Geographic distribution patterns of small mammals in Swaziland in relation to abiotic factors and human land-use activity

Swaziland is a small, topographically diverse southern Africa country whose mammalian fauna has been poorly studied. The distributions of small mammals in Swaziland were surveyed at 39 localities. A total of 15 species of rodents and ten species of insectivores were captured during the survey. The number of species of insectivore captured at a locality was positively correlated with mean annual rainfall, while the number of rodent species captured was negatively correlated with altitude. The number of rodent species captured was lower on Swazi Nation Land compared with privately owned land or protected land (reserves). This was probably due to the radical habitat alteration that had taken place on Swazi Nation Land, inter alia overgrazing by livestock, cultivation of maize and deforestation. The effect of this habitat alteration on the number of rodent species was more pronounced in high-lying areas of Swaziland. This may have been due to the fact that a large number of the rodent species inhabiting high-lying areas require thick, tall grassland habitats, whereas many of the low-lying species prefer more open habitats with less grass cover. Since grazing acts to reduce grass cover, it is suggested that the species inhabiting high-lying areas would be more affected by overgrazing, than low-lying species.     

The productivity of pine plantations in relation to previous land use

Summary Differences in the productivity of establishedP. radiata plantations on pasture and forest soils were found to be reproducible withP. radiata seedlings in a glasshouse environment. The growth of seedlings on pasture soil exceeded that of seedlings on native forest soil (the ‘primary pasture effect’). After a history of pine on both native and pasture soils a residual effect of pasture on seedling growth was evident (the ‘secondary pasture effect’). However, the effect of a history of pine plantation (the ‘pine effect’) was to decrease the productivity of both native and pasture soil as assessed by seedling growth. These effects were not related to changes due to land management in mycorrhizal infection or in soil structure. The analysis of seedling growth leads to the conclusion that soil fertility, particularly the availability of nitrogen and phosphorus, has changed.     

安徽省家畜分布与土地利用类型关系的研究

本文采用灰色系统理论与方法,研究了安徽省及其各畜牧区的家畜(禽)分布随土地利用类型及人口密度的变化规律,建立了家畜(禽)分布密度的灰色静动态模型。结果表明,安徽省由北向南旱地面积从54％下降到2％;林地则由5.5％上升到62％;水田和水面主要分布在江淮丘陵和沿江平原区。人口密度对各类畜禽的分布密度有较大的影响,关联度为0.65—0.83;旱地比率是影响草食动物分布密度的最主要因素,并联度高达0.9以上;水面的比重对家禽密度的影响高于其它因子。用土地利用类型因子及人口密度所建立的模型,对家畜的实际分布密度及其变化规律的拟合误差在2％左右。     

城乡森林分布格局与土地利用对策

根据1988年及2003年南京市城镇边界, 利用遥感影像和DEM数据,以及缓冲区分析法,将南京地区2003年植被图由城区向远郊分成8个城乡梯度带,依次命名为Ⅰ带,Ⅱ带,Ⅲ带,……,Ⅷ带,研究了各带森林分布格局,以及地形条件和土地利用对策对森林分布格局的影响.结果表明,各带山体占地率与森林覆盖率呈极显著正相关,且各带山体森林覆盖率显著高于平地森林覆盖率,其基本格局为：Ⅰ＞Ⅱ,Ⅱ＜Ⅲ,Ⅲ≈Ⅳ,Ⅳ＞Ⅴ＞Ⅵ＞Ⅶ＞Ⅷ;在不同的城乡梯度带,城市化地区城建用地、生态用地和生产用地3种主要土地利用方式的价值输出不同.城区城建用地价值突出,林地覆盖率最低;城区外围10 km内的近郊的生态环境价值输出相对较高,林地覆盖率亦高于其它各带;离城稍远,以农业为代表的物质生产价值渐居主导地位,森林覆盖率则随之下降.     

Aggregating land use quantity and intensity to link water quality in upper catchment of Miyun Reservoir

Eutrophication resulting from nutrient enrichment decreases water quality and harms ecosystem structure and function, and its degree is significantly affected by land use in the catchment. Quantifying the relationship between eutrophication and land use can help effectively manage land use to improve water quality. Previous studies principally utilized land use quantity as an indicator to link water quality parameters, but these studies lacked insight into the impact of land use intensity. Taking the upper catchment of Miyun Reservoir as a case study, we developed a method of aggregating land use quantity and intensity to build a new land use indicator and tested its explanatory power on water quality. Six nutrient concentrations from 52 sub-watersheds covering the whole catchment were used to characterize the spatial distribution of eutrophication. Based on spatial techniques, empirical conversion coefficients, remote sensing data, and socio-economic statistical data, land use intensity was measured and mapped visually. The new land use indicator was calculated and linked to nutrient concentrations by Pearson correlation coefficients. Results demonstrated that our new indicator incorporating intensity information can quantify the different nutrient-exporting abilities of different land use areas. Compared to traditional indicators that only incorporate land use quantity, most Pearson correlation coefficients between the new indicator and water nutrient concentrations increased. This new information enhanced the explanatory power of land use on water nutrient concentrations, and so will be able to help us understand the impact of land use on water quality and guide decision making for better land use management.     

北方农牧交错带土地利用类型对土壤养分分布的影响

对北方农牧交错带多伦县5种土地利用类型进行118个土壤样点分析表明,农田土壤养分含量最低,草地含量处中等,林地含量最高.分别对4种不同土地利用类型在4种＞15.坡的小流域进行布点采样,研究不同土地利用结构对土壤有机质、速效磷、速效氮和全氮的影响.结果表明,在垂直方向上,由坡底到坡中到坡顶,对应的耕地-草地-林地土壤养分要比对应草地-林地-耕地这一土地利用类型中土壤营养元素含量高出1倍左右,说明此种土地利用类型具有较好的土壤养分保持能力,从而优化出最适合当地的土地利用类型,为改善生态环境、提高当地经济效益提供科学依据.     

沈阳市东部土地利用格局变化

以沈阳市东部１９７６～１９８９年的历史航空像片为基础,以地理信息系统（ＧＩＳ）技 术为手段,分析土地利用的空间格局及其变化．结果表明,针叶林、水田平均嵌块体大小增 加,旱地、落叶林、灌丛平均嵌块体大小减少;分数维值略有增加．预示嵌块体形状逐步复 杂化;多样性指数、均匀性指数增加．优势度和蔓延度指数由原来的１．６３２７和８９．２０２２分 别减少到１．３２２６和８８．２７４４,说明景观嵌块体的空间分布趋于均匀,嵌块体的聚集分布状 况将随时间的推移逐步分散化．此外．本文对沈阳东部土地利用格局变化的原因进行了剖 析．     

Effectiveness of natural protected areas to prevent land use and land cover change in Mexico

This study evaluated the extent to which natural protected areas (NPAs) in Mexico have been effective for preventing land use/land cover change, considered as a major cause of other degradation processes. We developed an effectiveness index including NPA percentage of transformed areas (agriculture, induced vegetation, forestry plantations, and human settlements) in 2002, the rate and absolute extent of change in these areas (1993–2002), the comparison between rates of change observed inside the NPA and in an equivalent surrounding area, and between the NPA and the state(s) in which it is located. We chose 69 terrestrial federal NPAs, decreed before 1997, that were larger than 1,000 ha, not urban/reforested with non-native vegetation, not islands and not coastal strips, and estimated the extent of transformed areas using 1993 and 2002 land use/land cover maps. Over 54% of NPAs were effective, and were heterogeneously distributed by management categories: 65% of Biosphere Reserves, 53% of Flora and Fauna Protection Areas, and 45% of National Parks. 23% of NPAs were regarded as weakly effective, and the remaining 23% as non-effective. We recognize the importance of NPAs as a relevant conservation instrument, as half of NPAs analyzed (particularly biosphere reserves) prevented natural vegetation loss compared with their geographic context. Our results suggest that conservation based on NPAs in Mexico still faces significant challenges. Our approach can be expanded for evaluating the effectiveness of NPA in other regions, as land use/land cover maps are now available almost worldwide.     

Projecting the potential distribution of ticks in China under climate and land use change

Ticks are known as vectors of several pathogens causing various human and animal diseases including Lyme borreliosis, tick-borne encephalitis, and Crimean-Congo hemorrhagic fever. While China is known to have more than 100 tick species well distributed over the country, our knowledge on the likely distribution of ticks in the future remains very limited, which hinders the prevention and control of the risk of tick-borne diseases. In this study, we selected four representative tick species which have different regional distribution foci in mainland China. i.e., Dermacentor marginatus, Dermacentor silvarum, Haemaphysalis longicornis and Ixodes granulatus. We used the MaxEnt model to identify the key environmental factors of tick occurrence and map their potential distributions in 2050 under four combined climate and socioeconomic scenarios (i.e., SSP1-RCP2.6, SSP2-RCP4.5, SSP3-RCP7.0 and SSP5-RCP8.5). We found that the extent of the urban fabric, cropland and forest, temperature annual range and precipitation of the driest month were the main determinants of the potential distributions of the four tick species. Under the combined scenarios, with climate warming, the potential distributions of ticks shifted to further north in China. Due to a decrease in the extent of forest, the distribution probability of ticks declined in central and southern China. In contrast with previous findings on an estimated amplification of tick distribution probability under the extreme emission scenario (RCP8.5), our studies projected an overall reduction in the distribution probability under RCP8.5, owing to an expected effect of land use. Our results could provide new data to help identify the emerging risk areas, with amplifying suitability for tick occurrence, for the prevention and control of tick-borne zoonoses in mainland China. Future directions are suggested towards improved quantity and quality of the tick occurrence database, comprehensiveness of factors and integration of different modelling approaches, and capability to model pathogen spillover at the human-tick interface.     

西双版纳地区土地利用的空间分析

利用西双版纳地区2003年TM数据,对土地利用结构及土地利用与海拔、坡度、水系等自然地理要素相互关系的空间进行分析.结果表明,耕地、林地和草地是该地区土地利用的主体,其中林地面积13 420 km²,占研究区总面积的74%;草地面积3 251 km²,耕地面积2 332 km²,分别占13%和18%.林地、耕地和草地面积随海拔高度具有单峰变化的曲线特征,在海拔1 000～1 200 m处林地分布最多,耕地和草地面积达到峰值时的海拔约为900 m.受人为活动影响强的用地类型坡度指数较低,城乡建筑用地和耕地的坡度指数为5°和14°,人为活动影响较弱的林地草地坡度指数较高,分别为22°和20°.河谷内随缓冲距离增加,土地利用呈现规律性变化,耕地、城镇居民点、未利用地3种土地利用方式主要集中在河谷底部近水域处,远离河谷林地草地组分增加明显.西双版纳地区自然生态系统相对原生,具有林地为基质,河流为廊道,坝区、沟谷农业景观镶嵌分布的特点.     

Habitat preferences and biomasses of small mammals in Swaziland

This paper describes the distribution and abundance of small mammals in Swaziland in relation to quantified habitat features. Eighteen habitat sites were sampled at seven different locations in all four geographical regions of Swaziland. Small mammal diversity (as described by the Shannon diversity index) was positively correlated with vegetation density. A total of twelve species of rodents and seven species of shrews were captured; however, only six species were caught at more than three sites. Small mammal biomasses and densities were highest at the highveld and middleveld sites. Tall grassland at all elevations supported a high diversity of small mammals. Highveld montane forest supported a high biomass and diversity of species, while no species were captured in moist forest in the Lubombo mountains.     

江西新建县土地利用时空动态特征分析

在RS与GIS支持下,以江西省新建县为研究区,采用与土地利用动态度相关的一系列时空特征指数,研究了1991、1996和2000年3个时间段上土地利用的时空动态特征.结果表明,单一土地利用动态中建设用地变化动态度最大;1991～2000年间研究区域综合土地利用动态度年均变化速度为0.165%,其中前5年变化速度比后4年快,为后者1.5倍多.1991、1996和2000年土地利用程度综合指数分别为243.68、244.08和244.87,稍高于全国平均水平23192.新建县1996～2000年各种土地利用类型总的空间转移量(转出或转入)比前一时段有所下降,土地利用变化逐渐由双向转移向单向不平衡转移转化.     

Plant diversity declines with recent land use changes in European Alps

Against a background of increasing land use intensification on favorable agricultural areas and land abandonment on less arable areas in the Alps, the aim of this investigation was to detect whether and how 10 differently used types of grassland can be distinguished by site factors, plant species composition, and biodiversity. By using a very large number of vegetation surveys (936) that were widely distributed in the Central Alps, site parameters and species composition of the different land use types were compared by discriminant analyses and various biodiversity indices. Results showed that land use is a significant factor affecting the development of different grassland communities with site factors playing a subordinate, yet important role. The 10 land use types studied can be clearly differentiated from one another by single species as well as by species composition. Our study found that the number of plant communities along with the number of species decreases constantly and significantly with increasing land use intensity and on abandoned land. For example, on average, extensively used meadows have more than three times as many species as intensively used meadows. Further, the most even distribution of species (Evenness index) is reached in intensively used meadows, whereas on pastures and abandoned land, some species become dominant forcing other species to recede. The results confirm that due to current trends in agriculture, such as land abandonment and land use intensification, plant diversity in the Alps is decreasing considerably.     

土地利用强度变化的空间异质性研究

以晋江市为例,以系统网格采样法获取研究样本,以地统计学理论和半方差函数为工具,探讨晋江市1989～2001年人类对土地景观干扰活动的空间异质性.结果表明,研究时段人类干扰活动存在明显的空间异质性,尤其是NE-SW向的方向性结构突出,主要原因在于交通干线的影响;各级行政中心成为其生长极点;交通干线与行政中心联合作用,使人类干扰呈现明显的点-轴格局.     

西双版纳不同土地利用方式下土壤氮矿化作用研究

氮在森林生态系统的养分循环中很重要,常把土壤氮矿化速率作为生态系统中氮有效性和氮损失的指标.在云南省中国科学院西双版纳热带生态站周围,用顶盖埋管法,对季风常绿阔叶林、季节雨林、橡胶林、受过严重干扰的季节雨林、鸡血藤次生林和旱谷地的氮矿化速率进行研究.结果表明,在6种土地利用方式下,净氮矿化速率和硝化速率由大到小依次为受过严重干扰的季节雨林＞鸡血藤次生林＞季节雨林＞季风常绿阔叶林＞橡胶林＞旱谷地.在西双版纳地区橡胶林和旱谷地被认为是受人为干扰较严重的土地利用方式,这两种土地利用方式与各种森林下土壤中的氮矿化速率和氮储量相比均低,达到显著水平.较低的氮矿化速率与土壤本底氮储量低有关,也与土壤中真菌数量较少有关.对西双版纳6种常见土地利用方式的土壤氮储量和氮循环速率的研究表明,受过严重干扰的季节雨林在恢复多年后土壤中养分的转化速率与原生林接近,而林地被转化为农业或经济林用地后氮储量和氮矿化速率均显著降低.     

科尔沁沙地不同土地利用和管理方式对土壤质量性状的影响

研究了科尔沁沙地退化草地开垦后,在14年不同的土地利用和管理方式下土壤物理、化学和生物学性状的特征。结果表明,农林(林草)复合利用模式在土壤粒级组成、孔隙分布、持水性能、有机质和N、P养分、酶活性等方面表现出较好的质量性状特征。有机无机配施、精细管理的灌溉农田次之,而粗放管理的旱作农田。土壤质量性状严重恶化,逐步向流沙方向演变,与科尔沁原生景观草地土壤相比,管理良好的利用系统,土壤物理性状、P含量和一些酶活性指标提高,但有机质和全氮含量明显低,表明已退化生态系统C、N库的恢复和重建需要较长的时间。研究结果表明,不同的土地利用方式和管理措施显著影响土壤质量变化的程度和方向;调整土地利用结构,基本农田实行精细管理,旱作农田退耕还草还林是保护土地资源。实现区域生态恢复和重建的根本选择。     

Current range condition in relation to land management systems in semi-arid savannas of Swaziland

Rangeland condition was assessed in the lowveld of Swaziland to determine the current status with emphasis on contrasting different land management systems and soil classes in two study areas. The assessment incorporated the grass and woody plant layer. The methods employed to evaluate the grass layer were ecological condition index (ECI) and weighted palatability composition (WPC). The government ranch had significantly higher ECI (mean 714.5) and WPC (mean 61) than the communal land (mean: ECI – 533.5; WPC – 48.7) and the game reserve (mean: ECI – 578.9; WPC – 47.9). The ECI and WPC values did not differ between the soil classes in most cases (range: ECI 551.5–645.9 and WPC – 43.7–57.6). The density of all woody plants and encroaching plants alone were the highest in communal land. Basal cover ranged from poor (2–3%) to good (>5%), while bare ground was rated from low (<1%) to high (>5%). Overall results showed great variability of studied variables at site and landscape levels of resolution. Generally, the grass layer was rated between fair and good when assessed on the basis of ecological and palatability merits. There was a clear indication of advancement of bush encroachment.     

Changes in the distribution of alien plants along roadsides in relation to adjacent land use over the course of 40 years

Roads have become one of the main corridors supporting the dispersal of alien plants and their penetration and integration into native vegetation communities in new areas. The aim of this study was to use data sampled in 1970, 1994, and 2010 in order to check for changes in the spread of alien species along roadsides in relation to the adjacent land use. The results show that nutrient influxes and mechanical disturbance associated with the onset of intensive farming had a significant impact on the spread of the plant species in this study. In general, a significant increase was documented in the spread of species of invasive status. A different trend in the spread of archaeophytes and neophytes was observed in cases in which a road was adjacent to the meadow. Most of the archaeophytes in these habitats spread significantly in the first 20 years, and the distribution of neophytes did not show an increasing tendency. The highest rate of expansion was observed for plants propagating only by seed and in the built-up area of municipalities. Plants exhibiting both seed and vegetative propagation prevailed in the vicinity of meadows and forest vegetation.     

太湖流域土地利用与景观格局演变研究

基于遥感、GIS技术和景观生态学方法,以太湖流域为研究区域,在1985年、1995年和2000年的土地利用图基础上,分析了土地利用与景观格局演变.结果表明,15年间,太湖流域农田呈减少趋势,建设用地、林地、草地、水体呈增加趋势,其中农田的减少占土地利用总减少量的89.64%,建设用地的增加占土地利用总增加量的79.21%;由于人类活动的干预,太湖流域景观结构与景观异质性发生了较大变化.从景观尺度上看,斑块密度、多样性指数和均匀度指数呈降低趋势,边界密度、优势度指数、景观形状指数呈增加趋势;从斑块尺度上看,各景观组分的异质性指数及其变化过程有较大的差异,体现了景观生态系统的复杂性.人口增长、经济、政策等因素是太湖流域近15年景观格局动态变化的主要驱动力.太湖流域土地利用变化产生了景观碎化、边缘效应、生境退化等景观生态效应.可通过调整景观尺度上的土地利用方式,使太湖流域生态建设及水土资源实现可持续发展.     

土地利用/景观生态学研究中的马尔可夫链统计性质分析

马尔可夫链在土地利用和景观生态学研究中得到了广泛应用,而应用中通常假设土地利用变化为满足马尔可夫性的一阶时齐马尔可夫链,对马尔可夫链的统计性质是否成立却很少进行检验.本文以北京市土地利用变化监测数据为算例,提出了马尔可夫链统计性质的皮尔逊χ² 拟合优度检验方法.检验结果表明,土地利用研究中通常假设的时齐性和马尔可夫性(一阶性)在统计学上并不成立,即北京土地利用演变过程为非时齐的高阶马尔可夫链.相对于马尔可夫统计性质的似然比检验中转移概率大于零的要求,皮尔逊χ²检验对转移概率的要求相对宽松,允许转移概率为零,所以应用的范围较似然比检验更为广泛.