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1.
Temperate grazing lands in Garhwal Himalaya are rich in herbaceous vegetation and extensively used for grazing by locally owned livestock. Capillipedium parviflorum is a frequently occurring and dominant grass species under Pine canopy in associate with several herbs. Beside, grazing and extensive fire, interactions among associated species is a determining factor of community structure. In this article the dominant diversity pattern of vegetation in temperate grazing land along two different altitudes and having different slope aspects is described. Interaction between dominant and co-dominant species with their niche appearance and niche overlap measurement was also observed and presented here. South and west facing slopes had maximum species and diversity values while east north facing slopes had higher species dominant. Capillipedium parviflorum and other grasses had maximum niche values and were dominant and co dominant species. Three types of interspecific interaction were observed between species and grasses were observed as succeeding species in all sites of different topographic conditions. Dominant diversity pattern along with resource partitioning and interspecific competition is discussed and presented here.  相似文献   

2.
Summary The biomass and productivity of a montane grassland of Garhwal Himalaya were estimated with the objectives to compare these values of the dominant exotic species, Eupatorium glandulosum HBK. (Asteraceae) with other species, and to compare the sites more dominated by this species with other study sites. The effect of dominance of this species on other species was undertaken because of its continuous spread in the grasslands of the Garhwal Himalaya causing replacement of some native grasses and economically important herbaceous plants. Out of six study sites, SW1, SW2, and NE1 were more dominated by Eupatorium glandulosum. Total net primary productivity (TNP) ranged from 1528.5 to 2163.4 g m−2 yr−1. Eupatorium glandulosum showed individual highest biomass on all the study sites, and the sites more dominated by this species showed higher values of primary productivity, thereby reducing the biomass and production of other species on these sites.  相似文献   

3.
This paper deals with effects of sheep and goat grazing on plant species diversity, species richness and species composition in two important conservation areas of the Western Himalaya; the Valley of Flowers (VOF) National Park and the Great Himalayan National Park (GHNP). The VOF is a completely Protected Area as it is devoid of livestock grazing whereas, 20,000 sheep and goats annually graze in GHNP. Both the National Parks possess sub-alpine and alpine vegetation that is distributed in 13 major habitat types. Present investigations indicate that all the habitat types in VOF are higher in plant species diversity and richness compared to habitat types in GHNP. Similarly, all three eco-climatic zones in VOF are higher in species diversity and richness compared to GHNP. Species diversity also decreases with increasing altitude in both the National Parks. The findings of this study are discussed in the light of the management and conservation of alpine meadows of the Western Himalayas.  相似文献   

4.
This work was undertaken to analyze nutrient contents of vegetation in an alpine meadow—Tungnath, North-West Himalaya, India. The study pertains to the uptake, transfer and release of four main macronutrients (organic carbon, total nitrogen, total potassium and total phosphorus) in grazed (exposed to extensive grazing by cattles) and ungrazed (grazing completely prohibited) communities. Mineral concentration was recorded higher for the ungrazed sites compared to the grazed sites, and maximum standing state of nutrients was found in roots. Belowground compartment (roots) contributed maximum share of mineral elements to soil. Litter nutrients release was low because of low microbial activity and continuous removal of phytomass. Observations reveal that there was very little amount of nutrient release from phytomass and vegetation in alpine are very poor source of mineral recycling. Low transfer rate of minerals from one compartment to other is adequate for greater amount of these minerals that are translocated back into the storage organs. A small proportion get removed through rain splash or through the removal of hay during grazing as relatively high release rates in ungrazed sites when compared to grazed sites was observed. This translocation can be considered as an important adaptation in alpine plants for survival during adverse environmental conditions, against all types of biotic pressures and also for regeneration in the forthcoming growing season.  相似文献   

5.
In July 2000, a 490-ha wildfire burned a portion of a long-term grazing study that had been established in 1924 at the US Sheep Experiment Station north of Dubois, Idaho, USA. Earlier vegetation measurements in this tall threetip sagebrush (Artemisia tripartita spp. tripartita) bunchgrass plant community documented significant changes in vegetation due to grazing and the timing of grazing by sheep. A study was initiated in May 2001 using 12 multiscale modified Whittaker plots to determine the consequences of previous grazing practices on postfire vegetation composition. Because there was only one wildfire and it did not burn all of the original plots, the treatments are not replicated in time or space. We reduce the potential effects of psuedoreplication by confining our discussion to the sample area only. There were a total of 84 species in the sampled areas with 69 in the spring-grazed area and 70 each in the fall- and ungrazed areas. Vegetation within plots was equally rich and even with similar numbers of abundant species. The spring-grazed plots, however, had half as much plant cover as the fall- and ungrazed plots and the spring-grazed plots had the largest proportion of plant cover composed of introduced (27%) and annual (34%) plants. The fall-grazed plots had the highest proportion of native perennial grasses (43%) and the lowest proportion of native annual forbs (1%). The ungrazed plots had the lowest proportion of introduced plants (4%) and the highest proportion of native perennial forbs (66%). The vegetation of spring-grazed plots is in a degraded condition for the environment and further degradation may continue, with or without continued grazing or some other disturbance. If ecosystem condition was based solely on plant diversity and only a count of species numbers was used to determine plant diversity, this research would have falsely concluded that grazing and timing of grazing did not impact the condition of the ecosystem.  相似文献   

6.
The snowline in Himalaya is rising ceaselessly due to regional and global climatic change. Upward rising of snowline leads to the formation of moraines. Due to extreme environmental conditions the existing vegetation of the moraine is scanty, rigorous and possesses different ecological adaptation. Ablation zone of the glacier is covered by a thick pile of supra glacial moraines and is characterized by several serrac ice sections, melting into pools of supra glacial lakes because of subsidence and fast degenerating nature of the glacier. Anaphalis triplinervis was observed to have highest importance value in ablation moraine zone. Here the species richness increased remarkably partially due to the invasion of plant species from lower alpine belt. The fresh lateral moraine displays distressed soil features with mosaic type of vegetation. Gaultheria trichophylla is a dominant plant species here and is associated with other stunted and cold resisting species. The old lateral moraine is dominated by Potentilla atrosanguinea with co-dominant species Iris kemaonensis and Danthonia cachemyriana.  相似文献   

7.
The composition of the germinable seed bank was studied in four vegetation states of the Festuca pallescens grasslands in semiarid Patagonia during four years. The aim of this study was to test whether above-ground vegetation states resulting from grazing exclusion or different combinations of grazing and topography are reflected in different states of the germinable seed bank. The size of the total and dicot germinable seed bank was positively related to the total cover in each state. Dicots dominated all germinable seed bank states. Carex patagonica increased its cover as well as its germinable seed bank under grazing disturbance. Grazing did not reduce the germinable seed bank of perennial grasses in uplands where the grazing pressure is lower as compared with slopes. In slopes the germinable seed bank of perennial grasses was significantly reduced by grazing. A reduction of the length of the grazing period in late spring increases the germinable seed bank of perennial grasses both in upland and slope. These results are interpreted in the frame of a model of management techniques where grazing exclusion during late spring and late summer increases the seed bank of the perennial grasses and promotes their establishment in uplands. The artificial addition of seeds of perennial grasses and the manipulation of the soil surface in order to increase "safe sites" appear as management alternatives that deserve further evaluation to improve plant reestablishment in slopes.  相似文献   

8.
Soil microbial populations can fluctuate in response to environmental changes and, therefore, are often used as biological indicators of soil quality. Soil chemical and physical parameters can also be used as indicators because they can vary in response to different management strategies. A long-term field trial was conducted to study the effects of different tillage systems (NT: no tillage, DH: disc harrow, and MP: moldboard plough), P fertilization (diammonium phosphate), and cattle grazing (in terms of crop residue consumption) in maize (Zea mays L.), sunflower (Heliantus annuus L.), and soybean (Glycine max L.) on soil biological, chemical, and physical parameters. The field trial was conducted for four crop years (2000/2001, 2001/2002, 2002/2003, and 2003/2004). Soil populations of Actinomycetes, Trichoderma spp., and Gliocladium spp. were 49% higher under conservation tillage systems, in soil amended with diammonium phosphate (DAP) and not previously grazed. Management practices also influenced soil chemical parameters, especially organic matter content and total N, which were 10% and 55% higher under NT than under MP. Aggregate stability was 61% higher in NT than in MP, 15% higher in P-fertilized soil, and also 9% higher in not grazed strips, bulk density being 12% lower in NT systems compared with MP. DAP application and the absence of grazing also reduced bulk density (3%). Using conservation tillage systems, fertilizing crops with DAP, and avoiding grazing contribute to soil health preservation and enhanced crop production.  相似文献   

9.
Ecological conditions following removal of exotic plants are a key part of comprehensive environmental management strategies to combat exotic plant invasions. We examined ecological conditions following removal of the management-priority buffelgrass (Pennisetum ciliare) in Saguaro National Park of the North American Sonoran Desert. We assessed soil, vegetation, and soil seed banks on seven buffelgrass site types: five different frequencies of buffelgrass herbicide plus hand removal treatments (ranging from 5 years of annual treatment to a single year of treatment), untreated sites, and non-invaded sites, with three replicates for each of the seven site types. The 22 measured soil properties (e.g., pH) differed little among sites. Regarding vegetation, buffelgrass cover was low (≤1 % median cover), or absent, across all treated sites but was high (10–70 %) in untreated sites. Native vegetation cover, diversity, and composition were indistinguishable across site types. Species composition was dominated by native species (>93 % relative cover) across all sites except untreated buffelgrass sites. Most (38 species, 93 %) of the 41 species detected in soil seed banks were native, and native seed density did not differ significantly across sites. Results suggest that: (1) buffelgrass cover was minimal across treated sites; (2) aside from high buffelgrass cover in untreated sites, ecological conditions were largely indistinguishable across sites; (3) soil seed banks harbored ≥12 species that were frequent in the aboveground vegetation; and (4) native species dominated post-treatment vegetation composition, and removing buffelgrass did not result in replacement by other exotic species.  相似文献   

10.
The effects of aspect, altitude, and slope have been observed on the moist temperate forests of Abies pindrow Spach in the Garhwal Himalaya, India. Four aspects, namely, north-east, north-west, south-east and south-west, have been studied to understand the growth behaviour of A. pindrow at varying altitudes. The total basal cover was found to be highest (5099.6 cm2/100 m2) on the north-east facing slopes, and lowest (3092.7 cm2/100 m2) on the south-east facing slopes. The A. pindrow was found to be associated with Quercus semecarpifolia as a main companion species on all the faces, whereas, Lyonia ovalifolia, was associated only on the west facing slopes.  相似文献   

11.
Over the last fifty years, almost half of the steppe rangeland in the Central Anatolian Region of Turkey (CAR) has been converted to cropland without an equivalent reduction in grazing animals. This shift has led to heavy grazing pressure on rangeland vegetation. A study was initiated in June 2003 using 6 multiscale Modified-Whittaker plots to determine differences in plant composition between areas that have not been grazed in 27 years with neighboring grazed plant communities. A total of 113 plant species were identified in the study area with the ungrazed plots containing 32 plants more than the grazed plots. The major species were Astragalus acicularis, Bromus tomentellus, Festuca valesiaca, Genista albida, Globularia orientalis, Poa bulbosa, and Thymus spyleus ssp rosulans. Grazing impacts on forbs were more pronounced than for grasses and shrubs. Based on Jaccard’s index, there was only a 37% similarity of plant species between the two treatments. Our study led to four generalizations about the current grazing regime and long-term exclosures in the steppe rangeland around the study area: (1) exclosures will increase species richness, (2) heavy grazing may have removed some plant species, (3) complete protection from grazing for a prolonged period of time after a long history of grazing disturbance may not lead to an increase in desirable plant species with a concomitant improvement in range condition, and (4) research needs to be conducted to determine how these rangelands can be improved.  相似文献   

12.
Dry grasslands are one of the most species rich and endangered types of vegetation in Europe. In the Czech Republic, dry grasslands are mainly of anthropogenic origin and were formed as a result of grazing after the clear-cutting of thermophilous oak woods. Gradual changes in the farming landscape throughout the 20th century, particularly in the 1960s, resulted in the abandonment of the relatively infertile habitats of dry grasslands. After abandonment, dry grasslands decline and degrade due to the gradual overgrowth of woody species and expansion of perennial tall grasses. In the year 2000, a grazing management program was introduced in the protected areas within the territory of Prague City to maintain the species diversity of dry grasslands. The responses of the expansive grass species, Arrhenatherum elatius L. and multiple woody species (especially, Prunus spinosa L.) to differences in grazing periods were monitored for over a decade. Grazing in spring through the end of June had the greatest impact on the reduction of A. elatius and woody species. Grazing in the height of summer through autumn did not reduce the cover of these plants, and may support the prosperity of both A. elatius and the woody species due to higher levels of nutrients.  相似文献   

13.
ABSTRACT: Multiple anthropogenic stressors, including increased watershed imperviousness, destruction of the riparian vegetation, increased siltation, and changes in climate, will impact streams over the coming century. These stressors will alter water temperature, thus influencing ecological processes and stream biota. Quantitative tools are needed to predict the magnitude and direction of altered thermal regimes. Here, empirical relationships were derived to complement a simple model of in‐stream temperature [developed by Caissie et al. Canadian Journal of Civil Engineering 25 (1998) 250; Journal of Hydrology 251 (2001) 14], including seasonal temperature shifts linked to land use, and temperature surges linked to localized rainstorms; surges in temperature averaged about 3.5°C and dissipated over about 3 h. These temperature surges occurred frequently at the most urbanized sites (up to 10% of summer days) and could briefly increase maximum temperature by >7°C. The combination of empirical relationships and model show that headwater streams may be more pervasively impacted by urbanization than by climate change, although the two stressors reinforce each other. A profound community shift, from common cold and coolwater species to some of the many warmwater species currently present in smaller numbers, may be expected, as shown by a count of days on which temperature exceeds the “good growth” range for coldwater species.  相似文献   

14.
Applying the threshold concept to rangeland management is an important challenge in semi-arid and arid regions. Threshold recognition and prediction is necessary to enable local pastoralists to prevent the occurrence of an undesirable state that would result from unsustainable grazing pressure, but this requires a better understanding of the pastoralists’ perception of vegetation threshold changes. We estimated plant species cover in survey plots along grazing gradients in steppe and desert-steppe areas of Mongolia. We also conducted interviews with local pastoralists and asked them to evaluate whether the plots were suitable for grazing. Floristic composition changed nonlinearly along the grazing gradient in both the desert-steppe and steppe areas. Pastoralists observed the floristic composition changes along the grazing gradients, but their evaluations of grazing suitability did not always decrease along the grazing gradients, both of which included areas in a post-threshold state. These results indicated that local pastoralists and scientists may have different perceptions of vegetation states, even though both of groups used plant species and coverage as indicators in their evaluations. Therefore, in future studies of rangeland management, researchers and pastoralists should exchange their knowledge and perceptions to successfully apply the threshold concept to rangeland management.  相似文献   

15.
Depletion of vegetation by overgrazing in arid environments has long-lasting effects on the environmental quality over extended geographic areas. An adequate inspection of habitat changes requires scaled up procedures that would allow assessing end-points of environmental status in broad areas that would be based on processes occurring at the plant canopy level. Our purpose was to find indicators of land degradation–conservation status for use in land monitoring programs and in planning management practices that would be amenable to further up-scaling for use with remotely sensed imagery. In several sites of the Patagonian Monte differing in the impact of grazing management, we evaluated vegetation attributes at three spatial scales. At the population scale, we found that the severity of grazing impact was characterized by the reduction of the palatable grass, P. ligularis, outside and inside shrub canopies. At the vegetation patch scale, we found that land degradation by domestic herbivore impact was characterized by changes in attributes of patch shape (radius, height, internal canopy cover) and patch abundance. At the plant community scale, we found that the structure of the plant canopy as described using Fourier analysis of cover data changed after long-term grazing impact consistently with the modifications in plant population and patch structures. We present a conceptual multiscale scenario of structural changes triggered by domestic herbivore impact, and quantitative indicators of plant structure and processes useful to develop management strategies of the Patagonian-Monte that would conserve its natural habitats. The developed end-points are also amenable for use in land conservation assessment through remotely sensed imagery.  相似文献   

16.
This study aimed to analyze the ecological, socio-economic and policy implications of land-use diversity in a traditional village landscape (900–1,000 m amsl.) in the Garhwal region of Indian Himalaya. The village landscape was differentiated into three major land-use types viz., forests, settled agriculture and shifting agriculture. Settled agriculture was further differentiated into four agroecosystem types viz., homegarden system (HGS), rainfed agroforestry system (RAS), rainfed crop system (RCS) and irrigated crop system (ICS), and shifting agriculture system (SAS) was differentiated into different stages of a 4-year long cropping phase and a 7-year long fallow phase, and forests into Community Forests (CF) and Reserve Forests (RF). HGS is the most productive agroecosystem, with soil organic carbon and nutrient concentrations significantly higher than all other forest/agricultural land-uses. Farmers capitalize upon crop diversity to cope with the risks and uncertainties of a monsoon climate and spatial variability in ecological factors influencing productivity. The SAS, a land-use adopted as a means of acquiring inheritable rights over larger land holdings provided in the policies during the 1890s, is less efficient in terms of land productivity than the traditional RAS and HGS but is maintained for its high labour productivity coupled with availability of high-quality fuelwood from fallow vegetation. Dominance of fodder trees in the RAS seems to derive from policies causing shortage of fodder available from forests. Cultural norms have favoured equity by allowing hiring of labour only from within the village community and income from non-timber forest products only to the weaker section of the society. Conversion of rainfed to irrigated cropping, a change facilitated by the government, improves agricultural productivity but also increases pressure on forests due to higher rates of farmyard manure input to the irrigated crops. Existing forest management systems are not effective in maintenance of a large basal area in forests together with high levels of species richness, soil fertility and resistance to invasive alien species Lantana camara. Farmers have to spend huge amount of labour and time in producing manure, managing livestock and other subsidiary farm activities. Interlinkages among agriculture, forests and rural economy suggest a need of replacing the present policies of treating agricultural development, forest conservation and economic development as independent sectors by an integrated sustainable development policy. The policy should promote technological and institutional innovations enabling parallel improvements in agricultural productivity and functions of forest ecosystems.  相似文献   

17.
Some effects of domestic sheep grazing on vegetation and soils were measured at four sites in the western Mojave Desert. Although sheep have grazed the Mojave Desert for the past 50–100 years, the effects of grazing on the desert ecosystem are largely unknown.The results reflect only short-term effects of grazing, because fenced control areas were not available for study. Heavy grazing caused a 60% reduction in the above-ground biomass under creosote bushes (Larrea tridentata), and sheep trampling caused an increase in soil strength and decreased intershrub annual densities 24 and 28% in two areas. The average area per individual (cover) of burrobush (Ambrosia dumosa) decreased 16–19% and the cover of spiny hop-sage (Grayia spinosa) decreased 29% under grazing pressure. The volumes of individual Ambrosia were 21 and 65% less in two heavily grazed areas than in two lightly grazed areas; the volume of goldenhead (Acamptopappus sphaerocephalus) was 68% less in one heavily grazed area.These changes indicate that the range quality of the Mojave Desert is deteriorating under sheep grazing pressures. Trampling reduces annual cover and disrupts the soil surface, thus promoting wind erosion. The loss of annual biomass and shrub cover should adversely affect reptiles and rodents by removing food sources and protection. Soil strength increases may retard future growth of annuals, further contributing to erosion and food source losses. Studies should be initiated to determine the long-term effects of grazing in the Mojave Desert.  相似文献   

18.
Wild burros (Equus asinus), protected by the 1971 Wild Free-Roaming Horse and Burro Act on some federal lands but exotic animals many ecologists and resource mangers view as damaging to native ecosystems, represent one of the most contentious environmental management problems in American Southwest arid lands. This review synthesizes the scattered literature about burro effects on plant communities of the Mojave Desert, a center of burro management contentions. I classified 24 documents meeting selection criteria for this review into five categories of research: (i) diet analyses directly determining which plant species burros consume, (ii) utilization studies of individual species, (iii) control-impact comparisons, (iv) exclosure studies, and (v) forage analyses examining chemical characteristics of forage plants. Ten diet studies recorded 175 total species that burros consumed. However, these studies and two exclosure studies suggested that burros preferentially eat graminoid and forb groups over shrubs. One study in Death Valley National Park, for example, found that Achnatherum hymenoides (Indian ricegrass) was 11 times more abundant in burro diets than expected based on its availability. Utilization studies revealed that burros also exhibit preferences within the shrub group. Eighty-three percent of reviewed documents were produced in a 12-year period, from 1972 to 1983, with the most recent document produced in 1988. Because burros remain abundant on many federal lands and grazing may interact with other management concerns (e.g., desert wildfires fueled by exotic grasses), rejuvenating grazing research to better understand both past and present burro effects could help guide revegetation and grazing management scenarios.  相似文献   

19.
Summary In the present paper efforts have been made to identify an environmentally sustainable and economically gainful strategy for agricultural development in the Himalayan region in Uttar Pradesh State, India. In the underdeveloped rural habitat that exists, a strategy, where the economics of environmentally sustainable development can be studied, is urgently required. The findings have been based on an empirical investigation of 150 sampled households spread over fifteen villages. It was found that the state of Himalayan agriculture and allied activities was in a critical condition, requiring urgent attention in order to improve the human environment. Suggested viable improvements in Himalayan agricultural development may be grouped into four categories, viz., an expansion of the cultivated area, where the land use pattern and other factors are discussed; full utilisation of irrigation potentialities, in which water management is discussed; improvement in the cropping pattern, where the whole system of cropping is analysed; and modifications in the use of agricultural appliances, specially in hoeing, ploughing and inter-culturing implements. Based on a critical analysis of these four identified aspects, economically viable, ecologically sound and socially justified environmental planning may be effectively framed.Dr H.C. Pokhriyal is Head of the Department of Economics at Garhwal University Campus, Tehri, and Dr N.S. Bist is Professor and Head of the Department of Economics at Garhwal University, Srinagar Garhwal, Himalaya, U.P., India.  相似文献   

20.
Aibi Lake in north Xinjiang is a typical lake of the arid area, but with a peculiar wetland–arid area ecosystem. Due to the climate becoming drier and the disturbance of human activities, the eco-environment of Aibi Lake catchment has degraded. It was found in our study that there were spatial–temporal changes of vegetation cover, plant species, and soil physical and chemical properties in the catchment. In the upper section of alluvial–fluvial plains, the desertified steppe of Stipa and Artemisia spp. is developed with vegetation cover of some 50%. Haloxylon ammodendron desert occupies the lower section with vegetation cover of some 60%. In these regions with an intensive human disturbance, vegetation has degraded into herb vegetation of annual plant complexes. On the margins of the alluvial–fluvial fans, the lakeshore, and the surrounding regions where the river mouths join the lake, different azonal vegetation—Phragmites communis marsh, Phragmites communis meadow, and Tamarix shrubs—have developed with a vegetation cover of some 80%. On heavier, salinized land, succulent halophyte desert vegetation dominated by Halocnemum strobilaceum has formed with a fractional canopy cover of 10–15%. Haloxylon persicum, Aristida pennata, and other species with a vegetation cover of 30–50% grow in the sand desert zone on the periphery in the lake. In contrast with the 1950s, the vegetation cover around the lakebed and at the river deltas has slightly increased; however, the vegetation cover around the periphery of the lake has decreased and the plant species have still degraded. The surface soils on the windward area and the dried lakebed that have lost vegetation protection have become coarser, whereas the land on the leeward side of the lake has accumulated fine particles. In contrast with the 1980s, soil organic matter has declined markedly. The analyses of climatic data show that the number of days of drifting dust in Jinghe County and Bole City increased in the last 20 years. In the investigation, we found that intensively developed land, the bare lakebed, and abandoned cultivated land provided a great deal of material for drifting dust. In conclusion, we consider the eco-environmental degradation resulting from the inappropriate human activities and put forward recommendations for land-use adjustment and dust control.  相似文献   

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