The Influence of Thoreau's View of Nature On Current Ecology

The American author Henry David Thoreau,preceded by his instructor,Emerson,inherited the idea of transcendentalism and was the proponent of the integrity of human and nature.By the two-year experience ...     

红枫秋冬转色期叶色变化的生理特性

以红枫(Acer palmatum Atropurpureum)两头红"品系成龄植株为材料,测定10月下旬至12月上旬红枫秋冬转色期叶绿素、花色素苷和可溶性糖含量的变化,比较不同光照强度及温度对叶色的影响.结果表明:叶绿素含量开始下降缓慢,10月31日后迅速下降,树冠背阴面叶片中的叶绿素含量显著高于向阳面,阳面东向显著高于阳面西向;叶绿素a/b先增加后下降;花色素苷含量开始缓慢增加,11月21日之后显著升高;可溶性糖含量在11月21日之前迅速增加,之后趋于稳定;花色素苷与叶绿素含量呈显著负相关;温度与花色素苷和可溶性糖含量之间均呈显著负相关.     

珍稀动物麋鹿的保护研究概述

麋鹿属于国家一级保护动物,国内外学者在麋鹿种群健康繁衍和保护事业方面进行了大量的研究工作.文中介绍了麋鹿的生物学特征、种群、行为学、生境学、遗传多样性、药用价值及国外研究现状,提出国内需在分子细胞生物学层次上开展麋鹿的相关研究工作,以促进麋鹿种群的保护和健康繁衍.     

天目山槭树植物种质资源与开发价值评价

天目山槭树共有22种(含种下级单位),占浙江槭树植物总种数的62.9%.对天目山槭树植物的地理分布、观赏价值、园林应用进行总结,以期为开发利用这一资源提供科学依据.     

基于Lab模型的4种日本彩叶枫的叶色分析及其色彩应用

基于Lab色彩模型对4种日本彩叶枫的一年生枝叶及多年生枝叶进行色彩变化分析,并探究其叶色变化在园林景观应用中的色彩影响,利用色彩心理学知识对其园林景观应用提出建议。结果得出:橙之梦及红舞姬的叶片尖端色彩更明亮,叶片的明暗变化更为突出。而卡苏及酒红鸡爪槭的色彩多浅淡,同一叶片的不同部位的色彩明度均较高,明暗变化较小,酒红鸡爪槭的色彩差异值最高。园林园艺工作者们应该在掌握色彩心理的基本原理下进行彩色植物的应用,在应用中要注意色彩明暗度的使用,把握彩色植物的使用比例,切忌大面积的使用,造成视觉冲击,产生视觉疲惫及心理焦虑。     

中国林蛙蝌蚪期饲料配方的研究

为研究一种适合林蛙蝌蚪生长的饲料配方,试验选用林蛙蝌蚪受精卵共800只,分为4个大组,每大组设两个重复,共8个小组,分别饲养在8个水盆中,每盆100只。试验对比研究了蛋白质含量分别为37.765%、31.628%、23.535%及11.562%的4种饲料。试验结果表明,饲喂蛋白质含量为23.535%的一组蝌蚪重量最大,体长最长,发育的也最为良好。同时通过试验分析证明,从蝌蚪发育到变态前的饲料应以植物性饲料为主并适当的加入部分动物性饲料,这样才有利于蝌蚪的生长发育。此外,还提出用传统方法配制蝌蚪饲料的不足及解决的办法。     

Sugar maple (Acer saccharum Marsh.) decline during 1979–1989 in northern Pennsylvania

Sugar maple decline has been observed in northern Pennsylvania since the early 1980s. We investigated the interactions between soil moisture stresses in sugar maple and other factors, such as soil chemistry, insect defoliation, geology, aspect, slope, topography, and atmospheric deposition. In the summer of 1998, we sampled 28 sugar maple (Acer saccharum Marsh.) plots drawn from the USFS Forest Inventory and Analysis (FIA) plots, containing declining and non-declining sugar maple trees across northern Pennsylvania for a variety of soil physical and chemical parameters, site characteristics, and tree health. Foliage from declining plots was found to have significantly lower base cations and higher Mn as compared to that from non-declining plots. Soils in declining plots had lower base cations and pH, a Ca:Al⁻≤1, lower percent clay and higher percent sand and rock fragments than soils on non-declining plots, suggesting that trees on declining plots are at risk of nutritional and drought stress. Regression relationships between foliar and soil chemistry indicated that foliar nutrition was highly correlated with soil chemistry in the upper 50 cm of the soil. Declining sugar maple plots in this study occurred at higher elevations on sandstone dominated geologies. Soils were found to be base poor-sandy soils that contained high percentages of rock fragments. Soils below 50 cm on declining plots had lower soil pH and foliar chemistry indicated lower foliar base cations. A trend, while not significant was found with declining plots experiencing a greater number of and more severe insect defoliations.     

Sweet trees, sour circumstances: the long search for sustainability in the North American maple products industry

Maple sugar and maple syrup have long been important non-timber forest products in North America. We examined the historical and the scientific literature to determine the long-term sustainability of the industry in an economic, an ecological, and a cultural context. During the 18th and 19th centuries, maple sugar was an inexpensive substitute for cane sugar and a cash crop that fit into the work schedule of the northern farmer. Maple syrup replaced maple sugar as the mainstay of the industry at the end of the 19th century as increasingly cheaper cane sugar and other sweeteners undercut the sugar market. Active government intervention and support have made Quebec the major bulk supplier of maple syrup today. Quebec alone produces approximately 80% of the world’s supply of maple products. A series of good sap years and production in excess of demand, however, has recently reduced the price of bulk syrup and the profit of producers in Quebec. Producers in the United States have focused on the more lucrative and price stable retail syrup market.

Farming practices in the late 18th and early 19th centuries tended to clear away sugar maple on the more fertile, level sites and preserve sugar maple as a source of fuel wood, sugar and syrup on the less accessible, marginal sites. The crude tapping procedures employed at the same time often killed the trees. Widespread grazing in the 20th century and more recently diameter-limit cutting of even-aged stands have hindered the regeneration of the sugarbush. An emphasis on monocultures and global warming currently threatens the sustainability of the sugarbush. On the whole, however, the maple products industry has probably increased sugar maple’s representation in the forest. From a cultural standpoint, the industry represents a positive work experience that unites families, connects one to the land, and provides a sense of continuity with the past.     

枫香种源生物量和NRA对供氮水平的响应差异

为研究不同纬度枫香种源经过无营养胁迫生长后对供氮水平的响应差异,按种源与氮2因素裂区设计砂培试验,以N水平为主处理,枫香种源为副处理,3次重复,随机排列(水平内种源间).结果表明:低氮胁迫会刺激枫香叶片提前形成花青素变红,且低纬区种源变红早于高纬区种源;另外低纬区种源与高纬区种源硝酸还原酶活性(NRA)存在各自的变化规律.以最高生物量为对照,在0 N水平下福建延平种源生物量降低最少(54.54%),且具有较高的生物量,但其在2N水平生物量迅速降低,耐肥性较差;其它种源生物量变化趋势一致.各种源根冠比从0 N到1/2 N水平均迅速降低:广西南丹＞福建延平＞浙江永康＞安徽泾县,即随着纬度的升高,枫香种源根冠比受N的影响越来越小.统计分析发现,福建延平种源在无N及低N水平时NRA极显著高于其它种源,且具有较高生物量,受环境影响较小(主要是棚内重复间光照的差异),可以认为福建延平是优良的耐低N型种源.     

Individual-tree diameter growth model for sugar maple trees in uneven-aged northern hardwood stands under selection system

An individual-tree diameter model was developed for sugar maple (Acer saccharum Marsh.) in northern hardwood stands managed under selection system. We fitted long-term remeasurement data to a linear mixed model to account for the temporal autocorrelation of the remeasurements. The model was evaluated using independent data from two physiographic regions and representing a range of tree diameter classes, residual basal areas and years since cut. We compared our model to several individual-tree models based on data from stands with varied management histories. Several competition indices were also tested for an improvement in model fitting and prediction. Our model had lower bias and prediction error when compared to two previous models, as it better accounted for the increased diameter growth that occurred in trees from appropriately managed stands. The addition of a tree-specific competition index failed to improve model fit and predictive ability over stand-level basal area.