Analysis of regional variation of height growth and slenderness in populations of six urban tree species using a quantile regression approach

Inventory data of six urban tree species from seven cities across Germany were used to model regional variation of height growth, allometric scaling, and slenderness over a wide range of size and age using a quantile regression approach. Variation within and between species and cities was large. Height did not reach an asymptote but declined at higher ages, presumably because of reduction cuts. Allometric scaling and slenderness varied with wind climate, modulus of elasticity, and coefficient of drag. Our data do not support the use of a threshold value of slenderness in tree risk assessment.     

道路景观设计方法探讨

提出对道路景观的规划、调查、定位等系统分析,从而在道路的形态、周边环境的借景及路域生态系统的景观绿化等方面,探讨了道路景观设计的方法。     

添加铁、锰及镉对桑愈伤组织生长的影响

镉、锰和铁添加浓度为５×１０－５Ｍ和１０－－４Ｍ时，对桑愈伤组织生长有明显抑制作用，而镉和铁或镉和锰复合添加条件下，桑愈伤组织的生长受阻更为严重。镉或锰的添加促进桑愈伤组织对铁的吸收，但愈伤组织中镉的含量却因铁的添加浓度增大而下降。锰和镉两元素的吸收具相互促进作用，因而对桑愈伤组织的毒性更大。     

河北坝上三种饲用树种的年生长模型与饲草产量研究

通过河北坝上地区三个常见树种两年的研究说明，三个树种的年生长符合Ｌｏｇｉｓｔｉｃ方程，其生物量显著高于当地天然草地产量，而且其营养价值也很高。三人树种以榆树表现最好，建议其成为坝上区首先考虑的饲料种之一。     

植保无人飞机喷施叶面肥作业参数对枇杷冠层雾滴沉积分布的影响

为探究植保无人飞机（大疆T30）作业参数对枇杷冠层雾滴沉积分布的影响。本文利用3个因素（作业高度、作业速度、亩用液量）,3因子的正交实验,进行植保无人飞机喷洒枇杷树的喷雾试验。试验结果表明：从雾滴沉积密度、雾滴覆盖率和雾滴穿透性等因素来看,植保无人飞机对枇杷树的最佳作业参数为：作业高度2.0m、作业速度4.5m·s-1、亩用液量2.0L。对雾滴穿透冠层的影响最大的因素是工作高度;在1.5m的作业高度下雾滴沉积穿透性最佳。本研究对指导植保无人飞机枇杷树精准喷施叶面肥具有重要意义。     

四川地区区域性果树的园林观赏性综合评价

对四川地区10种区域性果树进行了观赏性的综合评价,以期为其在园林绿化中的应用提供参考资料。采用灰度关联分析法,选择了花量与花色、花期、果形与果色、挂果期、株形和株高6个指标,对四川地区10种区域性果树的园林观赏性进行综合评价。结果表明,石榴的观赏性与理想果树最接近。其次是荔枝、脆红李、甜樱桃、水蜜桃、柠檬、苹果、雷波脐橙、五星枇杷和红心猕猴桃,其中五星枇杷（γ5=0.5960）和红心猕猴桃的观赏性较差（γ6=0.5715）。石榴、荔枝、脆红李、甜樱桃和水蜜桃的观赏性较好,可广泛的应用于园林绿化。     

Examining the impact of shade on above-ground biomass and normalized difference vegetation index of C3 and C4 grass species in North-Western NSW,Australia

Previous investigations have detected a directional trend in the normalized difference vegetation index (NDVI) of pastures around scattered paddock trees and identified shade from the tree as the most likely causal factor. This study uses a field experiment to quantify the effect of varying levels of shade on the above-ground biomass and NDVI of three grass species native to Australia (Microlaena stipoides, C₃, shade tolerant; Austrodanthonia richardsonii, C₃, prefers full sunlight, and Chloris ventricosa, C₄, prefers full sunlight) in different seasons. The study demonstrates that shade had little influence on the above-ground biomass of C₃ species but significantly reduced biomass in the C₄ species. Until early winter, the NDVI of each species was generally significantly higher in all shaded treatments than in the no-shade treatment. This suggests that shaded plants retained a higher proportion of green biomass and/or changed leaf shape, increased leaf area and chlorophyll content. Regardless, although not proven in this experiment, it is likely shade prolonged the retention of green plant material into mid to late winter. Overall, this experiment explains the directional trends in NDVI around scattered trees found in previous work and suggests that shade from scattered trees prolongs green pasture production in a range of native grass species, without loss of C₃ pasture biomass.     

钾对苹果树水分利用效率及有关参数的影响

以２年生盆栽新红星／平邑甜茶苹果树为试材,初步探讨了土壤不同水分状况下钾对水分利用效率（ＷＵＥ）及有关参数的影响,结果表明,充足供水时,施钾肥植株的气孔导度（Ｇｓ）增大,光合速率（Ｐｎ）和蒸腾速率（Ｔｒ）同时被提高,但Ｔｒ的提高幅度更大,导致了ＷＵＥ的降低;土壤干旱时,钾可明显提高植株的ＷＵＥ,不同处理的ＷＵＥ大小顺序为：高Ｋ〉中Ｋ〉低Ｋ〉ＣＫ,植株施钾肥后,Ｇｓ增大,Ｐｎ被提高,但Ｔｒ却下降,说     

杉木建筑材林密度管理技术与生长效应的研究

根据杉木人工林现有林调查材料、固定样地材料及密度管理试验林材料，分析了不同立地类型、不同密度的杉木林分生长效应，在建立数学模型的基础上，提出了杉木建筑材林合理密度管理技术。     

树木木质素含量的遗传变异研究进展

针对木质素含量这一数量性状的遗传变异规律进行了综合评述。木质素含量在种、群体、个体等不同层次上均表现出复杂的变异模式,环境因素有着不同程度的影响。木质素的合成途径有可能存在多条途径的替换或切换,然而利用基因工程技术对某些酶如ＰＡＬ、４ＣＬ、Ｃ４Ｈ和ＣＣＲ等酶改造时,在一定的程度上可以降低木质素含量,而对其它酶如ＯＭＴ、ＣＡＤ和Ｆ５Ｈ等酶改造时,并不降低木质素含量,有此酶基因的反义转化可以改造木质素