The influence of seed addition and cutting regime on the success of grassland restoration on former arable land

Questions: Can seed addition enhance the success of establishing species‐rich grassland on former arable land? Are sowing date and cutting regime important in determining success? Location: Aberdeen and Elgin, northeast Scotland, United Kingdom. Methods: A field experiment was conducted at two sites to assess the effect of seed addition, sowing date and cutting regime on the vegetation developing on former arable land, the aim being to compare the success of different treatments at producing a species‐rich grassland. Results: Sowing a seed mix resulted in the establishment of vegetation very distinct from the species‐poor vegetation dominated by perennial grasses which otherwise developed, though establishment success of the sown grassland species was highly variable between sites. Where establishment of the sown species was poor, sowing date had no significant effect on species composition, whereas the cutting regime was very important. Cutting the vegetation significantly increased both the number and abundance of sown species compared with the uncut control. Conversely, where establishment had been good, the cutting regime in the first year had little effect on species composition. Cutting the vegetation at least twice a year appeared to be the most effective management over the length of the experiment. Conclusions: Sowing a seed mixture significantly reduced the abundance and number of naturally colonising species, effectively controlling problem weed species such as Senecio jacobaea and Cirsium vulgare, highlighting the agronomic value of sowing seed mixtures on fallow farmland. The sowing of a seed mix on former arable land has demonstrated that it is feasible to create vegetation similar in character to that of species‐rich grasslands.     

Long-Term Effects of Reclamation Treatments on Plant Succession in Iceland

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.     

Restoration of species‐rich flood‐plain meadows from abandoned arable fields in NE France

Abstract. Attempts to restore species‐rich flood‐plain meadows from abandoned arable fields in the valley of the river Meuse, NE France, were studied. The study area was sown with a commercial seed mixture, composed of Phleumpratense, Festuca pratensis, Lolium perenne and Trifolium repens. The above‐ground vegetation in the study area 1, 2 and 3 yr after restoration was compared to (1) the vegetation present during the previous 5‐yr fallow stage and (2) target flood‐plain meadows. Before restoration, the above‐ground fallow vegetation was dominated by ruderal and annual species, while only very few meadow species were present. Sowing led to tall, dense vegetation, mainly dominated by the sown species. Ruderal and annual species had decreased 3 yr after restoration, but target species were still poorly represented. Species richness was significantly lower in the sown site than in the semi‐natural target meadows and the vegetation had a different composition. Analysis of the soil seed bank of the restored meadow showed that only a few meadow species were present and that it was dominated by a few ruderal species. Three years after sowing, the vegetation of our experimental site is moving slowly towards the target communities but impoverished seed sources seem to limit the success of this restoration operation and will lead to under‐saturated communities.     

Shrub encroachment in the Alps gives rise to the convergence of sub‐alpine communities on a regional scale

Question: How does Alnus alnobetula colonization affect plant communities in sub‐alpine grasslands undergoing land abandonment on a regional scale? Location: Savoie, French Alps. Methods: Variations within and between communities were monitored in 243 plots within three types of stands representing an A. alnobetula colonization chronosequence from grassland to dense vegetation. They were tested for species richness, species strategies and species distribution through multivariate analysis. Regional variations were assessed at three sites along a rain shadow gradient. Results: We detected a convergence of the understorey communities along an A. alnobetula colonization gradient at all sites, associated with a reduction in species richness and the replacement of stress related strategists by competitor strategists. This convergence was unaffected by the rain shadow gradient although it was a key factor of plant distribution. Conclusions: The dense cover and the soil properties provided by A. alnobetula stands buffered the heterogeneity of sub‐alpine communities induced by a rain shadow gradient throughout the study region. It facilitated the development a homogeneous understorey community dominated by competitor related strategists while excluding grasslands stress adapted species through competition processes. The resulting community, although species‐poor, has an interesting conservation value. Accordingly, as a ‘native invader’, A. alnobetula does not display typical traits of biological invaders. Future experimental research on the interactions between A. alnobetula and components of the understorey would be particularly interesting in a severe environment that promotes facilitation among plants.     

Mechanisms blocking Pinus sylvestris colonization of Mediterranean mountain meadows

Abstract. In southern Mediterranean Pinus sylvestris forests there are grassy meadows that resist invasion of trees despite the proximity to seed sources. In this study, we investigate the mechanisms blocking colonization by Pinus sylvestris of the meadows. Two experiments were conducted in which seeds were sown either at 1 cm depth or on the surface to simulate dispersal, and three treatments of vegetation removal were applied: Disturbed (where the herbaceous layer was eliminated, exposing the mineral soil), Clipped (vegetation cut at ground level) and Control (no disturbance of the herbaceous layer). In addition, the effect of seed predators was controlled by using wire cages in the case of the surface sown experiment. When seeds were sown at 1 cm depth, seedling emergence was not reduced by the herbaceous layer. In contrast, when seeds were surface sown and predators were excluded, the rate of emergence was low in the Control treatment, intermediate in Clipped and high in Disturbed. Seedling emergence was, however, minimal when predators were not excluded, irrespective of the disturbance level. Seedling survival and growth after three years of study were similar among treatments. The results show that the seed predation and the physical barrier created by the herbaceous layer are the two mechanisms blocking the encroachment of Pinus sylvestris onto these Mediterranean mountain meadows, limiting the regeneration and potential expansion of the forest.     

Vegetation and Soil Development in Compost‐Amended Iron Oxide Precipitates at a 50‐Year‐Old Acid Mine Drainage Barrens

Acid mine drainage (AMD) barrens result from destruction of vegetation within AMD flow paths. When exposed to air, soluble iron in AMD undergoes oxidation and hydrolysis to form ferric iron (oxyhydr)oxides which accumulate on soil surfaces. A restoration experiment was conducted at a 50‐year‐old AMD barrens created by discharge from an abandoned underground coal mine. The objective was to determine whether vegetation could be established by altering rather than removing surface layers of acidic precipitates at a site representative of other mining‐degraded areas. Three zones in the barrens were identified based on moisture content, pH (2.7–3.3), and thickness of precipitates (0–35 cm). Our hypothesis was that application of the same reclamation method to all zones would fail to sustain >70% vegetative cover in each zone after four growing seasons. The method consisted of applying 11 t/ha lime and 27 or 54 t/ha compost before rototilling (top 15 cm) and mulching with oat straw containing viable seeds for a nurse crop. Lime‐only plots were included for comparison, and all amended plots were sown with a mine reclamation seed mix. Oats, sown species, and indigenous species dominated cover in the first, second, and fourth growing seasons, respectively. In the fourth year following reclamation, compost‐amended plots had >70% cover and improved soil properties in all three zones, providing evidence to reject our hypothesis. Vegetative restoration of AMD barrens did not require removal of highly acidic precipitates, since they could be transformed at low‐cost into a medium that supports indigenous plants.     

Vegetation establishment on chalk marl spoil: the role of nurse grass species and fertiliser application

Abstract. The Channel Tunnel workings on the UK side have yielded nearly 4 million m³ of chalk-marl spoil which now forms a 36 ha landscaped reclamation platform. To establish vegetation of amenity and conservation interest on the spoil, seed mixtures of native wild flowers and grasses were sown with Lolium perenne (perennial rye grass) as a nurse species. Potentially, L. perenne is a suitable nurse species for grassland creation on infertile substrates as it provides rapid initial cover and stability, but it is non-persistent and declines in vigour with time, allowing wild flower species sown alongside to expand their cover and spread in the longer term. On very low fertility substrates like chalk marl, an initial application of fertilizer is needed to encourage plant growth. Results are reported of a fertilizer experiment on Channel Tunnel spoil to determine appropriate levels of fertilizer for establishment of species-rich grassland vegetation. An area hydroseeded with L. perenne and wild flowers in autumn 1992 was subjected to factorial treatment of four levels each of N and P in spring 1993. The results the following summer showed significant positive effects of nitrogen and phosphorus on L. perenne biomass and a negative impact of nitrogen on densities of wild flower species, especially legumes, establishing in the L. perenne sward. In general, low fertilizer applications encouraged low productivity and maximal species richness in the vegetation. Conversely high applications encouraged high productivity and competitive exclusion of sown wild flower species. Fertilizer applications must therefore balance encouragement of the stabilising nurse grass sward, while preventing competitive exclusion of wild flowers by the nurse grass.     

基于多时相Landsat遥感影像的海州露天煤矿排土场植被时空特征分析

矿区土地复垦是目前土地整理的一项重要内容,也是矿区可持续发展实现的保障.矿区植被及其恢复状况是矿区土地复垦质量的一种重要的指示器,表征土地复垦的程度与质量.研究基于1975～2000年共4期遥感影像,构建植被覆盖度指数,考察辽宁省阜新市海州露天煤矿排土场25a来植被生长状况及时空变化特征.分析结果表明:1975～2000年间,研究区植被处于不断生长、逐渐恢复的状态,并存在明显的空间差异.时间尺度上,植被覆盖度较高(0.4～0.6)的区域所占面积比例从1975年的14.04%增长到2000年的34.83%;空间分布上,植被覆盖度低(0～0.25)的区域多分布在台地之间相连接的边坡位置上,植被覆盖度较高(0.25～0.6)的区域则分布于台地内部的平坦地面上.     

Microhabitat Preference of Egernia napoleonis in Undisturbed Jarrah Forest,and Availability and Introduction of Microhabitats to Encourage Colonization of Restored Forest

An animal's microhabitat requirements can impact its ability to colonize restored areas, particularly species requiring slow developing microhabitats, such as logs and woody debris piles. Introduction of these microhabitats may be required to facilitate colonization by some species. Restored bauxite mine‐pits in the Jarrah (Eucalyptus marginata) forest of south‐western Australia contain introduced log piles at densities of 1 ha^?1. However, these have not facilitated colonization by Napoleon's skink (Egernia napoleonis), which rely on logs for habitat and are largely absent from restored sites. We radio‐tracked 12 skinks in unmined forest to determine their microhabitat preferences and examined differences in vegetation structure, and microhabitat and food availability, between restored and unmined forests to identify reasons for their absence. Restored and unmined forests differed in canopy, mid‐ and understory cover and ground substrates, which were all potential barriers to colonization. Food availability was similar between restored and unmined forest, thus not a barrier to colonization. Skinks primarily utilized long logs, large woody debris piles, and large trees; microhabitats that were scarce or absent in restored sites and, therefore, potential barriers to colonization. Using this information, we introduced small woody debris piles into restored sites in close proximity to unmined areas containing skinks to facilitate skink colonization. This showed early signs of success and suggested that the lack of logs and woody debris were barriers to colonization. However, further monitoring is required to accurately determine the long‐term value of woody debris piles in facilitating skink colonization.     

Travelling to a former sea floor: colonization of forests by understorey plant species on land recently reclaimed from the sea

Questions: What are important forest characteristics determining colonization of forest patches by forest understorey species? Location: Planted forests on land recently reclaimed from the sea, the Netherlands. Methods: We related the distribution of forest specialist species in the understorey of 55 forests in Dutch IJsselmeer polders to the following forest characteristics: age, area, connectivity, distance to mainland (as a proxy for distance to seed source) and path density. We used species of the Fraxino‐Ulmetum association for the Netherlands as reference for species that could potentially occur in the study area. Results: Area and age of the surveyed forests explained a large part of the variation in overall species composition and species number of forest plant species. The importance of connectivity and distance to the mainland of forest habitats became apparent only at a more detailed level of dispersal groups and individual species. The importance of forest parameters differed between dispersal groups and also between individual species. After 60 years, 75% of the potential pool of wind‐dispersed species has reached the polders, whereas this was only 50% for species lacking specific adaptations to long‐distance dispersal. However, the average percentage of successful colonizing species present per forest was substantially lower, ranging from 15 to 37%. Conclusions: The data strongly suggest that the colonization process in polder forests is still in its initial phase, during which easily dispersed species dominate the vegetation. Colonization success of common species that lack adaptations to long‐distance dispersal is affected by spatial configuration of the forests, and most rare species that could potentially occur in these forests are still absent. Implications for conservation of rare species in fragmented landscapes are discussed.     

Sacred sites in north‐western Morocco – naturalness of their vegetation and conservation value for vulnerable plant species

The vegetation and flora of 86 sacred sites (surroundings of tombs of local saints, cemeteries) in NW Morocco was studied to assess their conservation value for undisturbed Mediterranean evergreen forests and vulnerable plants. Habitats were mapped, based on life form, maximum height and cover value, and classified according to naturalness. Vascular plants were classified according to pre‐defined risk factors like stenochory or grazing sensitivity. Naturalness index and refugial value were calculated for each site. Only 20% of the mapped site area was closed forest. On many places, human impact had created a vegetation mosaic. Most of the vulnerable plants were mesophilous forest species or grazing sensitive taxa. Endemic species occurred only rarely. The occurrence of vulnerable plants and the naturalness of the vegetation were positively correlated. Sacred site extension had no significant effect on the number of vulnerable species. Results indicate a limited relevance of sacred sites in northern Morocco for the protection of intact forests and vulnerable plants. However, these localities can play an important role as stepping stones in agricultural landscapes. They protect plants, sensitive to opening of the tree layer, to deforestation and to intense grazing. Certain formerly widespread forest communities survived exclusively on sacred sites.     

Recruitment and growth of herb‐layer species with different colonizing capacities in ancient and recent forests

Abstract. Forest herbs differ greatly in their capacity to recolonize secondary forests established on former agricultural land. We investigated whether interspecific differences in recruitment or growth can account for differences in colonization success. Seeds and adults of two species with limited colonization capacities (Anemone nemorosa and Primula elatior) and two species with high colonization capacities (Ranunculus ficaria and Geum urbanum) were introduced in ancient and recent forest sites within the Muizen forest (Belgium). At all sites, half of the plots were also cleared of above‐ground vegetation. Seedling establishment was similar in recent and ancient forest sites. However, both the number and subsequent survival of seedlings of the two hemicryptophytes (G. urbanum and P. elatior) were significantly lower when vegetation cover was present, while seedling number and survival of the two geophytes (A. nemorosa and R. ficaria) were less influenced by vegetation cover. Adult performance of P. elatior and G. urbanum was significantly better in the nutrient enriched recent forest stands and in the absence of vegetation cover. Performance of A. nemorosa and R. ficaria was not affected by any of these factors. We conclude that the extent of seed limitation is probably the main cause for the different colonization capacities of the species investigated.     

Management impacts on vegetation dynamics of hyper‐eutrophicated fields at Berlin,Germany

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.     

Road Slope Revegetation in Semiarid Mediterranean Environments. Part I: Seed Dispersal and Spontaneous Colonization

The importance of neighboring vegetation as a seed reservoir for spontaneous colonization of adjacent road slopes was analyzed in a semiarid region of east Spain. Two independent methodological approaches were used to examine the relative contribution of seed from neighboring vegetation and the efficiency of different seed dispersal strategies in plant colonization. We first used a randomization test to compare floristic similarity between road slopes, neighboring flora, and local flora (the regional species pool found in the same climate and soil conditions as the road slopes). Second, we compared seed dispersal mechanisms of road slope vegetation with those of the surrounding area using frequency analysis. Species composition of road slopes was more similar to that of the flora of adjacent surrounding areas than expected by chance. Anemochorous (wind‐dispersed) plants were over‐represented in road slopes 8 years after road slopes were built. We concluded that seed dispersal from neighboring vegetation is an important factor in the vegetative colonization of road slopes. However, this initial species pool was also strongly shaped by the harsh environmental conditions of roadcuts and southern aspect. These results have important implications in road slope restoration because they suggest that naturally vegetated areas should be maintained adjacent to road slopes to enhance seed immigration from species adapted to local site conditions, which will accelerate the successional process. The application of this single reclamation strategy and mixed strategies that combine the use of natural colonization and soil amendment for road slope restoration in Mediterranean environmental conditions is discussed.     

Salamander diversity of reforested abandoned surface coal mines in the Appalachian Region,U.S.A.

Surface coal mining is a pervasive form of land use and leading cause of deforestation in the Appalachian Region of the United States. Contemporary reclamation practices tend to produce strongly altered landscapes that inhibit forest succession, so there is a need for the development of alternative methods. Surface coal mines that preceded modern reclamation laws, known as abandoned mine lands, have become reforested in many locations and may serve as a model for improving the restoration of forests in postmining landscapes. I compared salamander diversity between 5 forests growing atop abandoned surface coal mines to 5 similar aged reference forests in southeastern Ohio using time constrained transect searches in autumn 2012 and spring 2013. The survey revealed 1,480 salamander individuals, representing 11 different species from 3 different families. The vast majority of salamanders (93%) were from the family Plethodontidae. Salamander species richness was significantly higher in reference forests than in mined forests, but this difference was contingent on the presence of stream‐dependent species in the reference forests. Salamander relative abundance was not significantly different between reference and mined forests. This survey demonstrates that reforested abandoned surface coal mines can provide suitable habitat for many forest‐dependent, terrestrial salamander species, but impaired water quality of headwater streams may limit the colonization of these forests by stream‐dependent species.     

Geographic Range,Habitats, and Host Plants of Bromeliad‐living Jumping Spiders (Salticidae)1

Although spiders are a very diverse group on vegetation, their associations with plants are poorly known. Some salticid species specifically use Bromeliaceae as host plants in some regions of South America. In this study, I report the geographic range of these spider‐bromeliad associations, and whether the spiders inhabit particular bromeliad species and vegetation types, as well as open areas or interior of forests. Nine salticid species were found to be associated with up to 23 bromeliad species in cerrados (savanna‐like vegetation), semideciduous and seasonal forests, coastal sand dune vegetation, restingas, inselbergs, highland forests, chacos, and rain forests at 47 localities in Brazil, Paraguay, Bolivia, and Argentina. Some species were typically specialists, inhabiting almost exclusively one bromeliad species over a large geographic range (e.g., Psecas chapoda on Bromelia balansae), whereas others were generalists, occurring on up to 7–8 bromeliad species (e.g., Psecas sp., Eustiromastix nativo, and Coryphasia sp. 1). The regional availability of bromeliad species among habitats may explain this pattern of host plant use. More jumping spiders were found on bromeliads in open areas than on bromeliads in the interior of forests. These results show that several jumping spider species may be strictly associated with the Bromeliaceae in the Neotropics. This is one of the few studies to show host‐specific associations for spiders on a particular plant type over a wide geographic range.     

Effect of Low Vegetation on the Recruitment of Plants in Successional Habitat Types1

I assessed the role of low vegetation (plants ca 1 yr old and ≤50 cm tall) as a biotic facilitator or barrier in the recruitment of different growth forms and species in primary forests, secondary forests, and old‐fields (abandoned pastures) in southeastern Mexico. I removed by hand all plants (≤100 cm tall, including roots) and litter from 20, 0.25 m² plots in each habitat. For 1 yr, I counted the number of plant species (5–50 cm tall) recruited, grouped them into different growth forms, and compared them to undisturbed control plots. Prior to manipulation, the standing density of trees and lianas was highest in primary and secondary forests. Shrubs were more abundant in secondary forests, whereas herbs, epiphytes, and hemi‐epiphytes were more abundant in old‐fields. Herbaceous plants appeared as important components of the community in all habitats. The removal of low vegetation increased total plant recruitment in all habitats. Considering each growth form, the absence of vegetation increased recruitment in primary forests for herbs, in secondary forests for epiphytes and hemi‐epiphytes, in old‐fields for trees, and for lianas in primary forests and old‐fields. In vegetation removal plots, recruitment of species was greater in pastures, lower in secondary forest, and similar in primary forest with respect to control plots. Depending on habitat type, species, and growth form, the presence of low vegetation may act as a recruitment barrier or facilitator for different species, affecting plant community structure, diversity, and composition in different habitats.     

The influence of aspect on the early growth dynamics of hydroseeded species in coal reclamation areas

Question: Does aspect affect hydroseeding success and the development of vegetation during early vegetation establishment on the steep slopes of coal wastes during the reclamation process? Location: Open‐pit coal mine near Villanueva de la Peña, northern Spain. Methods: In the first year after hydroseeding, we monitored the dynamics of hydroseeded species in three permanent plots of 20 m² on north‐ and south‐facing slopes every two months. Soil properties and weather conditions were also monitored. Results: Aspect was related to total plant cover during early revegetation, and south‐facing slopes had the lowest cover. Aspect also influenced the early dynamics of hydroseeded grasses and legumes establishing on these slopes. Grass cover was greater on the north slope throughout the study, but differences in plant cover between north and south slopes appeared later for the legumes. Aspect also affected the relative contribution of both of grasses and legumes to the total plant cover, with grasses dominant on both northern and southern slopes, except during the summer on the southern slope. The species with the greatest difference in cover between the north‐ and south‐facing slopes were Festuca spp., Lolium perenne and Trifolium repens. Conclusion: In coal mine reclamation areas of Mediterranean climates, differences in the development of hydroseeded species depended on the slope of the coal mine reclamation areas, and this information is of importance to managers in selecting species for use in reclamation.