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1.
人类活动强度空间化是分析人类活动区域差异及其变化过程的基础,也是准确辨识土地变化驱动因素、合理调控人类活动的科学依据。当前人类活动强度研究多以数理方法对代用指标进行空间化,缺乏对人类活动机理过程的反映,也制约了人类活动强度空间异质性的展现。本文以青藏高原放牧活动为研究对象,在综合放牧喜好和草地管理策略的基础上,从放牧行为机理的角度,提出了区分放牧区与非放牧区的方法;以放牧密度衡量草地整体放牧压力,以放牧概率刻画放牧活动的空间差异,构建了区域放牧强度空间化模型。并以高原典型牧业县—泽库县为例,基于乡镇级牧业数据和自然地理基础信息进行了实证研究。结果表明：空间化结果较好反映了泽库县放牧强度的空间特征;直接指标的选取和客观的赋值方法提高了放牧强度空间化结果的准确性;比现有研究结果更能体现出县域内放牧强度的空间差异,且放牧强度变化过程与同期NDVI值变化具有较好的耦合性。本文为人类活动空间化方法研究提供了有益参考。 相似文献
2.
Intensive grazing in spring–summer has been responsible for environmental degradation of the Gurbantunggut Desert in recent years. The coverage of plants and biological crusts, sand surface stability and physicochemical characteristics of soil on the dune surface were conducted in 2002 (winter grazing) and 2005 (spring–summer grazing). The results showed that over 80% of the total area of the dune surface was covered by well-developed biological crusts and plants in 2002, when the interdune and middle to lower part of dune slopes were stabilized and only the crest had 10–40 m wide mobile belt. Affected by spring–summer grazing in 2005, over 80% of the total cover of biological crust was destructed and the plant coverage only reached 1/5 of that in 2002, especially the ephemeral plant cover had a great change. The value of sand transport potential in 2005 only reached 1/3 of that in 2002, but the total surface activity in 2005 was 1.6 times stronger than that in 2002. Meanwhile the mobile area began to expand from the dune top to the whole dune surface following spring–summer grazing. Compared with 2002, medium sand content of the dune surface soil increased by 13.9%, while that of fine and very fine sands decreased by 7.4% and 8.0% respectively in 2005 and the soil organic matter in 2005 was only about 1/2 of that in 2002. It is obvious that the presence of snow cover and frozen soil in winter could avoid the surface structure destruction in winter, while spring–summer grazing made excessive damage to biologic crusts and ephemeral plants. Spring is the main windy season in Gurbantunggut Desert and therefore intensive activity of dune surface occurred following spring–summer grazing, which led to a great loss of fine sand and organic matter. It can be seen that grazing season have a significant influence on the sustainable development of the desert ecosystem in Northwest China. 相似文献
3.
The grassland biome of South Africa is a major resource for livestock farming; yet the soils of these rangelands are stressed differently by various management systems. The aim of this study was to investigate how basic soil properties respond to different management systems. For this purpose we sampled rangeland management systems under communal (continuous grazing), commercial (rotational grazing) and land reform (mixture of grazing systems) farming. Within each of these systems a grazing gradient was identified with decreasing grazing pressure with increasing distance to the water points. Results showed that communal farms with continuous grazing were generally depleted in the respective nutrient stocks. The depletion increased with rising grazing pressure. Along that line there was a breakdown of macroaggregates with losses of the C and N stored therein. However, the commercial farms also exhibited a decline of macroaggregates and their associated C content nearby the water points. Aggregate fractionation is a sensitive indicator for detecting the beginning of soil degradation in this biome; yet, degradation was less pronounced under the rotational grazing of the commercial farms than under communal property right conditions. Hence, soil analyses confirm that fences and appropriate grazing periods are needed to manage these rangelands sustainably. 相似文献
4.
放牧对古尔班通古特沙漠南部半固定沙垄地表性质的影响 总被引：1，自引：0，他引：1
Intensive grazing in spring-summer has been responsible for environmental deg- radation of the Gurbantunggut Desert in recent years. The coverage of plants and biological crusts, sand surface stability and physicochemical characteristics of soil on the dune surface were conducted in 2002 (winter grazing) and 2005 (spring-summer grazing). The results showed that over 80% of the total area of the dune surface was covered by well-developed biological crusts and plants in 2002, when the interdune and middle to lower part of dune slopes were stabilized and only the crest had 10-40 m wide mobile belt. Affected by spring-summer grazing in 2005, over 80% of the total cover of biological crust was destructed and the plant coverage only reached 1/5 of that in 2002, especially the ephemeral plant cover had a great change. The value of sand transport potential in 2005 only reached 1/3 of that in 2002, but the total surface activity in 2005 was 1.6 times stronger than that in 2002. Mean- while the mobile area began to expand from the dune top to the whole dune surface following spring-summer grazing. Compared with 2002, medium sand content of the dune surface soil increased by 13.9%, while that of fine and very fine sands decreased by 7.4% and 8.0% re- spectively in 2005 and the soil organic matter in 2005 was only about 1/2 of that in 2002. It is obvious that the presence of snow cover and frozen soil in winter could avoid the surface structure destruction in winter, while spring--summer grazing made excessive damage to biologic crusts and ephemeral plants. Spring is the main windy season in Gurbantunggut Desert and therefore intensive activity of dune surface occurred following spring-summer grazing, which led to a great loss of fine sand and organic matter. It can be seen that grazing season have a significant influence on the sustainable development of the desert ecosystem in Northwest China. 相似文献
5.
放牧强度对科尔沁沙地沙质草地植被的影响 总被引：5，自引：3，他引：2
为了研究科尔沁沙地沙质草地在不同放牧强度下植被特征的变化规律,比较了围封、中度放牧、重度放牧3种条件下的植被盖度、群落组成、物种多样性、地上/地下生物量和凋落物量等植被特征的变化特征。结果表明:(1)围封、中度放牧和重度放牧沙质草地的优势植物均为一年生植物,但围封和中度放牧中多年生禾本科植物优势度高于重度放牧,重度放牧沙质草地一年生植物所占优势度最大;(2)放牧强度对沙质草地植被盖度、地上生物量及凋落物量有显著影响。随着放牧强度的增加,植被盖度、地上生物量和凋落物量均降低;(3)围封、中度放牧和重度放牧沙质草地物种丰富度及多样性差异均不显著;(4)放牧强度和土壤深度及其交互作用均能影响地下生物量。随着放牧强度的增加,总的地下根系生物量减小。而重度放牧草地中, 3个土壤深度间地下根系生物量差异不显著。放牧改变了沙质草地植物群落的组成、极大降低了植被盖度和生产力;尤其是重度放牧急剧增加了一年生植物的优势、且对浅层根分布的减少影响最大。 相似文献
6.
Xueqin Wang Yuanming Zhang Jin Jiang Weikang Yang Hongxu Guo Yongfeng Hu 《地理学报(英文版)》2009,19(3):299-308
Intensive grazing in spring–summer has been responsible for environmental degradation of the Gurbantunggut Desert in recent
years. The coverage of plants and biological crusts, sand surface stability and physicochemical characteristics of soil on
the dune surface were conducted in 2002 (winter grazing) and 2005 (spring–summer grazing). The results showed that over 80%
of the total area of the dune surface was covered by well-developed biological crusts and plants in 2002, when the interdune
and middle to lower part of dune slopes were stabilized and only the crest had 10–40 m wide mobile belt. Affected by spring–summer
grazing in 2005, over 80% of the total cover of biological crust was destructed and the plant coverage only reached 1/5 of
that in 2002, especially the ephemeral plant cover had a great change. The value of sand transport potential in 2005 only
reached 1/3 of that in 2002, but the total surface activity in 2005 was 1.6 times stronger than that in 2002. Meanwhile the
mobile area began to expand from the dune top to the whole dune surface following spring–summer grazing. Compared with 2002,
medium sand content of the dune surface soil increased by 13.9%, while that of fine and very fine sands decreased by 7.4%
and 8.0% respectively in 2005 and the soil organic matter in 2005 was only about 1/2 of that in 2002. It is obvious that the
presence of snow cover and frozen soil in winter could avoid the surface structure destruction in winter, while spring–summer
grazing made excessive damage to biologic crusts and ephemeral plants. Spring is the main windy season in Gurbantunggut Desert
and therefore intensive activity of dune surface occurred following spring–summer grazing, which led to a great loss of fine
sand and organic matter. It can be seen that grazing season have a significant influence on the sustainable development of
the desert ecosystem in Northwest China.
Foundation: National Basic Research Program of China, No.2009CB421303; National Natural Science Foundation of China, No.40771032; National
Science Supporting Program, No.2007BAC17B03
Author: Wang Xueqin (1964–), Ph.D and Associate Professor, specialized in aeolian sand geomorphology, desertification and its control. 相似文献
7.
放牧对古尔班通古特沙漠南部 沙垄地表性质的影响 总被引：2，自引：0，他引：2
分别于2002 年和2005 年对古尔班通古特沙漠南部的同一条半固定沙垄, 进行了放牧前后的地表覆盖(包括植物和生物结皮)、沙面活动强度和土壤理化性质的系统监测和研究。 主要结论如下: 2002 年, 自然沙垄80%以上的地表被植物和生物结皮所覆盖, 除沙垄顶部外, 其他部位基本处于稳定状态。2005 年受放牧干扰的影响, 生物结皮破损率达到80%以上, 同期植物覆盖不及2002 年的1/5, 特别是短命植物变化最明显。2005 年输沙势只有2002 年的1/3, 但沙面活动强度是2002 年的2.6 倍, 活动区域也从垄顶部扩展至整个沙垄表面。 放牧后地表组成物中的中沙含量增加了13.9%, 而细沙和极细沙含量分别减少了7.4%和 8.0%, 沙垄各部位有机质含量在放牧后一个风季即下降了近1/2。可见, 放牧造成地表保护条件的多重损害, 使沙漠地表稳定性趋于丧失。其细粒物质及有机质的大量流失, 也将对我国温带荒漠生态系统的可持续发展产生重要影响。 相似文献
8.
We examined change in areal extent of mountain meadows and fields of deciduous shrubs and conifer saplings in the central western Cascade Range of Oregon, based on analysis of aerial photographs taken in 1946 and 2000. These nonforest vegetation patches are distinctive habitats in dominantly forested landscapes, such as the Cascades, and change in extent of these habitats is of interest to scientists and land managers. We mapped and dated even-aged forest stands of probable postfire origin around the nonforest patches, using tree-ring analysis and interpretation of aerial photographs. We used these and archival data to interpret possible influences of past wildfire and sheep grazing on the extent of nonforest patches. The total area of nonforest vegetation patches decreased from 5.5 percent of the study area in 1946 to 2.5 percent in 2000. Significantly more cases of contracted patches were observed for mesic and xeric meadows which have adjacent forest established after wildfire in the approximately 150 years preceding 1946. A higher proportion of mesic (47 percent, n = 47) than xeric (17 percent, n= 115) meadows contracted between 1946 and 2000. Broad-leaved shrub fields were unchanged, probably because of topo-edaphic controls, dense cover of shrubs, and snow effects; but all fields of conifer saplings underwent succession to forest. We observed no strong influences of sheep grazing on the extent of meadows. 相似文献
9.
为探究放牧对丘间低地植被群落及土壤的影响，分析了浑善达克沙地丘间低地在重度和轻度放牧下植被的地上生物量、物种重要值、物种丰富度、Shannon-Wiener多样性指数、Pielou均匀度指数、Simpson生态优势度指数及0~10 cm土壤中黏粒、粉粒、砂粒、有机碳和全氮含量。结果表明：（1）植被地上生物量、土壤黏粒、粉粒、砂粒、土壤有机碳和全氮含量在不同放牧程度下存在极显著差异（P<0.01），物种丰富度、Shannon-Wiener多样性指数和Pielou均匀度指数在不同放牧程度下差异不显著（P>0.05），Simpson生态优势度指数在不同放牧程度下差异显著（P<0.05）。（2）放牧区植被以禾本科为主，禾本科植被地上生物量占整个植被群落的54.88%~57.76%；重度放牧区植被地上生物量为63.59 g·m-2，比轻度放牧区低26.61%。（3）羊草（Leymus chinensis）和狗尾草（Setaria viridis）是放牧区的优势种，其重要值依次为14.16%（重度放牧区）和19.10%（轻度放牧区）、13.40%（重度放牧区）和15.42%（轻度放牧区），重度放牧下雾滨藜（Bassia dasyphylla）、克氏针茅（Stipa krylovii）和猪毛蒿（Artemisia scoparia）的重要值较显著高于轻度放牧区，而羊草则低于轻度放牧区。（4）重度放牧加剧了土壤沙漠化，使砂粒含量增加，草地生产力下降，土壤有机碳和全氮含量降低。 相似文献
10.
A. Hoshino Y. Yoshihara T. Sasaki T. Okayasu U. Jamsran T. Okuro K. Takeuchi 《Journal of Arid Environments》2009,73(6-7):687-690
The objective of this study was to clarify whether the changes in percent cover of plant functional types (i.e., life forms and growth forms) along a grazing gradient reflect the livestock number, which would reinforce the reliability of using a grazing gradient design and improve the management of rangeland. We selected two livestock camps that for many years have had different numbers of livestock, with approximately six times more sheep-equivalents at site 1 than at site 2. Vegetation was sampled in 10 quadrats on five transects along the grazing gradient at each site. In each quadrat, we recorded percent cover of each plant species. Our findings suggested that vegetation changes along the grazing gradient under different livestock numbers were characterized by changes in the cover of life forms: perennial species were replaced by annual species near the camps (10–50 m). However, we did not find growth form change that reflected the difference in the number of livestock. 相似文献
11.
Yabello牧场是埃塞俄比亚博拉纳的一个半干旱地区的牧场,目前面临着草场退化的严重挑战。植被覆盖的变化、过度放牧和季节性变化极大地影响了Yabello牧场的牧草组成和生物量。本文评估了植被覆盖、放牧和季节对Yabello牧场的牧草组成和生物量的影响。首先采用1 m×1 m的随机样方进行实验,根据植被覆盖类型和放牧变化选择样点,并对季节影响进行评估。使用SAS统计软件和MicrosoftExcel分析牧草组成、牧草高度和质量数据。本研究总共记录了26种草种,其中Chloris roxburghiana, Chrysopogon aucheri和Chrysopogon aucheri草种均表现出最高的平均单种覆盖高度和生物量产量。因此,建议将这些草种用于研究区域退化草地的恢复。研究结果还表明,植被覆盖类型、放牧和季节变化是决定牧草种类组成、牧草高度和生物量产量的关键因素。最后,研究结论还认为控制灌木丛植被并平衡放牧水平的可持续管理对于该地区的可持续牧草生产和生物多样性保护至关重要。 相似文献
12.
The effect of intensive grazing and browsing of domestic stock and wildlife on the number of species and abundance of vegetation was investigated in the Hoanib River catchment, north-western Namibia. The seasonal abundance of ground cover, bare earth, canopy cover, annual grass, perennial grass and annual forbs were measured in each of the focus-study areas. In three of the focus areas where the ranges of both domestic stock and wildlife were restricted either by fencing or water availability, impact on the vegetation was greatest. The final focus area was a more ‘open range’ system that allowed for the free movement of wildlife. Under these conditions the species abundance and availability of browsing and grazing was greater than the other focus areas during both the wet and dry seasons. However, very little difference in abundance and availability of vegetation was observed between focus areas in both seasons regardless of landuse. There is generally a low abundance of perennial grasses and browse species affording the ecosystem little resistance and resilience to disturbance caused by grazing and drought. 相似文献
13.
放牧对内蒙古羊草群落土壤呼吸的影响 总被引：11，自引：0，他引：11
采用静态暗箱法,比较测定了放牧对内蒙古锡林河流域羊草群落土壤呼吸的影响以及水热等相关环境因子与土壤呼吸的关系。结果表明:放牧没有改变羊草群落土壤呼吸的季节性变化特征,但降低了土壤呼吸速率的年幅度;生长季放牧样地土壤呼吸速率显著低于封育样地,非生长季两样地土壤呼吸强度均处于较低水平,而且出现负通量的现象,放牧使羊草群落土壤呼吸年总量下降了约33.95％;从全年来看,无论是围栏还是放牧样地,封育样地和放牧样地土壤呼吸与温度因子均显著正相关(p<0.01,n=15),其中与10cm处地温相关性最好,但放牧降低了土壤呼吸对温度变化的敏感性;生长季水分影响作用高于温度,围栏封育样地0~10cm土壤含水量的变化可以解释土壤呼吸变异的87.4％,放牧样地10~20cm和20~30cm土壤含水量的变化共同可以解释土壤呼吸变异的74.9％。 相似文献
14.
15.
春夏季放牧对古尔班通古特沙漠南部土壤种子库和地上植被的影响 总被引：6，自引：5，他引：1
位于新疆北部准噶尔盆地腹地的古尔班通古特沙漠,是世界上温带荒漠生物多样性的精华和最为丰富的典型区域。历史上这里就是北疆羊和部分马匹重要的冬牧场,但近年来的放牧活动在春夏季也开始进入沙漠腹地,使地表性质与植被覆盖发生了明显改变。应用野外随机取样与室内萌发实验相结合的方法,对比研究了古尔班通古特沙漠南部春夏季放牧和冬季放牧沙垄土壤种子库差异及其与地上植被的关系。结果表明：冬季放牧沙垄种子库种数为24种,而春夏季放牧沙垄有20种,后者明显减少了植物种数。冬季放牧沙垄种子库密度为(353.2±87)粒·m-2,而春夏季放牧沙垄为(189.1±23)粒·m-2,比前者减少了88%。两类沙垄土壤种子库的生活型组成都以一年生植物为主,相似性系数为0.711。相同沙垄不同部位的物种相似性系数在0.429～0.600之间,异质性较大,尤其表现在除垄顶之外的其他部位。冬季放牧沙垄和春夏季放牧沙垄地上植被中分别有植物36种和26种,各生活型所有物种均为后者低于前者,其中短命、类短命物种数量减少幅度最大。春夏季放牧沙垄地上植被的物种多样性和均匀度降低,而优势度升高。回归分析显示,冬季放牧沙垄定植群落有21%的变异来源于土壤种子库,而春夏季放牧沙垄有51%的变异来源于土壤种子库,可见不同季节的放牧干扰显著影响土壤种子库及其与地上植被的相关关系。 相似文献
16.
研究了科尔沁沙地南缘土地覆盖由流动沙地向人工林地、农田及固定沙地等转变后,0~60 cm土层有机碳储量的变化。结果表明：农田土壤有机碳含量增加最明显,为流动沙地的3.97倍且相同层间差异均显著;樟子松（Pinus sylvestris var. mongolica）林地、新疆杨（Populus alba var. pyramidalis）林地、小叶锦鸡儿（Caragana microphylla）群落土壤有机碳含量较流动沙地分别增加79.78%、138.20%、73.07%,差异主要在0~20 cm土层;围封草地和中度放牧草地分别增加116.85%和133.71%,差异主要在0~40 cm土层;固定沙地比流动沙地增加49.44%,差异主要在0~20 cm土层。土地覆盖类型转变后,由于受到土壤容重的影响,土壤有机碳密度在0~20 cm土层变化较明显。8种土地覆盖类型可分为4组：CL1（农田）、CL2（新疆杨林地、围封草地、中度放牧草地）、CL3（樟子松林地、小叶锦鸡儿群落、固定沙地）和CL4（流动沙地）。另外,土壤有机碳含量和密度在土壤剖面上的分布也随着土地覆盖类型的变化而不同。 相似文献
17.
基于意愿价值评估法的禁牧政策生态补偿定量分析——以宁夏盐池县为例 总被引：2，自引：2，他引：0
禁牧政策作为生态补偿实践的重要内容,是解决中国广大牧区生态问题的战略性举措。合理的补偿标准是促进禁牧政策有效实施和持续推进的关键因素,因而受到学者广泛关注。本文以宁夏盐池县为例,应用Logistic回归模型分析城乡居民支付意愿及农户受偿意愿的影响因素,并采用意愿价值评估法(CVM)定量评估盐池县禁牧政策的补偿标准。结果表明:(1)农户的支付意愿与年总收入、羊只饲养规模正相关,与年龄、禁牧前后非农收入变化率、对禁牧政策的接受态度负相关;(2)县城居民的支付意愿与年龄负相关,与对环境的关注度正相关,与职业存在相关性;(3)农户的受偿意愿与人均粮食产量、羊只饲养规模正相关,与禁牧前后非农收入变化率负相关;(4)应用多重对应分析法得出影响农户支付水平和受偿水平的因素均为羊只饲养规模。结合CVM公式和Spike模型,对农户的支付、受偿标准及县城居民的支付标准进行定量评估。 相似文献
18.
The continuous increase of livestock production in Inner Mongolia has caused severe degradation of the grassland ecosystems in recent years. Previous grazing experiments have shown a wide range of vegetation responses between the biome types on a global scale, but there is still a lack of sufficient studies to discern the relative responses of a given biome type. We conducted a meta-analysis of vegetation coverage (VC), plant density (PD), total biomass (TB), above-ground biomass (AGB), under-ground biomass (UGB) and Shannon-Weaver Index (SI) in different grassland types in Inner Mongolia obtained under conditions of different grazing intensities and durations. The results showed that grazing decreased VC, TB, AGB, UGB, and PD significantly. Compared to the global and national average values, the negative effects of grazing to steppe biomass in Inner Mongolia were higher than that on the global scale, while less pronounced than that in China. TB of the meadow steppe in Inner Mongolia increased by 40% under moderate grazing intensity and duration because of compensatory growth. SI of the desert and meadow steppe showed negative linear relationships with the grazing intensity in Inner Mongolia. The percentage changes in AGB, PD, and SI to grazing showed quadratic relationships with the mean annual temperature of the experimental year. With increasing mean annual precipitation, the negative effects of grazing on UGB and SI first decreased and then increased, with that of VC and grazing showing a cubic relationship. 相似文献
19.
The Waite–Nicolson rangeland management method for semi-arid chenopod shrublands predicts that smaller paddocks with medium to moderate stocking rates help to preserve the native vegetation. Vegetation cover around waterpoints in three small paddocks (<2000 ha) from Middleback Station, South Australia was studied using multivariate analysis. Data from quadrats sampled along radiating transects were tested for correlations with a number of site features and grazing history factors. Two significant associations were detected: quadrats with an abundance of Rhagodia parabolica and less palatable species such as Maireana pyramidata, and Atriplex stipitata were correlated positively with proximity to water points, paddock age and stocking rate, and negatively with paddock size. In contrast, quadrats with species such as Rhagodia ulicina and the more palatable M. sedifolia were correlated with increasing distance from the water points and paddock size, but negatively with age and stocking rates. Transect direction was not correlated with either group. Twelve of the 20 species examined, including the important forage species A. vesicaria, also were not correlated with those paddock and grazing features included here. These results suggest that the distribution of some chenopod shrub species in fenced paddocks is still possibly affected by a combination of these factors in the long term by grazing at densities of 6 ha sheep−1 and that the method, although maintaining the fodder species, may not be preserving biodiversity at these grazing levels, although further study is needed. 相似文献
20.
F. Ouellet A. Langlois E. A. Blukacz-Richards C. A. Johnson A. Royer E. Neave 《自然地理学》2017,38(2):143-158
AbstractPeary caribou is the northernmost designatable unit for caribou species, and its population has declined by about 70% over the last three generations. The Committee on the Status of Endangered Wildlife in Canada identified difficult grazing conditions through the snow cover as being the most significant factor contributing to this decline. This study focuses on a spatially explicit assessment tool using snow model simulations (Swiss SNOWPACK model driven in an off-line mode by spatialized meteorological forcing data generated by the Canadian Regional Climate Model) to characterize snow conditions for Peary caribou grazing in the Canadian Arctic. The life cycle of Peary caribou has been subdivided into three critical periods: summer foraging and fall breeding (July–October), winter foraging (November–March), and spring calving (April–June). Winter snow conditions are analyzed and snow simulations compared to Peary caribou island counts to identify a snow parameter that could potentially act as a proxy for grazing conditions and explain fluctuations in Peary caribou numbers. This analysis concludes that caribou counts are affected by simulated snow density values >300 kg m?3. A software tool mapping possibly favorable and unfavorable grazing conditions based on snow is proposed at a regional scale across the Canadian Arctic Archipelago. Specific output examples are given to show the utility of the tool, mapping pixels with cumulative snow thickness above densities of 300 kg m?3, where cumulative seasonal thicknesses >7000 cm are considered unfavorable. 相似文献