地形因子对闽南山区尾巨桉造林的影响

通过对不同地形条件下尾巨桉山地造林的对比试验研究,结果表明：在闽南山区尾巨桉造林受地形因子的影响生长有显著差异,在海拔800 m以下,山坡的中、下部坡位尾巨桉生长较好;在山脊和山谷生长较差;在缓坡比在陡坡生长好;东坡和东北坡相对比较容易受风害;北坡和山谷地带比较容易受冻害。     

岩溶峰丛洼地土壤养分空间分异特征及影响因子分析

研究了典型岩溶峰丛洼地土壤养分在坡地和洼地的空间分异特征，并探讨了土地利用方式和地形因子对土壤养分空间分布的影响。结果表明：土壤养分在坡地和洼地存在显著差异，受长期耕作影响，有机碳、全氮、全磷、全钾、碱解氮和速效钾在洼地的含量显著低于坡地。而速效磷在洼地的含量显著高于坡地，说明施肥对土壤的有效磷含量具有重要作用；在坡面尺度，土地利用方式是有机碳、全氮、全磷、全钾、碱解氮、速效磷等养分的主要影响因子。地形因子对有机碳等上述养分和速效钾、PH值有显著影响，但其方差贡献均小于土地利用方式（速效钾和PH值除外）；种植制度对洼地土壤有机碳、全磷、全钾、速效钾有显著影响，牧草地在一定程度上有利于有机质的积累；有机碳、全氮、碱解氮等养分整体表现为随着土地利用强度的增加而显著降低，自然坡地和撂荒地的有机碳含量较高，分别为耕地的3.35倍和1.91倍，生态系统表现为“碳汇”趋势。耕地的有机碳含量显著偏低，生态系统表现为“碳源”趋势，不利于农业生态系统的健康发展。木豆-板栗地的有机碳、全氮等养分显著高于耕地，退耕在一定程度上有利于有机质等养分的积累，但是对坡面尺度土壤养分的分析表明木豆-板栗地的有机碳等养分显著低于自然坡地和撂荒地，说明土壤理化性质要恢复到自然水平，还需要较长时间。     

Pre-EuroAmerican settlement forests in Redwood National Park,California, USA: a reconstruction using line summaries in historic land surveys

Extensive logging in the twentieth century destroyed much of the coniferous forests in the lower Redwood Creek basin of Redwood National Park. Restoration of cutover lands requires the identification of historical, pre-logging reference conditions. Field notes from the original Public Land Surveys were used to reconstruct the pre-EuroAmerican settlement forests. Most reconstructive studies based on historic surveys rely on bearing tree evidence over large areas to determine vegetation patterns over several hundreds to thousands of square kilometers. Due to the small size of the study area (approximately 200 km²), bearing tree evidence could not accurately reconstruct the vegetation at this scale. Instead, lists of the overstory and understory vegetation for each surveyed mile (line summaries) were employed. Analysis of line summaries evidence identified the historical importance, geographical range, and environmental influences on woody species and vegetation communities. Topography, especially elevation, and soil texture were significantly correlated with plot-scale ordination scores derived from non-metric multidimensional scaling. The influence of topography and distance to ocean coast on the historical distribution of dominant woody species concurs with findings from present-day field studies of local and regional old-growth forest. A comparison with present-day vegetation maps revealed that coast redwood (Sequoia sempervirens), Douglas fir (Pseudotsuga menziesii), Sitka spruce (Picea sitchensis), and red alder (Alnus rubra) experienced the most substantive changes in the vegetation as a result of twentieth century land use activities.     

Assessing topographic patterns in moisture use and stress using a water balance approach

Through its control on soil moisture patterns, topography’s role in influencing forest composition is widely recognized. This study addresses shortcomings in traditional moisture indices by employing a water balance approach, incorporating topographic and edaphic variability to assess fine-scale moisture demand and moisture availability. Using GIS and readily available data, evapotranspiration and moisture stress are modeled at a fine spatial scale at two study areas in the US (Ohio and North Carolina). Model results are compared to field-based soil moisture measurements throughout the growing season. A strong topographic pattern of moisture utilization and demand is uncovered, with highest rates of evapotranspiration found on south-facing slopes, followed by ridges, valleys, and north-facing slopes. South-facing slopes and ridges also experience highest moisture deficit. Overall higher rates of evapotranspiration are observed at the Ohio site, though deficit is slightly lower. Based on a comparison between modeled and measured soil moisture, utilization and recharge trends were captured well in terms of both magnitude and timing. Topographically controlled drainage patterns appear to have little influence on soil moisture patterns during the growing season. In addition to its ability to accurately capture patterns of soil moisture in both high-relief and moderate-relief environments, a water balance approach offers numerous advantages over traditional moisture indices. It assesses moisture availability and utilization in absolute terms, using readily available data and widely used GIS software. Results are directly comparable across sites, and although output is created at a fine-scale, the method is applicable for larger geographic areas. Since it incorporates topography, available water capacity, and climatic variables, the model is able to directly assess the potential response of vegetation to climate change.     

<Emphasis Type="Italic">β</Emphasis>-Diversity and vegetation structure as influenced by slope aspect and altitude in a seasonally dry tropical landscape

Topography strongly affects the distribution of insolation in the terrain. Patterns of incoming solar radiation affect energy and water balances within a landscape, resulting in changes in vegetation attributes. Unlike other regions, in seasonally dry tropical forest areas the potential contribution of topography-related environmental heterogeneity to β-diversity is unclear. In Mt. Cerro Verde (Oaxaca), S. Mexico, we: (1) modelled potential energy income for N- and S-facing slopes based on a digital elevation model, (2) examined the response of vegetation structure to slope aspect and altitude and (3) related variations in plant diversity to topography-related heterogeneity. Vegetation survey and modelling of potential energy income (SOLEI-32 model) were based on 30 plots equally distributed among three altitudinal belts defined for each slope of the mountain; combining the three altitudinal belts and the two slopes produced six environmental groups, represented by five vegetation plots each. Potential energy income was about 20% larger on the S than on the N slope (9,735 versus 8,138 MJ/m²), but it did not vary with altitude. In addition, the temporal behaviour of potential energy income throughout the year differed greatly between slopes. Vegetation structure did not show significant changes linked to the environmental gradients analysed, but altitude and aspect did affect β-diversity. We argue that the classic model of slope aspect effect on vegetation needs reconsideration for tropical landscapes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

生物炭对山坡地烟叶产量和氮肥利用效率的影响效果评价

山坡地土壤有机质含量低和保水保肥能力差是导致烤烟产量普遍低于山间平地的重要原因之一。生物炭可以改善土壤物理化学性质,提升土壤保水保肥能力,本试验研究其对烤烟产量和氮肥利用效率的影响。通过二因素两种地形（山坡地、山间平地）和6个生物炭施用量处理（0、4.5、9.0、13.5、18.0、22.5t/hm ²）的大田试验,评价生物炭对烟叶产量和产值、烟株农艺性状、氮肥利用效率和氮素表观损失量的影响。结果表明,山坡地烤烟产量和产值显著低于山间平地。同一生物炭施用量条件下,山坡地烟叶产量和产值相对增幅显著高于山间平地。当生物炭施用量介于0~13.5t/hm ²时,山坡地烟叶产量和产值均随生物炭施用量增加而显著增加;而进一步提高生物炭施用量,烟叶产量和产值增加不显著。山间平地烟株氮素吸收量、氮肥农学利用率和氮肥回收利用率均显著高于山坡地烟株。与不施生物炭的对照相比,山坡地烟株氮肥农学利用率和氮肥回收利用率相对增幅均显著高于山间平地烟株。随着生物炭施用量增加,氮素表观损失量显著降低。相对于山间平地而言,山坡地植烟区应用生物炭的增产增收和提高氮肥利用效率的效果更加显著,其适宜生物炭施用量为13.5t/hm ²。     

Accounting for extensive topographic and pedologic secondary information to improve soil mapping

Soils generally vary in a quite complex way. To assess and model spatial variability, several variables can be sampled in addition to the target used to quantify and describe the main phenomenon under study. One of the major advantages of geostatistics over simpler spatialization methods is that sparsely observations of the primary attribute can be complemented by secondary attributes that are more densely sampled. Two methods were applied to incorporate dense secondary information: multicollocated cokriging, which restricts the neighbourhood to the only secondary data collocated with the available data of the primary variable and simple cokriging with varying local means related to crisp classes. The objective of this paper was to find the method that best improves the estimation of primary attributes through dense secondary information for the study area, which was the province of Siena in central Italy, an area of about 3820 km². Soil samples were taken at 742 locations and depth, sand and clay contents and available water capacity were determined.     

地形和土壤属性对大豆产量的影响

正确理解作物产量的变异性特征及其影响因素是对农田地块进行科学管理的基础。地块的地形特征是导致作物产量变异形成的主要因素。本文选择代表不同地形特征的洼地农田和岗地农田为研究对象,分析地形对土壤属性和大豆产量的影响以及它们之间的相互关系。研究结果显示,洼地农田与岗地农田的土壤属性和大豆产量均存在显著性差异(P<0.05)。洼地农田的土壤养分含量较高,但土壤结构较差,其平均重量直径(MWD)和几何平均直径(GMD)显著小于岗地农田,质量分形维数(Dm)显著大于岗地农田;在两类农田地块中,大豆产量的差别较大,洼地农田的大豆产量仅为岗地农田的62%。相关性分析表明,大豆产量与土壤结构稳定性和地块高程呈极显著正相关(P<0.01);土壤有机碳和土壤养分对大豆产量没有显著影响。     

Seasonal dynamics of soil microbial biomass in coastal sand dune forest

Sand dunes are a typical landscape in the coast of western Taiwan, where Casuarina forests were established decades ago to stabilize sand dunes and protect the inland vegetation. Study of microbial biomass in such an ecosystem may give insights into the role of microbes in soil fertility and nutrient cycling. We established our study sites in two topographic units based on elevation and drainage types: upland and lowland. The study lasted for 2 years, and soil samples were collected every 3 months. Microbial biomass C (C_mic) and N (N_mic) were high in a shallow humic layer that rested on top of the soil (1222–1319 mg kg⁻¹ for C_mic and 245–276 mg kg⁻¹ for N_mic) and declined sharply to only one-tenth of the above values in the underlying surface soil (0–10 cm depth). Microbial biomass C_mic and N_mic in humic and surface soil were not significantly different between upland and lowland sites. In the upland soils, the mean C_mic was highest in autumn for both the humic and surface soil, and lowest in spring and summer for the humic layer and summer for the surface soil layer. In the lowland soils, the C_mic was highest in winter for both humic and surface soil, and lowest in spring and autumn for the humic layer and spring and summer for surface soil. Strong fluctuations of C_mic and N_mic were associated with the soil moisture prior to sampling, which appeared to control the size of microbial biomass in this environment. Temperature had little effect on the dynamics of soil microbial biomass in the sand dune forest ecosystem.     

漳州市30年暴雨时空分布特征与影响条件分析

利用漳州市1971～2000年30年地面降水观测资料,对漳州市暴雨的时空分布及其影响系统进行分析。结果表明,暴雨月时间分布呈现年头年尾少、年中多趋势,6～8月为暴雨高峰期;年平均暴雨日数和汛期3～10月暴雨日数地理分布呈现西南偏多、南北偏少特征;冬季暴雨日数分布呈现由南自北逐渐减少特征;暴雨落区与漳州地形特征紧密相关;暴雨主要在南支槽、西南急流、热带气旋影响的天气条件下发生。