贵州省黔南州森林景观与地形因子关系研究

根据贵州省黔南州森林资源调查数据资料,并从DEM中提取海拔、坡度、坡向及地表粗糙度4个地形因子,研究地形因子对黔南州森林景观的影响.研究结果表明,黔南州6种森林景观在海拔上的分布比例呈现中间高两边低的特点,集中分布于海拔400～1 200 m;森林景观随坡度的分布变化呈现不均匀分布,以斜坡为最高点,曲线变化趋势接近于正...     

两种分辨率DEM在不同空间尺度下的差异—以黄土高原丘陵区为例

以黄土高原丘陵区的局部山区为研究区域,利用空间分辨率为5m和30m的数字高程模型(DEM)数据,通过ArcGIS软件提取其海拔、坡度、地表粗糙度和太阳辐射4个地形因子,结合SPSS中的Mann-whitney检验分析不同空间尺度下(缓冲半径R为100～5 000m)5m和30m分辨率的DEM之间的差异。结果表明,随着空间尺度变化,5m和30m分辨率DEM中提取的地形因子的变化趋势是相同的;当R≥500m,30m分辨率的DEM的海拔显著大于5m分辨率的海拔;当R≥1 500m,30m分辨率DEM的坡度显著大于5m的坡度;当R≥2 500m,30m分辨率DEM的地表粗糙度显著大于5m的地表粗糙度;但R≥1 000m时,30m分辨率DEM的太阳辐射显著小于5m分辨率的太阳辐射。其中坡度与太阳辐射呈显著负相关关系。对于地形比较复杂的山地丘陵区,选择高分辨率的DEM更能清楚地反映地形特征。     

基于DEM的成都市基本地貌形态研究

以成都市30 m×30 m分辨率的ASTERGDEMV2版DEM为数据源,基于ARCGIS10.2构建邻域分析法的地形起伏度批量提取模型,提取不同大小矩形邻域窗口的地形起伏度,运用均值变点分析法确定最佳计算单元,在此基础上,将最佳计算单元的地形起伏度与海拔分级图进行空间联合,得到成都市的基本地貌形态类型图。结果表明:成都市地形起伏度提取的最佳计算单元为14×14网格大小(176 400 m2),中起伏度及以下地形占98.54%。全市基本地貌形态类型有20种,其中主要类型5种,面积占96.52%。从空间分布格局来看,西北部的龙门山脉地形起伏变化多样,集中分布了13种类型;低海拔丘陵类型主要集中在龙泉山脉及龙门山脉与成都平原接合部区域,在中部及东部呈零星分布。低海拔平原和低海拔台地两种主要类型主要分布在龙泉山脉与龙门山脉之间及龙泉山脉的西南部。     

基于高差与标准差法的中国地形起伏度研究

指出了地形起伏度是研究地貌、水文、地质灾害等的重要数据。利用局地高差与标准差法,通过邻域分析及变点分析计算得到全国1∶100万DEM数据的最佳地形起伏度统计单元为11×11,提出了标准差计算地形起伏度的分级标准为:平坦地形(0~5m);小起伏(5~15m);中起伏(15~45m);山地起伏(45~140m);高山起伏(>140m),最终得到了中国地形起伏度分级图。通过与实际地形地貌资料进行对比,1∶100万DEM数据提取地形起伏度的结果完全满足山体完整性与区域普适性原则,标准差分级标准具有可用性。     

基于DEM的关中城市群地形地貌特征分析

关中城市群在我国“一带一路”和现代化建设中具有重要战略地位,对其地形地貌进行研究,可为该地区国土空间规划、地质灾害防治、生态环境治理提供数据支持。以关中城市群为研究对象,基于分辨率为30 m×30 m的DEM数据,运用ArcGIS软件,提取高程、坡度、坡向、地形起伏度4个地形因子,采用均值变点法确定了提取地形起伏度的最佳邻域分析单元。结果表明：研究区坡向主要为东南坡、东坡和西南坡,各坡向所占比例相差不大;坡度以缓坡和低于25°的陡坡为主;主要为低海拔和中海拔地区;地形起伏度以丘陵为主,其次为平原。     

地表起伏对区域扶贫成本的影响浅析

指出了地表起伏度是地表起伏情况直接指标,同时也能反映地形复杂程度。地表起伏对区域经济发展、农业生产、地质灾害发育条件等具有重大影响,与当地人民的生产生活紧密相关。以贵州14个深度贫困县为例,通过模型获取了地表起伏度指数,并分析了其与贫困人口、财政专项扶贫资金分配的关系,从而探究了地表起伏度对区域扶贫成本的影响。结果显示:整体而言地表起伏度与财政专项扶贫资金呈负相关,同时地表起伏度与各县人口、贫困人口呈负相关;而与人均财政专项扶贫资金、贫困人口比例表现出正相关趋势,这表明地表起伏度越大,区域贫困程度越高,单人所需财政扶贫力度越大,所需扶贫资金越多,从而使得区域扶贫成本增加。     

山地城市骑行绿道选线适宜性评价研究 ——以云南省普洱市为例

以云南省典型山地城市普洱市为例,通过问卷调查及访谈、实地调查、专家咨询等方法,筛选出山地城市骑行绿道选线影响因子,运用层次分析法(AHP)构建适宜性评价模型,对普洱市思茅区骑行绿道适宜建设区域进行评价。结果表明,山地城市骑行绿道选线除强制考虑地质灾害和空间管制因素外,主要受自然环境基底、景观资源、交通环境、使用需求的影响,其中自然环境基底影响最大,最适宜区域分布在海拔600～1 200 m、坡度0～8°地形较平坦的城镇及其周边;适宜区及基本适宜区为海拔900～1 500 m、坡度0～20°区域;不适宜区域为海拔高于1 700 m、坡度大于20°区域。     

海南霸王岭坡垒分布格局初步研究

通过实地调查,对坡垒随地形因子(海拔、坡向、坡度)的分布规律进行了分析。结果表明,坡垒分布主要集中在中低海拔600~900 m,先随海拔增高而增加,海拔700~800m时候达到最高值,随后随海拔升高而减少;不同坡向对坡垒数量分布影响为:北坡西南坡东北坡南坡西北坡西坡东南坡东坡,阴坡上分布的坡垒数显著高于阳坡上的分布数量;坡垒集中分布在坡度20~25°范围内。可见坡垒的分布格局与海拔、坡向及坡度密切相关。     

普洱市七叶莲野生资源分布研究

在全面调查普洱市七叶莲野生资源地理分布基础上,采用主成分分析法研究七叶莲野生资源地理分布与气候、地形之间的关系,并对海拔与七叶莲枝叶总皂甙含量做相关性分析。调查结果表明:七叶莲野生资源在普洱全市均有分布,在喀斯特地貌区域分布尤为集中,其水平分布范围为99°20′11″E~101°55′04″E,22°18′20″N~24°17′58″N,垂直分布范围为海拔500~1 900 m。经主成分分析表明,影响七叶莲地理分布的主要水热指标的排序为湿度因子热量因子降水因子;相关分析结果表明,七叶莲所分布的海拔与其林木枝叶总皂甙的含量具负相关关系,其相关系数为-0.948,最高海拔(1 460 m)与最低海拔(1 006 m)的七叶莲枝叶总皂甙含量比为1.0∶1.5。     

黄冈市地形起伏度及其与人口、经济的相关性研究

为研究革命老区黄冈市的经济发展、环境保护与社会协调之间的关系,基于分辨率为30m的数字高程模型AsterGDEM,运用GIS技术提取黄冈市地形起伏度,以此为基础分析了黄冈市地形起伏度与人口分布和经济发展之间的关系。结果表明:黄冈市的地形起伏度区域分异显著,西南部起伏较小,东北部较大;黄冈市地形起伏度随海拔的升高而逐渐增加;黄冈市地形起伏度与人口密度和经济密度存在显著的负相关。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.