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This study examines mass movement associated with land use change, particularly deforestation, from multiple perspectives. The significance of such understanding is related to the degree of impact landsliding may cause on human settlements and economic activities, and on forest ecosystems. In this paper, the distribution of hillslope instability in the Sierra Norte, Puebla, Mexico is addressed by means of a diachronic analysis, which involves the development of vegetation indexes, as well as vegetation fragmentation derived from Landsat-5 (TM) and Landsat-7 (ETM+) satellite images from 1989 and 1999, respectively. The time period was chosen to compare vegetation cover conditions prior and after the extreme October 1999 rainfall event that triggered hundreds of slope failures in the study area. Results suggested there was a significant vegetation reduction from 1989 to 1999, which was strongly expressed by an increase of 809 km2 of bare surfaces. Additionally, areas with highest vegetation density (91–100%) decreased considerably, from 1245 to 363 km2, resulting in a net vegetation reduction of 70%. Furthermore, it was possible to highlight that landslide concentration was much higher on surfaces that were bare and had low vegetation density (0–50%), representing 85% of hillslope instability, than on surfaces having a greater density of vegetation cover. Land use change and land degradation are precursors to environmental hazards, such as mass movement events, that pose serious threats to regional population distributions and economic vitality. 相似文献
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不同植被格局对梁峁坡-沟坡的侵蚀动力作用机制 总被引：2，自引：0，他引：2
[目的]探究不同植被格局对梁峁坡—沟坡的侵蚀动力作用机制,为进一步揭示草地坡面侵蚀规律和植被减蚀效应研究提供科学依据。[方法]以梁峁坡—沟坡为研究对象,采用室内降雨模拟降雨和三维激光扫描技术,分析不同植被格局对梁峁坡—沟坡侵蚀动力作用机制。[结果]径流流速和含沙量共同影响着坡面侵蚀动力过程,径流流速是主要影响因素。坡面的侵蚀产沙来源主要位于沟坡内,不同植被格局下梁峁坡与沟坡产沙比例的不同,反映了植被调控侵蚀的范围和强度的不同。草带位于梁峁坡中下部时,不但能够有效降低梁峁坡的侵蚀程度,而且能够有效抑制和减缓沟坡内的径流流速,大幅度降低梁峁坡下部和沟坡内的侵蚀程度。[结论]不同植被格局可以通过影响径流流速和含沙量来调控梁峁坡—沟坡侵蚀动力。 相似文献
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桂西北喀斯特峰丛不同土地利用方式坡面产流产沙特征 总被引：25，自引：7，他引：18
由于缺乏长期定位观测资料,西南喀斯特山区坡地水土流失规律一直不明确,严重影响了该区石漠化综合治理和水土流失防治工作的成效和进程。该文基于13个大型径流小区(宽20m、投影面积>1000m2)5a(2006-2010年)的定位观测资料,分析了桂西北喀斯特峰丛洼地不同利用方式坡面降雨产流规律和地表侵蚀产沙特征。结果表明:观测期内年降雨量为1300～2000mm,无论平水年还是丰水年,不同利用方式坡面次降雨径流系数<5%,地表产流很少,降雨几乎全部入渗。不同利用方式地表侵蚀产沙模数虽有较大差异,但土壤侵蚀以微度(<30t/(km2a))为主,部分甚至只有0～5t/(km2a)。植被类型、土地利用方式对坡面降雨产流的影响较小,但人为干扰会增加地表侵蚀产沙量。该文为喀斯特坡地植被恢复重建和水土流失防治提供参考。 相似文献
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北京山区果园水平阶整地措施的水土保持效益 总被引：2，自引：0，他引：2
坡地果树产业已成为北京山区市县农业的重要组成部分.坡地果园坡度大,地表覆盖低,土壤侵蚀严重.水平阶整地是北京山区坡地果园的重要水土保持措施之一,定量测算坡地果园土壤侵蚀速率和水平阶整地措施的水土保持效益对于实现资源环境和经济的可持续协调发展具有重要的实际意义.分别采集北京山区无措施（昌平）和水平阶整地措施（密云、怀柔）后的土壤样品,通过测定137 Cs面积活度换算土壤侵蚀速率,估算北京山区坡地果园水平阶整地措施的水土保持效益.结果表明：昌平、密云和怀柔坡地果园的土壤侵蚀速率分别为5 331、2 494和1 970 t/（km2·a）,水平阶整地措施减少50％的土壤侵蚀量,可起到降低土壤侵蚀的作用;但是由于年久失修,没能完全发挥其应有的水土保持功效. 相似文献
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以“一带一路”区域为研究区，基于1990−2018年的逐月历史气候数据和1981−2016年的逐年植被物候数据，采用趋势分析和统计分析等方法研究极端气候事件和植被物候的时空变化规律，并选取欧洲东南部耕地、中国北部内蒙古草原、印度中部耕地和泰国北部耕地为典型农业区，分析典型极端气候事件对生长季的影响规律。结果表明：（1）“一带一路”区域的极端气候事件主要以极端热事件和极端冷事件为主，且总体上呈现增加的趋势。极端高温事件的增加趋势明显，而极端低温事件则表现出减少的趋势；（2）生长季始期（SOS）、生长季末期（EOS）和生长季长度（LOS）总体上随纬度位置层状变化，海拔和降水也显著影响生长季。在全球变暖的影响下，“一带一路”区域大部分地区的SOS呈提前的趋势，而EOS呈延后的趋势，这导致了LOS的普遍延长；（3）当极端高温事件发生时，SOS普遍提前，而EOS普遍延后。极端低温事件则会导致SOS的延迟和EOS的提前。此外，极端气候事件越剧烈，对植被物候的影响越大。 相似文献
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植被恢复对侵蚀坡地表层土壤性质的影响 总被引：4，自引：0，他引：4
为了评价表层土壤有机碳和养分对放牧和不同植被类型互作的反应,选择四川省西昌市西溪乡牛郎村马家松坡放牧丘陵坡地,分别在坡顶、上、中、下部各层采集有乔木(桉树)、灌木(米油枝)、草本3种类型植被覆盖以及无植被覆盖的0—5 cm表层土壤,测定分析了土壤容重、土壤有机碳、速效氮含量。结果表明,植被对改善表层土壤有机碳和速效氮含量的作用大小顺序为:米油枝>草本植物>桉树。米油枝、草本植物能显著提高土壤有机碳和速效氮含量,桉树改善表层土壤有机碳和速效氮含量的作用则比较小。不同坡位对土壤有机碳、速效氮含量无显著影响。不同植被类型下表层土壤容重变化为:米油枝下土壤<桉树下土壤<草地<裸地。米油枝能显著降低表层土壤容重,而在不同坡位间无显著差异。不同植被类型下表层土壤对放牧的反应不同。放牧显著降低了桉树林下表层土壤有机碳和速效氮的含量,对米油枝和草本植物覆被下表层土壤性质的影响不显著。 相似文献
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D.A. Saunders 《Biological conservation》1989,50(1-4):99-135
The wheatbelt of Western Australia is an area of about 140 000 km2 which has undergone massive changes since European settlement in 1827. Clearing of native vegetation for agricultural development has removed up to 93% of the original vegetation in some areas and replaced it with exotic grasses, cereal crops and frequent watering points. The remaining vegetation is made up of thousands of remnants of various sizes, shapes and degreees of isolation scattered across the landscape.
The avifauna of the wheatbelt is examined at the regional level, the district level and at the level of the individual remnant and changes over the last 80 years or so are described. Two species of bird have gone extinct in the wheatbelt out of 148 species of land birds recorded in the region over the last 80–90 years. At the district level, more species have become extinct, the numbers depending on the extent of the removal of native vegetation and length of time since clearing took place. There is demonstrable loss of bird species at the level of the individual remnant; in the example cited (81 ha) three species have gone extinct over the last 10 years.
This rapid loss of species from district avifaunas means that remnant vegetation needs to be retained intact and conservation agencies should develop assessment techniques to identify reserve networks which include the species that have declined so that management can concentrate on them. Priorities for management should then be developed and local communities involved in the management of their local conservation systems or networks. 相似文献
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Habitat remnants on urban green-space areas (i.e. parks, gardens and golf courses) sometimes provide refuge to urban-avoiding wildlife, leading some to suggest these areas may play a role in wildlife conservation if they are appropriately designed and managed. The high densities observed on some green-space areas may however be attributed to external influences. Localised efforts to enhance the habitat value of urban green-space areas may therefore have little more than a cosmetic effect. This study investigated environmental factors influencing bird, reptile, mammal and amphibian diversity on Australian golf courses to assess the efficacy of small-scale conservation efforts. Abundance and species richness did not simply reflect local habitat qualities but were instead, partly determined by the nature of the surrounding landscape (i.e. the area of adjacent built land, native vegetation and the number of connecting streams). Vertebrate abundance and species richness were however, also associated with on-site habitat characteristics, increasing with the area of native vegetation (all vertebrates), foliage height diversity and native grass cover (birds), tree density, native grass cover and the number of hollows (mammals), woody debris, patch width and canopy cover (reptiles), waterbody heterogeneity and aquatic vegetation complexity (frogs). Localised conservation efforts on small land types can benefit urban-avoiding wildlife. Urban green-space areas can provide refuge to urban-avoiding vertebrates provided combined efforts are made at patch (management), local (design) and landscape (planning) scales. 相似文献
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The endangered Australian subtropical rainforest understorey shrub Triunia robusta, is restricted to the south-east Queensland region of Australia. The potential pre-clearing and current distribution of the species was modelled by relating species presence at recorded locations to correlated abiotic and biotic factors, which in combination, were then used as a surrogate for predicting distribution of the species habitat over its known range. From a defined study area of 330,000 ha, output of geographic areas likely to contain T. robusta habitat at three levels of probability were generated for pre-clearing vegetation, and vegetation classified as remnant in 1999. Potential pre-clearing distribution was compared with potential current distribution to ascertain the likely impact of clearing of native vegetation on the extent, pattern, and contiguity of T. robusta habitat. For pre-clearing vegetation, a total area of 45,480 ha was identified as potential T. robusta habitat. For vegetation classified as 1999 remnant, 13,440 ha were identified, representing an overall reduction of 70% in potential habitat for T. robusta. The model was partially validated, with T. robusta found at six new locations. Allowing for errors from spatial mismatching, five of the sites were located within habitat patches predicted by the model. A number of local areas containing high densities of predicted habitat patches were identified to guide searches for unrecorded populations. Strategically located areas linking known populations containing suitable or potentially suitable habitat that may be available for introduction of new populations were identified. The results indicate that the species former centre of range was in lowland areas adjacent to the north arm of the Maroochy River. Clearing and fragmentation of T. robusta habitat is the most likely cause of the apparent decline in distribution and abundance of the species. 相似文献
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桂西北岩溶山区峰丛洼地土壤水分动态变化初探 总被引：25，自引：0，他引：25
土壤水分是岩溶山区植被恢复和生态环境建设的关键性限制因素。在桂西北岩溶山区峰从洼地，分析了不同利用方式坡面、洼地土壤水分的动态变化规律，结果表明：坡面土壤水分（0～20cm）为中等变异，不同利用方式间具有一定的差异，自然灌丛、撂荒地土壤含水量较高，但板栗、木豆林地土壤含水量较低，且易受外界条件的干扰，其栽种早期应注意采取一定的蓄水保墒措施；与坡地相比，洼地受外界条件的干扰相对较小，土壤剖面含水量为增长型，其变化主要发生在表层，为中等变异；土壤水分沿坡面的分布规律较为复杂，在植被类型相对一致的条件下，坡位的影响相对较小。 相似文献
12.
基于GIS的三江并流区泥石流危险性评价 总被引：1，自引：0，他引：1
三江并流区位于怒江、澜沧江、金沙江三江并流地带,是中国泥石流灾害频发地区。在分析泥石流灾害特征的基础上,选取坡度、岩性、断裂、植被和人类工程活动作为三江并流区泥石流危险性评价指标。基于ArcGIS平台建立了泥石流危险性评价数据库、图形数据库和属性数据库,通过对各评价因子归一、分级和赋权处理,建立了泥石流危险性评价模型,对三江并流区泥石流危险性进行了评价,得到危险性区划图。研究结果与实际灾情吻合,可为确定减灾目标,优化防灾措施,制定减灾决策等提供重要依据。 相似文献
13.
北京山区暴雨泥石流激发雨量条件 总被引：1，自引：0，他引：1
泥石流是北京山区常见的一种山地灾害,也是威胁山区生态环境的头号安全问题.分析该区的泥石流激发雨量条件对于该区山洪泥石流预测预报具有指导意义.笔者搜集18场降雨数据,分析该区泥石流的激发雨量特征.结果表明:激发降雨的峰值降雨时段介于3 ～9h,峰值时段平均降雨强度达22.6 ～ 50.0 mm/h,累积雨量达91.9 ～ 350.0 mm,峰值降丽时段雨量占累积雨量的63.9％～100.0％,这说明激发泥石流的降雨过程具有历时短、雨量集中、突发性强的特点.用修正后的李氏法进行雨场分割,得到该区泥石流激发的降雨强度-历时和累积雨量-历时关系.最后,以密云区北部山区为例分析3期植被盖度和泥石流激发雨量条件.归一化植被指数和像元线性分解模型分析表明,1989-1991、2004-2005和2011-2012年植被覆盖度分为64.48％、68.57％和72.48％;相应的泥石流雨量激发条件也随着植被覆盖度的增加而增大,可见植被恢复盖度对泥石流的形成具有一定影响.本文统计分析得出的泥石流激发雨量条件可为该区山洪泥石预测预报和监测预警指标选取提供参考. 相似文献
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通过对比四川省巴塘县的118处沟谷泥石流及33处坡面泥石流的植被覆盖率,发现植被对于坡面泥石流具有较好的抑制作用,但对沟谷泥石流作用则不明显。造成这种差别的原因在于坡面泥石流的物源主要是坡体表面侵蚀,植被根系组成的网状锚固层可以减缓乃至消除这种侵蚀效应;沟谷泥石流的物源主要来自沟岸崩塌,但植被对于中厚层的崩滑体锚固能力差,当降雨超过一定阈值后即可暴发泥石流。基于这种特点,建议将生物工程作为坡面泥石流的主要治理手段;对于沟谷泥石流而言,既不能将植被覆盖率作为易发程度的判别标准,也不宜作为综合治理中的主要环节。 相似文献
15.
黑土区坡耕地横坡垄作措施防治土壤侵蚀的土槽试验 总被引：13，自引：3，他引：10
为了研究黑土区坡耕地横坡垄作防治坡面土壤侵蚀的效应,该文利用8 m×1.5 m的试验土槽,设计3个降雨强度(50、75和100 mm/h)、1个典型坡度(5°)以及横坡垄作和无垄作(平坡裸地对照试验)的试验处理进行模拟降雨试验,研究东北黑土区横坡垄作坡面在不同降雨强度下的防治坡面侵蚀效应。结果表明:横坡垄作在50 mm/h降雨强度下坡面基本不发生土壤侵蚀,但在75和100 mm/h降雨强度下会发生断垄,造成防蚀效应急剧降低。横坡垄作坡面的径流和侵蚀过程均明显存在以断垄时间为界的突变,在3个降雨强度下,横坡垄作断垄前可使坡面径流量和侵蚀量分别减少97.7%和99.1%以上,坡面蓄渗率达到97.2%以上;而断垄后坡面径流量和侵蚀量分别增加23.3~25.9倍和136.8~171.5倍,蓄渗率下降至50%以下。试验研究表明横坡垄作在≤50 mm/h的降雨强度下具有很好的坡面防治侵蚀效应,但当遇到强降雨时易发生断垄,防蚀效应急剧降低。 相似文献
16.
P. Kardavani 《植物养料与土壤学杂志》1979,142(1):109-115
Investigations on some soils of the Lut-e-Zangi Ahmed desert, Iran ”?Lut-e-Zangi Ahmed”? is a part of the Lut desert, which is located in south-eastern Iran. The Lut desert is one of the warmest and driest deserts of the world. It is very poor in vegetation and water, particularly in useful water. The evaporation is nearly hundred times more than the precipitation during the year (Evap. = 5000), precip. = 50 mm/year. In the research of “Lut-e-Zangi Ahmed”-SW part of the Lut desert-where its soils were entirely unknown, it is tried to get information about the most important properties of the desert-soils and possibility of agricultural use, through the profiles and analyses. The average elevation of the “Lut-e-Zangi Ahmed” is 500 m above the sea-level. The region is very poor in vegetation. There are many large areas on which no vegetation exists. The only useful water (underground water) is found in this part of the Lut desert. There are different zonal-intrazonal and azonal soils in the “Lut-e-Zangi Ahmed” (compare Ganssen 1968) for example: Hamada-desert soils, grey and light-brown saline desert soils, fine textured alluvial soils and sand desert soils. The soils are salty (EC from 11-5 12 mmhos/cm) and neutral to weak alkaline. They are poor in organic matter, phosphor and nitrogen too. The predominating part of the area investigated is not suitable for agricultural use. Only 150 ha are arable land, because it is possible to get here suitable groundwater for desalinization and irrigation. 相似文献
17.
喀斯特峰丛洼地坡面土壤水分空间变异研究 总被引：25，自引：4，他引：21
以线形取样方式测定了喀斯特峰丛洼地坡面表层(0～5、5～10、10～15 cm)的土壤水分,采用经典统计结合地统计学方法分析了其空间分布特征及变异结构。结果表明：在坡面特定土地利用结构下(上坡到下坡分布有自然坡地、退耕地和耕地),表层土壤水分沿上坡向下具有不断减小的变化趋势,坡面纵向和横向土壤水分均呈中等变异,横向上由于特殊的土壤分布和地形地貌特征使得变异程度较纵向强烈,土地利用和坡度因子是造成坡面土壤水分分布和变异的重要因素;半方差分析显示,坡面表层土壤水分具有明显的块金效应和较大的基台值,呈中等或较强的空间相关性,土壤水分总体上具有较好的变异结构和空间连续性,因此可以应用地统计学方法在该地区开展土壤水分空间变异研究。 相似文献
18.
The influence of native vegetation clearing and different further soil managements on fungal propagule population diversity
was studied in the present work. In each of the 3 years (1998, 1999, and 2000), soil samples were collected at the depth of
0–7.5 cm from sites under native vegetation (V0); naturalized prairie, cleared in 1982 (P16); conventional tillage, cleared
in 1972 (T26); and direct drilling, cleared in 1958 (D40). Fungal population size and relative abundance of fungal genera
were studied by plate counts and further identification of isolates on potato dextrose agar. The undisturbed site and the
other sites with increasing time elapsed since native vegetation clearing and different management history showed a distinctive
distribution of fungal genera. There were significant differences (p<0.05) among the sites in the abundance of fungal genera analyzed in all the 3 years. Principal component analysis based on
relative fungal genus abundance differentiated the sites with 75% variance explained by the first and second components. Diversity
and abundance of isolated fungal genera were increased as density of Penicillium spp. decreased, suggesting a competitive effect of this fungal genus. The largest diversity was found in the site under no-till
management. The different distribution and relative abundance of the fungal genera studied seemed to be influenced strongly
by the management and the presence of surface residue in the no-tilled site. 相似文献
19.
Dated shorelines of late Pleistocene pluvial Lakes Lahontan (Great Basin Desert, northwest Nevada) and Mojave (Mojave Desert, eastern California) provide timelines for the assessment of alluvial fan sedimentation at the lake margins during the late Pleistocene to early Holocene. Two sets of alluvial fan systems have been mapped: the Stillwater fans, feeding Lake Lahontan; and the Zzyzx fans, feeding Lake Mojave. Their contrasting morphologies suggest different responses of the two fan systems to late Pleistocene to early Holocene climatic change. At the time the Stillwater fan systems underwent minimal sedimentation, with the catchment hillslopes apparently stable. The Zzyzx fans experienced major changes in water and sediment supply from the catchment hillslopes. There was a major phase of hillslope debris-flow activity, followed by fanhead trenching and distal fan progradation. Both areas were wetter and colder in the late Pleistocene than they are today, but during the transition to the Holocene the Zzyzx area was more likely to experience intense rains associated with the monsoonal penetration of warm moist tropical air into the Southwest. Vegetation reconstructions for the late Pleistocene to the early Holocene suggest that catchment hillslopes in the Mojave supported a desert shrub vegetation, but those in the Stillwaters supported juniper woodland and grasses at low elevations and pine at higher elevations. Contrasts in hillslope vegetation cover together with storm activity may account for the different responses of the alluvial fans to climatic change during the Pleistocene to Holocene climatic transition. After the falls in lake levels of Lakes Lahontan and Mojave in the early Holocene, both areas underwent aridification, resulting in reductions in hillslope vegetation cover. Increased storm runoff led to fanhead trenching and distal progradation of the alluvial fans. Variations in fan style at that time may relate primarily to base-level conditions resulting from different gradients on the exposed lake shores. 相似文献
20.
《国际水土保持研究(英文)》2022,10(4):597-609
Rangeland hillslopes provide much of the sediment supplied to channel systems and their lengths exert a fundamental constraint on hillslope diffusive processes. However, information regarding lengths of rangeland hillslopes, and how best to estimate them, is limited. In this study, three groups of watersheds (10 in total) were selected from the Walnut Gulch Experimental Watershed according to their geology, soil and vegetation characteristics. Group 1 watersheds were at lower elevations dominated by shrubs, Group 3 were at high elevations dominated by grass, and Group 2 were mixed shrub and grass. Their hillslope lengths were calculated from 1 m-resolution DEMs using three methods: a flow routing algorithm, slope-area relationships, and inverted relationship with drainage density. Parameters that characterize the current watersheds, including Hack's exponent and coefficient, watershed shape coefficient, channel concavity and steepness, and surface roughness, were quantified and related to hillslope lengths. Results shows: (1) estimated hillslope lengths were different for the three methods and between the three groups of watersheds; (2) hillslope lengths that measured from the flow routing algorithm for the ten selected watersheds primarily ranged from 30 to 100 m, with a median value of 63.0 m, which was 20%–50% greater than those derived from slope-area plots or drainage densities; (3) hillslope lengths estimated from the flow routing method were greater in Group 3 watersheds than in Group 2 and then in Group 1 watersheds. We attributed these differences in hillslope lengths to the historic epeirogenic pulses, watershed and drainage network morphology, and differences in vegetation characteristics; (4) measured hillslope lengths from the flow routing algorithm were best correlated with hillslope relief, then surface roughness, channel steepness and concavity. These results would benefit the applications of hydrological and erosion models in rangelands. 相似文献