Sustainable Rangeland Grazing in Norse Faroe

The introduction of domestic livestock, particularly sheep, and rangeland grazing by Norse settlers to Faroe during the ninth century has generally been described as a major pressure on a sensitive landscape, leading to rapid and widespread vegetation change and contributing to land degradation. This view has, however, been developed without consideration of Norse grazing management practices which may have served to minimize grazing impacts on landscapes as well as sustaining and enhancing vegetation and livestock productivity. These alternative scenarios are considered using a historical grazing management simulation model with Faroese climate and vegetation inputs and given archaeological, historical and palaeoenvironmental parameters. Three contrasting rangeland areas are investigated and, based on the maximum number of ewe/lamb pairs the rangeland could sustain, modeling suggests that utilizable biomass declined with the onset of grazing activity, but not to a level that would cause major changes in vegetation cover or contribute to soil erosion even under climatically determined poor growth conditions. When rangeland areas partitioned into what are termed hagi and partir are modeled, grazing levels are still within rangeland carrying capacities, but productivities are variable. Some rangeland areas increase biomass and livestock productivities and biomass utilization rates while other rangeland areas that were too finely partitioned were likely to suffer substantial decline in livestock productivity. Partitioning of rangeland is a likely contributor to long-term differentiation of landscapes and the relative success of settlements across Faroe beyond the Norse period.     

Early primary succession on Mount St. Helens,Washington, USA

Abstract. The north slope of Mount St. Helens was sampled with 141 circular 100-m² plots to describe vegetation and environmental patterns 13 yr after the 1980 eruption. At least 114 vascular plant taxa were encountered. We recognized four habitat types: Refugia, Pumice barrens, Pyroclastic surfaces and Drainages. A fifth category, Lupine patches, includes samples on primary surfaces that were rapidly colonized. Refugia provided small enclaves where underground portions of several species survived the eruption. They retained an inconsistent array of forest understory species and contained 86 species (mean = 20.8 per plot). Refugia are dominated by woody species such as Penstemon cardwellii, Rubus spp., Ribes spp. and Alnus sinuata, with herbs such as Agrostis diegoensis, Luzula parviflora and Anaphalis margaritacea. Anaphalis represents a suite of species that invaded Refugia after the eruption. Diversity (N₂ and H′) is significantly greater in Refugia than in any other habitat. No plants survived on primary sites, which remain sparsely vegetated and dominated by readily dispersed taxa. Total richness ranges from 36 species (9.9 per plot) on pyroclastic surfaces, through 42 species (11.2 per plot) in drainages, to 66 (11.7 per plot) on Pumice barrens. H′ and N₂ of the three habitats do not differ significantly. Lupine-dominated vegetation occurs sporadically in Pyroclastic and drainage habitats. Lupine patches are characterized by high Lupinus cover and a suite of invaders. These sites have high cover and 52 species (12.6 per plot). H′ and N₂ scores were significantly lower than any other habitat due to strong lupine dominance. Canonical Correspondence Analysis showed that site history and slope contributed most to species composition. Geographic effects accounted for 10 25 % of the explained species-environment relationship. Forest understory species have migrated only short distances and have made negligible contributions to vegetation development. A few species common in Refugia, including Agrostis diegoensis and Carex mertensii, have invaded barren surfaces, but most have not. Refugia also have been invaded by open site species abundant on the Pumice Plain. The heterogeneity of plots within habitat types and small statistical linkage of vegetation to environmental and spatial factors suggests that stochastic events have played a leading role in early primary succession.     

Lentic Meadows and Riparian Functions Impaired After Horse and Cattle Grazing

Perennially and intermittently available water in lentic, spring-fed herbaceous meadows supports wetland plants that build and maintain absorbent soil organic matter, capture sediment, prevent erosion, and thereby sustain riparian ecosystems. Enhanced forage and available water attract a diversity of wildlife and grazing animals that can degrade riparian vegetation through prolonged overuse. We tested novel monitoring methods and adapted existing methods to obtain quantified vegetation data that have been consistently linked to riparian functionality and compared these data to ungulate species use. We quantified ungulate use with time-lapse cameras at 10 Nevada spring-fed herbaceous meadows where core greater sage-grouse (Centrocercus urophasianus) habitat, public land grazing allotments, and free-roaming horse (Equus caballus) herd management areas (Bureau of Land Management) or territories (U.S. Department of Agriculture Forest Service) overlapped. Free-roaming horses used most study sites over longer periods and grazed more intensely than cattle or domestic sheep. Native ungulate grazing intensity was comparatively negligible. Free-roaming horses selected spring-fed meadow sites on average 51 (±33 [SE]) times more than the surrounding rangelands, and cattle selected them 30 ± 23 times more. Within the wettest area of a site, study sites with longer duration of use and higher intensity of use had more soil alteration and bare ground. Riparian ecosystem degradation occurred where meadows had limited rest or recovery time from grazing during the growing season. At all sites we noted loss of riparian function, especially within the hydric areas with the highest potential to grow abundant cover of stabilizing wetland plant species. Transects for monitoring soil alteration and vegetation cover in this hydric location can provide a leading indicator of riparian recovery or degradation and help in adjusting free-roaming horse population levels or livestock management strategies. © 2021 The Wildlife Society.     

Acceleration of vegetation succession on eroded land by reforestation in a subtropical zone

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.     

Seed burial depth,seedling emergence,and height as affected by animal trampling in marl soils

Depending on the plant species, animal trampling significantly affects vegetation by affecting seed burial in marl soil (MS). Soil seed bank dynamics (SSBDs) and seedling characteristics were investigated under light, moderate, and heavy grazing intensities in a MS and non-marl soil (NMS). Considering the seed characteristics and appendages, SSBDs and seedling characteristics significantly changed under grazing intensities (p?<?0.05) where the greatest change was observed in MS (more than NMS). Seed size and seed sphericity index showed a significant positive relationship with seed burial depth under heavy grazing, while the seed length and width and the presence of appendages had the strongest negative correlation with seed burial under exclosure/light grazing (p?<?0.05). Depth of 4–6 cm had the most seed numbers under heavy grazing. Moreover, heavy grazing reduced the diversity index in SSB by 34%, while the diversity index in vegetation has decreased by 41% compared to control.

     

Directional and non‐directional vegetation changes in a temperate salt marsh in relation to biotic and abiotic factors

Abstract. The effects of reduction and cessation of sheep grazing on salt‐marsh vegetation were studied on a formerly intensively grazed salt marsh in northern Germany. Plant species cover was recorded in 45 permanent plots from 1992 to 2000. In 1995, physical and chemical soil parameters were analysed. Results of Redundancy Analysis (RDA) indicated that salinity and the depth of anoxic conditions below the surface were the most important soil factors related to the spatial vegetation pattern. Furthermore, plant species distribution was influenced by present and past grazing intensity, by soil grain size and nitrogen content. Vegetation changes over 9 yr were analysed by non‐linear regression. The cover of Aster tripolium, Atriplex portulacoides, and, to a lesser extent, Artemisia maritima and Elymus athericus increased due to reduced grazing pressure, whereas the cover of Salicornia europaea decreased. After a strong increase in the first years Aster decreased 2 to 6 yr after abandonment. In the mid salt‐marsh zone Puccinellia maritima was replaced by Festuca rubra. The cover of Puccinellia, Festuca, Suaeda maritima, Glaux maritima and Salicornia fluctuated strongly, probably due to differences in weather conditions and inundation frequency. Species richness per 4 m² generally increased while vegetation evenness decreased during the study period. Only in the high salt marsh abandoned for 9 yr did the number of species decrease slightly. Thus far, cessation of grazing did not lead to large‐scale dominance of single plant species.     

Changes in the vegetation of Quercus pubescens woodland after cessation of coppicing and grazing

Abstract. The cessation of coppicing and grazing in Quercus woodlands, with its subsequent changes in the structure, composition and functioning of vegetation communities, is becoming more frequent throughout the Mediterranean Basin. In southern France, we have studied successional changes in Quercus pubescens woodlands by visiting previously studied sites 18 yr later. Changes in vertical structure, species richness, floristic composition, life form and dispersal type were analysed and compared between woodlands that had previously been grazed or ungrazed. Both successions showed a decline in vegetation cover in the 0–25 cm height class and in the height class immediately under the canopy layer, due to oak litter accumulation and tree ageing. In post‐grazing succession, the abandonment of grazing and associated burning has allowed the vegetation cover to increase in the 0.25‐2 m height class. In both successions, grassland species decreased in frequency and forest species increased, a trend which was stronger in undisturbed succession. Species richness decreased with time in the undisturbed succession, but remained stable in the post‐grazing succession mainly because of the slow decline of plants linked to grazing. In undisturbed succession, therophytes and hemicryptophytes decreased. In contrast, therophytes and hemicryptophytes remained stable in post‐grazing succession. In both successions, endozoochorous species (notably Ruscus aculeatus) increased. Plants dispersed by non‐animal vectors decreased in undisturbed succession, but stability was observed in most of the dispersal types in post‐grazing succession. These results showed that a time‐lag existed between undisturbed succession and post‐grazing succession, the latter remaining at a younger stage of successional development due to more recent impact of grazing. However, both successions have converged suggesting that most of the traces of grazing on vegetation will disappear within a few years. The vegetation of these coppices, regardless of the previous grazing regime, will become increasingly similar to the vegetation of undisturbed woodlands. However, their floristic composition will probably never be identical to that of undisturbed woodlands, mainly because of the rarity of these undisturbed woodlands and of the short‐distance dispersal of many forest plant species.     

基于结构方程模型分析荒漠啮齿动物优势种对不同放牧干扰的响应

放牧被认为是草地生态系统的主要干扰之一。许多研究表明,放牧影响了啮齿动物的个体条件、繁殖、种群动态、群落组成及群落多样性等多个方面。由于受传统统计学方法的限制,这些研究只是单独的对放牧作用进行假设检验,而没有将多个假设放在同一个框架内进行验证。2006—2011年,采用标志重捕法对内蒙古阿拉善荒漠区不同放牧生境中啮齿动物优势种的数量进行研究并使用结构方程建模的方法将可能影响荒漠啮齿动物优势种的环境因子(气候条件、土壤硬度、植物隐蔽、植物生物量等19个指标)与啮齿动物优势种种群动态结合后进行多假设检验,旨在找出不同放牧干扰下制约优势啮齿动物环境因子的发生途径。结果表明:气候条件对五趾跳鼠和三趾跳鼠有直接不利影响,隐蔽对于两足活动的五趾跳鼠有负效应,而对四足活动的子午沙鼠有正效应。植物生物量对五趾跳鼠有正效应,但对子午沙鼠有负效应。土壤硬度的增加间接的有利于五趾跳鼠,对子午沙鼠有直接的正效应。因此荒漠啮齿动物优势种种群动态是多个过程共同作用的结果,气候条件是驱动啮齿动物种群动态的根本原因,而放牧会因为改变植物隐蔽而影响啮齿动物在群落中的组成。     

Vegetation re‐establishment on land previously subject to control of Pteridium aquilinum by herbicide

Abstract. Vegetation development after conventional bracken control with herbicide in the uplands is often slow and rarely results in the development of the target community. Two experiments were established on contrasting sites to investigate cost‐effective methods for the re‐establishment of vegetation dominated by Calluna vulgaris (heather), which is the usual target community seen as the desired replacement for Pteridium aquilinum in the uplands by many land managers. At one site, where grazing intensity was low and shelter was sufficient to prevent rapid Pteridium litter loss, the necessary treatments to establish Calluna were to disturb the litter and add a source of Calluna seeds. A difference between continued Pteridium control or a relaxation of control was not observed over the time‐scale of the experiment. At the second site, where grazing intensity was high and shelter minimal, vegetation dominated by Rumex acetosella had developed on a thin but dense litter layer. To enhance Calluna regeneration it was necessary to prevent sheep grazing, disturb the remaining litter layer and add a source of Calluna propagules. A nurse crop hindered Calluna establishment due to its vigorous growth. At neither site was an initial application of fertilizer an aid to Calluna establishment. It is possible to devise methods for the re‐establishment of Calluna at sites where previous attempts at Pteridium control alone have not had the desired effect on vegetation development. However, the precise choice of methods used is dependent on the grazing management at the site. High levels of livestock grazing prevented Calluna establishment, but some trampling may aid litter breakdown. The ability to adjust stocking rates and access to the site by machinery are critical factors to take into account in producing an effective strategy for long‐term Pteridium control and its replacement by target vegetation.     

Effects of Erosion from Mounds of Different Termite Genera on Distinct Functional Grassland Types in an African Savannah

A key aspect of savannah vegetation heterogeneity is mosaics formed by two functional grassland types, bunch grasslands, and grazing lawns. We investigated the role of termites, important ecosystem engineers, in creating high-nutrient patches in the form of grazing lawns. Some of the ways termites can contribute to grazing lawn development is through erosion of soil from aboveground mounds to the surrounding soil surface. This may alter the nutrient status of the surrounding soils. We hypothesize that the importance of this erosion varies with termite genera, depending on feeding strategy and mound type. To test this, we simulated erosion by applying mound soil from three termite genera (Macrotermes, Odontotermes, and Trinervitermes) in both a field experiment and a greenhouse experiment. In the greenhouse experiment, we found soils with the highest macro nutrient levels (formed by Trinervitermes) promoted the quality and biomass of both a lawn (Digitaria longiflora) and a bunch (Sporobolus pyramidalis) grass species. In the field we found that soils with the highest micro nutrient levels (formed by Macrotermes) showed the largest increase in cover of grazing lawn species. By linking the different nutrient availability of the mounds to the development of different grassland states, we conclude that the presence of termite mounds influences grassland mosaics, but that the type of mound plays a crucial role in determining the nature of the effects.     

Long‐term vegetation changes in experimentally grazed and ungrazed back‐barrier marshes in the Wadden Sea

Abstract. Vegetation succession in three back‐barrier salt marshes in the Wadden Sea was studied using a data set comprising 25 years of vegetation development recorded at permanent quadrats. The effect of livestock grazing on succession was assessed by comparing quadrats where grazing was experimentally prevented or imposed. We studied changes at the species level as well as at the level of the plant community. Special attention is given to effects on plant species richness and community characteristics that are relevant for lagomorphs (hares and rabbits) and geese. Inundation frequency and grazing were most important in explaining the variation in species abundance data. The three marshes studied overlap in the occurrence of different plant communities and the observed patterns were consistent between them. Clear differences in frequency and abundance of plant species were observed related to grazing. Most plant species had a greater incidence in grazed treatments. Species richness increased with elevation, and was 1.5 to 2 × higher in the grazed salt marsh. Grazing negatively influenced Atriplex portulacoides and Elymus athericus, whereas Puccinellia maritima and Festuca rubra showed a positive response. The communities dominated by Elymus athericus, Artemisia maritima and Atriplex portulacoides were restricted to the ungrazed marsh. Communities dominated by Puccinellia maritima, Juncus gerardi and Festuca rubra predominantly occurred at grazed sites. As small vertebrate herbivores prefer these plants and communities for foraging, livestock grazing thus facilitates for them.     

Utilisation of Wadden Sea salt marshes by geese in relation to livestock grazing

To arctic breeding geese, the salt marshes of the International Wadden Sea are important spring staging areas. Many of these marshes have always been grazed with livestock (mainly cattle and sheep). To evaluate the influence of livestock grazing on composition and structure of salt-marsh communities and its consequences for habitat use by geese, a total of 17 pairs of grazed and ungrazed marshes were visited both in April and May 1999, and the accumulated grazing pressure by geese was estimated using dropping counts. Observed grazing pressure was related to management status and to relevant vegetation parameters.The intensity of livestock grazing influences the vegetation on the marsh. Salt marshes that are not grazed by livestock are characterised by stands with a taller canopy, a lower cover of grasses preferred by geese, and a higher cover of plants that are not preferred.Overall goose-dropping densities are significantly lower in ungrazed marshes compared to marshes grazed by livestock. Some ungrazed marshes had comparatively high goose grazing pressure, and these were all natural marshes on a sandy soil, or artificial mainland marshes with a recent history of intensive livestock grazing. Goose grazing is associated with a short canopy. The plant communities with short canopy, dominated by Agrostis stolonifera, Festuca rubra and Puccinellia maritima, together account for 85% of all goose droppings in our data.The sites that were not visited by geese differed very little from those that were visited, in the parameters we measured. This might indicate that there was no shortage of available habitat for spring staging geese in the Wadden Sea, in the study period.     

Carbon sequestration and soil restoration potential of grazing lands under exclosure management in a semi‐arid environment of northern Ethiopia

Exclosures are used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, this study assessed the impact of grazing exclosure on carbon sequestration and soil nutrients under 5 and 10 years of grazing exclosures and freely grazed areas in Tigray, northern Ethiopia. Carbon stocks and soil nutrients increased with increasing grazing exclusion. However, open grazing lands and 5 years of grazing exclosure did not differ in above‐ and belowground carbon stocks. Moreover, 10 years of grazing exclosure had a higher (p < 0.01) grass, herb and litter carbon stocks compared to 5 years exclosure and open grazing lands. The total carbon stock was higher for 10 years exclosure (75.65 t C ha^‐1) than the 5 years exclosure (55.06 t C ha^‐1) and in open grazing areas (51.98 t C ha^‐1). Grazing lands closed for 10 years had a higher SOC, organic matter, total N, available P, and exchangeable K + and Na + compared to 5 year's exclosure and open grazing lands. Therefore, establishment of grazing exclosures had a positive effect in restoring degraded grazing lands, thus improving carbon sequestration potentials and soil nutrients.     

Use of Plant Strategy Ordination,DCA and ANOVA to elucidate relationships among habitats of Salix planifolia and Salix monticola

Abstract. Detrended Correspondence Analysis (DCA) was used on a data set of 112 species from 14 stands dominated by Salix planifolia and/or S. monticola. Environmental variables were determined which might be important to explain differences in stand vegetation composition, and willow stature (height), in willow carrs in the Rocky Mountain National Park. Correlation of environmental variables with DCA stand scores indicate that peat depth and soil redox potential are highly related to the primary DCA axis. Soils in stands of S. planifolia are more reduced in the early summer and have greater peat depths, than soils in stands of S. monticola. The second DCA axis is related to a water chemistry gradient of hydrogen ion, sulphate, and ammonium concentration. Four environmental variables selected by correlation analysis were regressed on stand scores from the first two DCA axes. Regression coefficients of August soil redox potential and soil water pH were significantly non-zero on the primary DCA axis. In addition to overall vegetation relationships elucidated by DCA, the relationships between willow stature and environmental variables were tested by simultaneous ANOVAs. ANOVA results and DCA ordinations indicate that S. planifolia and S. monticola plants achieve the greatest stature in the least reduced soils, and in shallow peat. Competitive, stress tolerant, and ruderal plant strategy theory applied to the vegetation data produced an arrangement of stands highly correlated to the DCA Axis 1 stand arrangement. These correlations indicate that the primary axis of vegetation structure can be extracted either by species composition, or species morphology/physiology relationships. Concurrent use of DCA and plant strategy theory is suggested as a tool for the prediction of community composition.     

Influence of livestock grazing on vegetation in a saline area in Northeast Thailand

The influence of grazing by water buffalo (Bubalas bufalis) and cattle (Bos taurus) was estimated for vegetation inside and outside cages in a saline area at Khon Kaen, Northeast Thailand. The home range of water buffalo and cattle shifted in response to the period of rice cultivation: during the rice-growing season these animals grazed on roadsides and abandoned places such as the study area; after rice harvest they grazed mainly rice stubble on the paddy. The vegetation in the study area was divided into three types: 1) dominated by the annual grassesChloris barbata andIschaemum rugosum; vegetational cover and plant height in the cage increase due to the increase of these grasses; 2) thorny shrub patch ofMaytenus mekongensis; other species in this patch almost died a year after experimental elimination of this shrub; this salt-tolerant shrub not only protected the co-existing species from grazing, but also suppressed salt accumulation; 3) almost pure stand ofPanicum repens; livestock preferred this perennial grass over others. Electrical conductivity (EC) of surface soil did not increase under the vegetation protected from grazing. Litter and other organic matter in the soil suppressed the upward movement of brine. Grazing led to an increase of bare ground where NaCl accumulated, and modified the heterogeneity of vegetation, which was reflected in the degree of salt accumulation.     

Woodlands on farms in southern New South Wales: A longer-term assessment of vegetation changes after fencing

Summary Fencing incentive programmes have been widely used throughout Australia to assist landholders to fence remnant woodland vegetation, to control grazing and improve native vegetation condition. This study investigated vegetation and soil condition in remnant woodlands fenced for 7–9 years in the Murray catchment area in southern New South Wales. Surveys were undertaken at 42 sites, where vegetation condition was assessed in paired fenced and unfenced sites. Semi‐structured interviews were also conducted with landholders to gather management information. Woodlands surveyed were Yellow Box/Blakely's Red Gum (Eucalyptus melliodora/E. blakelyi, 15 sites), Grey Box (E. microcarpa, 13 sites) and White Cypress Pine (Callitris glaucophylla, 14 sites). Fencing resulted in a range of responses which were highly variable between sites and vegetation types. In general, fenced sites had greater tree regeneration, cover of native perennial grasses, less cover of exotic annual grasses and weeds, and less soil compaction than unfenced sites. However, there was greater tree recruitment in remnants to the west of the study area, and tree recruitment was positively correlated with time since fencing. Within sites, tree recruitment tended to occur in more open areas with a good cover of native perennial grasses, as compared to sites with a dense tree canopy, or dominated by exotic annuals grasses or weeds. Forty‐eight per cent of fenced sites had no tree regeneration. There was a significant decline in native perennial grasses, and increase of several unpalatable weeds in many fenced areas, suggesting certain ecological barriers may be preventing further recovery. However, drought conditions and associated grazing are the most likely cause of this trend. A range of grazing strategies was implemented in fenced sites which require further research as a conservation management tool. Continued long‐term monitoring is essential to detect key threats to endangered woodland remnants.     

Is livestock grazing compatible with amphibian diversity in the High Mountains of Córdoba, Argentina?

The High Mountains of Córdoba, Argentina have a long evolutionary history of grazing by large herbivores. However, about 400?years ago, European livestock were introduced and gradually replaced native herbivores. Since the 1920s, domestic herbivores have been the only large herbivores present in the area, causing severe soil erosion and a threat to the system diversity. The endemic fauna of the region includes four amphibian species. We evaluated the effect of livestock rearing on amphibian diversity and water bodies in woodlands and grasslands of the High Mountains of Córdoba. The work was conducted on stream stretches and ponds in two contrasting grazing situations: an area with livestock presence and another area where livestock was excluded 14?years ago. The following variables were recorded at each sampling site: amphibian richness and abundance, percentage of emergent, submerged and peripheral vegetation in areas surrounding the water bodies, water pH, and water dissolved O₂. No significant differences were detected in amphibian diversity between streams of both grazing situations, whereas a greater diversity (p?<?0.01) was observed in ponds in grazed grasslands. Our results suggest that livestock rearing, qualitatively measured as grazing and 14?years of livestock exclusion, in the study area would not have negative effects on amphibian diversity. This finding might be due to the long evolutionary grazing history of the area, large-scale livestock exclusion exhibiting a novel scenario. The ongoing reintroduction of native grazers may provide the benefits of grazing without the consequent soil erosion and habitat degradation associated with domestic livestock.     

A field assessment of the success of moorland restoration in the rehabilitation of whole plant assemblages

Question: How successful is restoration that is focused on a single dominant plant at enabling the reassembly of the whole vegetation assemblage and what factors affect the relative success of such restoration? Location: Moorlands in England and Scotland, UK. Methods: Vegetation composition was sampled in grassdominated (degraded), restored and long established Calluna vulgaris‐dominated (target) areas within eight moorland restoration sites. Additional soil and biogeographic data were collected. Data were analysed by Canonical Correspondence Analysis, which allowed the impact of moorland management to be examined. Results: All sites showed good restoration success when the dominant managed species (Calluna vulgaris, Molinia caerulea and Nardus stricta) were considered. Restoration success of the remainder of the plant assemblage, disregarding these dominant species, was lower with restored samples at some sites differing little from their respective degraded samples. Moors restored solely by grazing exclusion were more similar to their respective targets than were those restored by more intensive mechanical means. The most important factors in explaining vegetation assemblages were management status (i.e. whether samples represented degraded, restored or target parts of the moor) and latitude. Conclusions: The project demonstrates that, where possible, restoration should be attempted by grazing exclusion alone. Furthermore the importance of applying local restoration targets and of monitoring the whole plant assemblages when assessing the success of moorland restoration is highlighted.     

Can Organic Amendments Be Useful in Transforming a Mediterranean Shrubland into a Dehesa?

Transforming a shrubland into a dehesa system may be useful for recovering certain productive and regulatory functions of ecosystems such as grazing potential, soil erosion control, and also for reducing the risk of wildfire. However, the productivity of the herbaceous cover and tree development in the transformed system may be limited by soil fertility, especially after wildfire events. Previous studies have shown that adequate doses of sewage sludge may improve soil fertility and facilitate plant recovery, but few studies have focused on plant biodiversity assessment. Here, we compare the effects of sewage sludge that has undergone different post‐treatments (dewatering, composting, or thermal drying) as a soil amendment used to transform a fire‐affected shrubland into a dehesa, on tree growth and pasture composition (vegetation cover, species richness, and diversity). In the short term, sewage sludge causes changes in both pasture cover and tree growth. Although no major differences in vegetation species richness and composition have been detected, fertilization using sewage sludge was shown to modify the functional diversity of the vegetation community. Rapid replacement of shrubs by herbaceous cover and ruderal plants (e.g. Bromus hordeaceus and Leontodon taraxacoides) and of the three grass species sown (Festuca arundinacea, Lolium perenne, and Dactylis glomerata) was observed, whereas N‐fixing species (leguminous) tended to be more abundant in nonfertilized soils and soils amended with composted sludge. These results indicate that sewage sludge modifies the functionality of vegetation when applied to soils, and that the response varies according to the treatment that the sludge has undergone.     

Impact of grazing and atmospheric nitrogen deposition on the vegetation of dry coastal dune grasslands

Abstract. A five-year experimental study was carried out to examine the combined effects of grazing and atmospheric nitrogen deposition on the vegetation of three dry dune grasslands: one short species-rich, one short species-poor, and one predominated by tall graminoids. Additional fertilization with nitrogen had no significant effect, neither in grazed nor in non-grazed plots. Exclusion of grazing by rabbits resulted in an increase in the frequency of perennial graminoids and a decrease in the frequency of annual graminoids and herbs. Nevertheless, species diversity remained the same in the species-rich grassland. During the experiment, the above-ground biomass increased in all nongrazed plots and the amount of bare soil and mosses decreased. The vegetation changes occurred mainly within one year after the exclusion of grazing. An exception is the grass-dominated site where the amount of Calamagrostis epigejos increased gradually from ca. 20 % in the first two years to about 50 % in the fourth and fifth year. Grazing by rabbits seems essential to prevent graminoids to become predominant in the dry dunes. If graminoids are dominant, grazing by horses can be an appropriate method to restore the original grassland vegetation. After six months of grazing by horses the grass-dominated site showed a decrease of the frequency of perennial graminoids, from 95 % to 80 %, and an increase of the frequency of perennial herbs, from 2.5 % to between 13 and 20 %.