不同干扰荒漠生境中子午沙鼠的繁殖及种群动态特征

子午沙鼠(Merionesmeridianus)广泛分布于我国西北部地区,是荒漠啮齿动物群落的优势鼠种。种群繁殖特征是动物生活史参数中的一个重要组成部分,是种群数量补充的重要来源,而干扰是影响繁殖特征的重要因素。本研究于2012~2014年,在位于蒙古阿拉善左旗南部典型荒漠的野外实验区,设置禁牧、开垦、过牧、轮牧4种不同干扰样地,使用铗日法对实验样地子午沙鼠相对数量及繁殖特征进行调查。4种不同干扰生境中的子午沙鼠种群数量具有显著差异,禁牧过牧轮牧开垦;雌雄性比在轮牧生境中最高,开垦生境次之,禁牧生境最低;4种干扰生境中,轮牧样地子午沙鼠雌鼠怀孕率显著高于禁牧、过牧和开垦样地;雄鼠的睾丸下降率在过牧干扰样地显著高于其他3种干扰方式样地,轮牧样地雄鼠睾丸下降率最低;雌鼠平均胎仔数在4种干扰生境间无显著性差异;轮牧干扰样地繁殖指数显著高于其他3种干扰方式样地;繁殖指数、怀孕率及睾丸下降率对密度的反馈作用最为明显,但在不同的干扰生境中其反馈特征有差异。综上,子午沙鼠在轮牧生境中各繁殖特征指数最高,繁殖能力最强,种群密度相对较高,更适合其生存,其密度制约效应表现最为明显。     

Does grazing induce intraspecific trait variation in plants from a sub‐humid mountain ecosystem?

Livestock grazing represents an important human disturbance for vegetation worldwide. We analysed the intraspecific differences in mean trait values between different grazing regimes (ungrazed and grazed) and explored whether these differences are consistent across species in a sub‐humid mountain ecosystem in Central Argentina. We selected 14 species of eight different families, co‐occurring in both regimes and comprising herbaceous (grasses and forbs) and woody (shrubs and trees) plants. For each species and grazing regime we measured 12 traits related to plant size, carbon fixation and water use. We found that plants in the grazed regime had consistently smaller leaves and shorter stature and internodal length than plants of the same species under the ungrazed regime. For the remaining traits the responses were species‐specific. Dry matter content, leaf tensile strength and minimum leaf water potential (Ψ_leaf) showed contrasting responses to grazing. Specific leaf area, wood density and potential water content of wood showed almost no significant responses except for very few species. Neither leaf area per shoot mass nor leaf area per sapwood area differed significantly between grazing regimes. Our study suggested that the intraspecific variation found for the size‐related traits would allow species to respond to grazing without modifying markedly other structural traits, a plastic response that might increase the probability of species success.     

Changes in composition and structure of a tropical dry forest following intermittent cattle grazing

In northwestern Costa Rica, cattle are being used as a "management tool" to reduce the amount of combustible material, mainly dominated by Hyparrhenia rufa, an African grass. This project is being developed within Parque Nacional Palo Verde and Reserva Biológica Lomas Barbudal, both of which form part of the only remaining tropical dry forests in Mesoamerica. To determine the short-term effects of cattle grazing on the natural vegetation, we compared the floristic composition within Palo Verde in an area under intermittent cattle grazing with an area that has not been grazed. There were significantly fewer plant species in the area with intermittent cattle grazing compared to the area with no grazing. Floristic composition of these two habitats was different as reflected by both Fisher's alpha values and the Shannon index of diversity, both of which were significantly higher in the ungrazed site. The ungrazed area contained more plant species and was more similar to mature forest. The structure of the vegetation was significantly different between the intermittently grazed and ungrazed sites with more small stems (1-5 cm dbh) and fewer large stems (> 5 cm dbh) in the intermittently grazed habitat. These results indicate that cattle grazing has an impact on the dry forest by reducing the relative abundance and density of larger tree species and by changing the species composition and structure of the community. The current management plan implemented in Palo Verde and Lomas Barbudal is not appropriate because of the impact that cattle have on the structure of the natural vegetation and should not be considered a viable alternative in other protected areas of dry forest in the Neotropics. We suggest that alternative fire prevention measures be evaluated including hand-cutting H. rufa, the creation of more frequent and larger fire breaks, and the development of green breaks.     

Effects of long-term grazing on the morphological and functional traits of Leymus chinensis in the semiarid grassland of Inner Mongolia, China

Livestock grazing represents a major human disturbance to grasslands throughout the world. We evaluated the effects of long-term grazing (>20 years) on a dominant perennial grass species, Leymus chinensis (Trin.) Tzvel., in the semiarid grassland of Inner Mongolia, China, in terms of its morphological and functional responses. L. chinensis, one of the most abundant species in semiarid grassland, had significantly smaller leaf area, fewer vegetative tillers and shorter shoot internodes length, but significantly greater specific leaf area for the individuals in the grazing plot than those in the exclosure (grazing-free) plot. Long-term grazing also altered the relative distribution of biomass to leaves, roots and rhizomes. The biomass, coverage and the number of species were lower in the grazing plot by 50–70% in comparison with those in the grazing-free plot. In addition, the long-term grazing substantively decreased the physiological capacities of this grass species, including significantly lower net photosynthetic rate, apparent quantum efficiency, photochemical efficiency of PSII and water use efficiency. Significantly higher stable oxygen isotope ratios (δ ¹⁸O) of the soil water in the grazing plot than those in the grazing-free plot indicated a much higher soil evaporation in the grazing plot because of less litter coverage. Seasonal patterns in the δ ¹⁸O values of the stem water of L. chinensis and three other common species in the grazing and grazing-free plots indicated that plants in the grazing and grazing-free plots might shift their water sources differently from a dry month (June) to a wet month (August). This study illustrated the importance of using different approaches to study the possible responses of grass species in arid regions to human disturbances, such as long-term grazing.     

Dynamics of cryptogamic soil crusts in a derived grassland in south‐eastern Australia

We examined the dynamics of cryptogamic soil crusts in a derived (disclimax) grassland near Orange in south‐eastern Australia. Changes in the cover of cryptogamic crusts and floristics and abundance of the constituent species were measured on four treatments with two levels each of grazing and cultivation. Twenty‐two lichens, mosses and liverworts were found at the study site and, of these, 13 were collected in the quadrats. Three moss species (Barbula calycina, Eccremidium arcuatum and Bryum pachytheca) and one lichen species (Cladonia tessalata) accounted for 67% of total cover‐abundance scores. Generally, cover‐abundance was significantly higher in the unvegetated microsites than in the vegetated microsites. Species richness was not significantly different between the four grazing‐cultivation treatments but, on average, there were significantly more species in the unvegetated microsites (mean = 3.2 species) than in the vegetated microsites (0.54 species). Grazing and cultivation resulted in significantly greater cover of bare ground and consequently significantly greater crust cover. Averaged across all treatments, approximately half of the area of unvegetated soil was occupied by cryptogams. Overall, the results indicate that lichens and bryophytes are important components of derived temperate grasslands, surviving in even densely vegetated swards. This study suggests that strategies which disturb the soil surface (e.g. grazing and cultivation) will stimulate the abundance and cover of soil crust organisms by increasing the availability of unvegetated microsites.     

围封与放牧管理对高寒草甸植物功能性状和功能多样性的影响

植物功能性状能够响应生存环境的变化并直接决定着生态系统功能。为了揭示围封与放牧管理对物种共存和驱动群落构建的影响机理,该研究以青藏高原东缘高寒草甸为对象,分析了围封与放牧处理对植物功能性状和功能多样性的影响。结果显示:(1)在群落水平,放牧显著降低了比叶面积和植物高度;在物种水平,放牧群落中多数杂类草比叶面积减小,而莎草类和禾草类的比叶面积在处理间无显著差异。(2)叶干物质含量与比叶面积在围封和放牧处理中均呈显著负相关关系,在放牧处理中,叶干物质含量与植物高度呈显著的二次函数关系,即随着叶干物质含量的增大,植物高度先减小后增大;在同等比叶面积的情况下,与围封相比,放牧降低了叶干物质含量;在相同叶干物质含量的情况下,与围封相比,放牧降低了植物高度。(3)放牧在总体上降低了种间性状的平均差异,植物性状表现出趋同响应,具体表现为放牧减小了叶干物质含量和植物高度的种间差异;与围封相比,放牧显著提高了功能均匀度,减小了功能分离度。研究表明,不同植物种对放牧的响应模式存在差异,放牧降低了种间对光资源的竞争,可能增加了对土壤养分的竞争,放牧驱动群落构建的过程中,土壤养分是非常重要的作用因子,说明放牧影响物种共存依赖于对多种资源的竞争。     

轮牧时间对荒漠草原土壤种子库特性的影响

探讨季节性放牧下土壤种子库的特性对荒漠草原合理利用具有重要作用。以宁夏荒漠草原为对象,通过封育(FY)、传统时间轮牧(FG)、延迟开始轮牧(YG)、提前结束轮牧(TG)、延迟开始并提前结束轮牧(YT)和自由放牧(ZY)处理,研究了0～5、5～10、10～15 cm土层土壤种子库物种组成、种子库密度、垂直分布、多样性及其与地上植被的关系,探讨了种子库与土壤环境因子的关系。结果表明: 研究区土壤种子库物种组成共有9个科21个种。土壤种子库物种组成以TG种子库种类最多,达13种,而FY和ZY土壤种子库种类最少,各8种。ZY土壤种子库密度显著高于FY、YG、TG、YT;FY的土壤种子库中多年生植物种子数量最多,达32.0%;ZY种子库中多年生植物种子数最少,仅为12.4%,主要以有性繁殖的一年生杂类草种子为主;土壤种子库主要集中于0～5 cm表层土壤,随着土层深度的增加,土壤种子库大小降低。土壤种子库的优势度和多样性均以FY最高,优势度、多样性和均匀度均以ZY最低。土壤种子库与地上植被的相似性总体较低,相比之下FG及ZY种子库与地上植被相似性较高,FY最低。土壤水分、有机质、全氮、全磷、土壤容重是影响土壤种子库的主要土壤因子。与传统全年自由放牧相比,季节性四区轮牧能使荒漠草原土壤种子库多年生植物种类、密度以及种子库物种丰富度、多样性和均匀度增加,虽作用不及长期封育草地,但对荒漠草原的利用与保护具有重要意义。     

The role of geologic grazing refuges in structuring Mediterranean grassland plant communities

We tested the hypothesis that small rock-enclosed geologic refuges have an important role in maintaining grazing-sensitive species in grassland with a long history of intense grazing. The study was carried out in Mediterranean grassland in a basalt landscape in northern Israel. Community composition was compared in 63 sites between samples of 1 m² quadrats in two microhabitats: (1) rock-enclosed, presumed “refuges” and (2) rock-adjacent, “near refuges” but just outside them, accessible to cattle grazing. Median refuge area was 2.75 m², median rock height and diameter around refuges were 1.10 m and 1.50 m. Median height of residual dry herbage was 1.41 m in refuges, compared to 0.38 m outside, indicating the difference in grazing intensity. Species richness at three scales (quadrat, site, all sites) was significantly greater in the near-refuge than in the refuge habitat. In the latter, many annuals were excluded by dominance of tall perennials. Twelve species (of 103) had significantly higher cover in refuges, including tall perennial grasses, tall annuals, climbers, and a shrub. A total of 53 species with a strong significant negative response to refuges were mostly small and medium height annuals. The intermediate group of 38 species with weak or non-significant responses to refuges included, among others, dominant tall grasses that were abundant both in refuges and just outside them. The latter, as well as most refuge-positive species had shown a positive response to protection in exclosures. The results support the hypothesis that small rock-enclosed habitats—more so than artificial exclosures—are effective grazing refuges for rare, grazing-susceptible species. The contribution of refuges to species richness at the landscape scale is much greater than their proportion of the area. Dispersion from refuges maintains small populations of rare species near refuges and can initiate expansion into the landscape when grazing pressure is lowered.     

Study on the effects of different levels of grazing and exclosure on vegetation and soil properties in semi-arid rangelands of Iran

Livestock grazing is one of the main factors of vegetation and soil degradation in arid and semi-arid rangelands of Iran and causes changes in diversity, vegetation, litter and soil characteristics. Therefore, this study has been conducted aimed to examine the effects of exclosure and livestock grazing on vegetation and soil. For this purpose, two grazing areas of medium and high grazing intensity and two exclosure areas (Non-grazing livestock) with duration of 8 and 11 years were selected for sampling. Then, we identified plant species, percentage of coverage of each species, measurement of diversity indices, species similarity and soil chemical properties including electrical conductivity (mho), acidity, organic matter(%), organic carbon (%), nitrogen (%), phosphorus (mg/L) and bulk density (gr/cm³) in each area and they were compared using variance analysis. The results showed that exclosure significantly at 5% level reduced organic matter percentage, electrical conductivity and organic carbon percentage, but it caused a significant increase in soil bulk density at 1% level. Similarity of plant species due to the reduction of livestock grazing intensity and increasing exclosure duration. The results also indicate Livestock grazing increased Coverage of plant family such as Poaceae, Zygophyllacea in the area due to the increase of plant species such as Peganum harmala and Poa bulbosa (non-pleasant species of class III). Based on the results, despite increasing the diversity of plant species in the area over time, increasing diversity does not increase dominant species of the area, as well as companion species increased in the composition of vegetation. It concluded that exclusion has a significant effect on vegetation improvement, vegetation cover percentage, diversity, palatability and litter percentage in the region.     

Kobresia tibetica tussocks facilitate plant species inside them and increase diversity and reproduction

Many plant species grow inside tussocks of some graminoids, but the underlying mechanisms remain unclear. We address whether some species occur and flower mainly inside tussocks so that species diversity and sexual reproduction are higher inside than outside tussocks, and whether relieving biological and physical stress is the mechanism associated with the facilitative process. In a heavily grazed grassland on the eastern Tibetan Plateau, where both physical (due to high altitude) and biological conditions (due to heavy grazing) are extremely harsh, we investigated vegetation in paired plots inside and outside 150 Kobresia tibetica tussocks and measured tussock basal area (=plot area). We also measured temperatures at soil surface, 5 and 10 cm depth and the number of animals (yaks, sheep and horses) grazing inside and outside tussocks. Sixty-seven percent of the species occurred and 42% flowered more frequently inside than outside tussocks, but none less frequently. Inside tussocks 78% species flowered, but outside tussocks only 31% did. Consequently, number of species, number of flowering species and number of inflorescences were all markedly larger inside than outside tussocks. Differences in number of species, number of flowering species and number of inflorescences inside and outside tussocks increased with increasing tussock basal area. Soil temperatures were lower inside than outside tussocks, but grazing intensity was much larger outside tussocks. Therefore, tussocks of K. tibetica facilitated the species inside them likely by grazing prevention, but not by increasing warmth. This study provides evidence that plant species colonizing tussocks of graminoids can be facilitated by the tussock species, and facilitation by grazing prevention may be one mechanism causing the coexistence of the species inside tussocks.     

Influence of grazing and fire on breeding birds and perennial plants in Cyprus scrub and forest systems

Grazing and browsing by sheep and goats has been an important anthropogenic influence on ecosystems in the Mediterranean region for centuries. This influence has changed significantly in recent decades, with a general shift from range grazing to the penning of animals. The intermediate disturbance hypothesis (IDH) proposes that perturbation - including anthropogenic disturbance - is the norm for Mediterranean ecosystems, and that higher species diversity is found under conditions of continuous, moderate disturbance. Here we test the IDH as it relates to grazing of scrub and open forest habitats in Cyprus, while also testing for the effects of fire. We carried out surveys of breeding birds and vegetation at 48 study sites in scrub and open woodland across Cyprus. We estimated relative grazing pressure (past and present) and fire history at these sites, and tested for associations between these factors, breeding bird species richness and perennial vegetation diversity. We found moderate current grazing reduces density of lower and middle level scrub, and a higher level of diversity of perennial vegetation at moderately over intensively grazed sites. We found that moderate historical grazing pressure had a positive influence on richness of breeding bird species in lower scrub habitat such as phrygana, but that this effect was weaker the taller and denser the habitat. By contrast, current grazing pressure had a negative effect on species richness in lower scrub, but species richness in grazed habitats was higher in denser, taller scrub habitat such as garrigue and maquis. Our study suggests grazing plays an important role in maintaining habitat heterogeneity but the impact on avian species richness depends on the density and height of the vegetation.     

Impacts of grazing intensity and increased precipitation on a grasshopper assemblage (Orthoptera: Acrididae) in a meadow steppe

1. Grasshoppers are dominant herbivores in grassland ecosystems, and many studies have examined how grazing by large herbivores and precipitation patterns individually influence the dynamics of grassland grasshopper assemblages, but their combined effects are largely unknown. 2. In this study, grazing intensities (ungrazed, moderate, and heavy) were manipulated and precipitation (ambient and increased amount of rainfall) altered in a field experiment to test the effects of grazing and altered precipitation on a grasshopper community in a meadow steppe in northeastern China. 3. It was found that grasshopper species richness did not change according to different grazing intensities under ambient precipitation, but was significantly higher (by 38.1%) in moderate grazing intensities under increased precipitation. Grasshopper abundance increased considerably with increasing grazing intensities in ambient precipitation treatments; however, grasshopper abundance in heavy grazing intensities was significantly lower (by 32.9%) than in the other two grazing intensities under increased precipitation. Moreover, the responses of grasshopper abundance to grazing under altered precipitation were species‐specific. 4. Grazing effects on grasshopper species diversity were mediated through the species richness and biomass of grasses (food resources), but the effects on grasshopper abundance were mediated through plant height (vegetation structure) under altered precipitation. 5. These results suggest that appropriate grazing by large herbivores would be considered as beneficial management practices for maintaining grasshopper diversity and abundance under conditions of increased precipitation in grassland ecosystems. Additionally, greater attention should be paid to the population dynamics of different grasshopper species to better understand the responses of grasslands to grazing and altered precipitation.     

Effect of cultivating croplands and grazing in arid grassland habitats on the conservation of melitaeine butterflies in a mountainous area in Northern China

In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different loca-tions, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe. These two species of butterflies coexist in this area, in which grazing and cultivation are the main disturbances. Grazing and cultivation have a reciprocal effect on E. aurinia, rather than M. phoebe. We observed that E. aurinia preferred to occupy patches with moderate grazing and imbedded with small and discontinuous croplands, where E. aurinia also has high population density. The percentage of E. aurinia larval groups in the ribbings was significantly higher than that of M. phoebe, whereas larvae of both species tended to increase in recent years. Our data also showed that the population density and the patch occupancy rate of both E. aurinia and M. phoebe were the highest under moderate grazing. It indicates that cultivation of small and dis-continuous croplands within the patch has a significant effect on the population density of both spe-cies of melitaeine butterflies. Thus, to artificially create or maintain semi-natural habitats, comple-mented by moderate grazing, might be an ecological strategy to conserve melitaeine butterflies effec-tively. Considering the distinct impacts of cultivation and grazing on the population distribution and dynamics of the two different species, human disturbance in the mountainous area might be strategi-cally involved in proposing conservation plans for the target species in the future.     

Land use and drought interactively affect interspecific competition and species diversity at the local scale in a semiarid steppe ecosystem

Few studies have considered interactive effects of grazing and drought on species composition and the relative contribution of species to total biomass, although it is important to understand the short-term dynamics and community succession in grazed ecosystems. We monitored species diversity and relative biomass contribution at one site protected from grazing since 1979 (UG79), and at winter grazing (WG) and heavily grazed (HG) sites. Continuous heavy grazing resulted in lower plant height and more but small individuals (tillers or stolons). Drought significantly reduced total plant density on all sites. Grazing affected species diversity more than drought. Species richness at site UG79 was significantly higher than at sites WG and HG, while drought only tended to reduce species diversity. Drought stress and grazing disturbance interactively controlled species competition and functional groups. Both perennial grasses and forbs had greater contribution to total biomass at site UG79, and perennial grasses contributed more than 97% of total biomass at site WG. The contribution to total biomass of annual forbs and semi-shrubs significantly increased at site HG after two dry years. The significant decrease in Potentilla acaulis and a substantial increase in annual species at this site indicate that the perennial vegetation of this ecosystem is in great danger of extinction under conditions of prolonged drought.     

基于草本群落、牧道特征对野果林放牧干扰强度的评价

客观、综合评价野果林放牧强度对正确认识林牧矛盾,制定科学合理的放牧制度具有重要意义。目前的研究主要集中在野果林放牧对植被群落特征和物种多样性影响上,然而野果林放牧活动本身的关注以及放牧强度的量化方法等方面尚不明确。基于此以新疆野果林6个典型放牧区为试验地,分析对比各放牧区的草本群落组成结构、生长特征、物种多样性以及牧道特征,并筛选出评价放牧干扰强度的主导因子,对其放牧干扰强度进行定量评价。结果表明:(1)草本群落特征方面,杏花沟物种数最多,且以禾本科种属植物为优势种;但莫乎儿沟草本密度比杏花沟高1.26%;各放牧区物种多样性水平存在显著差异,与其他放牧区相比,莫乎儿沟Shannon-Wiener多样性、Simpson优势度指数最高,分别为1.92、0.84,而吾都布拉克沟的Pielou均匀度指数最大;(2)牧道特征方面,伊勒格代沟的牧道密度显著大于匹里青沟,分别为19.23%、14.77%,而杏花沟的牧道宽度显著大于大西沟;在牧道分布格局上,除匹里青沟外,其他放牧区皆为均匀分布;(3)相关性分析表明草本群落结构特征、物种多样性水平及牧道特征指标间均存在较好的相关关系,对其12个指标主成分分析筛选出草本群落盖度、生物量、Shannon-Wiener多样性指数、Simpson优势度指数以及牧道密度与格局指数可作为评价放牧干扰强度的主导因子,依据牧压指数判定杏花沟与莫乎儿沟为轻、中度放牧干扰,大西沟、伊勒戈代沟、吾都布拉克沟与匹里青沟为重度或极度放牧干扰。当前新疆野果林整体受到放牧重度干扰,急需优化或者制定科学的放牧制度维护野果林的可持续发展。     

Response of plant functional traits to grazing for three dominant species in alpine steppe habitat of the Qinghai–Tibet Plateau,China

Above-ground biomass (AGB) is an important indicator of grassland ecosystem performance. Easily measured plant functional traits (PFTs) may provide useful predictors of the response of plants to grazing. Understanding the response of PFTs to grazing and the relationship between PFTs and AGB is very important for effectively predicting the response of ecosystems to grazing and rangeland management. A grazing experiment was conducted in Gangcha County, Qinghai Province, in the northeastern part of the Qinghai–Tibet Plateau in 2012 and 2013. We investigated the response of PFTs in three dominant species (Elymus nutans, Kobresia humilis, and Stipa purpurea) to grazing, using six stocking rates. Plant height (PH), plant weight, leaf area, and leaf dry biomass of these three dominant species had significantly negative relationships with stocking rate. Leaf thickness (LT) of these three species usually showed a unimodal response to grazing. Specific leaf area generally showed a quadratic relationship with grazing intensity. No consistent effects of grazing were observed on nitrogen content per unit mass (N _mass) and nitrogen content per unit area (N _area). PH, leaf area, and leaf dry mass (LDM) were positively associated with AGB, but LT, N _mass, and N _area had no statistically significant association with AGB. We thus conclude that PH, leaf area, and LDM best predict the effects of grazing on AGB. Finally, 2.87 sheep/ha is recommended as the optimal stocking rate in this region to maintain the health of this grassland ecosystem and to allow for sustainable development.     

Using ants to manage sustainable grazing: Dynamics of ant faunas along sheep grazing gradients conform to four global patterns

Ants are considered an important faunal group for the functioning of arid rangelands, they have a long history of use for environmental monitoring, and exhibit four global patterns in grazing lands: (i) soil and vegetation type are primary determinants of ant community composition, and have a far greater effect on ant community composition than grazing; (ii) grazing induces species compositional change, but does not necessarily affect species richness or abundance; (iii) a species response to grazing is not necessarily consistent across habitats; and (iv) approximately one‐quarter to one‐half of species that are common enough for statistical analysis have significant responses to grazing. Here we report the patterns of arid zone ant faunas as they exist after several decades of sheep grazing in southern Australia, and examine the extent to which they conform to the four global patterns. We measured ant faunas along grazing gradients (varying distance to water) in seven paddocks containing two soil and two vegetation types on five pastoral properties. Total site abundance and richness of ants did not differ significantly with distance from water, but the abundance of 10 (34%) of the 29 most common species did differ; three were increasers, three were decreasers, and four had mixed responses dependent on soil/vegetation type. Rare species showed no trend with grazing intensity. The ant fauna of the more structurally complex vegetation types appeared to be the most vulnerable to grazing effects. Multivariate analysis showed soil type was the primary factor influencing ant faunal composition, followed by vegetation structure; however, grazing treatment effects were present. This study fully supports the recently identified global patterns of ant responses to grazing. It also shows that sampling regional ant faunas using widely dispersed traps can detect ant faunal patterns comparable to studies that use smaller‐scale grids of traps.     

Cattle and Weedy Shrubs as Restoration Tools of Tropical Montane Rainforest

Over the last 150 years, a large proportion of forests in Latin America have been converted to pastures. When these pastures are abandoned, grasses may slow re‐establishment of woody species and limit forest regeneration. In this study, we explored the use of cattle in facilitating the establishment of woody vegetation in Colombian montane pastures, dominated by the African grasses Pennisetum clandestinum (Kikuyo) and Melinis minutiflora (Yaraguá). First, we described woody and herbaceous vegetation in grazed and non‐grazed pastures. Second, we tested the effect of grazing and seed addition on the establishment and growth of woody species. We also determined if the effect of grazing was different in P. clandestinum and M. minutiflora pastures. We found that low stocking density of cattle greatly increased density, number of branches per individual (a measure of “shrubiness”), and basal area of woody species, but also reduced woody plant species richness and diversity. In the grazed area, the shrubs Baccharis latifolia (Chilca) and Salvia sp. (Salvia) were the most abundant. The combined effect of grazing and shading from the shrubs reduced herbaceous vegetation by 52 to 92%. In the grazing/seed addition experiment, grazing increased establishment of woody seedlings, particularly of the shrub Verbesina arborea (camargo), but the largest effect was seed addition. Where grasses are an important barrier to regeneration, grazing can facilitate the establishment of shrubs that create a microhabitat more suitable for the establishment of montane forest tree species.     

Linking grazing response of species abundance to functional traits in the Tibetan alpine meadow

Whether grazing response of species abundance can be predicted by plant functional trait remains a challenge untested in a specific ecosystem. We measured species abundance and relevant functional traits for 30 common component species in a moderately grazed and a control community over 3 years (2005, 2006 and 2007) in a Kobresia capillifolia dominated alpine meadow on the Tibetan Plateau. Our objective was to examine species response to grazing and to test the relationship between the response of species abundance and functional traits in grazed and control habitats. Our results showed: i) in terms of species relative abundance and saturated height (the maximum height of an adult individual), most component species significantly decrease in response to moderate grazing and the effect differed among species and between functional groups. ii) The response of species abundance was significantly negatively correlated with saturated height, but not correlated with specific leaf area or seed size. We concluded that the response direction of species abundance to grazing can be predicted by functional traits, whereas it is a weak predictor of the extent of grazing response in species abundance.     

Recreating Grasslands in Swedish Rural Landscapes – Effects of Seed Sowing and Management History

Recent loss of plant species richness in Swedish semi-natural grasslands has led to an increase in grassland recreation and restoration. To increase the establishment of declining species favoured by grazing and to re-establish original species richness, seed sowing has been discussed as a conservation tool. In this study, I examined to what extent seed sowing in former arable fields increases species richness and generates a species composition typical of semi-natural grasslands. Six grassland species favoured by grazing (target species) and six generalist species favoured by ceased grazing, were studied in a seed-addition experiment. Four different seed densities were used on four different grassland categories, two grazed former arable fields, one continuously grazed grassland and one abandoned grassland. Target and generalist species emerged in all grassland categories, but seedling emergence was higher in the grazed than in the abandoned grassland. Target species had higher emergence in the two grasslands with the longest grazing continuity. Seedling emergence and frequency of established plants of each target species were positively associated. The largest fraction of seeds germinated at an intermediate sowing density, 20–50 seeds/dm², suggesting that aggregation of seeds positively affects emergence up to a certain threshold. In conclusion, artificial seed sowing may induce the recreation of typical grassland communities on former arable fields, which may be an important contribution to increase the total grassland area and species richness in the landscape.