不同。但相对于基部种子,顶部种子扩散距离更远,拓展到新生境的能力更强,相对较高的幼苗根冠比和净光合速率增强了其幼苗建植能力,对自然种群的更新补充有着更重要的生态学意义,对扩大种群和植被更新有更大的贡献。  相似文献   

8.
本文研究了秋冬季节淡水大米草(Spartina densiflora)沼泽中野生豚鼠(Cavia a perea)的丰度、繁殖和微生境利用,以及其对当地植被和棉鼠类(Sigmodontine)啮齿动物的影响。野生豚鼠喜好S.densiflora覆盖度高的生境。繁殖个体(成体)主要利用矮草为主的斑块,幼体则主要利用禾本科植物为主的斑块。结果说明,野生豚鼠微生境的利用受捕食风险和食物种类的影响。在淡水沼泽中,野生豚鼠的丰度、繁殖、体重和微生境利用没有季节性变化,它们对植物的取食和活动跑道的建造对植被结构和同域的啮齿类动物没有负面影响。通过对具有中度季节性变化的淡水生境中的豚鼠种群和具有高度季节变化的草地和路边中的豚鼠种群进行比较,表明野生豚鼠的种群动态以及豚鼠种群对植被和与其共生的啮齿动物群落的影响都受到冬季植被盖度的限制。  相似文献   

9.
李媛媛  董世魁  朱磊  温璐  李小艳  王学霞 《生态学报》2013,33(15):4683-4691
以三江源区不同退化程度高寒草甸和不同恢复年限人工草地作为研究对象,通过野外调查与采样、实验室分析,探究了高寒地区退化天然草地与人工恢复草地的植被群落繁殖构件数量变化.结果表明:在群落水平上,天然草地退化和人工草地建植会对植物繁殖构件的数量和生物量产生影响.随着天然草地退化程度的增加,营养枝数量和生物量则明显下降,而繁殖枝的数量和生物量明显升高(P<0.05);随着人工草地恢复年限的增加,营养枝的数量和生物量逐渐增加,而繁殖枝的数量和生物量则逐渐降低(P<0.05);随着恢复年限的增加,人工草地繁殖构件的变化逐渐接近未退化天然草地.在功能群水平上,植物繁殖构件数量亦随草地退化程度和人工恢复年限而变化.随着恢复年限的增加,禾本科、莎草科、杂类草的营养枝数量和生物量均呈现显著增加(P<0.05),而繁殖枝数量和生物量则显著下降,禾本科的繁殖构件数量远远大于莎草科和杂类草;随着退化程度的增加,三大功能群的营养枝枝数和生物量显著增加(P<0.05),而繁殖枝则呈现相反的趋势.实证了草地退化和人工恢复改变植物群落繁殖分配对策的科学假设,为高寒草地植被恢复重建技术的发展和更新提供理论支撑.  相似文献   

10.
 本项研究自1983年起在锡林河中游对放牧退化的冷蒿(Artemisia frigida)占优势的草原群落变型进行封育恢复实验与长期监测。每年在植物生长季以15天为间隔进行取样测定,即每年测定9期,每期做10或20个1m×1m的样方。测定项目包括:群落中各植物种群的地上现存生物量、密度、高度、花(果)枝数等。还采用改进的样方方差法监测植物种群空间分布格局的动态。并同时在保护良好的羊草+大针茅(Leymus chinensis+Stipa grandis)群落中进行测定取得完全对应的数据,作为对照系列。以上两种群落的土壤水分与养分动态的长期监测由本站土壤组承担。根据连续十二年监测数据的分析,对退化草原群落的性质与特征提出以下的认识,并对退化草原恢复演替的驱动因素进行厂探讨。1.草原退化演替阶段是与一定强度的放牧压力保持平衡而相对稳定的群落变形,退化阶段取决于牧压强度与持续的年代。2.当群落退化到冷蒿为主要优势种的阶段时,与原生群落的种类组成相比,只发生一定的数量消长变化,对群落的物种丰富度影响不大。3.退化群落植物种群空间格局的均匀性较高,随着恢复演替的进展,因一些种群斑块增大而使空间不均匀性增强。4.退化群落与其原生群落的种—生物量关系呈对数正态模式,其演替过渡阶段成为分割线段模式,也反映出群落资源分配格局与群落空间格局的关系。5.退化草原的显著特征是植被生产力下降,冷蒿群落的生物量下降到原生群落的30%~40%,家畜嗜食的植物种减少50%~70%总生产力不足原生群落的30%。6.退化群落在自然封育条件下能够迅速恢复的原因,可归结为植物在削除放牧干扰后的种群拓殖能力与群落资源(水分,矿质养分等)的剩余。群落资源条件是种群拓殖的物质基础,从而成为恢复演替的动力。  相似文献   

11.
Availability of seeds and provision of “safe sites” for seedling recruitment are essential for successful restoration of seminatural grassland communities. Inability to provide species‐specific conditions for seedling recruitment appears to be a major factor limiting establishment of fen‐meadow species on restoration sites. This contention was tested in the field for both germination and establishment conditions for a selection of fen‐meadow species. A Cirsio‐Molinietum fen meadow and an agriculturally semi‐improved species‐poor grass dominated rush pasture were used. Seeds of Carex ovalis, Cirsium dissectum, Molinia caerulea, Succisa pratensis, and Holcus lanatus were sown onto treatments comprising either irrigation or no irrigation, presence or absence of existing vegetation canopy, and presence or absence of soil disturbance. Germination of all except H. lanatus was higher in the fen meadow than in the rush pasture. The fen‐meadow site was less susceptible to drought, provided more light to the seed environment, and showed a stronger day–night variation in relative humidity compared with the rush pasture. All the fen‐meadow species responded strongly to the experimental treatments, whereas H. lanatus showed only a small response. Soil disturbance was the major factor that increased germination. Removal of the vegetation canopy improved germination only in S. pratensis. Conditions affecting survival of seedlings were different from those affecting seed germination. Seedling survival was greater on the fen‐meadow site than on the rush pasture. Canopy presence was the major factor that reduced seedling survival. Few seedlings survived in the presence of the rush pasture canopy. Irrigation and soil disturbance were of minor importance for seedling survival on both sites. Safe sites for seed germination and seedling establishment of fen‐meadow species existed on the fen meadow even without soil disturbance and gap creation. Safe sites for seedling recruitment were not present in the rush pasture. The need for species‐specific definition of safe site characteristics at the two stages of seedling recruitment (i.e., for seed germination and for seedling survival) was demonstrated. The implications of these findings for restoration of seminatural grasslands are discussed.  相似文献   

12.
Brazil’s Atlantic Forest biome is severely degraded and fragmented throughout its range. Developing effective techniques to restore pasture and agriculture back to native vegetation is therefore a priority for legal and conservation purposes. In this study, we evaluate the ability of artificial bird perches to enhance the arrival of new seeds and seedling establishment in a degraded, semi-deciduous seasonal portion of the Atlantic Forest in southern Brazil. Specifically, we assess the influence of previous land use and habitat types on the abundance, species richness and ecological traits of bird-dispersed seeds, as well as on seedling establishment. Eight sampling sites were established, each containing one unit with seed traps and restoration plots under artificial perches and one similar unit without the perches. These sites were located in pasture and agriculture, distributed between riparian and sub-montane areas. Monthly sampling was conducted over two years between December 2005 and November 2007, resulting in the evaluation of 25,755 seeds and 56 endozoochoric seed species. The most abundant species were the pioneers Cecropia pachystachya Trécul and Solanum americanum Mill. Experimental units with perches received significantly more seeds than control units. Moreover, seed arrival was higher in sub-montane areas and on former pasture sites. Species richness followed a similar pattern of higher seed arrival, but there was no effect of vegetation type. Ecological characteristics of seeds were associated with land use type: former pastures received more tree seeds and pioneer species than expected by chance. Seedling establishment was very low in all treatments, with only eight seedlings established in perch plots by the end of the experiment. We conclude that despite artificial perches significantly increasing the arrival of endozoochoric seeds onto degraded lands, seedling establishment is drastically limited in these areas, compromising the efficacy of this technique for restoration purposes.  相似文献   

13.
Passive restoration methods offer great promise for tropical regions where resources are limited but the success of such efforts can be variable. Using trait-based theory, we investigated the likely trajectories of passive restoration efforts in a degraded Nigerian montane forest system recently protected from burning and cattle grazing. We quantified the density, species richness, and functional trait dispersion of dispersed seeds and seedling communities at increasing distances from the forest edge. We then determined which plant traits are responsible for colonisation by quantifying changes in functional-trait dispersion and relative frequencies of dispersal-linked traits with increasing distance from the forest. We found a rapid decrease in density and species richness, and significant species turnover in both seeds and seedlings just beyond the forest edge. This was mirrored by a significant decline in functional-trait dispersion and a shift in the relative frequencies of dispersal-linked traits. These findings suggest that the reassembly of plant communities adjacent to remnant forest is dependent on functional traits present in these remnant source populations, providing support for the incorporation of trait-based theory in restoration management.  相似文献   

14.
The density of seeds in soil seed banks and the species composition of both seed banks and aboveground vegetation were examined in naturally restored sites (NRS) and aerially seeded sites (ASS) in the Hunshandak sandlands of northern China. Five sites were naturally restored 1, 2, 4, 8, and 15 years ago and four sites were aerially seeded 1, 2, 5, and 7 years ago. In total, 36 species were recorded in the seed bank and 41 species in the aboveground vegetation for all NRS, whereas the numbers were 17 and 19, respectively, for ASS, indicating that the NRS can support higher diversity of species than the ASS. During the initial 2 years of restoration, introduced alien shrubs by aerial seeding dominated the vegetation of ASS, although there were indigenous pioneer species in the seed bank which failed to establish in the community. In contrast, indigenous species were dominant components in both the seed bank and the vegetation at the NRS. These findings suggest that the establishment of introduced species might have restricted the germination of certain indigenous pioneer species. Seed bank density of NRS significantly increased with time from 459 ± 76 seeds m−2 at NRS2 to 3,351 ± 694 seeds m−2 at NRS15, showing that the seed bank in degraded grassland is large enough to allow natural restoration. It is not always necessary to actively introduce seeds to enhance vegetation diversity.  相似文献   

15.
Abstract Araucaria Forest expansion over grassland takes place under wet climate conditions and low disturbance and it is hypothesized that isolated trees established on grassland facilitate the establishment of forest woody species beneath their canopies. Forest with Araucaria angustifolia is a particular type of Brazilian Atlantic Forest and the main forest type on the highland plateau in south Brazil, often forming mosaics with natural Campos grassland. The objectives of this paper were to evaluate the role of isolated shrubs and trees as colonization sites for seedlings of Araucaria Forest woody species on grassland, to determine which species function as preferential nurse plants in the process and the importance of vertebrate diaspore dispersal on the structure of seedling communities beneath nurse plants. The study was conducted in São Francisco de Paula, Rio Grande do Sul State, where we sampled isolated shrubs and trees in natural grassland near Araucaria Forest edges. Seedlings were counted and identified, and seedling diaspore dispersal syndromes, size and colour were registered. We detected 11 woody species with a potential role in nucleating grassland colonization by forest species. Beneath the canopies of nurse plants more forest species seedlings were found compared with open field grassland and the seedlings had diaspores mostly dispersed by vertebrates. Also, more seedlings were found under the canopy of A. angustifolia than beneath other nurse plant species. We conclude that A. angustifolia trees established on grassland act as nurse plants, by attracting disperser birds that promote colonization of the site by other forest species seedlings, and that under low level of grassland disturbance, conservation of frugivorous vertebrate assemblages may increase forest expansion over natural grassland and also facilitate the regeneration of degraded forest areas.  相似文献   

16.
Coastal sand dunes support various ecosystem services, including storm protection and tourism. Restoration programs are often critical to preserve this ecosystem due to its fragility and high degree of degradation. Dune restoration still suffers from a general lack of knowledge of the ecological processes controlling tropical dune communities. We investigated if facilitation can increase restoration success by assisting plant survival in a Brazilian coastal dune degraded by buggies at the Environmental Protection Area of Jenipabu, RN, Brazil. We performed two field experiments on dune crest sites degraded by buggies. The first experiment tested how the presence of established vegetation and coconut mesh, mimicking soil‐stabilizing effect of vegetation, facilitates seedling survival and establishment of the early successional dominant dune plant Canavalia maritima (Fabaceae). The second experiment tested if coconut mesh and initial irrigation would allow the establishment of C. maritima outside the vegetation, using both seeds and transplants. We found that the presence of established vegetation positively affected seedling survival. Application of mesh positively affected microclimatic conditions and slightly increased survival, but only for seeds. Initial irrigation only had a small effect on transplanted seedlings survival. Nevertheless, there was extreme seedling mortality in the experiment in particular from sand burial. We conclude that restoration of these dune crests is very difficult. Facilitation by vegetation can reduce plant mortality by sand burial and desiccation, but successful restoration is likely to require a major effort involving a very high number of seedlings or seeds.  相似文献   

17.
Despite growing recognition of the conservation values of grassy biomes, our understanding of how to maintain and restore biodiverse tropical grasslands (including savannas and open‐canopy grassy woodlands) remains limited. To incorporate grasslands into large‐scale restoration efforts, we synthesised existing ecological knowledge of tropical grassland resilience and approaches to plant community restoration. Tropical grassland plant communities are resilient to, and often dependent on, the endogenous disturbances with which they evolved – frequent fires and native megafaunal herbivory. In stark contrast, tropical grasslands are extremely vulnerable to human‐caused exogenous disturbances, particularly those that alter soils and destroy belowground biomass (e.g. tillage agriculture, surface mining); tropical grassland restoration after severe soil disturbances is expensive and rarely achieves management targets. Where grasslands have been degraded by altered disturbance regimes (e.g. fire exclusion), exotic plant invasions, or afforestation, restoration efforts can recreate vegetation structure (i.e. historical tree density and herbaceous ground cover), but species‐diverse plant communities, including endemic species, are slow to recover. Complicating plant‐community restoration efforts, many tropical grassland species, particularly those that invest in underground storage organs, are difficult to propagate and re‐establish. To guide restoration decisions, we draw on the old‐growth grassland concept, the novel ecosystem concept, and theory regarding tree cover along resource gradients in savannas to propose a conceptual framework that classifies tropical grasslands into three broad ecosystem states. These states are: (1) old‐growth grasslands (i.e. ancient, biodiverse grassy ecosystems), where management should focus on the maintenance of disturbance regimes; (2) hybrid grasslands, where restoration should emphasise a return towards the old‐growth state; and (3) novel ecosystems, where the magnitude of environmental change (i.e. a shift to an alternative ecosystem state) or the socioecological context preclude a return to historical conditions.  相似文献   

18.
Principles of Natural Regeneration of Tropical Dry Forests for Restoration   总被引:13,自引:1,他引:12  
Tropical dry forests are the most threatened tropical terrestrial ecosystem. However, few studies have been conducted on the natural regeneration necessary to restore these forests. We reviewed the ecology of regeneration of tropical dry forests as a tool to restore disturbed lands. Dry forests are characterized by a relatively high number of tree species with small, dry, wind‐dispersed seeds. Over small scales, wind‐dispersed seeds are better able to colonize degraded areas than vertebrate‐dispersed plants. Small seeds and those with low water content are less susceptible to desiccation, which is a major barrier for establishment in open areas. Seeds are available in the soil in the early rainy season to maximize the time to grow. However, highly variable precipitation and frequent dry spells are important sources of mortality in seeds and seedlings. Collecting seeds at the end of the dry season and planting them when soil has sufficient moisture may increase seedling establishment and reduce the time they are exposed to seed predators. Germination and early establishment in the field are favored in shaded sites, which have milder environment and moister soil than open sites during low rainfall periods. Growth of established seedlings, however, is favored in open areas. Therefore, clipping plants around established seedlings may be a good management option to improve growth and survival. Although dry forests have species either resistant to fire or that benefit from it, frequent fires simplify community species composition. Resprouting ability is a noticeable mechanism of regeneration in dry forests and must be considered for restoration. The approach to dry‐forest restoration should be tailored to this ecosystem instead of merely following approaches developed for moister forests.  相似文献   

19.
Summary   Both reservation of small remnants and ecological restoration of degraded areas will be crucial if the Victorian Western (Basalt) Plains grassland community is to be conserved in the long term. This study examined the potential of direct seeding as a technique for grassland restoration by recording the initial establishment and subsequent recruitment success of 64 (predominantly perennial) grassland species direct sown onto a constructed site. Forty-three (67%) of the sown species emerged and established during the 2-year study and a further three species were recorded in subsequent years. In the second year, 32 species increased their number either through seedling or vegetative recruitment and 30 species dispersed beyond their original sown plot. Seed size was not correlated with field emergence but life form did influence initial field success for some groups. The finding that many species are able to establish and recruit under the study conditions supports the need for further investigation of direct seeding in the restoration of grassland communities.  相似文献   

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