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1.
Abstract. In this study, we examined the colonization of unvegetated, dry slopes in the lignite‐mining area of Goitsche, Germany. The plots, characterized by different habitat conditions, were studied from 1994–2000. The vegetation development on treated plots was compared to untreated plots showing spontaneous succession. For initial treatments we used fresh plant clippings from a species‐rich sandy grassland (Armerion elongatae) mowed at the end of July. Soil seed bank samples, taken at the beginning of the experiments and cultivated for 18 months, confirmed that the vegetation development on the slopes started with primary succession. Because seed rain is considered to be an important factor in primary succession, we also studied the diaspore input during the first year. The hospitable Quaternary substrate of Site I (pH = 4.1–4.7, 92 % sand) supports fast vegetation development on treated and untreated plots. On treated plots, we have identified plant assemblages similar to initial stages of the Armerion elongatae community. On control plots, Coryne‐phorion communities have established spontaneously. At Site II (mixed Quaternary and Tertiary substrate, pH = 3.0–3.5,40 % sand) the total cover and number of psammophytic species was low. Treated plots showed development towards ruderal sandy grassland, but the establishment of Calamagrostis epigejos would eventually lead to monodominant stands. Untreated control plots showed basically the same pattern, however the development was slower. At Site III (pH = 1.8–2.8, 34 % sand), the hostile Tertiary substrate impeded the succession on both treated and untreated plots because low pH and therefore high amounts of Al3+ produced elemental toxicity to plants. The application of plant clippings accelerated the vegetation development in sites with a pH exceeding 3. On plots with the initial treatment, vegetation cover and total number of species were higher than on untreated plots. The application of fresh plant clippings from areas with similar habitat conditions appears to be a viable alternative to traditional restoration methods.  相似文献   

2.
Long-Term Effects of Reclamation Treatments on Plant Succession in Iceland   总被引:3,自引:0,他引:3  
The long‐term effects (20–45 years) of reclamation treatments on plant succession are examined at two localities in Iceland that were fertilized and seeded from 1954 to 1979 with perennial grasses or annual grasses, or left untreated. The areas that underwent reclamation treatments had significantly higher total plant cover (7–100%) than the untreated control plots (<5%), and floristic composition was usually significantly different between treated and untreated plots. Dwarf‐shrubs (Calluna vulgaris and Empetrum nigrum), bryophytes, biological soil crust, grasses, and shrubs characterized the vegetation in the treated plots, but low‐growing herbs that have negligible effects on the environment, such as Cardaminopsis petraea and Minuartia rubella, and grasses characterized the control plots. The seeded grass species had declined (<10%, the perennials) or disappeared (the annuals) but acted as nurse species that facilitated the colonization of native plants. It seems that by seeding, some factors that limit plant colonization were overcome. Soil nutrients, vegetation cover, litter, and biological soil crust were greater in the treated areas than the control plots. This may have enhanced colonization through an increase in soil stability and fertility, increased availability of safe microsites, increased moisture, and the capture of wind‐blown seeds. This study demonstrates the importance of looking at the long‐term effects of reclamation treatments to understand their impact on vegetation succession.  相似文献   

3.
We report on spontaneous and directed succession on a dry sandy landfill site of low fertility at Berlin‐Malchow, Germany. Changes in species composition and cover were followed on unmown and mown permanent plots of 2 × 2 m size through 5 years of vegetation development. Species richness on unmown plots was relatively constant during the time of observation, with 20 to 25 species per 4 m2. Total cover of unmown plots continuously increased from approximately 10% in the first year to 80% in the fifth year. There are no clearly discernible sequential successional stages until present. The species composition includes species of all life forms, which colonized the site immediately after the initiation of the succession process representing the initial floristic composition type of vegetation development. However, perennial grasses and herbs gradually increased in cover up to approximately 40%. Woody plants were also present from the first year of succession and increased up to more than 20% cover in the fifth year, forming a shrub layer (>0.5 m) after the second year. Mowing significantly increased species richness, which was evident from the third year onward. This effect was mainly due to the reduction of the tall perennial grass Calamagrostis epigejos. Solidago canadensis and woody species were also significantly affected (lower cover and height), whereas short perennial herbs like Plantago lanceolata and Trifolium repens benefited from mowing.  相似文献   

4.
Based on field investigations in the East River basin in Guangdong Province, south China, the processes of vegetation development and vegetation succession on bare slopes with high erosion rates are studied. Different reforestation measures have been applied to the slopes, which have resulted in very different processes of vegetation development and succession. On an experimental plot with burned forest but surviving roots, the vegetation restored naturally and quickly because there was little soil erosion. However, in the plots suffering from long-term severe soil erosion, natural vegetation recovery on these barren slopes is very slow. After 26 years, a barren slope has only been partly colonized by poorly developed vegetation composed of heliophilous herbages and scattered shrubs. On the other hand, plantation of some selected wood species on the slope land has dramatically accelerated the vegetation recovery and succession. The plots were reforested with plantation of Acacia auriculiformis in the early 1980s. Twelve years later, the vegetation cover of the artificial forests reached 90% and an understory vegetation community consisting of local species had naturally developed. Reforestation with suitable strategies may control erosion and greatly accelerate vegetation succession in the eroded slope land in the subtropical zones.  相似文献   

5.
The tropical coastal dunes in central Gulf of Mexico have been stabilizing over the last decades resulting in reduced substrate mobility, and promoting primary succession. We describe changes in species richness and diversity in dune vegetation during 20?years. Our questions: (a) Do species richness and diversity increase over time as predicted by models of ecological succession or do they show a hump-backed manner similar to the observations in temperate coastal dunes?, (b) What is the interaction between vegetation cover and diversity and species richness?, (c) Is there a relationship between species diversity and succession rate and does succession rate change over time?, and (d) How do plant functional types change during succession? In order to answer these questions, we set 140 4?×?4?m permanent plots in a mobile dune area and monitored vegetation cover and species richness from 1991 to 2011. In time, diversity increased in a logistic manner toward an asymptotic value once vegetation cover surpassed 60?%. Species richness increased in a humped-back shape, also reaching a maximum peak at 60?% vegetation cover. The succession rate of diversity was measured by the Euclidean distance, and showed a significant humped-back relation, meaning that it was slower in early and late successional stages. The study supports the intermediate disturbance theory. The conservation of coastal dunes vegetation should focus on all, species-poor and species-rich habitats that help to maintain the ecological integrity of these ecosystems. The understanding of community dynamics and diversity patterns becomes an essential component of coastal dune management and conservation.  相似文献   

6.
An understanding of the processes involved in plant succession is pivotal in achieving an effective site restoration. In a former limestone quarry (northeastern Italy), we explored the effects of a technical reclamation on the plant community using changes in cover of vegetation layers and two sensitive plant traits (i.e. exotic status and life span), with a chronosequence approach. Four reclaimed areas of different ages (from 8 to 35 years old) and natural vegetation in the surroundings were investigated with seven permanent plots each, for a total of 35. Changes in vegetation layers and species richness of both exotic status and life span were analyzed by generalized linear (mixed) models. Relations with plant community assembly were also considered, using a multivariate approach. Both vegetation layers and plant traits were affected by the age of reclaimed areas, evidencing the main changes in plant succession. Annual and exotic species decreased toward the mature stages of reclamation and target vegetation, whereas overall plant diversity (species richness) was stable. Our findings show that both vegetation layer changes and plant traits can be used to assess the degree to which reclamation efforts produce results that approach the restoration of a natural vegetation reference. Implementation of management practices aimed at favoring native perennial species (e.g. appropriate seed mixtures, mowing, tree, and shrub planting) could limit weed‐control efforts, representing a reasonable trade‐off between biodiversity promotion and invasive plant control.  相似文献   

7.
Questions: (1) What are the most important abiotic environmental variables influencing succession in central European man‐made habitats? (2) How do these variables interact with one another and with variation in community properties? Location: Central, western and southern parts of the Czech Republic. Habitats included old fields, urban sites, spoil heaps after coal mining, sites at water reservoirs, extracted sand pit and peatland and reclaimed sites in areas deforested by air pollution. Methods: We investigated vegetation patterns on 15 succes‐sional seres, sampled by the same methods. Time of succession over which the data were available ranged from 12 to 76 years. The cover of vascular plant species (in %) was estimated in 5 m × 5 m plots. The relationships between vegetation characteristics (species composition, total cover, cover of woody species, species number and rate of dominant species turnover) and 13 abiotic site factors, including climatic and soil variables, were tested using CCA ordination and regression models. Results: Substratum pH, the only substratum characteristic, and climate were the environmental variables significantly affecting the vegetation patterns in the course of succession. The rate of succession, measured as the turnover of dominant species, was significantly more rapid in lowland than in mountain climates. On alkaline soils, species numbers in succession increased towards warmer climates. However, acid soils prevented any increase in species numbers, regardless of the climate. Surprisingly, forms of nitrogen and contents of C, P and cations did not exhibit any significant effect on the vegetation characteristics studied. Conclusions: Our approach, to compare a number of seres, can contribute not only to our understanding of succession, but also to help restoration projects to predict vegetation change because the crucial environmental variables, as identified by this study, are easy to measure.  相似文献   

8.
Cover and richness of a 5‐year revegetation effort were studied with ,respect to small‐scale disturbance and nutrient manipulations. The site, originally a relict tallgrass prairie mined for gravel, was replanted to native grasses using a seed mixture of tall‐, mixed‐, and short‐grass species. Following one wet and three relatively dry years, a community emerged, dominated by species common in saline soils not found along the Colorado Front Range. A single species, Alkali sacaton (Sporobolus airoides), composed nearly 50% of relative vegetation cover in control plots exhibiting a negative relationship between cover and richness. Seeded species composed approximately 92% of vegetation cover. The remaining 8% was composed of weeds from nearby areas, seed bank survivors, or mix contaminants. Three years of soil nutrient amendments, which lowered plant‐available nitrogen and phosphorus, significantly increased relative cover of seeded species to 97.5%. Fertilizer additions of phosphate enhanced abundance of introduced annual grasses (Bromus spp.) but did not significantly alter cover in control plots. Unmanipulated 4‐m2 plots contained an average of 4.7 planted species and 3.9 nonplanted species during the 5‐year period, whereas plots that received grass herbicide averaged 5.4 nonplanted species. Species richness ranged from an average 6.9 species in low‐nutrient, undisturbed plots to 10.9 species in the relatively high‐nutrient, disturbed plots. The use of stockpiled soils, applied sparingly, in conjunction with a native seed mix containing species uncommon to the preexisting community generated a species‐depauperate, novel plant community that appears resistant to invasion by ruderal species.  相似文献   

9.
Abstract. The first 10 yr of old-field successional dynamics on the Argentine Inland Pampa were studied on a series of adjacent plots established consecutively between 1978 and 1989. We examined differences in species abundance patterns among plots in order to detect the spatial and temporal variability of succession. Perennial grasses steadily increased in cover and replaced the dominant annual species after 5 yr. Pioneer dicots persisted in older seral stages with 20 — 23 species/plot. Overall, exotic species (mostly the grasses Lolium multiflorum and Cynodon dactylon) contributed much to the plant cover in these communities. Native grasses comprised 45 % of total cover at years 7 — 10 of succession, but occurred with less than 7 species/plot. Substantial variation was found in the successional pathway, which reflected the particular sequence from annual forbs to short-lived and perennial grasses in the various plots. The course of succession was apparently influenced by a 2-yr period of unusually high rainfall. Deyeuxia viridiflavescens, a native perennial grass virtually absent before the wet period, spread over the study area and dominated seral communities for 3 yr, irrespective of plot age. Climatic conditions thus affected the successional turnover of life forms by increasing the rate of colonization by perennial grasses. We further point out the constraints imposed on secondary succession by the life histories of ‘available’ species.  相似文献   

10.
Ecosystems with highly pulsed water supply must be better understood as climate change may increase frequency and severity of intense storms, droughts and floods. Here we collected data over 3 years (2016–2018) in the episodic wetland outflow channel (Aluize), Banhine National Park, in which the system state changed from dry to wet to dry. Field sampling included vegetation records, small‐scale vegetation zoning, the seed bank and water and soil quality. The same main plant species were found in both dry and wet conditions across the riverbed of the outflow channel. We found only very few diaspores of plants in the soil after prolonged drought. In the subsequent flooded state, we examined very dense vegetation on the water surface, which was dominated by the gramineous species Paspalidium obtusifolium. This species formed a compact floating mat that was rooted to the riverbed. The Cyperaceae Bolboschoenus glaucus showed high clonal growth in the form of root tubers, which likely serve as important food reservoir during drought. Soil and water analyses do not indicate a limitation by nutrients. We outline how resident people may change the plant community structure with an increasing practice of setting fire to the meadows in the dried‐up riverbed to facilitate plant regrowth as food for their livestock.  相似文献   

11.
The succession of species-rich wetland vegetation in dune valleys into species-poor dwarf shrub vegetation was followed by means of permanent vegetation plots, in which the cover of vascular plant, moss and lichen species were recorded over a period of up to 33 years. Low density cattle grazing is an effective substitute for rabbits in stalling this succession, thus preserving the local plant species diversity. The influence of direct rabbit grazing pressure on the vegetation was studied in exclosures. The differences were significant, but not long-lasting after the exclosures had been opened again to the rabbits. Cladina lichen-rich Empetrum-heathland in the dunes is a stage in a probably cyclic succession that might be triggered by grazing. The total vascular plant, moss and lichen diversity of the dune ecosystem can be maintained by a combination of extensive cattle grazing and a regular but limited re-creation of pioneer situations.  相似文献   

12.
The transitions between ecosystems (ecotones) are often biodiversity hotspots, but we know little about the forces that shape them. Today, often sharp boundaries with low diversity are found between terrestrial and aquatic ecosystems. This has been attributed to environmental factors that hamper succession. However, ecosystem properties are often controlled by both bottom-up and top-down forces, but their relative importance in shaping riparian boundaries is not known. We hypothesize that (1) herbivores may enforce sharp transitions between terrestrial and aquatic ecosystems by inhibiting emergent vegetation expansion and reducing the width of the transition zone and (2) the vegetation expansion, diversity, and species turnover are related to abiotic factors in the absence of herbivores, but not in their presence. We tested these hypotheses in 50 paired grazed and ungrazed plots spread over ten wetlands, during two years. Excluding grazers increased vegetation expansion, cover, biomass, and species richness. In ungrazed plots, vegetation cover was negatively related to water depth, whereas plant species richness was negatively related to the vegetation N:P ratio. The presence of (mainly aquatic) herbivores overruled the effect of water depth on vegetation cover increase but did not interact with vegetation N:P ratio. Increased local extinction in the presence of herbivores explained the negative effect of herbivores on species richness, as local colonization rates were unaffected by grazing. We conclude that (aquatic) herbivores can strongly inhibit expansion of the riparian vegetation and reduce vegetation diversity over a range of environmental conditions. Consequently, herbivores enforce sharp boundaries between terrestrial and aquatic ecosystems.  相似文献   

13.
Folia Geobot. Phytotax., Praha, 22: 339–354.—The primary succession of vegetation (higher plants) was studied on large dumps from brown coal mining in N.W. Bohemia, Czechoslovakia. Three differently aged stages were investigated (1977–1986), using permanent plots and transects. Changes in the species composition, the participation of life forms, and the species diversity were expressed on the basis of cover data for a period of 30 years of the succession. The data were processed by an ordination technique (DCA).  相似文献   

14.
Non‐native plant species often colonize retired agricultural lands, creating monocultures with low species diversity that provide poor wildlife habitat. We assessed whether sowing a mix of 29 locally adapted native species reduced invasion of non‐native plant species compared to allowing vegetation to colonize naturally following tillage. There was a sampling date × treatment interaction for canopy cover of perennial exotic plant species. Plots that were not sown to natives had two to six times greater canopy cover of exotic species than did plots with both preparation (woody vegetation removed, plowed, and disked) and control (no preparation or sowing) plots. Canopy cover of exotic plants was similar in prepared‐only and control treatments from October 2008 to June 2010, ranging from 8 to 40%. Percent absolute canopy cover of native vegetation was 10–20 times greater on prepared and planted plots than on prepared‐only plots during March 2009 to June 2010. Sowing a mix of locally adapted native species may inhibit encroachment by non‐native species for up to two years after sowing on retired agricultural land in the Lower Rio Grande Valley of Texas.  相似文献   

15.
Abstract. Question: Does the degree and timing of disturbance contribute significantly to the pattern and process of regeneration in plant communities as a consequence of the availability and number of species of propagules present? Location: Acid grassland at 230 m a.s.l., eastern Scotland, UK. Methods : Plots were surface disturbed or had their soil profile inverted at monthly intervals at 12 dates during a year. Seed bank and seed rain were assessed at each treatment time. The effect of disturbance intensity and timing on the regenerating vegetation was assessed. Results: Removing the seed bank significantly slowed regeneration, as it contributed 43 % of developing cover after one year where it was present. At an individual seed level, seed in the seed rain had a much higher likelihood of contributing to the regenerating vegetation than a seed in the seed bank. Some species showed a reliance on the seed bank for regeneration, and hence there was a significant difference in the vegetation that developed between plots with the seed bank intact and those where it was removed. Winter disturbed plots (little seed rain) had slower rates of re‐vegetation than summer disturbed plots. Timing had little effect on species composition, though a significantly higher cover of perennial forb species developed on the winter disturbed plots. Conclusion: Removing the contribution of the seed bank had a greater effect on the composition of regenerating vegetation than the effect of seasonal variation on the seed rain.  相似文献   

16.
We conducted a 2-yr study in commercial apple orchards in Nova Scotia to assess the effects of ground cover treatments and insecticides on population density and fruit injury caused by tarnished plant bug, Lygus lineolaris (Palisot de Beauvois). The design was a split-plot with insecticides applied to whole orchard blocks and ground cover treatments applied to plots nested within orchard blocks. Ground cover treatments were 1) standard herbicide use, 2) enhanced weed control in tree rows, and 3) treatment two plus use of a selective herbicide in laneways. Treatments had few significant effects on vegetation in the tree row, but in laneways, known dicot hosts of L. lineolaris were suppressed and nonhost grasses promoted with treatment 3. Ground cover treatments did not affect cumulative captures of adult tarnished plant bugs on white sticky traps located in the plots but did affect captures in sweep nets. Split-plot ANOVA indicated no significant effect of insecticides on injury in either year, but ground cover treatments were significant in 2001. The lowest ranking rates of injury in both years were in orchards treated before bloom with a pyrethroid insecticide, either cyhalothrin-lambda or cypermethrin. The highest ranking rate of injury occurred in an orchard where insecticide was not applied until after bloom despite a high prebloom capture of L. lineolaris adults on orchard perimeter sticky traps. Fruit injury values for the ground cover treatment 3 were 63.3% (n.s.) and 50.0% (P < 0.05), respectively, of those in the standard treatment in 2000 and 2001.  相似文献   

17.
Abstract. This paper reports on vegetation dynamics on terrestrial, temperate grassland sites at the upper range of the productivity scale, i.e. on abandoned sewage fields (fields once used for waste water disposal) at Berlin‐Blankenfelde, Germany. I studied regeneration and the influence of different management practices (removal of top soil and mowing in late summer). Changes in species composition and cover were followed on permanent plots of 2m × 2m size through five years of vegetation development. At the outset of the experiment the abandoned fields were dominated by dense Urtica dioica /Elymus repens stands. Species richness was 7 species/ 4m2, and it remained low on unmanaged plots during the time of observation (7.6 species/plot in year 5). Removal of 20 cm of top soil caused a severe decline of Urtica and a large increase in species richness (21 species in year 1 after disturbance). Mowing was slightly higher compared with unmown plots on both initially excavated and unexcavated plots. Total cover was always near 100 % (except immediately after top soil removal). Colonization of bare soil was very rapid and in late summer of the first year after disturbance cover already increased towards 100%. On all plots the vegetation was mostly dominated by perennial herbs and grasses. Winter season gaps are occupied by Galium aparine, a large‐seeded annual scrambling climber. Monocarpic perennials behaved as winter annuals in most cases. Woody species were inhibited by dense above‐ground biomass and litter cover. The paper questions whether succession on abandoned sewage fields may proceed towards a woodland stage and advises how vegetation of such hyper‐eutrophicated sites can be managed towards higher diversity.  相似文献   

18.
We examined a method for revegetation of cut-slopes in Tochigi, Japan, using only natural plant dispersal from the surrounding vegetation. We examined plant establishment in six plots in a cut-slope in bedrock (inclination: 65°, direction: S45°W) treated with various types of netting and fertilizer. We surveyed the plant communities, individual trees, and seed rain on the cut-slope, as well as the plant community on the undisturbed upper slope. Revegetation method using polyethylene netting with fertilizer and water-retention material was the most effective. The resulting plant community was dominated by Pinus densiflora, with a cover of 49.0±11.4% after 5 years. This plant community consisted of 19 species, including ten tree species and a density of 26.2 trees/m2. Revegetation method using palm-fiber netting with fertilizer also resulted in high plant cover after five years, although little revegetation grew on this plot in the earlier years. The roughness of the palm fiber may have inhibited revegetation. Application of fertilizer was essential for the success of this natural revegetation method. In addition, the revegetated plant community was strongly influenced by seed rain from the vegetation of the upper slope. The number of trees that became established was much lower than the number of tree seeds that were dispersed, possibly because of the absence of soil. We recommend that soil is allowed to accumulate or that a base of material to facilitate plant growth is added. Successful revegetation was achieved even under the harsh conditions of this cut-slope.  相似文献   

19.
植被演替早期的优势物种是影响演替进程的重要因素。以半干旱黄土高原地区退化耕地植被的自然恢复为对照,于植被恢复的早期引入两年生豆科植物草木樨(Melilotus officinalis L.),在种植密度为11.3kg.hm-2条件下,考察了6年内引入草木樨对退化耕地植被恢复过程中植物群落演替进程的影响。结果表明,与自然恢复植被相比,草木樨的引入不仅可以提高地表植被覆盖度和加速植物群落演替进程,促使一些群落演替后期物种如冷蒿(Artemisia frigida)、阿尔泰狗哇花(Heteropappus altaicus)和短花针茅(Stipa breviflora)等在植被恢复的第3年出现,同时有利于提高植被生产力和稳定性。同自然恢复相比,试验期间引入草木樨后的植被地上平均生物量提高67.90%。同时,植被恢复早期生物多样性与土壤全氮含量呈显著正相关,而草木樨的引入有利于提高土壤全氮含量;在植被恢复初期(2003~2005)引入草木樨的土壤全氮平均含量比自然恢复高7.32%;试验期间土壤速效磷含量与物种丰富度呈显著负相关。因此,在半干旱区黄土高原退化耕地植被恢复早期阶段,两年生豆科植物草木樨的引入和磷肥的施用对于加快植被恢复有着积极作用。  相似文献   

20.
《Acta Oecologica》2004,25(3):137-142
We studied patterns of small mammal abundance and species richness in post-fire habitats by sampling 33 plots (225 m2 each) representing different stages of vegetation recovery after fire. Small mammal abundance was estimated by live trapping during early spring 1999 and vegetation structure was sampled by visual estimation at the same plots. Recently–burnt areas were characterised by shrubby and herbaceous vegetation with low structural variability, and unburnt areas were characterised by well developed forest cover with high structural complexity. Small mammal abundance and species richness decreased with time elapsed since the last fire (from 5 to at least 50 years), and these differences were associated to the decreasing cover of short shrubs as the post-fire succession of plant communities advanced. However, relationships between vegetation structure and small mammals differed among areas burned in different times, with weak or negative relationship in recently burnt areas and positive and stronger relationship in unburnt areas. Furthermore, the abundance of small mammals was larger than expected from vegetation structure in plots burned recently whereas the contrary pattern was found in unburned areas. We hypothesised that the pattern observed could be related to the responses of small mammal predators to changes in vegetation and landscape structure promoted by fire. Fire-related fragmentation could have promoted the isolation of forest predators (owls and carnivores) in unburned forest patches, a fact that could have produced a higher predation pressure for small mammals. Conversely, small mammal populations would have been enhanced in early post-fire stages by lower predator numbers combined with better predator protection in areas covered by resprouting woody vegetation.  相似文献   

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