不同土地利用型态下潜在蒸散发量比较--以二次林生态系统与茶园生态系统为例

于栖兰山庄二次林与宜兰县大同乡之玉兰茶园内，以蒸发皿法量测与估算此二试验区之日潜在蒸散发量，了解在不同土地利用型态下，其日潜在蒸散发量的表现差异情况。研究结果发现，茶园生态系统之日潜在蒸散发量明显高于二次林生态系统之日潜在蒸散发量。究其原因为，茶园生态系统的经营型态属开放式经营型态，故整体茶园生态系统均匀曝晒于阳光下，因此接收足量之太阳辐射能，导致其日潜在蒸散发量较高。而栖兰山庄二次林生态系之表现情形则不尽相同，由于二次林生态系统内，其高、矮茎植物丛生，此差异性结构将产生互相遮阴现象，使得土壤之蒸发量与矮茎植物之蒸散量减少。此外，二次林生态系统的组成中亦多含深根性植物，其水土保持特性相对于茶园生态系统也有较佳的表现。研究中亦发现，在冬季时期，若将二次林生态系统开辟为茶园生态系统时，二次林生态系统每公顷土地之水分逸失量将增加100～150t。

新店溪流域土地利用型态与径流特性之研究

土地利用是人与环境互动展现在地表的现象,土地利用的议题一直是地理学研究中重要的课题。近年来,都市化及社会结构的迅速发展和变化,土地面临极大的开发压力,尤其是在不当的开发行为中,所造成的各种土地利用型态,不仅使得流域的径流特性发生变化,更造成人民的生命财产产生威胁。因此,该研究以台湾新店溪流域宝桥子集水区为例,收集前人应用SPOT卫星影像所判释出1989年、1990年、1993年、1994年、1995年、1997年、1998年、1999年、2001年共9个时期的研究区各种土地利用型态数据,采用美国农业部水土保持局所研发的径流曲线指数法,分析出上述9个时期中,不同土地利用型态下的标准径流曲线值,再依据历年雨量资料整理出上述各年的前期5日降雨型态,将径流曲线值加以修正后,求出年径流系数值。该研究进一步运用多元回归分析方法,探讨研究区土地利用型态与径流特性二者间之关系。结果显示,利用林地、农地、草地、都市用地、水体这5种地表土地利用型态,所能说明的年径流系数值的总变异程度,达80%以上,可供后续研究者参考。

台湾西南部泥岩土地利用型态与环境劣化趋势之分析

台湾泥岩恶地因其特殊之土壤理化性质及区域微气候的相互恶性循环,衍生生态环境等问题。在以往之35年,裸化面积从1967年的2532hm2,至2001年11月已扩大为15539hm2。其表土大量流失、崩塌、河川含砂量激增、植被退化与微气候变异等破坏,更显示泥岩之环境劣化问题。以SPOT卫星影像判识泥岩裸露面积,探讨不同时期之地景变异,并应用地景生态理论量化泥岩地表不同土地利用之空间结构变化,分析地景结构变迁之生态内涵与生态指标意义。因子分析结果其主要变异为多样性因子与形状破碎型因子所影响,而应用马可夫链模式计算出不同时期之土地利用变迁内涵,此结果搭配指标分析可解释泥岩裸露面积与竹林面积皆持续扩大,乃由人为土地利用之活动及植被变迁所引起。

Ecological Effects of Land Use Patterns in Red Soil HillyRegion

Plant biomass and biodiversity, element accumulation and return, water loss and soil erosion, and changesin soil properties were studied for up to 10 years after conversion of sparse tree-shrubby grass land into thefollowing four land use patterns: masson pine (Pznvs massonzana Lamb.) land, beautiful sweetgum (Ltq-uidambar fomosana Hance) land, vegetation reservation land, and artificial mowing land. The annualbiomass production of the masson pine land was 5060 kg ha￣-1 being 4.9, 2.1, and 6.0 times that of the beau-tiful sweetgum land, the vegetation reservation land, and the artificial mowing land, respectively. Comparedwith the background values, the number of plant species for the vegetation reservation land increased by 10species after 10 years of land utilization, while for the masson pine and the beautiful sweetgum decreased by4, and for the artificial mowing land by 9. For masson pine land, total amount of N, P, K, Ca, and Mg neededfor producing 1000 kg dry matter was only 3.5 kg, annual element return through litter was 22 kg ha￣-1, bothof which were much lower than those of the other patterns. Vegetation reservation was an effective measureto conserve soil and water and improve soil fertility in the red soil hilly region. Artificial mowing arousedserious degradation of vegetation and soil. Some measures and suggestions for management and exploitationof the red soil hilly region such as masson pine planting, closing hills for afforestation, and stereo-agricultureon one hill are proposed.

Land Use Situation and Strategies under the Background of New Urbanization in Yunnan Province

Scientific analysis and determination of land use lays foundation for regional sustainable development under the background of new urbanization. The research made a comprehensive analysis on land uses in Yunnan under the background of urbanization and proposed strategies for further development, providing references for land uses scientific decision making.

Sensitivity analysis of the De Nitrification and De Composition model for simulating regional carbon budget at the wetlandgrassland area on the Zoige Plateau,China

Although mathematical models(e.g., De Nitrification and De Composition(DNDC) provide a powerful tool to study regional carbon budget, it is still difficult to obtain accurate simulation results because there exists large uncertainties in modeling regional carbon budget. Through the investigation on the sensitivity of model output parameters to the input parameters, sensitivity analysis(SA) has been proved to be able to identify the key sources of uncertainties and be helpful to reduce the model uncertainties. However, some input parameters with discrete values(e.g., land use type and soil type) and the regional effect of the sensitive parameters were rarely examined in SA. In this paper, taking the Zoige Plateau as a case area, we combined the one-factor-ata-time(OAT) with Extended Fourier Amplitude Sensitivity Test(EFAST) to conduct a SA of DNDC for simulating the regional carbon budget, including Gross Primary Productivity(GPP), Net Primary Productivity(NPP), Net Ecosystem Productivity(NEP), autotrophic respiration(Ra), soil microbial heterotrophic respiration(Rh) and ecosystem respiration(Re). The result showed that the combination of OAT and EFAST could test the contribution of the input parameters with discrete values to the output parameters. In DNDC model, land use type and soil type had a significant impact on the regional carbon budget of the Zoige Plateau, and daily temperature was also confirmed to be one of the most important parameters for carbon budget. For the other input parameters, with the change of land use type or soil type at regional scale, the sensitive parameters of carbon budget would vary accordingly. The SA results would provide scientific evidence to optimize DNDC model and they suggested that we should pay attention to the spatial/temporal effect of SA and try to use the appropriate data in simulation of the regional carbon budget.

Spatio-temporal Pattern and Spatial Heterogeneity of Ecotones Based on Land Use Types of Southeastern Da Hinggan Mountains in China

Ecotones have received great attention due to its critical function in energy flux, species harbor, global carbon sequestration, and land-atmosphere interaction. This study investigated land use pattern and spatial heterogeneity of the ecotones among agricultural land, forest land, and grassland of the southeastern Da Hinggan Mountains in the northeastern China. The change of these delineated ecotones under different slopes and aridity conditions was analyzed by two landscape indices, edge density(ED) and core area percentage of landscape(CPL), to explore the inter-linkage between spatial structure of ecotones and socioeconomic development and land management. Specifically, the ecotones such as agriculture-forest(AF) ecotone, forest-grassland(FG) ecotone, and agriculture-forestgrassland(AFG) ecotone moved from the arid southeast to the humid northwest. The flat area with small slope is more edge-fragmented than the steep area since the ED decreases as the slope increases. The AF ecotone mostly found in the humid region is moving to more humid areas while the agriculture-grassland(AG) ecotone mostly found in the dry region is moving towards the drier region.

The Effect of Land Use on Soil Organic Carbon Stocks in Lake Victoria Crescent Agro-Ecological Zone, Uganda

The effect of land use on soil organic carbon （SOC） stocks and depth distribution of SOC was investigated in the Lake Victoria Crescent ago-ecological zone of Uganda. Soil samples were collected from six land use types at 0-30, 30-60 and 60-90 cm from profile pits dug in similar soils and slopes. Results indicated that SOC stocks significantly differed across the various land use systems. SOC also varied significantly by depth. The highest SOC and pH were recorded under natural forest-strict nature. Grassland had the lowest SOC but the highest bulk density （BD）. Phosphorous （P） was the highest in banana-coffee systems and the lowest under tea plantations. The lowest values of pH and BD were found in highly disturbed natural forest. The upper layers of the soil （0-30 cm） stored higher amounts of SOC compared to other depths （30-60 cm and 60-90 cm）. Land use therefore has a significant effect on SOC and other soil physical and chemical properties.

Determining soil redistribution in Dian Lake catchment by combined use of caesium-137 and selected chemical properties

Recent development in the use of the environmental radionuclide caesium-137 for documenting rates and soil redistribution on the cultivated or uncultivated land and estimating rates of sediment deposition on represents an important advance that overcomes many of the limitations of the conventional techniques commonly applied in such investigations. A study on soil redistribution （including soil erosion and deposition） was carried out in the Dian Lake catchment, Yunnan Province, using ^137Cs and selected chemical properties. The average soil erosion rate was 1,280.2 t km^2 yr^-1. Soil erosion rate occurring on different parts of the slope was significantly different on different parts of the slope, increasing.from the top. the bottom to the middle slope. The average soil erosion rate is also different with the land use type and that of the cultivated land （1, 672. 8 t km^-2 yr^-1） is higher than oJ the uncultivated land （1.161.2t km^-2 yr^-1 ）. The result shows that landform, slope gradient and land use type are key factors that influence the size of soil erosion. In addition, we also find the SOC and TN contents and amount of the soil erosion to be correlated in the soil. With the soil erosion occurring, there are land degradation and the local eco-environmental problems, such as water eutrophication in Dian Lake.

Contributions of Social-ecological Drivers to Land Use Transitions in Protected Areas on the Tibetan Plateau:Shifting from Strong Intervention to a New Balance

The establishment and management of protected areas(PAs)often involve modifying traditional land use rights and changing the production and living activities of locals,which can lead to changes in the factors that drive land use transitions.Our understanding of the spatiotemporal patterns of land use transition and the contributions of social-ecological drivers remains incomplete.In this study,we focused on the Yarlung Zangbu Grand Canyon National Park and examined how social-ecological factors influence land use transitions by developing a theoretical model of land use transitions within PAs.Our findings revealed that cropland,shrubland,grassland,and wetland experienced net losses in area,while forestland,water,ice/snow,barren land,and impervious land exhibited fluctuating growth patterns from 1985 to 2020.The net decrease in grassland was 157425.60 ha,while the net increase in forest was 140709.20 ha.The quality of land habitat increased from 0.5158 to 0.6656.Land use dominant and recessive transitions displayed varying spatial characteristics and scales across different time periods.In particular,the degree of influence of policy factors on land use dominant transition declined from 0.0800 in 1985-1990 to -0.0432 in 2010-2020,while its influence on land use recessive transition declined from 0.00058 in 1985-1990 to 0 in 2010-2020.The results show that social-ecological factors intricately influenced different types of land use transitions,leading to a shift from a balanced state to a new equilibrium.These results enhance our understanding of the spatiotemporal patterns and complex dynamics of land use transitions within PAs,providing insights and practical implications for effective land management in PAs by considering the land-human relationships.

Model-based analysis of spatio-temporal changes in land use in Northeast China

Spatially explicit modeling techniques recently emerged as an alternative to monitor land use changes. This study adopted the well-known CLUE-S(Conversion of Land Use and its Effects at Small regional extent) model to analyze the spatio-temporal land use changes in a hot-spot in Northeast China(NEC). In total,13 driving factors were selected to statistically analyze the spatial relationships between biophysical and socioeconomic factors and individual land use types. These relationships were then used to simulate land use dynamic changes during 1980–2010 at a 1 km spatial resolution,and to capture the overall land use change patterns. The obtained results indicate that increases in cropland area in NEC were mainly distributed in the Sanjiang Plain and the Songnen Plain during 1980–2000,with a small reduction between 2000 and 2010. An opposite pattern was identified for changes in forest areas. Forest decreases were mainly distributed in the Khingan Mountains and the Changbai Mountains between 1980 and 2000,with a slight increase during 2000–2010. The urban areas have expanded to occupy surrounding croplands and grasslands,particularly after the year 2000. More attention is needed on the newly gained croplands,which have largely replaced wetlands in the Sanjiang Plain over the last decade. Land use change patterns identified here should be considered in future policy making so as to strengthen local eco-environmental security.