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1.
Abstract. The process of colonization of cattle dung patches and its relation to endozoochorous dispersal is analysed in a Mediterranean pasture. Dung pats dropped in spring and winter were marked, and the vegetation developing on them during the first two years of colonization was followed. The influence of endozoochorous seeds on dung colonization is assessed through the study of: (1) the vegetation on spring and winter dung pats and the seed contents of both, which is abundant in the former and negligible in the latter; and (2) the vegetation on spring dung pats compared with that of the surrounding pasture. The origin of plants growing on dung (either seeds in the manure or in the soil seed bank) was traced by studying dung colonization under controlled conditions in pots with manure put on seed-free sand, and on pasture turf. The results indicate that endozoochorous seeds germinate in manure; they are the main source of recovery in gaps generated by dung pats. The micro-succession involved is independent of the type of pasture. A small-scale spatial pattern results in which gaps of old dung are dominated by endozoochorous species. Thus, dung patches enhance the similarity between grazed communities, and the variation within communities.  相似文献   

2.
Seed dispersal via ingestion and defecation by large herbivores provides a possible aid for ecological restoration of plant communities, by connecting source communities of target species with habitat restoration sites. It is also a possible threat due to invasion of weeds, grasses or exotic species. Insight into the factors determining internal seed dispersal could therefore improve the management of grazed ecosystems.

We recorded viable seed density in cattle, sheep and pony dung samples and monitored dung pat colonisation in the field. In addition, we counted the distribution of dung pats in plots spread over all habitat units in our study site.

The three herbivore species appeared to disperse large quantities of many species (61 in total) from a variety of plant families, monocots as well as dicots. The density of viable seeds in herbivore dung and the colonisation of dung pats were positively correlated with Ellenberg nitrogen indicator values and seed supply, but not with seed mass or shape.

The results imply that many seeds are dispersed from high productive to low productive parts of the grazed area. In free-ranging systems, we therefore recommend enclosure and separate management of plant communities on nutrient-poor soils with high conservation interest. For habitat restoration sites we recommend integrated grazing only with target plant communities on nutrient-poor soils and not with plant communities on nutrient-richer soils.  相似文献   


3.
Deterministic models assessed the effects that contaminated dung from insecticide-treated cattle had on populations of three hypothetical species of dung fauna that dispersed randomly and could double their numbers every 1-28 weeks at low density. Insecticide was allowed to kill 2-98 % of adults and prevent 16-100% of breeding in pats produced immediately after cattle treatment, with toxicity declining to < 1% in pats produced 2-23 days later. Treatment intervals were 10-40 days. The modelled impact of insecticide was affected little by approximately four-fold variations in: length and density dependence of the attractive life span of pats, frequency of pat occupation by immature adults, distribution of pat toxicity during treatment interval, and changes in dispersal rates due to age and population density. Of greater importance were variations in: pat toxicity, treatment interval, frequency of pat occupation by breeding adults, density dependence of recruitment and death, natural adversity and mortality in dormancy, general rate of dispersal, and the size and shape of the area with treated cattle. Overall, it seemed that wide variations in the impact of contamination will occur in the field, but in many situations the risk to dung fauna can be substantial, especially for slow breeding beetles, and muscoids contacting insecticide on cattle. Risk extends outside the treated areas, for a distance equal to several daily displacements of the insects. Untreated refuges for species survival should be compact blocks at least 25 daily displacements wide.  相似文献   

4.
The relationship between domestic cattle and vegetation change in a savanna woodland was evaluated with respect to dung deposition and the dispersal and establishment of mesquite (Prosopis glandulosa var. glandulosa, Mimosaceae), a cosmopolitan woody invader of grasslands in the southwestern USA. Dung deposited in autumn disintegrated rapidly, leaving patches of bare ground ranging from 50 to 900 cm2. Herbaceous cover on gaps created by dung deposition recovered to levels comparable to neighboring vegetation by the end of the following growing season. Vegetation colonizing gaps consisted primarily of grasses not found in the surrounding vegetation. Dung deposition increased species diversity and spatial heterogeneity of the herbaceous vegetation and contributed to the development of a fine-grain mosaic of small patches of varying successional age-states.The role of cattle in facilitating the ingress and establishment of mesquite has broader implications with regard to the conversion of grasslands to woodlands. On the site with cattle, mesquite seedlings were found in 75% of dung pats surveyed in September (mean =4.2 seedlings per pat; maximum =50). Although seedling survival in dung (79%) was only 16% greater than that of mesquite emerging from seeds experimentally sown away from dung, no seedlings were found on areas without cattle. Mean (± SE) density of mesquite seedlings ranged from 12±2 to 15±2 m-2 on the site with cattle. Seed densities away from parent plants averaged 10.7 m-2 and 0.0 m-2 on areas with and without cattle, respectively. Seed densities beneath adult plants were comparable between sites.The high density of seedlings on areas with cattle, in contrast to absence of seedlings on the area without cattle, suggests rates of invasion of grasslands by mesquite would have increased substantially in North America following the settlement and introduction of domestic ungulates. Prior to the introduction of livestock, poor seed dissemination and germination may have limited its Holocene spread.  相似文献   

5.
Local plant community composition and structure may be largely influenced by germination and seedling establishment from seeds dispersed in animal dung, through seed input, gap creation and nutrient enrichment. With an experimental approach we assessed (1) what the effect is of dung deposition on the number of seedlings in the plant community 3 months and 1 year after dung deposition, (2) what the effect is of this seedling establishment on the local plant community characteristics such as species richness and (3) if this effect interacts with large-scale soil disturbance which removes the close canopy, such as sod-cutting. Viable seeds of monocotylous species were abundantly present in the dung, and dung deposition led to a higher number of monocotylous seedlings after 3 months. However, this effect was no longer significant after 1 year. Moreover, the proportion of viable monocotylous seeds that effectively established in the field after 3 months was less than 5%. A lower number of viable seeds of the less-dominant dicotylous species was dispersed in the dung but they had a higher cover and species richness after 1 year. This resulted in an increased total small-scale species richness and diversity after dung deposition through a decreasing dominance of monocotylous species. Sod-cutting had a pronounced effect on seedling emergence: viable seeds dispersed by dung had a higher probability of successful establishment when the dung was deposited in large gaps. This indicates that an increase of safe sites associated with disturbance strengthens the effects of seed dispersal and gap creation by dung deposition.  相似文献   

6.
  • Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining plant populations of its constituents and enabling plants to colonize new habitats. Successful endozoochorous dispersal implies that seeds not only get consumed and survive the digestive tract but are also able to develop into viable seedlings in a dung environment.
  • We experimentally assessed the germination probability and timing of 15 annual and perennial temperate European grassland species in cattle and horse dung and in different climatic conditions (greenhouse and outdoor conditions).
  • Interspecific variation in germinability and germination timing are found, while life strategy had only an effect on germination timing. We found adverse effects of both cattle and horse dung on the germination characteristics of all tested grassland species, but the effects of cattle dung were more pronounced. In comparison with the control treatment, fewer seeds emerged in dung and more time was needed to germinate. Also, germination metrics clearly differed between the artificial greenhouse and outdoor conditions, with generally a lower germinability in outdoor conditions.
  • According to our results, a large cost seems to be associated with endozoochorous dispersal in this stage of the life cycle, as seed dispersal effectiveness strongly depends on the quality of the deposition site with a lowered survival and germination probability when seeds are deposited in dung.
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7.
Abstract. Seed banks in cattle dung, soil under cattle dung and soil under vegetation and growth response of plant species to the changes in soil nitrogen availability were studied in an alvar limestone grassland on Öland, Sweden, in order to analyse the impact of dung deposition and decomposition on the formation of patches of plant species. Results suggest that patches of four plant species could result from cattle dung deposition and decomposition. Impact of dung could proceed in three ways: (1) by changing the relative abundance of species in the soil seed bank under dung, and/or (2) by influencing the deposition of seeds in the dung, and/or (3) by intensifying the growth of some species through nutrient release. Species patches could result from one or more of these aspects. For instance, patches of Arenaria serpyllifolia may be induced by dung deposition because of the dominance of its seeds in dung, while the pattern of Cerastium semidecandrum and Festuca ovina may be due to the abundance of their seeds in the soil seed bank under dung and their positive growth response to increased nitrogen availability.  相似文献   

8.
姜世成  周道玮 《生态学报》2005,25(11):2983-2991
研究并分析了松嫩草地牛粪中大型节肢动物种类组成及动态变化.结果表明,在草地牛粪中共调查到大型节肢动物7目20科43种,以鞘翅目、膜翅目和双翅目为主.依其食性不同,分为粪食性型(8科19种)、腐食性型(4科4种)、植食性型(4科6种)、捕食性型(5科11种)、杂食性型(2科5种)、尸食性型(1科1种)和寄生性型(1科1种).根据鞘翅目金龟总科中营粪食性型生活的粪甲虫对牛粪利用方式的不同,分为外生粪甲虫(6种)、内生粪甲虫(5种)、远生粪甲虫(2种)和偷窃寄生粪甲虫(1种).除了双顶嗡蜣螂,牛粪中大型节肢动物数量与鲜牛粪重量具有显著正相关关系(p<0.01).粪食性型种类数和个体数量随鲜牛粪堆置时间的延长而迅速减少,7d后消失,其个体总数量与鲜牛粪堆积时间呈显著的负相关关系(p<0.01),而与牛粪含水量呈显著正相关关系(p<0.01),各种大型节肢动物因其食性不同在鲜牛粪中占据不同的生态位.鲜牛粪中大型节肢动物以粪食性型占绝对优势,而干牛粪中则以捕食性型和杂食性型为主.牛粪中大型节肢动物种群季节动态变化受温度、降水量与牛粪含水量影响,鲜牛粪中大型节肢动物优势种为直蜉金龟(69.25%)和肖秋家蝇与东方角蝇幼虫(25.12%).4、5、6月份和9月份,优势种为直蜉金龟,7月和8月份,优势种为蝇幼虫.  相似文献   

9.
The two-phase dispersal event in which dung beetles move seeds after endozoochory is often assumed to be advantageous for plant regeneration. Because seeds are expected to end up in favourable and safe germination sites, it is considered as an example of directed dispersal. However, literature so far is restricted to tropical rain forest ecosystems, while data for temperate regions are lacking. In this study, the effect of dung beetles on seedling establishment of endozoochorically dispersed seeds is evaluated for a temperate grassland ecosystem. We performed a field experiment in which cages excluded dung beetles from horse and cattle dung samples with mixed-in grass seeds. Seed germination from these samples was significantly higher than that from samples which were accessible to dung beetles. This indicates that the effect of dung beetles on short-term seedling establishment was negative, which contrasts with the patterns found for large-seeded species used in tropical studies. This is most likely attributed to the lack of roller species and the larger depth at which tunneling Geotrupes species bury seeds.  相似文献   

10.
Long-distance dispersal of seeds is an important process in metapopulation dynamics and in plant migrations, but at the same time extremely difficult to observe or quantify directly. If seed dispersal ability were related to attributes of seeds or motherplants, long-distance seed dispersal would be predictable by indirect approximation using easy-to-measure traits. Seed size has been suggested to be such a key trait in seed dispersal ability. However, having smaller seeds also implies having more numerous seeds per plant individual (given equal reproductive effort), and consequently increases the probability of seeds being ingested accidentally. The question is whether small-seeded species are more abundant in herbivore dung because smaller seed size increases survival rate during gut passage or because they are produced (and ingested) in greater numbers than larger seeds. We investigated endozoochorous seed dispersal via cattle grazing a meadow, and related seed abundance in dung samples to seed attributes. We found that seeds were ingested and passed through the bovine intestinal tract in proportion to the numbers produced per unit area in the grazed vegetation. In contrast, no relationship could be found between endozoochorous dispersal potential (measured as abundance of seeds in dung samples corrected for seed output in the grazed vegetation) and seed attributes such as seed mass, seed shape (roundness), and thickness of the seed coat. This finding underlines the importance of seed number in plant dispersal ability. In addition, it shows that grazing mammals may constitute an important dispersal vector for many plant species conventionally classified as 'unspecialised'.  相似文献   

11.
Seed dispersal of dry-fruited shrubs has received little attention in Mediterranean areas despite their frequency in the vegetation and the consideration given to the dispersal of fleshy-fruited shrubs in the area. Red deer faeces has recently been found to contain large numbers of seeds from one of the most common shrubs of this group, gum cistus Cistus ladanifer, although its importance in the reproduction of the species is unknown. This study examines the role of the red deer as an effective disperser of C. ladanifer. For this purpose, we quantify i) the C. ladanifer seed content in red deer dung over a year, ii) the seed shadow generated by the red deer wish their faeces during the same period, and iii) the ability of the dung-borne seeds to germinate and establish as seedlings under field conditions within five years following excretion. The results reveal an extremely high seed Content of the species in red deer dung (up to 80.5 ± 41.9 germinable seeds g-1), which is virtually confined to the summer (July–August), when we estimate that a red deer defecates up to 24 000 seeds of the species per day. Furthermore, red deer mainly deposit gum cistus seeds amongst plant formations lacking the species: over the year, red deer excrete <2600 seeds m-2 in C. ladanifer-dominated scrub and 7400–8800 seeds m-2 in other plant formations. Under natural conditions, the dung-borne seeds have a more sniggered among-years germination pattern than free seeds in the soil. Though no seedling survived its first summer drought, the survival of seedlings sprouted from dung was significantly longer than that of control seedlings in the first and third years after deposition, and indistinguishable from it the second, fourth and fifth years. This is the first quantification of the importance of red deer to C. ladanifer dispersal and establishment, and suggests that endozoochory by mammalian herbivores can be very valuable for dry-fruited shrubs in the Mediterranean region.  相似文献   

12.
Seed dispersal has become an important issue in plant ecology and restoration management. In this paper we examined dung germinating seed content and seed deposition patterns of horses (Shetland and Konik breeds) and Scottish Highland cattle grazing two coastal dune nature reserves. Two times 2.5 l of fresh dung from each type of herbivore were collected during seven sessions in the main fruiting season. Dung samples were placed under greenhouse conditions after drying and cooling. Animal defecation patterns were derived from a study of herbivore activities during 6 h observation sessions 8 times a month. One hundred and seventeen plant species i.e. 27% of all species occurring in the study area, were recorded as seedlings emerging from the dung samples. The most abundantly and frequently recorded plant species were Urtica dioica, Juncus spp. and different species of Poaceae and Caryophyllaceae. In general seedling density is high (1158 seedlings/dung sample). Seedling density and species richness were further analysed in order to detect temporal variability and possible animal and site related characteristics. Dung deposition patterns reflect a non-random use of habitats and hence a non-random seed deposition among habitats. Calculated seed deposition per square meter ranged from a few (<10 germinating seeds) to more than 100 in the most frequently selected habitats. From the herbivores’ selective habitat use and their estimated mean retention time we can further assume their ability for inter-habitat endozoochorous seed dispersal. This characteristic of large herbivores is further discussed in the light of nature management and restoration.Indra Lamoot is an aspirant of FWO-Flanders.  相似文献   

13.

An experiment was performed during the grazing seasons of 1998, 1999 and 2000 to study the influence of the antiparasitic drug ivermectin and the nematophagous fungus Duddingtonia flagrans on cattle dung disintegration. The faeces originated from groups of animals that were part of a separate grazing experiment where different control strategies for nematode parasite infections were investigated. Each group consisted of 10 first-season grazing cattle that were either untreated, treated with the ivermectin sustained-release bolus, or fed chlamydospores of D. flagrans. Faeces were collected monthly on 4 occasions and out of pooled faeces from each group, 4 artificial 1 kg dung pats were prepared and deposited on nylon mesh on an enclosed pasture and protected from birds. The position of the new set of pats was repeated throughout the 3 years of the study. Each year, the dung pats were weighed 4, 6, 8 and 10 weeks after deposition and immediately afterwards replaced to their initial positions.

Results showed that there was no difference in faecal pat disintegration between groups. However, the time-lag between deposition and complete disintegration of the faeces varied significantly between deposition occasions. Dung pats disappeared within 2 weeks (visual observation) when subjected to heavy rainfall early after deposition, whereas an extended dry period coincided with faeces still remaining 12 months after deposition.

  相似文献   

14.
Epizoochorous dispersal of plant seeds is an important long-distance dispersal mechanism. Yet little is known about retention times of seeds in animal furs and hence about potential dispersal distances of the seeds. Here, we used marked seeds of 12 plant species to determine seed depletion curves on Galloway cattle and Haflinger horse in three vegetation types (forest, tall herbage vegetation and meadow), in both dry and rainy weather conditions. In the long fur of Galloway cattle, seeds were retained significantly longer than in the short fur of Haflinger horse. In general, seed retention times were not considerably affected by the structure of the surrounding vegetation. The impact of the weather was negligible, only affecting the retention of some plant species. Negative exponential functions were fitted to the seed depletion curves. Using the parameters of curve estimations in the different conditions of animal species and vegetation structure, half-life seed retention times of up to 13 h for Galloway cattle and up to more than 4 h for Haflinger horse could be calculated, with corresponding potential half-life dispersal distances in the order of magnitude of tens of metres to a few kilometres. Different seed traits correlated with seed retention times in the long cattle fur and in the short horse fur, respectively.  相似文献   

15.
Aiming at estimating the average N2-fixation in a pasture, ap preciating the great variability due to patchy urine and dung deposition, the in fluence of dairy cow excreta on biological N2-fixation in a perennial ryegrass–white clover mixture was studied using natural urine and dung. Application of urine as well as dung affected the N2-fixation by promoting the growth of grass and thereby the proportion of clover was significantly reduced. Also the proportion of clover-N derived from the atmosphere (pNdfa) was significantly reduced. In control plots clover dry matter constituted between 40 and 50% of the total dry matter production and the pNdfa ranged between 0.8 and 0.9. Addition of urine caused a significant increase in the grass growth rates, which was the primary reason for a decrease in proportion of clover. At the same time pNdfa decreased to 0.2–0.4 followed by an increase resulting in a total reduction of 45% in the N2-fixation in urine affected areas over a period of four months. The dung only affected the N2-fixation for a distance of up to 10 cm from the edge of the dung pats. In this border area the pNdfa decreased from 0.85 to 0.75 during one month after application followed by an increase, so that after three months there was no difference between pNdfa at 0–10 and 10–20 cm distance from the dung hill. The proportion of clover was lower in the 0–10 cm than in the 10–20 cm distance, which totally resulted in a total reduction of 20% in the N2-fixation over a period of four months in the 0–10 cm area around the dung pats. Considering the proportion of a pasture which may by affected by excreta at a stocking density of 4–6 cows ha-1, the length of the grazing period, the frequency of excretion and the area covered by individual patches, it was estimated that the N2-fixation in a grass-clover pasture would be reduced by 10–15% compared to the N2-fixation in a grass-clover sward not exposed to animal excreta.  相似文献   

16.
The effects of dung form and condition and of dung beetles on the emergence of seedlings from herbaceous seeds in sika deer dung were examined in a temperate grassland ecosystem dominated by Zoysia japonica and Hydrocotyle maritima. I conducted field experiments to compare seedling emergence between dung exposed to dung beetles and intact dung using both dung pellets and pats during a typical rainy month (June) and the hottest, drier month (August), when large numbers of seeds of the dominant species were present in the dung. The exposed dung was immediately attacked and broken up by dung beetles, whereas dung protected from the beetles remained intact. In June, at least 12 herbaceous species, including Z. japonica, H. maritima, Mazus pumilus, and Plantago asiatica, emerged from the dung, versus at least six species in August. Decomposition rates of the pellets in June and decomposition scores of the pats in June and August were positively correlated with the number of emerging seedlings, suggesting that the acceleration of decomposition by dung beetles can positively affect seed germination. In this system of interactions among sika deer, herbaceous plants, and dung beetles, sika deer dung prevented seeds from germinating, and beetles had an indirect positive effect on seedling emergence by accelerating decomposition of the dung, although the extent of the effect may depend on the dung type, plant species, and environmental factors.  相似文献   

17.
Tomas Roslin 《Ecography》2001,24(5):511-524
Recent modelling work shows that the composition of local communities can be influenced by the configuration of the surrounding landscape, but many of these models assume that all community members display the same type of extinction‐colonization dynamics. I use Aphodius dung beetles to test the hypothesis that interspecific differences in habitat selection and dispersal capacity may translate into differences in spatial population dynamics, even among closely related species coexisting on the same resource. If this is true, then groups of species with different characteristics would show different responses to landscape configuration. I first divided the area of Finland into a grid, and used collection records to describe regional variation in the Aphodius fauna of open cattle pastures. I then sampled dung beetles on 131 cattle farms, to examine whether the subset of species found on each farm was related to the density of pastures in the surrounding grid square. Finally, I used historical records to analyze changes in dung beetle communities during the last century, when there was great loss of pasture. Overall, I found no relationship between landscape characteristics and the total proportion of the regional species pool that was found on each farm. However, the distribution of species among guilds with different habitat specificity did relate to the configuration of the landscape, and the pattern was most pronounced in a specialists species with limited dispersal. Associations between community structure and landscape configuration were superimposed on two much larger and stronger patterns: a large‐scale latitudinal gradient in regional species richness, and a decelerating gain of species to local communities with an increasing regional species pool. I conclude that ecological variation among community members is a crucial factor in the analysis of local community composition, and that local species richness should always be conditioned on regional richness.  相似文献   

18.
Cattle influences gap dynamics in pastures in two ways: (1) by creating gaps and (2) by affecting the colonization process. This effect of cattle activity on gap revegetation can be subdivided in three main factors: herbage removal, trampling and dung and urine deposition. The objective of this study was to assess how these three effects moderate the plant succession following gap creation. In an exclosure, four controlled treatments simulating cattle activity (repeated mowing, trampling, manuring and untreated control) were applied on plots of 2 × 2 m. In the centre of each plot, one artificial gap of 60 × 60 cm was created. During three years, vegetation changes were monitored in spring and in autumn, with a square grid of 100 cells of 0.01 m2 centred on the gap. Our experiment confirmed that fine-scale gap creation may have a high impact on relative abundances of species in the community. The gap environment acts on species as a filter and this filtering was described in terms of regenerative attributes. Colonizers were species with small seeds, unspecialized seed dispersal, persistent seed bank and high vegetation spread. However, the role of dung deposition, herbage removal or trampling by cattle did not seem to be of primary importance in the revegetation process, but could moderate vegetation response. Therefore, the different cattle effects act as secondary filters that selectively favoured or disadvantaged different species from the gap-regenerating community. These complex interactions are probably keys to understand plant coexistence in perennial grasslands.  相似文献   

19.
Seed dispersal is a crucial process for the dynamics and maintenance of plant populations. Free-ranging animals are effective dispersal vectors because they can move between similar habitats and transport seeds into favourable environments. Dung samples from two species of common free-ranging mammals—deer and wild boar—were used to study endozoochorous dispersal of seeds in a military training area in western Bohemia. The area was abandoned after WWII, and the military training area was established in 1953. The vegetation consists of shrublands and dry grasslands. Data on the local species pool of grassland herbs and forbs were collected to compare the characteristics of dispersed versus non-dispersed plants. Deer and wild boar dispersed 84 plant species; however, species composition of seedlings emerging from dung samples showed significant differences between dispersal vectors and notable change across the growing season. 80% of all seedlings extracted from the dung samples belonged to stinging nettle, Urtica dioica. From trait analyses, seeds of endozoochorous plants had a higher longevity index in the soil seed bank than non-endozoochorous plants and more often possessed a mucilaginous surface. Our results show that deer and boar are successful, though not substitutable dispersers.  相似文献   

20.
Agroecosystems represent a large geographical footprint in most terrestrial landscapes, and management decisions within these systems affect their function in species conservation. We evaluated the effects that rangeland management systems (based on stocking density, rotation frequency, and the number of avermectin applications) have on conserving the dung arthropod community in the Northern Great Plains of North America. Comprehensive bioinventories of arthropods were collected from 16 rangelands using core samples of dung pats. Ivermectin was quantified in pats from each ranch using enzyme-linked immunosorbant assay (ELISA). Arthropods in dung were abundant (116,244 specimens) and diverse in eastern South Dakota (172 morphospecies). Rangelands managed with more regenerative practices (frequent rotation at high stocking densities and lack of ivermectin applications) had greater species richness, diversity, predator species abundance, and dung beetle abundance than more conventionally managed rangelands. Ivermectin quantity in cattle pats was negatively correlated with dung beetle abundance and diversity. This work shows that herd management (specifically high-intensity, frequent rotational grazing and eliminating prophylactic ivermectin use) that aims to mimic intensive grazing of large migrating herds of ruminants can foster dung arthropod community structure, a key trait correlated with nutrient cycling, pest suppression, and productivity of cattle-grazed rangelands.  相似文献   

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