SPOT5遥感影像在林业二类调查中的应用

采用ERDAS IMAGINE图像处理软件,对青海省互助县境内的北山林场的SPOT5遥感影像进行处理,包括原始数据导入、正射纠正、影像融合、波段组合、影像增强等处理过程以及数字正射影像图(DOM)的制作。探讨SPOT5遥感影像在林业二类调查中的应用处理方法及SPOT5影像的应用前景。经现地验证,以SPOT5遥感卫星影像为底图,通过人机交互目视解译方法区划判读小班能满足林业二类调查的需要,该影像数据能作为1∶10000专题图制作的基础数据。     

北京地区乔木郁闭度测量研究

比较了国内外已有的乔木郁闭度测量方法的优缺点,在样点法特别是观测管法的基础上,以北京延庆地区乔木林为对象,对郁闭度的激光测量进行了研究。实验改进了观察管法,对在野外测量乔木林郁闭度时精确测量所需样点数进行了研究,可以为野外快速、简洁、精确地测量乔木林郁闭度提供新的方法与参考。     

大叶桉叶面积测定方法的比较研究

对大叶桉叶面积测定的4种方法进行了比较研究,结果表明:不同测定方法测出的结果有显著差异(p＜0.05),测量方法的精确度由高到低依次为:回归分析法、叶面积仪器法、方格计数法和系数法.在回归分析法中,以叶长×叶宽为自变量的一元直线回归方程相关系数高达0.9970,与叶面积有极显著的正相关.回归分析法是大叶桉叶面积测定的一...     

森林经营认证评价指标体系的探讨——以黄丰桥国有林场为例

文章通过借鉴国内外森林经营认证已有的研究成果,归纳总结了影响森林经营认证的主要因素,并在此基础上建立了国有林场森林经营认证评价指标体系,提出了森林经营认证综合指数的新概念。     

混合方式对泡沫砂与土壤混合均匀性的影响

通过设置常规混合+风干态泡沫砂(CK)、常规混合+水浸态泡沫砂(1T)、常规混合+泥浆态泡沫砂(2T)、分层混合+风干态泡沫砂(3T)和分层混合+水浸态泡沫砂(4T) 5个处理,研究了不同混合方式对泡沫砂和土壤混合均匀性的影响,并采用容重的标准差和变异系数表征混合均匀性。结果表明:泡沫砂形态显著影响了混合均匀性。采用常规混合时,水浸态泡沫砂显著增加了0～10 cm和0～20cm土层混合均匀性,容重的标准差比风干态泡沫砂分别降低了188%和105%,容重的变异系数分别降低了62.1%和50.1%;与风干态泡沫砂相比,泥浆态泡沫砂不仅显著降低了不同土层的混合均匀性,还显著降低了混合物内部的混合均匀性,0～10 cm土层容重的标准差和变异系数分别比10～20 cm土层显著增加68.1%和50.8%。单变量分析表明,混合方式对混合均匀性无显著性影响,混合方式和泡沫砂形态之间无交互效应,泡沫砂形态是影响泡沫砂和土壤混合均匀性的主要因素。采用水浸态泡沫砂在常规混合方式下与土壤混合,不仅提高了混合物整体以及不同土层的混合均匀性,而且还降低了不同层次之间混合均匀性的差异。因此,建议采用常规混合+水浸态泡沫砂的方式混合土壤和泡沫砂。     

基于齿面移动法的齿轮飞溅润滑性能数值分析与验证

由于齿轮传动系统飞溅润滑过程中润滑油流动的复杂性,近年来数值仿真分析方法已逐渐成为评价飞溅润滑性能的重要手段。为解决齿轮飞溅润滑数值建模过程中由于啮合位置间隙太小而带来网格划分困难的问题,该文提出了采用齿面移动法对齿轮进行处理,即在保留所有轮齿和不改变齿轮安装位置的基础上,通过改变轮齿厚度来增大啮合区域间隙,以便于流体域网格划分。该文对不同处理方法获得的飞溅润滑仿真结果进行了对比分析,并结合试验数据,说明了齿面移动法相对于现有文献中的齿轮建模处理方法获得的润滑油飞溅效果更符合实际情况,搅油功耗计算结果误差在8%以内,且工程适用性更好。该研究为进一步分析车辆变速箱、驱动桥等齿轮传动系统的润滑状况提供了参考。     

沂水县农业生态经济类型分区研究

选择一些自然、经济、社会指标，以乡为基本单元，采用灰色星座聚类法对山东省沂水县农业生态经济进行分类，探讨其农业生态经济系统发展的规律，为该类区域社会、经济、生态协调发展和农业可持续发展提供依据。     

Response of denitrifying communities to successive soil freeze–thaw cycles

The effect of soil freeze–thaw cycles on the denitrification potential was examined based on the C₂H₂ inhibition method. The gross N₂O production curve of the soil sample (incubation with C₂H₂) showed minor changes between the freeze–thaw treatment and the unfrozen control. However, kinetics analysis revealed that the initial production rate, an indicator of the population density of denitrifying communities, decreased (P = 0.043) and the specific growth rate constant, an indicator of the activity of denitrifying communities, increased (P = 0.039) as a result of the freeze–thaw cycles in five of six soil samples examined. The increase in the specific growth rate constant suggested the stimulation of the activity of denitrifying communities that survived after the freeze–thaw cycles and may explain the minor suppression on the gross N₂O production in spite of decreasing the population density of denitrifying communities that was suggested by the initial production rate. The net N₂O production curve of the soil sample (incubation without C₂H₂) showed a remarkable change in one out of six soil samples, and in that one soil sample, N₂O release to the atmosphere was largely stimulated (7.6 times) by the freeze–thaw cycles. However, the stimulation of the N₂O release by the freeze–thaw cycles was even observed in two other selected soil samples (4.6 and 1.8 times), suggesting that an imbalance in the N₂O-producing and N₂O-reducing activities of denitrifying communities might complementally explain the N₂O release stimulated by the freeze–thaw cycles.     

Characterization of Treatment Processes and Mechanisms of COD, Phosphorus and Nitrogen Removal in a Multi-Soil-Layering System

Characteristics of the treatment processes inside a MSL system were investigated by using a laboratory-scale MSL system, which was set up in a D 10 × W 50 × H 73 cm acrylic box enclosing "soil mixture blocks" alternating with permeable zeolite layers. For the study of the treatment processes inside the system, wastewater, with mean concentrations (mg L⁻¹) of COD: 70, T-N: 12, T-P: 0.9, was introduced into the system at a loading rate of 1,000 L m⁻² d⁻¹. Treatment processes in the MSL system were different for the COD, P and N pollutants. Eighty percent of COD was removed in the 1st soil layer among the 6 layers, and the removal rate increased as water moved down and finally reached 90% in the last layer of the system. Phosphorus concentration was lower under the soil mixture layers than under the permeable layers, presumably because P was adsorbed mainly by soil and mixed iron particles. The P concentration in water gradually decreased in the lower layers of the system. The concentration of PO₄^3--P was generally lower in the aerated MSL system than in the non-aerated one. NH₄⁺-N was adsorbed and nitrified in the upper part of the system. The NO₃⁻-N concentration was lower in water under the soil mixture layers than under the permeable layers, indicating that denitrification mainly occurred in the soil mixture layers.     

基于PSR模型的能源-生态复合区生态安全预警研究——以山西省忻州市为例

[目的]以山西省忻州市为例,探讨能源与生态复合区生态安全预警,为区域生态保护规划及区域高质量发展提供依据。[方法]基于PSR概念模型框架,从人口、资源、经济、环境、生态要素选取了21个指标建立了能源—生态复合区生态安全预警评价指标体系,采用熵值法确定权重,对山西省忻州市2000—2018年生态安全预警进行分析。[结果]①2018年忻州市14县综合预警值介于0.356 2～0.587 0之间,平均值为0.491 2,预警等级处于中警至轻警范围内。其中忻府区、定襄、五台、繁峙、静乐5县(区)警情为中警状态,其余7县(市)均为轻警状态,忻州市整体生态安全并不乐观,生态安全等级较低。②2000—2018年忻州市生态安全预警值呈波动缓慢上升趋势,警情为中警等级的县减少,轻警等级的县增加。[结论]研究区生态安全空间上呈现不均衡性,警情整体趋于改善,主要取决于系统压力中的经济、资源、环境压力趋缓。