Analysis of root fractal characteristics in remote areas of the Taklimakan desert,China

Fractal geometry is a potential new approach to analyze the root architecture, which may offer improved ways to quantify and summarize root system complexity as well as yield ecological and physiological insights into the functional relevance of specific architectural patterns. Fractal analysis is a sensitive measure of root branching intensity and fractal dimension expresses the ＂space filling＂ properties of a structure. The objective of this study was to find out the fractal characteristics of root systems in a remote area of the Taklimakan desert in China. The entire root system of two naturally occurring species were excavated and exposed with shov- els in 2007. The species were Tamarix taklamakanensis and Calligonum roborovskii. A one-factorial ANOVA with species as factor showed statistically a highly significant difference in fractal dimensions, indicating differences in their pattern of root branching. There was no relationship between root diameter and two parameters of fractal root models a and q, representing general characteris- tics of root systems, for either species （a： the ratio of the sum of root cross-sectional areas after a branching to the cross-sectional area before root division; q： the distribution of the cross-sectional areas after branching）. We have found significant linear relation- ships between the diameter after branching and root length and biomass respectively, because of the self-similarity of root branching. Branching rules are the same for roots of all sizes and lengths. Root biomass for the root systems of entire trees can be estimated by measuring the diameter of each root at the base of the trunk or the diameter after branching. We have shown that the diameter of each root at the base of the trunk and the diameter after branching are effective indices that can be measured easily in order to estimate the root lengths, biomass and other parameters of root architecture.

堆场扬尘污染控制措施的绩效评估研究

颗粒物是我国大气环境污染的首要污染物之一,而扬尘是大气颗粒物的主要来源,已经严重影响到大气质量及人们的生存环境,堆场扬尘是我国扬尘的重要来源之一,对环境和居民健康产生了一定危害和影响,因此从源头上控制堆场扬尘污染对提升环境大气质量具有重要意义.方案优化选择是科学控制扬尘的重要环节,本研究从效益和成本两个层面构建出包括抑尘效果、环境协调性、技术稳定性、成本系数和实施难易度在内的堆场扬尘控制方案优选绩效评估模型,并在信息熵理论的基础上对堆场扬尘5种控制方案进行绩效评估试验研究.结果表明,环境协调性和技术稳定性对方案绩效评估的影响较大;试验条件下抑尘网是经济有效的堆场扬尘控制方案,洒水可作为备选方案;基于信息熵理论的堆场扬尘控制措施绩效评估计算简单,评估结果客观全面,可为堆场扬尘的控制措施选择提供科学依据.

杉木和柳杉人工林的土壤理化性质对比

以四川龙门山地区杉木和柳杉人工林为研究对象,对比分析两种人工林林下0~10 cm土层的土壤理化性质,并采用主成分分析法对土壤肥力进行综合评价。两种林型的土壤均呈弱酸性,样地间土壤有机质、全氮、全磷、全钾、碱解氮、速效钾含量差异显著(p <0. 05)。基于全国第二次土壤普查养分分级标准,两种林型的全氮和碱解氮含量均呈极富水平。柳杉林样地土壤全氮和碱解氮含量分别为杉木林样地的2. 3倍和2. 4倍。两个样地的土壤有机质含量处于中等以上水平,柳杉林样地的土壤有机质含量为杉木林样地的2. 3倍。两种林分的全钾、速效钾、全磷含量处于中等偏低水平,速效磷含量为缺乏状态。杉木和柳杉人工林土壤肥力质量综合得分分别为-0. 434和0. 866,表明柳杉人工林的土壤肥力优于杉木人工林的土壤肥力。

一种新型墙面绿化材料——墙面生态节能板

为了验证墙面生态节能板作为新型墙面绿化材料的可行性,通过对植物群落建立、植物根系生长以及保温隔热特征三方面的试验研究,得出以下试验结果:(1)种植紫穗槐的墙面生态节能板,在一年的生长季内植株株高和盖度呈先增大后减小趋势,于9月份达到最大值;(2)紫穗槐在三年内主根长显著减小,主根茎、侧根数、侧根茎呈不显著增大;(3)墙面生态节能板内温度比大气温度的变化缓慢,高温时段低于大气温度,低温时段高于大气温度。以上结果表明:墙面生态节能板能为植物生长提供合适的环境条件和物质支撑,建立起具有良好景观效果和生态功能的健康群落。植株根系生长缓慢,主根不发达,不侵蚀墙体,并且在一定程度上对建筑保温隔热,实现生态节能。

水中农药残留的二维相关荧光光谱检测

针对农药大量使用对人类健康以及环境污染造成严重的影响,论文提出并建立一种基于二维相关荧光谱定性定量分析水中西维因和百菌清农药的检测方法。配置40个不同浓度的西维因和百菌清的混合水溶液样品(西维因浓度:5×10-7~9.5×10-6 g·L-1,百菌清浓度:5×10-6~9.5×10-5 g·L-1)。研究了二维相关荧光谱特性,指出:通过二维相关荧光谱可以实现水中西维因和百菌清重叠荧光峰的有效解析。为了对比,分别建立定量分析水中西维因和百菌清浓度的二维相关荧光谱和三维荧光谱模型。对于西维因:二维相关荧光谱和三维荧光谱模型的预测均方根误差(RMSEP)分别为9.20×10-7和9.63×10-7 g·L-1;对于百菌清:两个模型的RMSEP分别为5.86×10-6和8.99×10-6 g·L-1。研究结果表明,基于二维相关荧光谱检测水环境中的农药不仅可行,而且能提供较好的分析结果。

Relationship between stand characteristics and soil properties of two typical forest plantations in the mountainous area of Western Sichuan, China

There is uncertainty and limited knowledge regarding stand characteristics and soil properties of middle-aged pure forest plantations in the mountainous area of Western Sichuan. Plantation forests are almost exclusively planted as monocultures in the Pengzhou forest farm in the western mountainous area of Sichuan Province. This study aimed to assess the spatial and ecological characteristics of middle-aged Cunninghamia lanceolata(Lamb.) Hook. and Cryptomeria fortunei Hooibr. in the Pengzhou forest farm. The relationships and differences between stand growth characteristics and forest soil composition were assessed on the two forests planted simultaneously within the same area and exposed to the same environmental conditions. Cr. fortunei grew sparse, and slower than Cun. lanceolata. Principal component analysis indicated that the soil properties in the Cr. fortunei plantation were better than those in the Cun. lanceolata plantation. Redundancy analysis revealed that the differences in stand structure were affected significantly by the total nitrogen content and pH value. Thus, we propose that Cr. fortunei is planted for priority consideration in the subtropical high mountain area. Further, tending operations and application of fertilizers need to be conducted in Cun. lanceolata forests. Based on theoretical and experimental data, the present study explains why local farmers are more willing to plant Cr. fortunei, and thus provides a useful theoretical reference for the development of sustainable plantations in the future.

基于信息熵的城市扬尘治理方案优选决策

城市扬尘的治理需要考虑到成本、效果以及对周围环境的影响等诸多因素,我国扬尘治理方案呈现明显的单一性和定性描述.因此,如何准确认识扬尘治理方案多属性决策对扬尘治理的实际工作具有重要意义.构建了城市扬尘治理方案优选评价指标体系,采用信息熵理论对方案优选的科学性和有效性进行实证研究.结果表明,抑尘周期和成本系数对扬尘治理方案优选具有较大的影响力,高压清洗方案可操作性高,适应性强,为最优方案;基于信息熵理论的扬尘治理方案优选决策计算简单,评价结果客观全面,可以很好的综合反映道路扬尘治理方案优选决策,可为城市扬尘治理提供科学依据.

内蒙古达乌尔鼠兔越冬群体大小与捕食风险的研究

达乌尔鼠兔(Ochotona dauurica)是内蒙古草原的主要鼠种之一,分布在草地和榆树(Ulmus pumila)疏林下,在冬季会形成数量不同的越冬集群。达乌尔鼠兔在秋季和冬季常常会受到艾虎(Mustela eversmanii)的攻击。为研究达乌尔鼠兔越冬集群大小与来自艾虎的捕食风险的关系,2004年10月上旬在内蒙古锡林郭勒盟锡林浩特市白音锡勒牧场的五连榆树疏林地,以洞口计数法调查分布于林下的达乌尔鼠兔种群,采用洞口数量多少作为鼠兔秋季集群大小的指标。清除实验区达乌尔鼠兔洞群范围内的所有鼬科动物粪便。1个月之后,分别统计洞群留有艾虎粪便和洞群被艾虎挖掘过的达乌尔鼠兔家族数量,分析了艾虎对不同大小集群的达乌尔鼠兔家群的捕食选择偏好。统计结果显示,艾虎在集群大的达乌尔鼠兔家群周围更容易留下粪便(P<0.05),并且更倾向挖掘集群大的达乌尔鼠兔家群(P<0.05)。这表明达乌尔鼠兔越冬家群成员数量越多,其来自艾虎的捕食风险就越大。从本次实验结果来看,越冬期间天敌选择性的捕食风险的存在抑制了达乌尔鼠兔越冬集群的增长,从而使其越冬家族数量维持在限定的规模和水平。