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排序方式: 共有996条查询结果,搜索用时 78 毫秒
831.
832.
833.
This study scrutinises the use of terrestrial laser scanning (TLS) to measure diameter at breast height (DBH) and tree height at individual tree species level. LiDAR point cloud scans are collected from uniformly defined control points. The result of processed TLS data demonstrates the precise measurements of tree height and DBH by comparing it with field data (DBH, tree height, tree species and location). The average tree height and DBH obtained through TLS measurements were 9.44?m and 43.30?cm, respectively. A linear equation between TLS derived parameters and field measured values were established, which gave the coefficient of determination (r2) of 0.79 and 0.96 for tree height and DBH, respectively. Further, these parameters were used to calculate above ground biomass (AGB) for individual tree species by considering a non-destructive approach. The total AGB and carbon stock from 80 different trees are computed to be 49.601 and 22.320?tonnes, respectively. 相似文献
834.
This study investigated the effects of sawdust as a soil amendment on certain growth parameters of Solanum esculentum Linn. grown in soil polluted with various concentrations of waste engine oil, and changes in the physicochemical properties of the soil. The purpose was to assess the soil remediation potentials of sawdust in waste engine oil-polluted soil. The experiment was divided into three regimes: control(air-dried soil without waste engine oil and with clean sawdust), polluted(waste engine oil-contaminated soil), and amended(oil-polluted soil amended with sawdust). Enough 3-kg soil samples were sieved and air-dried to prepare five treatment levels of waste engine oil-contaminated soil(30 m L, 1%; 60 m L, 2%; 90 m L, 3%; 120 m L, 4%; and 150 m L, 5%), as well as five additional treatment levels(the same amounts of oil contamination) in soil amended with sawdust. The treatment levels were replicated five times in a completely randomized design. A nursery bed was planted with a hybrid tomato variety(Roma V F) obtained from National Horticultural Research Institute(NIHORT) in Ibadan, Nigeria. During the maturation period, the growth parameters such as plant height, number of leaves, and number of branches per plant were determined and then the harvested plants were oven dried at 70 °C for 48 hours to determine their dry weights. The effects of the sawdust amendment on the soil were assessed by determining the soil p H(glass electrode p H meter), total nitrogen(Kjeldahl method), total phosphorus(Bray-1 solution), and potassium(on the leacheate by a flame photometer). Chromium, lead, and cadmium contents were determined using an atomic absorption spectrophotometer. Analysis of variance and a Duncan multiple-range test were employed to test significant differences in the soil properties of the three regimes. The growth performance of Solanum esculentum Linn. in the amended regime(soil with sawdust) at the 150-m L waste engine oil-contamination level was significantly higher than in the polluted regime(soil without sawdust). After plant harvest, the p H of the soil was shown to be clearly affected by the addition of waste engine oil. The control soil(air-dried only, no sawdust, no oil) had the highest p H value, 6.60, which was significantly different from the p H values at other levels of waste engine oil contamination. However, when amended with sawdust, the control soil had a significantly lower p H value than the unamended control soil. This study further demonstrates that sawdust has the potential of amending waste engine oil-contaminated soil for increasing tomato growth performance because it is capable of increasing the soil nutrient content and reducing the soil total hydrocarbon content. 相似文献
835.
亚热带森林参数的机载激光雷达估测 总被引:5,自引:2,他引:3
通过应用机载激光雷达数据,在分析云南省中部的78块样地的基础上提出2个预测森林不同生物特性的统计模型(加权平均高度的预测模型和生物量的预测模型),并讨论了预测结果及其精确性。从激光雷达数据中提取了2组变量(树冠高度变量组和植被密度变量组)作为自变量,采用逐步回归方法进行自变量选择。结果表明,激光雷达数据与森林的平均树高和地上各部分生物量有很强的相关性。对于3种不同森林类型(针叶林,阔叶林和混交林),平均树高估测均能达到比较高的精度;生物量的估测结果是针叶林优于阔叶林,混交林的生物量与激光雷达数据则没有明显相关性。最后,对回归分析的结果和影响预测精度的因素进行讨论,认为预测结果的精度可能与森林类型、激光雷达采样时间和采样密度以及坐标误差等因素有关。 相似文献
836.
Zinc remediation of aqueous streams is of special concern due to its highly toxic and persistent nature. Conventional treatment technologies for the removal of zinc are not economical and further generate huge quantity of toxic chemical sludge. Biosorption is emerging as a potential alternative to the existing conventional technologies for the removal of metal ions from aqueous solutions. Mechanisms involved in the biosorption process include chemisorption, complexation, adsorption–complexation on surface and pores, ion exchange, microprecipitation, heavy metal hydroxide condensation onto the bio surface, and surface adsorption. Biosorption largely depends on parameters such as pH, the initial metal ion concentration, biomass concentration, presence of various competitive metal ions in solution, and to a limited extent on temperature. Biosorption using biomass such as agricultural wastes, industrial residues, municipal solid waste, biosolids, food processing waste, aquatic plants, animal wastes, etc., is regarded as a cost‐effective technique for the treatment of high volume and low concentration complex wastewaters containing zinc metal. Very few reviews are available where readers can get an overview of the sorption capacities of agro based biomasses used for zinc remediation together with the traditional remediation methods. The purpose of this review article is to provide the scattered available information on various aspects of utilization of the agro based biomasses for zinc metal ions removal. An extensive table summarizes the sorption capacities of various adsorbents. These biosorbents can be modified using various methods for better efficiency and multiple reuses to enhance their applicability at industrial scale. We have incorporated most of the valuable available literature on zinc removal from waste water using agro based biomasses in this review. 相似文献
837.
838.
小型底栖动物是海洋生态系统的重要组成部分,其生物量估算的准确性影响着海洋生物资源分析和生态系统动力学的研究.对常用的小型底栖动物生物量估算方法进行了介绍,并指出了我国在使用体积估算法时存在的一些问题.在此基础上,对小型底栖动物生物量估算模型研究提出了几条建议. 相似文献
839.
青岛大沽河河口湿地芦苇的生长及生物量动态研究 总被引:1,自引:0,他引:1
根据2009年4~10月在大沽河河口湿地进行的芦苇(Phragmites australis)调查,研究该区域芦苇主要生长季节期间生长及生物量动态变化。结果表明:在生长季节,芦苇株高逐渐增加,10月最高达(2305.35±65.48)(平均值±标准误差,下同)mm;植株密度呈下降趋势,5月最高为(362.33±24.52)株.m-2,9月最低为(255.0±36.17)株.m-2;株高与植株密度二者无显著相关性。地上部生物量月间变化较大,总体呈上升趋势,最大值出现在10月,干质量变化范围为(37.59±13.94)~(7033.02±967.37)g.m-2。叶片、茎与叶鞘等构件生物量总体呈上升趋势,干质量最大值出现在10月,分别为(1264.32±202.19)、(3667.58±475.22)、(1123.78±178.37)g.m-2。5~10月,芦苇地上部同化器官与非同化器官生物量之比F/C值呈降低趋势,地上部非同化器官生物量对地上部总生物量的变化有较大贡献。初步分析表明降水量对芦苇地上部生物量增长有较大影响。芦苇地下各层生物量变化基本相同,月间差异不显著。芦苇根冠比5~10月处于0.29~1.93范围内。芦苇根冠比的变化受外界环境因素的影响,其变化与地上、地下生物量密切相关。根系生长变化与芦苇植株自身对营养等生存条件获取的自我调控有关。 相似文献
840.
Based on forest inventory data (FID) at sublot level,we estimated the carbon sequestration in forest vegetation of Beijing,China in 2009.In this study,the carbon sequestration in forest vegetation at sublot level was calculated based on net biomass production (ΔB) which was estimated with biomass of each sublot and function relationships between ΔB and biomass.The biomass of forested land was calculated with biomass expansion factors (BEFs) method,while those of shrub land and other forest land types were estimated with biomass,coverage and height of referred shrubs and shrub coverage and height of each sublot.As one of special forested land types,the biomass of economic tree land was calculated with biomass per tree and tree number.The variation of carbon sequestration in forest vegetation with altitude,species and stand age was also investigated in this study.The results indicate that the carbon sequestration in forest vegetation in Beijing is 4.12 × 106 tC/yr,with the average rate of 3.94 tC/(ha·yr).About 56.91% of the total carbon sequestration in forest vegetation is supported by the forest in the plain with an altitude of < 60 m and the low mountainous areas with an altitude from 400 m to 800 m.The carbon sequestration rate in forest vegetation is the highest in the plain area with an altitude of < 60 m and decreased significantly in the transitional area from the low plain to the low mountainous area with an altitude ranging from 200 m to 400 m due to intensive human disturbance.The carbon sequestration of Populus spp.forest and Quercus spp.forest are relatively higher than those of other plant species,accounting for 25.33% of the total.The carbon sequestration in vegetation by the forest of < 40 years amounts to 45.38% of the total.The carbon sequestration rate in forest vegetation peaks at the stand age of 30–40 years.Therefore,it would be crucial for enhancing the capability of carbon sequestration in forest vegetation to protect the forest in Beijing,to limit human disturbance in the transitional area from the plain to the low mountain area,and to foster the newly established open forest. 相似文献