短轮伐期日本落叶松家系生长性状遗传参数的变化

以湖北省建始县长岭岗林场 15年生日本落叶松自由授粉家系子代测定林为研究对象 ,研究纸浆材轮伐期内不同年龄阶段生长性状的家系间遗传变异、早 -晚相关关系及主要遗传参数随时间变化的趋势 ,确定早期选择年龄及早期选择因子。结果表明 :各年龄胸径、树高不仅在家系水平上存在着极显著的变异 ,家系内个体间也存在着丰富的变异 ,具有很大的遗传改良潜力 ,家系和家系内个体选择是日本落叶松改良的主体 ;性状的方差分量、遗传力、变异系数在树木生长过程中一直处于动态变化中 ,并表现出一定的规律性 ;胸径、树高的早 -晚相关十分紧密 ,且这种相关关系主要受遗传因素制约 ;对胸径和树高进行家系早期选择的最适年龄为 6年生 ,进行家系内个体选择年龄为 8年生 ,胸径作为早期选择指标较树高更能准确地表达成熟时的信息。     

近25年来新疆森林的动态变化

新疆森林主要有落叶针叶林、常绿针叶林、落叶阔叶林以及特殊灌木林4种类型,面积约为全疆植被面积的2%,但新疆森林在经济、社会和生态效益等方面却发挥着重要的作用.不同森林类型具有不同的NDVI变化特征,利用GIMMS NDVI数据集首先对新疆植被进行专家分类,然后分析近25年来新疆森林面积、蓄积量和密度的动态变化及其可能原...     

岭南水乡村落公共空间研究——以广州为例

岭南水乡村落的公共活动是联系每个村民的纽带,营造良好的公共空间对提高村民的生活质量和塑造和谐人居环境都有着重要意义。然而,在当前的岭南水乡村落中,公共空间未受到应有的关注,而且由于受到城镇化的影响,一些传统公共空间及其承载的传统公共活动日渐式微。文章试图从分析岭南水乡村落的公共空间和公共活动的现状及特点入手,解析岭南水乡公共空间的特征及现存的问题,结合聚龙村改造的实例,尝试探讨岭南水乡村落的公共空间优化措施,为岭南水乡村落公共空间的更新与构建提出一些建议。     

不同林龄尾巨桉林地土壤有机碳储量变化差异

为桉树人工林的土壤质量评价提供科学依据,研究了不同林龄(1a、2a、3a、5a、7a)尾巨桉林地0~60cm土壤和枯落物的碳含量及碳储量,测算了不同林龄桉树林地叶面积指数,乔木层、灌木层、草本层和枯落物层生物量。结果表明：土壤有机碳含量随土层深度增加而呈降低趋势,不同林龄0~20 cm土层有机碳含量差异显著,不同林龄相同土层之间土壤有机碳储量差异不显著;枯落物碳储量差异显著,大小顺序为：5 a (4.83 t·hm-2)>7 a (3.89 t·hm-2)>3 a (2.66 t·hm-2)>2 a (2.43 t·hm-2)>1 a (1.56 t·hm-2);0~60 cm土层土壤碳储量与叶面积指数呈负相关关系,与林龄、乔木层生物量、灌木层生物量、草本层生物量、枯落物层生物量之间呈正相关性,但相关性都不显著。     

淹水程度对滩地枫杨木材化学性质的影响

通过研究淹水程度对滩地枫杨木材化学性质的影响 ,以期全面了解滩地主要造林树种的化学性质 ,提出合理的定向培育技术及进一步综合利用措施 .研究结果表明 :滩地枫杨木材的 p H值均小于 6.5 ,属于酸性木材 ,第一、二组木材的 p H值分别为 5 .41和 5 .0 0 ,在 0 .0 5水平上差异显著 .除碱性缓冲容量外 ,第二组木材的酸性缓冲容量、总缓冲容量以及每降低 1p H值消耗的 HC1量均比第一组高 .淹水程度对滩地枫杨木材纤素含量几乎无影响 ,其值均为 45 .2 %左右 ;但第一、二组的半纤维素分别为 14 .0 4%和19.5 0 % ,增加了 3 8.9% ;第一、二组的木质素含量分别为 19.9%和 2 0 .6% ,增加了 3 .5 % .     

香果树种群开花物候、生殖构件特征及其影响因子分析

采用野外调查方法对武夷山香果树的开花物候、生殖构件及其影响因子相关性进行了研究,结果表明:武夷山23 a香果树个体开始进入生殖期,其单花花期为6.91 d,始花期随着树龄的增加逐渐提前,花期持续时间在3661 d之间;海拔对香果树种群的单花花期和开花进程产生显著影响,随着海拔的升高,香果树单花花期也呈上升趋势,始花期推迟。香果树个体均产86个花枝,7388朵花,95个果实,随着母树树龄的增加,其生殖构件数量均有不同程度的增长,其中80110 a香果树单花枝产果量较高;香果树生殖构件数量随着海拔的升高,其个体产花枝量和花数量均呈下降趋势,而其果实产量则有小幅度增加。香果树的树龄和光照、大气温度和湿度与其生殖构件数量存在极显著正相关关系,80110 a香果树、30000 Lx以上的光照强度、28℃气温以及70%湿度是其有性生殖较好的生殖年龄及微环境。建议对香果树原生境进行保护,严禁砍伐香果树母树;对香果树附近的高大乔木进行疏伐和间伐以改善香果树母树树冠的光照条件,将有利于其生殖构件的生长发育。     

Using composted wheat residue as a growth medium in culture of tomato

A greenhouse experiment was carried out to investigate the effects of different growing media on some properties of tomato (Lycopersicom esculentum L. cv. Falcato). Four growing media including wheat residue, composted wheat residue, coco peat + perlite, and coco peat + soil were applied in pot experiment with completely randomized design with three replications. The results showed that fruit yield, chlorophyll, and vitamin C contents of tomatoes grown in the composted wheat residue and coco peat + perlite treatments were significantly greater than the other growth media. Fresh weight of root and inflorescence were higher in the tomatoes cultivated in the composted wheat residue pots than the other media. Higher internode length and nutrient concentrations in leaf and fruit at the coco peat + perlite treatment were obtained as compared to the other growth media treatments. According to the results, it can be concluded that the coco peat + perlite can be substituted for by composted wheat residue for the cultivation of tomato.     

Temperature-dependent development of Ascotis selenaria (Lepidoptera: Geometridae) and its stage emergence models with field validation

Temperature-dependent development of Ascotis selenaria (Denis et Schiffermüller) was studied in the laboratory. Time to egg eclosion decreased with increasing temperature and ranged from 17.4 d at 16 °C to 5.0 d at 30 and 32 °C. Total development times of larvae decreased from 54.7 d at 16 °C to 17.3 d at 32 °C. The development time of pupae ranged from 29.7 days at 16 °C to 10.2 days at 30 and 32 °C. Eggs, larvae and pupae did not develop successfully to the next stage at 12 and 35 °C. The estimated lower temperature thresholds were 10.4, 9.3, and 9.8 °C for eggs, larvae, and pupae, respectively. Thermal constants of egg, larvae, and pupae were 88.5, 370.4, and 188.7 DD, respectively. Stage emergence models for eggs, larvae, and pupae of A. selenaria were constructed by using the development rate model (Lactin 2 function) and development distribution model (three-parameter Weibull function), which simulate the proportion of individuals shifted from one stage to the next. Pearson's correlation coefficients between actual observations in the field and model outputs were statistically significant with 0.99, 0.68 to 0.87 and 0.96 to 0.98 for egg, larval and pupal stage emergence model, respectively. The egg stage emergence model could be used to facilitate spraying time as it successfully predicted the first instar larval population. Predictability of the pupal stage emergence model was greatly improved when the physiological age of overwintering pupae was assumed to be in various state. The stage emergence models developed here should be useful to construct an A. selenaria population model.