施肥梯度对甘南高寒草甸植被特征的影响

通过小区控制施肥实验,研究了施肥梯度对青藏高原东缘高寒草甸植被特征的影响.结果表明,1) 施肥使线叶嵩草、波伐早熟禾、垂穗鹅观草等禾草的高度显著增加,异针茅、瑞玲草等非禾草类的高度减少.2) 随着施肥梯度的增大,群落的总密度逐渐下降, 禾草密度在不同施肥梯度下有时增加,有时减少,无一般性规律;而非禾草物种密度一般是减少的.3) 随施肥梯度的增加,地上生物量明显提高,多样性指数逐渐下降.施肥对群落密度、地上生物量和多样性的作用都要在2年以后才表现出明显的规律.     

沙漠化草地的恢复与重建途径

在分析国内外草地沙漠化治理现状的基础上,研究1985-1998年沙化草地的自然恢复与人工恢复,结果表明:自然恢复属于进展演替类型,经历"沙生、一年生植物群落"、"根茎禾草杂类草群落"和"丛生禾草群落"三个演替阶段,最终向地带性植被类型发展;其植被物种组成,覆盖度、产草量均呈增加趋势,土壤有机质增加,表土结构变好;人工恢复的效果显著,播种抗旱、抗风沙型植物,可以快速建成植被覆盖地面,同时生产大量优质牧草,是我国沙化草原恢复重建的一条重要途径.     

Effects of smoke,ash and heat shock on seed germination of seven species from Central Zagros rangelands in the semi-arid region of Iran

Fire products have been widely identified as germination cues for a number of species from both fire-prone and fire-free ecosystems. However, there is uncertainty about the effects of fire products on seed germination of semi-arid rangeland species. We examined the germination of seven dominant species from Central Zagros rangelands in the semi-arid region of Iran under various heat shock (60, 80 and 120 °C), aerosol smoke, ash and control treatments. Our findings showed that fire products could enhance, inhibit or not affect the seed germination of rangeland species in this area. The germination percentage of Astragalus adscendens increased following 60 °C heat treatment in comparison with the control. The germination of Astragalus verus, Bromus tectorum, B. tomentellus and Phlomis olivieri were increased significantly using smoke treatment (P<0.0001). The seed germination of B. tomentellus and B. tectorum was promoted by ash treatment, whereas the other species exhibited no response or were inhibited by fire products. In addition, smoke treatment shortened the overall germination time of B. tectorum. These findings suggest that fire products affect the germination of several species and can serve as potential tools for understanding the vegetation dynamics and restoration of disturbed semi-arid rangelands.     

基于TM NDVI的库尔勒市域植被覆盖动态变化

以库尔勒市域为研究区,基于1990、1998、2006和2011共4期TM遥感影像提取归一化植被指数（NDVI）,将NDVI结果输入到像元二分模型中计算得到研究区各时期植被覆盖度,然后根据研究需要将植被覆盖度划分为4个等级,最后计算覆盖度差值并结合各级覆盖度转移矩阵和土地利用情况分析了库尔勒市域植被覆盖度动态变化特征。结果表明,在1990、1998、2006和2011年间,库尔勒市域总体植被覆盖情况有所改善,植被恢复改善面积比退化面积多23.8%,其中东南部的扇形绿洲平原植被状况改善明显,北部和南部区域植被有所退化。     

基于像元二分模型的艾比湖湿地NDVI指数对微气候的响应

本研究提取了艾比湖湿地不同年份(1998、2007、2011、2014年)的NDVI指数,并进行了实地考察,然后利用像元二分模型对研究区植被覆盖状况进行估算,并分析其在时空分布上的特征及形成原因,建立影响植被覆盖与微气候变化的线性回归模型。结果表明,1)在空间分布上,西南部冲积平原植被覆盖等级最高,东北部覆盖等级略低于西南部,无覆盖和低覆盖等级分布面积最为广泛;在时间分布上,无覆盖面积处于下降趋势,低覆盖和中覆盖面积有所增加,较高覆盖与高覆盖等级面积处于下降趋势;2)不同植被覆盖度对气候变化的响应存在一定的差异;植被覆盖对降水量变化的反应最为强烈,在时间上具有一定的滞后性,对湿度变化的响应不明显,气温与植被覆盖水平之间存在线性函数关系。     

Milking performance evaluation and factors affecting milking claw vacuum levels with flow simulator

Milking performance of milking machines that matches the production capability of dairy cows is important in reducing the risk of mastitis, particularly in high‐producing cows. This study used a simulated milking device to examine the milking performance of the milking system of 73 dairy farms and to analyze the factors affecting claw vacuum. Mean claw vacuum and range of fluctuation of claw vacuum (claw vacuum range) were measured at three different flow rates: 5.7, 7.6 and 8.7 kg/min. At the highest flow rate, only 16 farms (21.9%) met both standards of mean claw vacuum ≥35 kPa and claw vacuum range ≤ 7 kPa, showing that milking systems currently have poor milking performance. The factors affecting mean claw vacuum were claw type, milk‐meter and vacuum shut‐off device; the factor affecting claw vacuum range was claw type. Examination of the milking performance of the milking system using a simulated milking device allows an examination of the performance that can cope with high producing cows, indicating the possibility of reducing the risk of mastitis caused by inappropriate claw vacuum.     

草地反射太阳光偏振特性测量个例分析

本文在中国科学院植的研究所岩石草原定位研究站对羊草和苔草样方进行太阳反射光偏振特性的测量。     

对退耕还林还草有关问题的进一步思考

阐述了“一退双还”政策措施提出的意义和实施情况,提出应进一步明确“一退双还”的目的,从思想和政策上解决重林木轻草灌的倾向,力戒形式主义和表面文章、讲求实绩实效,“以林为主”的绿化方针值得进一步深思和商榷,“一退双还”的责任制和利益机制需进一步完善等一系列问题,值得进一步深入思考和认真解决,以保证“一退双还”和国土绿化工作的持续和健康发展。     

森林资源档案管理系统的设计与实现

本文以加强森林资源档案管理的需要出发，分析了资源档案管理系统，在此基础上提出计算机管理系统的主要设计，介绍了相应软件系统。     

Natural and human disturbances affect natural regeneration of Swietenia macrophylla: Implications for rainforest management

In this paper we document how changes in forest structure mediated by natural (hurricane) and human (logging) disturbances affect natural regeneration of Swietenia macrophylla via its effects on seed predation, germination, and early recruitment. Work was carried out in two ejidos within the Mayan zone of Quintana Roo, differing with regard to their exposure to the effect of the hurricane Dean 2008 (Naranjal Poniente; high hurricane impact) and Señor (with no evidence of hurricane effects). We experimentally set S. macrophylla seeds in both hurricane conditions and contrasting logging effects, in three treatments: (1) open access, (2) rodent and insect access and (3) rodent and insect exclusion. We measured three dependent variables: (i) number of seeds predated, (ii) number of seeds germinated and (iii) number of seedlings established. We found that the three variables measured were differentially affected by logging and hurricane Dean. Seed predation was higher in areas with hurricane effects; germination showed no differences, but early recruitment was differentially affected by the two conditions, via an increasing of herbivory and sun exposition. Both types of disturbances studied occurred periodically in Yucatan Peninsula and elsewhere in tropics, so it is necessary to implement specific actions in order to face changes in mahogany natural regeneration stocks, and supporting the future management of tropical forests.