Comparison of aboveground vegetation and soil seed bank composition at sites of different grazing intensity around a savanna-woodland watering point in West Africa

Grazing removes a plant’s aboveground vegetative and reproductive tissues and can modify the soil seed bank, potentially impacting the restoration of preferred species. Knowledge about aboveground vegetation and species composition of soil seed bank and the processes that contribute to vegetation recovery on and surrounding watering points subjected to grazing is lacking. Successful restoration strategies hinge on addressing these knowledge gaps. We assessed the effects of livestock grazing on aboveground vegetation and soil seed bank characteristics along a river bank and surrounding areas subject to different grazing intensities and draw implications for restoration. Plots (50?×?50 m) were established along five transects representing differing levels of grazing intensity. Soil samples were taken from three layers within each plot to determine soil properties and species composition of soil seed bank using the seedling emergence method. Heavy grazing resulted in the disappearance of perennial grasses, a reduction in species diversity and a decrease in soil nutrients with increased soil depth. Overall, the similarity between the extant aboveground vegetation and flora within the soil seed bank was low. The soil seed bank was dominated by herbaceous species and two woody species, suggesting that many woody species are not accumulating in the soil. With increasing soil depth, the seed density and richness declined. Canonical correspondence analyses (CCAs) showed that emerged seedlings from the soil seed bank were significantly influenced by soil carbon, organic matter, total nitrogen, total potassium and soil cation exchange capacity. This finding suggests that current grazing practices have a negative impact on the vegetation surrounding watering points; hence there is a need for improved grazing management strategies and vegetation restoration in these areas. The soil seed bank alone cannot restore degraded river banks; active transfer of propagules from adjacent undisturbed forest areas is essential.     

黄土区露天煤矿排土场不同微地貌土壤种子库特征

黄土区露天煤矿排土场边坡水力冲刷强烈,不同植被恢复模式与水力作用耦合形成的不同微地貌可通过对种子的不同拦截作用而影响植被的恢复及发展。为了探讨排土场不同微地貌对种子的拦截效益及不同植被恢复模式的恢复潜力,选取不同恢复模式下形成的细沟、丛岛和草带三种微地貌为研究对象,以邻近裸坡为对照,研究不同微地貌土壤种子库特征及其拦截力。结果表明：（1）在不同微地貌中土壤种子库均以一年生藜科和禾本科植物为主;丛岛微生境的土壤种子库中有较丰富的物种和较高的多样性指数。（2）各微地貌的土壤种子库均具有表层聚集现象;草带微地貌中的土壤种子库总储量最大,且草带的0-2 cm土层处的土壤种子库密度显著高于各微地貌的各个土层（P<0.05）。（3）细沟和丛岛在上坡位对种子的拦截效果更好,草带在下坡位对种子的拦截效果更好。综上所述,沙蒿恢复模式形成的丛岛有利于增加土壤种子库的物种多样性,草带有利于增加土壤种子库的储量,故在黄土区排土场进行植被恢复时可以利用不同微地貌对土壤种子库分布特征的优势构建适宜的复合植被恢复模式。     

Seed dispersal in a polder after partial tidal restoration: Implications for salt‐marsh restoration

Question: The vegetation in a polder after partial tidal restoration does not resemble the targeted salt‐marsh vegetation. Is this difference in vegetation due to lack of dispersal or unsuitable abiotic conditions? What could be done for a better restoration of the site? Location: Northwestern France. Methods: Seeds were trapped at the single inlet of the polder with a 200‐μ m mesh net to estimate inputs of seeds from the bay. In parallel, seed dispersal was studied in the polder by placing Astroturf® seed traps on the surface of the sediment at three different elevations in three distinct areas. Abiotic conditions such as flooding frequency, water table level and soil salinity were monitored. Results: All but one species from the adjacent salt marshes were trapped at the inlet. Not all of these species were on the seed traps inside the polder. Seed dispersal was not homogeneous in the polder and seed trap content mostly discriminated in function of their elevation. Salinity and water logging at the bottom of the slope were very high compared to tolerance of most halophytes but decreased rapidly higher up the slope. Conclusions: The development of salt marsh target species is highly restricted by limited hydrochory inside the polder but also by unfavourable soil conditions induced by the actual hydrological regime. Halophytes are excluded at the bottom of the slope by abiotic conditions and out‐competed by sub‐halophytes higher up. In order to restore salt marsh vegetation inside the polder, a larger opening should be induced in order to increase the flooded surface, and diminish water logging and flooding frequencies.     

Factors Controlling Vegetation Establishment and Water Erosion on Motorway Slopes in Valencia, Spain

In semiarid Mediterranean areas, the widespread environmental impact caused by the construction of motorways, railways, and pipelines has created an increasing need for effective restoration. We examined the influence of slope characteristics on vegetation and water erosion on 71 motorway slopes in a semiarid Mediterranean region. Specifically, we studied the effect of slope angle, type (roadfill vs. roadcut) and aspect (north vs. south) on soil properties, vegetation cover, species richness, floristic composition, and water‐caused erosion. Temporal dynamics of soil water content was monitored and related to the soil water potential in order to explain possible differences in vegetation cover between slope types. The main factors influencing vegetation on motorway slopes were the angle, type, and aspect of the slope. Vegetation was almost completely lacking on roadcuts with slopes greater than 45°. On gentler slopes, vegetation cover was 44–78% on roadfills but did not reach 10% on roadcuts, regardless of aspect. The main soil properties affected by the slope type and aspect were the organic matter content, soil available P, and water content. Rill erosion, gully erosion, and mass movement were all significantly higher on roadcuts than roadfills. A total of 308 spontaneous colonizers and seeded species were recorded. The type and aspect of the slope also controlled species composition. The short duration of available water in the soil with respect to soil water potential proved to be a limiting factor to plant colonization on roadcuts and south‐facing slopes as well as the low soil fertility in the case of roadcuts. Our results underscore the difficulty of revegetating slopes with angles greater than 45°, where the probability of seeds moving downhill is high. Future efforts should focus on increasing the surface roughness or building terraces at regular intervals in order to reduce slope angle to less than 45° and favor seed trapping and germination. On gentler slopes, adjusting of seed mixes according to dominant species associated with each slope type and aspect should improve considerably the success of roadside revegetation.     

Performance of Vegetation in Reclaimed Slopes Affected by Soil Erosion

Soil erosion in reclaimed mines may affect plant colonization and performance, and may compromise restoration success; however, the magnitude of this effect has seldom been quantified. We monitored the dynamics of vegetation (seed bank density, seedling emergence, plant mortality, and seed production) during a growing season (2003–2004) in three constructed slopes with differing past erosion rates. The slopes are located in the Utrillas coalfield in Spain, which experiences a Mediterranean‐continental climate. In the most eroded slope, soil water availability was lower—especially in the interrill areas—and seedling emergence rate, plant survival, and seed production were also significantly lower than on the less eroded slopes. We found that vegetation recovery is dramatically constrained when rill erosion rate is 17 t ha^?1 yr^?1 and plant cover is 30%, but this effect disappears when plant cover is higher than 60%. Soil erosion in constructed slopes appears to inhibit natural plant colonization processes by increasing runoff water loss over the long‐term. Thus, when rill erosion networks develop, human intervention would be needed to minimize the loss of water and facilitate vegetation colonization.     

Restoration success of low‐production plant communities on former agricultural soils after top‐soil removal

Abstract. The success inrestoring seven low‐production vegetation types on former agricultural soil after top‐soil removal was investigated. The colonization and establishment of target species in permanent plots was recorded during the first nine years after restoration measures were taken. For each permanent plot abiotic site conditions were used to determine which of the vegetation types could persist there. A comparison of the actual vegetation in the permanent plots with reference releves of the selected vegetation type revealed a gradually increasing similarity during consecutive years for five vegetation types. This was due to the occurrence of an increasing number of target species and the number of permanent plots they occurred in. However, nine years after top‐soil removal a large number of the target species were still lacking from the vegetation in the permanent plots, although most were present in the local species pool. Seed dispersal therefore seems to be a major limiting factor for restoration of these low‐production vegetation types on formerly agricultural soils.     

丛枝菌根真菌侵染率对喀斯特坡地坡位与灌木物种的响应

明确丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)侵染率对喀斯特坡地坡位与物种的响应及其关键影响因子，是合理利用土壤AMF促进喀斯特植被恢复的前提。该研究在充分调查喀斯特峰丛洼地典型灌丛坡地环境背景信息的基础上，采用曲利苯蓝染色-镜检法检测并计算典型灌木黄荆(Vitex negundo)、红背山麻杆(Alchornea trewioides)和火棘(Pyracantha fortuneana)根系AMF侵染频度、侵染强度和丛枝丰度等侵染率参数。结果表明：(1)相同坡位火棘的侵染频度、侵染强度和丛枝丰度均显著低于红背山麻杆和黄荆；下坡位黄荆和火棘的侵染强度均高于中、上坡位，而中坡位红背山麻杆的丛枝丰度显著高于上、下坡位(P<0.05)。(2)物种显著影响AMF侵染频度、侵染强度和丛枝丰度，坡位显著影响AMF侵染强度，物种与坡位的交互作用仅对AMF丛枝丰度有显著影响(P<0.05)。(3)影响AMF侵染率的关键土壤因子是土壤深度和全钾含量(P<0.05)。因此，合理利用土壤AMF促进喀斯特地区植被恢复需要考虑地形与物种的选择，并应注重兼...     

Is the population turnover of patchy‐distributed annuals determined by dormancy dynamics or dispersal processes?

In species with fragmented distribution, regional turnover dynamics is given by the processes of local population extinction and patch (re)colonization by migrants spreading from neighboring occupied patches. In plants with dormant stages (e.g. seeds) and limited dispersal capacity, regional dynamics based on dispersal processes can be overridden by pseudo-turnover determined by signals inducing or breaking dormancy (e.g. due to changes in habitat quality) resulting in a low importance of habitat configuration and size.
In this study, I investigated the turnover dynamics of 5 annual plant species growing on ant mounds of Lasius flavus over three years. I analyzed whether the grassland-scale dynamics of these annuals is influenced by dispersal processes, or alternatively, by pseudo-turnover of soil seed populations. For that purpose I 1) searched for populations formed from soil seeds only, 2) compared the relative contribution of the soil seed bank and seed rain for population restoration after disappearance from the vegetation and 3) investigated whether colonization and extinction events are affected by patch isolation. I assumed if population turnover was rather a result of the soil seed bank dynamics then spatial effects would be hard to detect.
In spite of the presence of populations formed from soil seed and the relatively more important soil seed bank for potential population reestablishment, turnover dynamics followed the predictions of metapopulation theory. Population appearance was more probable in larger and less isolated patches. Probability of disappearance increased with decrease of population size that was negatively influenced by the patch size and its isolation. These findings indicate dispersal processes to be important in the turnover dynamics and only limited contribution of soil seed populations. Their small effectiveness is probably related to the low chance of recurrent disturbance on the mound surface.     

The response of ecosystem CO<Subscript>2</Subscript> exchange to small precipitation pulses over a temperate steppe

We evaluated the process of salt-marsh colonization in early successional stages of salt-marsh restoration and investigated how the sequence of species establishment related to different success factors. Vegetation data were collected by permanent plots from the restoration site and adjacent, reference salt marshes during three consecutive periods. Seed length, width and mass were used as dispersal traits, and Ellenberg moisture, salinity and nutrient indices as indicators of site suitability. Seed production in the reference site and seed bank in the restoration site were also investigated. The establishment of salt-marsh species within the restoration site was rapid (less than 5 years). The cover of plant species was not correlated between the restored and the reference sites at the first year of restoration, but this correlation was significant during the following years. Seed availability was more important in explaining the sequence of species establishment than salt and nutrient-limitation tolerance. The first colonizers are known as massive seed producers, with shorter seed length and lower seed mass, which probably increased buoyancy. Among dispersal and site traits, seed length and mass, and in a less extent salinity and nutrients, indicated a relationship with new colonizers. Despite few species have not (yet) appeared in vegetation and seed bank in the restoration site, the existence of an existing salt marsh adjacent to the restoration site is shown to be vital for fast colonization of newly created intertidal areas.     

岷江干旱河谷土石混合边坡不同种植处理下乡土植被的生态效益

岷江干旱河谷生态环境脆弱,植被恢复困难,大规模的公路建设极易对当地生态环境造成破坏。筛选适宜的植被恢复措施对干旱地区道路边坡的乡土植被恢复重建和生态功能提升尤为重要。以岷江干旱河谷极端退化的土石混合的道路边坡为案例,选取乡土灌木和草本植物构建植物群落,进行裸地播种、播种后覆盖纤维毯和添加腐殖土后播种并地表覆盖纤维毯3种不同的种植处理,揭示了不同处理下群落结构、土壤改良以及水土保持效益的差异。发现,乡土灌草群落是干旱河谷适宜的道路边坡植被恢复模式,种植后第3年群落特征趋近于岷江干旱河谷区自然生态系统的多年生灌草植被。纤维毯覆盖+覆土处理在促进植物生长和群落构建,水土流失防治上效果最好,群落总盖度为74%,群落总生物量为506.35 g/m²;生长季内,与自然恢复相比小区径流量减少了87.8%,泥沙流失量降低了92.1%。土壤改良效应在3种处理之间差异不明显,但是与自然恢复样地相比,各处理均提升了边坡0—20 cm土层土壤养分。不同种植处理下植物群落结构差异是影响干旱河谷土石混合的道路边坡水土流失的关键因子。     

采石场废弃地的生态重建研究进展

采石场的开采严重破坏了植被和土壤,形成了大量的裸露岩石斜坡,造成宏观景观支离破碎和极端的环境条件,限制了植物的生长。由于自然恢复所需时间长久,人工恢复被广泛应用于采石场废弃地的生态重建。自然演替过程是采石场生态重建的理论基础,自然演替理论可以为人工恢复措施提供指导。植物群落演替的早期阶段,非生物因素起主要作用,随着演替的推移,生物因素的重要性增强。邻近自然植被的土壤和繁殖体通过外力的扩散,对恢复起重要作用。除了非生物和其他的限制,先到达恢复地的物种竞争能力的变化能决定了演替过程。演替过程中的干扰因素往往成为演替重要的驱动力。裸露岩石斜坡的物理稳定性对植被恢复有重要影响,有机废物的使用和施肥可以影响恢复演替的方向和生物多样性。播种一定的植物能够改变恢复演替方向,加速演替过程。乡土物种适应了当地气候,能够促进演替。随着修复时间的延长,土壤有机质含量,植被覆盖度和物种丰富度不断增加,土壤微生物生物量随之增加。开展不同地区采石场植物种类的选育、研究乡土物种的功能特性、土壤微生物群落和酶的变化、植被演替过程的定位研究、植物种间的竞争关系、自然演替和人工恢复的比较研究、探索经济高效的采石场生态重建方法是未来的研究方向。     

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.     

Secondary seed dispersal of Erodiophyllum elderi,a patchily distributed short‐lived perennial in the arid lands of Australia

We investigated secondary dispersal of propagules of Erodiophyllum elderi (Asteraceae), a short‐lived perennial plant growing in small patches in the arid lands of southern Australia. In spite of its importance for population dynamics, secondary dispersal is a little understood process. We monitored the dispersal of 2280 large woody capitula (seed heads) released in six E. elderi patches for 9 months. Colour‐coded seed heads were located at night using UV light and their distance and direction from the release point were measured. Over the 9‐month period, more seed heads moved, and those that did, moved further in areas with high herbivore activity. Overall dispersal distance across the ground was limited to less than 30 m. Dispersal patterns were related to the topographical slope at the release site: seed heads moved further, and more dispersed on steeper slopes unless the steep slopes had sandy soil in which case seed heads were buried, caught or there was reduced sheet water flow limiting their dispersal potential. After several months, seed head dispersal virtually ceased as seed heads became stuck in the debris and soil after heavy rains or further dispersal became unlikely when seed heads reached locally low‐lying areas. Secondary dispersal patterns suggest two distinctly different influences associated with the presence of herbivores: the direct movement of seed heads by trampling from sheep (an introduced herbivore) and the indirect effect of a reduced standing biomass from grazing. Reduced vegetation cover allows seed head redistribution via sheet water flow during large rainfall events.     

Motor vehicles as vectors of plant species from road verges in a suburban environment

The objective of this study was to assess the potential contribution of car-borne flora to species dispersal in a suburban area in Flanders (Belgium). Therefore, motor vehicle-borne flora was evaluated monthly for a random sample of 20 cars between October 1988 and September 1989. At the end of the experiment 33 car-borne plant species, with a total of 690 seedlings were identified from mud, attached to these vehicles. There was considerable temporal variation in the mud mass attached to the vehicles and therefore also the size and composition of the vehicle-borne flora varied during the year. Because mud retention on cars is a crucial factor in seed dispersal, the number of emerging seedlings is negatively correlated with precipitation in the week preceding the sampling. The flora dispersed by vehicles consists mostly of species with small, light seeds and a persistent seed bank. Usually, they are pioneer species of nitrogen-rich habitats. The nature of the vehicle dispersed flora was compared with the local flora of road verges and differed significantly from this in, e.g., seed length, seed weight, ecological groups, Ellenberg indicator values for nitrogen supply, potential dispersal strategies and rarity. A larger resemblance with the flora of the zone immediately adjacent to the carriageway was found. We only found a low similarity to other motor vehicle-borne floras.     

Near‐natural methods promote restoration of species‐rich grassland vegetation—revisiting a road verge trial after 9 years

The present loss of species‐rich grasslands makes it vital to restore these valuable habitat types, including novel habitat variants such as road verges. Due to the lack of knowledge on long‐term outcomes of restoration initiatives, well‐designed studies comparing different restoration methods are needed. In this study, we examined fine‐scale vegetation recovery patterns over 9 years in a field experiment with several near‐natural restoration methods (adding local seed mixtures, transferring hay from local grasslands using hard or light raking, and natural regeneration) in a road verge. We compared this to standard revegetation (hydroseeding species‐poor commercial seed mixtures). We found major temporal changes in vegetation restored by local seed or hay transfer, before it gradually became more similar to the donor grasslands and seed mixtures, which served as references for the experiment. Natural (spontaneous) regeneration with seed dispersal from surroundings gave similar results, whereas areas revegetated using standard methods became more dissimilar to the reference sites during the study period. The main variation in species composition reflected the contrast between local donor grasslands and seed mixtures and the species‐poor early successional grasslands. We conclude that near‐natural methods (hay transfer and seeding) successfully restored species‐rich grassland, including road verges. This study underlines the importance of comparing several treatments over a sufficiently long period to assess their success in restoring species‐rich grassland.     

石林地质公园不同群落类型植物果实组成与种子散布特征

喀斯特植物群落果实类型和种子散布特征的研究, 对于理解喀斯特植物群落更新与拓展特征, 进而揭示喀斯特石漠化地区恢复植被的自然扩展机制及制定植被恢复规划具有重要意义。该研究以石林地质公园不同群落类型为对象, 研究不同群落的果实类型谱与种子散布谱, 以揭示果实类型与种子散布方式对恢复植被的影响。采用石林地质公园不同群落各1 hm ²样地记名计数法调查的维管束物种名录, 依据Flora of China对物种果实的描述确定其果实类型; 根据文献、数据库以及果实、种子形态性状确定种子散布方式。结果表明: (1)石林地质公园282种维管束植物共16种果实类型(含孢子), 其中瘦果、蒴果、浆果和核果的物种比例均大于10%。木本植物、草本植物、藤本植物的优势果实类型分别为核果、瘦果和浆果。石林地质公园各群落的木本植物、草本植物和藤本植物的果实类型谱差异不显著。在原生林、次生林、灌丛、灌草丛和人工辅助云南松林不同群落中, 浆果和核果的物种比例减少, 瘦果、颖果和蒴果的物种比例增加。(2)石林地质公园植物种子以动物传播为主, 其次为风传播。在原生林、次生林、灌丛、灌草丛和人工辅助云南松林不同群落中, 风传播的物种比例增加了73%-87%, 动物传播(包括鸟类传播)减少了31%-36%。(3)物种的种子散布方式直接影响到植被恢复物种和恢复策略的选择。基于恢复目标, 选择自然传播能力强的乡土物种或地带性植被关键种, 辅以传播廊道, 有助于喀斯特的植被恢复。     

Unraveling the dynamics of a ground‐dwelling beetle population exposed to quarry exploitation and restoration practices

Quarry exploitation and restoration practices are expected to have overarching and contrasting impacts on animal communities. Although many studies describe these impacts, they generally overlook the effects on population dynamics and individual movements. We assessed the impacts of quarry exploitation and restoration activity on population dynamics, individual movement, and habitat use of a sand‐dwelling specialist beetle (Scarites cyclops). The study was performed on three plots: one adjacent to the margin of quarry exploitation, another subjected to restoration practices, and a control plot with no disturbance. A capture‐mark‐recapture approach was undertaken to estimate population parameters, movement, and habitat use. In the exploitation plot S. cyclops exhibited lower probability of recapture and lower apparent survival, as well as many movements fleeing away from quarry limits. Habitat suitability modeling showed that the exploitation plot provided better habitat conditions for the species than the restoration plot. It exhibited higher bare ground cover with scattered clumps of vegetation and higher proportions of fine sand (<0.4 mm). In the restoration plot, S. cyclops population showed a lower abundance, with a higher rate of recaptures, and a more limited dispersal ability of the individuals. There is an apparent early stage of colonization by S. cyclops in the restoration plot, but movements may already be hampered by unsuitable habitat restoration (higher herbaceous cover and different soil texture). We suggest preserving suitable habitat patches in the vicinity of the impacted areas and providing dispersal routes. Beyond vegetation, soil texture must be considered to allow local animal communities to establish in restored areas.     

Fruit types and seed dispersal modes of plants in different communities in Shilin Geopark,Yunnan, China

喀斯特植物群落果实类型和种子散布特征的研究, 对于理解喀斯特植物群落更新与拓展特征, 进而揭示喀斯特石漠化地区恢复植被的自然扩展机制及制定植被恢复规划具有重要意义。该研究以石林地质公园不同群落类型为对象, 研究不同群落的果实类型谱与种子散布谱, 以揭示果实类型与种子散布方式对恢复植被的影响。采用石林地质公园不同群落各1 hm ²样地记名计数法调查的维管束物种名录, 依据Flora of China对物种果实的描述确定其果实类型; 根据文献、数据库以及果实、种子形态性状确定种子散布方式。结果表明: (1)石林地质公园282种维管束植物共16种果实类型(含孢子), 其中瘦果、蒴果、浆果和核果的物种比例均大于10%。木本植物、草本植物、藤本植物的优势果实类型分别为核果、瘦果和浆果。石林地质公园各群落的木本植物、草本植物和藤本植物的果实类型谱差异不显著。在原生林、次生林、灌丛、灌草丛和人工辅助云南松林不同群落中, 浆果和核果的物种比例减少, 瘦果、颖果和蒴果的物种比例增加。(2)石林地质公园植物种子以动物传播为主, 其次为风传播。在原生林、次生林、灌丛、灌草丛和人工辅助云南松林不同群落中, 风传播的物种比例增加了73%-87%, 动物传播(包括鸟类传播)减少了31%-36%。(3)物种的种子散布方式直接影响到植被恢复物种和恢复策略的选择。基于恢复目标, 选择自然传播能力强的乡土物种或地带性植被关键种, 辅以传播廊道, 有助于喀斯特的植被恢复。     

Restoration of high species density in calcareous grassland: the role of seed rain and soil seed bank

Abstract. A small-scale restoration experiment concerning a species-rich calcareous grassland was conducted over a 7-yr period. 20 yr of abandonment (1971-1990) resulted in both a strong reduction of the number of species and an absolute dominance of the shrub Crataegus monogyna and the grass Brachypodium pinnatum - which contributed 98% of the above-ground herb phytomass. The plot (3 m x 6 m) was cleared in September 1990 and thereafter yearly mown in autumn. Small soil seed bank samples were taken immediately after clearing and again in the autumn of 1996. The inner part of the plot showed a reduced soil seed bank compared to the plot underneath the vegetation outside the plot in 1990. Six years later an increased number of seeds in the soil in this inside area could be recorded mainly in the upper soil layer, although the amount was only 40% compared to the outside or control area. Ca. 20% of the species present in the restored vegetation were recorded in seed traps during the main seed dispersal period in 1997. Restoration of high species richness in the plot was a fast process during the first few years: from seven species in 1990 towards 39 three years later. This was significantly faster than the restoration process of the calcareous grassland at the same slope 20 yr earlier. This was probably due to the increased size of the community species pool at the site as a result of appropriate management during the last decades. Relative species number increase was highest at the largest scale during this experiment, viz. at the total plot area. The success of restoration of species-rich, dry grassland vegetation largely depends on the interaction between several conditions, e.g. seed availability, either originating from the seed rain or soil seed bank, favourable germination conditions and a successful development to a mature, seed producing individual. Germination and establishment strongly depend on suitable vegetation structure as a result of sustainable management.     

Restoration of Araucaria Forest: The Role of Perches, Pioneer Vegetation, and Soil Fertility

The Araucaria forest is Brazil's highly threatened subtropical forest ecosystem that has been disappearing in recent decades. Restoration programs involving this forest type are scarce, and there is a lack of scientific information on how ecological processes such as competition, facilitation, and seed dispersal influence natural forest restoration. This work aims to investigate how use of perches to attract seed dispersers and the influence of pioneer vegetation and soil fertilization could affect the colonization of woody species in a degraded area. An experiment was conducted in an abandoned field where the natural establishment of seeds and seedlings of woody species was monitored under factorial combinations of the following treatments: (1) pioneer vegetation (presence and absence); (2) soil fertility (addition of NPK and control); and (3) perches (presence and absence). Seed and seedling abundance, seed and seedling species richness, and seedling mortality were recorded monthly during 12 months. Seed abundance and species richness were significantly greater in places with perches than in control plots. These results were consistent over the year and more pronounced when the surrounding forest produced a higher amount of fruit. Species richness and abundance of seedlings were significantly greater in places with perches than in control plots, and in places with vegetation than without. Soil fertility did not influence seedling establishment. Facilitation and seed dispersal are important factors affecting the colonization of woody species in this subtropical area. Nutrient availability neither regulates the facilitation process nor influences species replacement during the early stages of Araucaria forest succession.