Successful restoration of abandoned terraced vineyards and grasslands in Southern Switzerland

Extensively managed semi-natural grasslands represent species-rich habitats and therefore play a key role for the maintenance of biodiversity in agricultural areas. In marginal and poorly accessible areas, the traditional management of grassland is frequently abandoned, which leads to the spread of forest. In Southern Switzerland, terraced vineyards (a special grassland type) and terraced grasslands are part of the cultural heritage and local biodiversity hotspots. Yet, many of them are overgrown by forest. In the past years, several abandoned terraced vineyards and grasslands have been restored by removing the forest, rebuilding the walls and re-introducing the traditional management. We examined restoration success by assessing plant species richness, diversity and species composition in both the aboveground vegetation and soil seed bank in (1) restored, (2) abandoned for 25–50 years, and (3) permanently used areas of six terraced vineyards and six terraced grasslands. Plant species richness and diversity were reduced and species composition altered in the aboveground vegetation of abandoned vineyards and grasslands compared to the permanently used and restored ones. However, species richness, Shannon-diversity and species composition of the aboveground vegetation did not differ between restored and permanently used areas, indicating a successful restoration of the vegetation 10–15 years after restoration. In abandoned vineyards, species richness of plants emerging from the soil seed bank was slightly higher than in permanently used and restored vineyards. No difference in seedling species richness was found between abandoned, permanently used and restored terraced grasslands. Our results showed that the soil seed bank played a minor role for the re-establishment of the above-ground vegetation. We assume that the large species pool in the surroundings and the presence of dispersal vectors are essential for the successful passive restoration of abandoned grassland in this region.     

The soil seed bank and understorey regeneration in Eucalyptus regnans forest,Victoria

Abstract The soil seed bank and its relation to the extant vegetation in a Eucalyptus regnans F. Muell. forest in the Central Highlands of Victoria were examined. The average seed density was 430 germinable seeds m^?2 to a depth of 2 cm. There was a polynomial regression relationship between the density and species richness of seeds in soil and forest age (0. 6–54 years). Species richness was not significantly different among soil depths (0- 2 , 2- 5 , 5–10 and 10–20 cm) in the forest stand of 54 years old. More seeds germinated from the 5–10 cm depth than from the other depths. Forbs accounted for 73% of the total germinable seeds and there was no germination of E. regnans. The number of species, particularly woody plant species, germinating from the soil seed bank were significantly lower than in the extant vegetation. However, almost all species present in the soil seed bank were present in the vegetation. The soil seed bank provides an important source for the rapid regeneration of understorey vegetation following clear-cutting and slash-burning in the E. regnans forest. The rapid understorey establishment may play an important role in protecting soil from erosion, in nutrient conservation, replacement and redistribution. The soil seed bank may also be a necessary source of maintaining genetic diversity in the forest over the long term.     

Seed bank dynamics and tree‐fall gaps in a northwestern Mexican Quercus‐Pinus forest

Questions: How does the seed bank respond to different types of tree‐fall gaps and seasonal variations? How does the soil seed bank influence recovery of the standing vegetation in the mature forest and tree‐fall gaps? Location: 1800 — 2020 m a.s.l., Quercus‐Pinus forest, Baja California Sur, Mexico. Methods: Seed size, species composition and germination were estimated under different environmental conditions during dry and rainy seasons: a mature forest plot and gaps created by dead standing trees, snapped‐of f trees and uprooted trees. The soil seed bank was investigated using direct propagule emergence under laboratory conditions, from soil cores obtained during both seasons. Results: 21 species, 20 genera and 14 families constitute the seed bank of this forest community. Fabaceae, Asteraceae, Euphorbiaceae and Lamiaceae were the most frequently represented families in the seed bank. Floristic composition and species richness varied according to the different modes of tree death. Species composition of seed banks and standing vegetation had very low similarity coefficients and were statistically different. Seed bank sizes varied between 164 and 362 ind.m^‐2 in the mature forest plot for the dry and rainy seasons, respectively, while soil seed bank sizes for gaps ranged between 23–208 ind.m^‐2 forthe dry season and between 81–282 ind.m^‐2 for the rainy season. Conclusions: Seed bank sizes and germination response were always higher in the rainy season under all the environmental conditions analysed. Results suggest that timing responses to gap formation of the soil seed bank could be more delayed in this temperate forest than expected.     

Vegetation and seed bank in a calcareous grassland restored from a Pinus forest

Question: What is the importance of the seed bank in the maintenance of the restoration potential of a 60‐year‐old abandoned calcareous grassland overgrown by Pinus trees? Location: ‘Les Pairées’, province of Luxembourg, Belgium. Methods: The seed bank and the above‐ground vegetation were surveyed in three adjacent stands, previously forming a unique calcareous grassland: a 60‐year‐old Pinus forest, a four‐year‐old clear‐cutting and a typical calcareous grassland. Floristic diversity was compared among stands and between vegetation and seed bank. Results: The species richness of the vegetation and the seed bank was significantly lower in the Pinus forest. More floristic similarities were found between the clear‐cutting and the calcareous grassland. Seed bank was essentially transient, dominated by annual species. Its correspondence with the above‐ground vegetation was weak. Conclusion: Very few calcareous grassland species have persisted in the Pinus stand. Four years after clear‐cutting, the stand was nearing restoration towards a calcareous grassland. Seed longevity in the soil was not the most explicative factor. Dispersal of propagules from adjacent sources was also important.     

Effects of patch size and basal area on avian taxonomic and functional diversity in pine forests: Implication for the influence of habitat quality on the species–area relationship

Relationships between avian diversity and habitat area are assumed to be positive; however, often little attention has given to how these relationships can be influenced by the habitat structure or quality. In addition, other components of biodiversity, such as functional diversity, are often overlooked in assessing habitat patch value. In the Sandhills Ecoregion of Georgia, USA, we investigated the relationship between avian species richness and functional diversity, forest basal area, and patch size in pine forests using basal area as a surrogate for overstory structure which in turn impacts vegetation structure and determines habitat quality within a patch. We conducted bird surveys in planted mature pine stands, during breeding season of 2011. We used three classes of stand basal area (BA): OS, overstocked (BA ≥ 23 m²/ha); FS, fully/densely stocked (13.8 m²/ha ≤ BA < 23 m²/ha); and MS, moderately stocked (2.3 m²/ha ≤ BA < 13.8 m²/ha). MS patches showed more structural diversity due to higher herbaceous vegetation cover than other two pine stocking classes of patches. Total species richness and functional richness increased with the size of MS patches, whereas functional divergence decreased with the size of OS patches (p < 0.05). Functional richness tended to be lower than expected as the size of OS patches increased. Greater richness of pine–grassland species was also found at MS patches. Percent cover of MS patches within a landscape influenced positively the richness of pine–grassland species (p < 0.05). Our results suggest that (a) avian species–habitat area relationship can be affected by habitat quality (structural diversity) and varies depending on diversity indices considered, and (b) it is important to maintain moderate or low levels of pine basal area and to preserve large‐sized patches of the level of basal area to enhance both taxonomic and functional diversity in managed pine forests.     

The role of the soil seed bank in vegetation recovery on an oceanic island severely damaged by introduced goats

Question: Are the seed banks of an isolated subtropical oceanic island capable of naturally regenerating vegetation either with species of the historical forest community or with the existing grassland community after severe damage to the vegetation by goats? Location: Nakoudojima Island, Bonin Archipelago (Ogasawara Shoto), Japan. Methods: Soil samples were collected at 0–5 cm and 5–10 cm depths from seven plots in forests, grasslands, artificially matted areas and bare land. Soil seed banks were assessed using the seedling emergence method followed by the hand‐sorting of ungerminated seeds. We determined the size and composition of the seed banks in upper soil layers of plots and compared the seed banks to the standing vegetation. Results: A total of 12 220 seedlings belonging to 42 species from 20 families germinated. Total mean seed density (0–5 cm depth) was low in all plots within forest, grassland, and heavily degraded vegetation types (34.7 ± 8.6 to 693.5 ± 123.6, 58.6 ± 7.8 to 107.1 ± 10.0, and 1.1 ± 0.5 to 7.2 ± 2.3 seeds/m², respectively). Forbs and graminoids dominated the seed banks of grassland and forest plots including Cyperus brevifolius, Gnaphalium pensylvanicum, Oxalis corniculata and Solanum nigrum, and these alien species comprised 90% of the density of the seed bank. There was little correlation between seed banks and standing vegetation of the island (Sørensen similarity coefficient values 0.26 to 0.45). Conclusions: If natural regeneration occurs from the seed bank of the island, future vegetation will not move toward the original forest community, because the seed bank is dominated by non‐native herbaceous grassland species. Though isolated, a few forest remnants with low species richness could be an important source for the natural re‐establishment of forest on the island; however, seed availability may be limited by either poor dispersal or pollination so that woody species will probably recover very slowly on this goat‐impacted island.     

桂北喀斯特石漠化地区不同植物群落土壤种子库特征及其与土壤养分关系

土壤种子库作为地上植被遗传信息库，对植被自然演替更新以及生态修复建设具有重要作用。为探明桂北喀斯特石漠化地区植被自然恢复潜力和恢复策略，该文选取恭城瑶族自治县喀斯特石漠化地区3种典型植物群落为研究对象，分析不同群落的土壤种子库结构、多样性及其对土壤养分特征的响应，以期为该地区石漠化治理和植被恢复提供理论依据。结果表明：(1)共计监测到幼苗3 648株，隶属于33科51属55种，其中1年生和2年生草本幼苗共20种，多年生草本幼苗21种，藤本幼苗5种、灌木幼苗3种、乔木幼苗6种；不同植物群落土壤种子库平均密度为三华李经济林(22 493 grain·m^-2)>青冈次生林(1 033 grain·m^-2)>金竹灌丛(793 grain·m^-2)。(2)土壤种子库植物生活型方面，三华李经济林主要分布1年生恶性杂草，青冈次生林和金竹灌丛则以多年生草本为主，木本植物占比较少；不同植被类型中土壤种子库物种多样性和相似性总体较低，同时与地上群落物种组成的相似性也较低。(3)研究区域的土壤元素存在高氮低磷的现象，其中磷元素为金...     

Soil seed bank,seedling recruitment and actual species composition in an old and isolated chalk grassland site

A soil seed bank study was conducted in an old and isolated chalk grassland site (area ca. 0.05 ha) with a high species richness in The Netherlands, over a two-year period. Each soil seed bank sample was divided into two halves: one part was sown immediately in trays with a layer of sterilized sand and put in a greenhouse, whilst the other half received a chilling period before being sown. Plant recruitment in the field was studied during the same period in permanently marked plots. Seeds of species which had become extinct during the period 1944–1970 were not found in the soil seed bank in the late eighties. One group of species still present in the actual vegetation neither showed any signs of recruitment from seed nor had a soil seed bank. Species in this group that do not recruit vegetatively can be considered as directly threatened by extinction. A group in the actual vegetation did not shown any recruitment, but nevertheless had germinable seed present in the soil. Among this group, there are some annuals; however, the majority of the species are characterized by the potential to recruit vegetatively. The majority of the species present in the actual vegetation (45%) demonstrate seedling recruitment and are also present as seeds in the soil, although there is some quantitative discrepancy between these categories. The seed bank did not reflect former stages of the actual vegetation. Based on the results, predictions can be made on the future development of the vegetation and on the fate of a number of species. Adjustment of the management regime is aimed at maintenance of the species richness of the site. This is important for nature preservation purposes since a high number (ca. 27%) of the species in the chalk grassland of this small site are on the Dutch Red List.     

Persistent soil seed banks in old-growth Hyrcanian Box tree (Buxus hyrcana) stands in northern Iran

Little is known about the soil seed bank and the influence of plant communities on the interaction between the seed bank and aboveground vegetation in the Hyrcanian temperate deciduous forest. We surveyed species composition and diversity of the persistent soil seed bank and the aboveground vegetation in six community types in old-growth Hyrcanian Box tree (Buxus hyrcana) stands in northern Iran. Fifty-two species with an average of 3,808 seeds/spores m⁻² germinated; forbs accounted for 64% of the seed bank flora. Thirty-four species in the aboveground vegetation were not presented in the seed bank, 32 species in the seed bank were not found in the vegetation, and 20 species were in both. The dominant tree species were Diospyros lotus and Alnus subcordata with an average of 17 and 4.6 seeds m⁻², respectively. Our results suggest that (1) vernal geophytes and shade-tolerant perennials are not incorporated in the seed bank, (2) early successional species are well represented in the seed bank, (3) plant community type has significant impacts on seed bank densities, and seed bank richness and diversity were significantly related to presence/absence of Box tree in the aboveground vegetation. The persistent seed bank contained species that potentially have a negative impact on the regeneration of forests, thus forest managers should retain old-growth Hyrcanian Box tree stands to conserve disturbance-sensitive indicator forest species.     

洮河上游紫果云杉群落土壤种子库特征及其与地上植被的关系

该研究以甘肃洮河国家级自然保护区大峪沟林区(TH)、冶力关林区(YLG)、尕海 则岔国家级自然保护区则岔林区(GZ)的紫果云杉(Picea purpurea)天然林群落为研究对象,通过样地调查与萌发实验,分析洮河上游紫果云杉群落土壤种子库特征,以揭示洮河上游紫果云杉群落土壤种子库特征及与地上植被的关系,为紫果云杉群落恢复和管理提供依据。结果表明：(1)3个林区土壤种子库共萌发27科45属50种植物,种子库密度在958~1 129粒/m²之间,草本植物是构成研究区土壤种子库的主体。(2)3个林区紫果云杉群落土壤种子库垂直结构明显,物种数及种子密度随土层的加深呈减少趋势。(3)3个林区地上植被物种数大于土壤种子库物种数,相似性系数在0.15~0.23之间,表现为极不相似性;土壤种子库的多样性指数除Pielou指数高于地上植被外,Margalef指数、Shannon Wiener指数、Simpson指数均低于地上植被。研究认为,洮河上游紫果云杉群落土壤种子库以草本植物为主,乔木和灌木的储量较小,特别是建群种紫果云杉的储量较小;地上植被和土壤种子库之间相互的贡献力较低,仅依靠紫果云杉林土壤种子库进行自然恢复,远不能缓解现阶段紫果云杉林退化的问题,因此需开展人工育苗、造林等措施来促进紫果云杉的更新与发展。     

The role of soil seed banks in the restoration of dry acidic dune grassland after burning of Ulex europaeus scrub

Question: Can the seed bank play a significant role in the restoration of plant communities of dry acidic dune grassland where fire has destroyed Ulex europaeus scrub? Location: Northern French Atlantic coast. Methods: One year after the fire, the seed bank and vegetation were sampled in 1 m × 1 m plots along three transects from the oldest scrub vegetation towards the grassland. Differences in species richness, seed density and contribution of ecological groups in the seed bank and vegetation along the transects were analysed. Results: Seed density and species richness in the seed bank decreased significantly from the grassland towards the centre of the scrub vegetation; 50% of the seed bank consisted of core species of the target plant community, such as Carex arenaria, Aira praecox, Rumex acetosella and Agrostis capillaris. Seeds of these species were also found in the deeper soil layers beneath the oldest scrub vegetation, indicating that they can be considered to be long‐term persistent. Beneath the youngest scrub vegetation, seeds of rare satellite target species also occurred. However, no target species were established on the burned site after one year, resulting in a large discrepancy between seed bank and vegetation. Conclusions: Although the seeds present in the soil indicate that restoration of the acidic grassland based on the seed bank is possible, additional management actions such as mowing and soil disturbance may be necessary to restrict resprouting of Ulex and to stimulate the germination of seeds of target species in the deeper soil layers.     

Long‐term seed bank dynamics in a temperate forest under conversion from coppice‐with‐standards to high forest management

Questions: How do changes in forest management, i.e. in disturbance type and frequency, influence species diversity, abundance and composition of the seed bank? How does the relationship between seed bank and vegetation change? What are the implications for seed bank dynamics? Location: An ancient Quercus petraea — Carpinus betulus forest in conversion from coppice‐with‐standards to regular Quercus high forest near Montargis, France. Methods: Seed bank and vegetation were sampled in six replicated stand types, forming a chronosequence along the conversion pathway. The stand types represented mid‐successional stages of stands in transition from coppice‐with‐standards (to high forest (16 plots) and early‐ and mid‐successional high forest stands (32 plots). Results: Seed bank density and species richness decreased with time since last disturbance. Adjusting for seed density effects obscured species richness differences between stand types, but species of later seres were nested subsets of earlier seres, implying concomitant shifts in species richness and composition with time since disturbance. Later seres were characterized by species with low seed weight and high seed longevity. Seed banks of early seres were more similar to vegetation than to later seres. Conclusions: Abandonment of the coppice‐with‐standards regime altered the seed bank characteristics, as well as its relationship with vegetation. Longer management cycles under high forest yield impoverished seed banks. For their persistence, seed bank species will increasingly rely on management of permanently open areas in the forest landscape. Thus, revegetation at the beginning of new high‐forest cycles may increasingly depend on inflow from seed sources.     

Seed bank composition and above-ground vegetation in response to grazing in sub-Mediterranean oak forests (NW Greece)

We investigate the persistent soil seed bank composition and its relation to the above-ground flora of grazed and non-grazed sub-Mediterranean deciduous oak forests of NW Greece. Twenty-eight taxa were recorded in the soil seed bank and 83 taxa (70 taxa in plots of seed bank sampling) in the above-ground vegetation. The dominant tree species and many woodland species found in the above-ground vegetation were absent from the soil seed bank. Similarity between the soil seed bank and the above-ground vegetation decreased with grazing, and grazing led to a decrease of species richness in above-ground vegetation and soil seed bank. Beta diversity of vegetation among grazed and among non-grazed plots did not differ, but was significantly higher between grazed and non-grazed areas. Beta diversity of the soil seed bank declined with grazing. When applying classification tree and logistic regression analyses, non-grazed forest sites are clearly differentiated by the presence of Phillyrea latifolia, Euphorbia amygdaloides and Brachypodium sylvaticum. PCA ordination of above-ground species composition reflected a gradient from sites grazed by ruminants to non-grazed sites, but no clear structure was detected in the seed bank.     

Geringe Samenbank von beweidbaren Arten für die Etablierung von Waldweiden im Schweizer Mittelland

Kipfer T. and Bosshard A. 2007. Low seed bank of herb species suitable for grazing hampers the establishment of wood pastures in the Swiss lowlands. Bot. Helv. 117: 159 – 167. Controlled forest grazing is expected to yield benefits for biodiversity conservation, landscape quality, and in some cases also for land use economy. In the Swiss lowlands, first attempts are being made to reintroduce forest grazing in productive beech forests, but methodic experience is still limited. One main issue concerns the development of the vegetation after forest stands have been thinned to improve light conditions: Will grassland vegetation establish spontaneously? The present study analyses the composition of the soil seed bank of four beech forest stands. The seed bank density ranged from 1’244 to 28’651 seeds m⁻². Seed banks mainly consisted of forest and ruderal species; most abundant were Juncus effusus, Carex sylvatica, Rubus spp. and Clematis vitalba. Seeds of grassland plants were restricted to a few species, and their abundance in the seed bank decreased rapidly with increasing distance from the forest edge. These results reveal that there is little potential for grasslands to develop spontaneously from the seed bank. The introduction of grassland species of local origin using the green hay method is therefore recommended to prevent soil degradation during the first years of grazing, to fulfil minimal biodiversity requirements and to lower the risk of an establishment of neophytes and other problematic plant species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Manuskript angenommen am 2. September 2007     

兰坪铅锌矿区植被恢复初期土壤种子库与地上植被关系的研究

尾矿废弃地是一种极端的生态系统,其植被恢复的研究将丰富传统的生态学理论。该研究通过野外植被调查与室内萌发实验相结合的方法,探讨了兰坪铅锌矿区植被恢复初期不同群落类型地上植被、土壤种子库及其相互关系。结果显示:（1）与对照群落（云南松林、高山栎灌丛）相比,尾矿区恢复期各群落（早熟禾人工草地、魁蒿群落、马桑灌丛）地上植被及土壤种子库的物种数、物种多样性均较低。（2）植被恢复时间较短的2个群落（魁蒿群落、人工草地）土壤种子库较地上植被物种多样性高。（3）尾矿区恢复期各群落地上植被及土壤种子库的优势种均主要由风播、种子繁殖的植物组成,菊科、禾本科占较大比例,这些植物在尾矿区植被恢复初期起重要作用。（4）尾矿区恢复期各群落土壤种子库与地上植被的物种相似性较高,各群落之间地上植被及土壤种子库的相似性则较低。研究表明,尾矿区恢复初期土壤种子库与地上植被紧密联系,群落改造方式、恢复时间对土壤种子库具有重要影响。     

The seed bank in an estonian calcareous grassland: Comparison of different successional stages

Seed bank species-composition and seed-density were determined in a successional calcareous (alvar) grassland in western Estonia. Three similar study areas were chosen to compare two different successional stages: open alvar grassland and overgrown areas with young pine forest 30 to 40 years old. In both successional stages, the centre and the edge of a relatively uniform stand were examined. Fifteen soil samples (7 cm in diameter, 5 cm deep) were taken from each of twelve sampling sites. The seedling emergence method was used to estimate seeds in the soil samples. A total of 69 species were detected in the seed bank, of which 18 did not occur in the vegetation. Eighty-nine taxa were recorded in the vegetation and of these 38 were not detected in the seed bank. Fifty-one species occurred both in the seed bank and in the vegetation. The three most abundant taxa in the seed bank wereCarex tomentosa, Linum catharticum andPlantago media, which together made up 49% of the seedlings recorded. Differences in the species compositions of seed bank samples from grassland and forest sites were negligible, although the species richness per area of the above-ground vegetation was significantly higher in the open grassland. The only species tending to be lost from forest site vegetation but still occurring in the forest soil seed bank wereArenaria serpylifolia, Cerastium fontanum andLinum catharticum. About half of all the emerged species from all samples belonged to the transient or short-term persistent seed bank. In the grassland sites there were more species which belonged to the transient seed bank than in the forest sites, where the seed bank contained more short-term persistent type seeds. The seed density was significantly higher in forest sites and lower in grassland sites, which may be explained by the better germination conditions in well-illuminated communities. On the basis of the current study it might be assumed that the soil seed banks of overgrown alvar grasslands which include young pine forests can play a certain role in grassland restoration management.     

Fire and regeneration: the role of seed banks in the dynamics of northern heathlands

Questions: How do species composition and abundance of soil seed bank and standing vegetation vary over the course of a post‐fire succession in northern heathlands? What is the role of seed banks – do they act as a refuge for early successional species or can they simply be seen as a spillover from the extant local vegetation? Location: Coastal Calluna heathlands, Western Norway. Methods: We analysed vegetation and seed bank along a 24‐year post‐fire chronosequence. Patterns in community composition, similarity and abundances were tested using multivariate analyses, Sørensen's index of similarity, vegetation cover (%) and seedling counts. Results: The total diversity of vegetation and seed bank were 60 and 54 vascular plant taxa, respectively, with 39 shared species, resulting in 68% similarity overall. Over 24 years, the heathland community progressed from open newly burned ground via species rich graminoid‐ and herb‐dominated vegetation to mature Calluna heath. Post‐fire succession was not reflected in the seed bank. The 10 most abundant species constituted 98% of the germinated seeds. The most abundant were Calluna vulgaris (49%; 12 018 seeds m^?2) and Erica tetralix (34%; 8 414 seeds m^?2). Calluna showed significantly higher germination the first 2 years following fire. Conclusions: Vegetation species richness, ranging from 23 to 46 species yr^?1, showed a unimodal pattern over the post‐fire succession. In contrast, the seed bank species richness, ranging from 21 to 31 species yr^?1, showed no trend. This suggests that the seed bank act as a refuge; providing a constant source of recruits for species that colonise newly burned areas. The traditional management regime has not depleted or destroyed the seed banks and continued management is needed to ensure sustainability of northern heathlands.     

Effects of 10-Year Management Regimes on the Soil Seed Bank in Saline-Alkaline Grassland

Background

Management regimes for vegetation restoration of degraded grasslands can significantly affect the process of ecological succession. However, few studies have focused on variation in the soil seed bank during vegetation restoration under different management regimes, especially in saline-alkaline grassland habitats. Our aim was to provide insights into the ecological effects of grassland management regimes on soil seed bank composition and vegetation establishment in mown, fenced, transplanted and natural grassland sites, all dominated by the perennial rhizomatous grass Leymus chinensis.

Methodology

We studied species composition and diversity in both the soil seed bank and aboveground vegetation in differently managed grasslands in Northeast China. An NMDS (nonmetric multidimensional scaling) was used to evaluate the relationship between species composition, soil seed banks, aboveground vegetation and soil properties.

Principal Findings

Fenced and mown grassland sites had high density and species richness in both the soil seed bank and aboveground vegetation. The Transplanted treatment exhibited the highest vegetation growth and seed production of the target species L. chinensis. Seeds of L. chinensis in the soil occurred only in transplanted and natural grassland. Based on the NMDS analysis, the number of species in both the soil seed bank and aboveground vegetation were significantly related to soil Na⁺, Cl^-, RSC (residual sodium carbonate), alkalinity, ESP (exchangeable sodium percentage) and AP (available phosphorus).

Conclusions

Soil seed bank composition and diversity in the saline-alkaline grassland were significantly affected by the management regimes implemented, and were also significantly related to the aboveground vegetation and several soil properties. Based on vegetative growth, reproductive output and maintenance of soil seed bank, the transplanting was identified as the most effective method for relatively rapid restoration of the target species L. chinensis. This approach could be beneficial for the restoration of dominant species in a wide range of degraded grassland ecosystems.     

荒漠草原-灌丛镶嵌体的植被稳态转变特征

以柠条锦鸡儿（Caragana korshinskii）灌丛引入形成荒漠草原-灌丛地镶嵌体为研究对象,选择其内部荒漠草地（DG）、草地边缘（GE）、灌丛边缘（SE）、灌丛地（SL）为试验样地,开展荒漠草原向灌丛地人为稳态转变过程土壤水分与植被变化特征研究。结果如下：各样地0-200 cm土层水分含量随着转变过程呈显著降低趋势（P<0.05）,其中荒漠草地、草地边缘和灌丛边缘样地的土壤水分均在秋季雨水补充期增加,灌丛地由于深层土壤水分过度消耗而愈加降低,且灌丛边缘和灌丛地深层水分显著低于荒漠草地、草地边缘（P<0.05）,垂直动态不显著;地上植被随样地转变除优势度指数表现为灌丛地多样性、均匀度、丰富度指数均显著低于各样地（P<0.05）,多年生优势草本蒙古冰草（Agropyron mongolicum）、短花针茅（Stipa breviflora）逐渐被一年生草本刺藜（Dysphania aristata）、猪毛蒿（Artemisia scoparia）所代替;土壤种子库萌发种类随样地转变逐渐减少,种子库密度则显著升高（P<0.05）,灌丛地以一年生草本植物为主（占总密度的97.51%）,荒漠草地则以多年生草本萌发为主,且各样地土壤萌发种子库及多年生草本多集中于0-5 cm土层（P<0.05）;转变过程荒漠草原和灌丛地植被地上地下相似度分别为0.14和0.19,均显著低于两边缘样地0.35,较两边缘样地群落更为稳定,呈现草原灌丛化过程中草地-灌丛共存的植被双稳态特征。     

Soil seed bank composition along a forest chronosequence in seasonally moist tropical forest,Panama

Abstract. We used a forest chronosequence at the Barro Colorado Nature Monument (BCNM) to examine changes in the abundance and species composition of seeds in the soil during forest succession. At each of eight sites varying from 20 yr to 100 yr since abandonment, and at two old-growth (> 500 yr) forest stands, we established two 160-m transects and sampled the surface 0–3 cm of soil in cores collected at each 5 m interval. Seed densities were estimated from the number of seedlings germinated from the soil over a six-week period. Contrary to expectation, neither the density of the soil seed bank, nor species richness or diversity were directly related to age since abandonment, but the density of the soil seed bank was correlated with the abundance of seed-bank-forming species in the standing vegetation. In marked contrast to published studies, herbaceous taxa were rare even in the youngest stands, and the common tree species, which accounted for most seeds in the soil, were present in all stands. The pioneer tree Miconia argentea (Melastomataceae) was the single most common species in the seed bank, accounting for 62% of seeds and present in 92% of soil samples. Rapid recovery of the vegetation of young regrowth stands on BCNM, when compared to sites elsewhere may be partly due to allochthonous seed rain from nearby mature forest stands and the lack of seed inputs of weeds and grasses from agricultural and pasture lands which may inhibit forest succession.