冰冻雪灾对黄山区毛竹林的损害及影响因子

研究安徽省黄山区2008年1月冰冻雪灾对毛竹林的损害及影响因子.结果表明:此次雪灾对毛竹林破坏严重,各类受损竹比例达45.8%,其中翻蔸竹13.9%,断裂竹9.4%,对竹林生态系统影响较大.从毛竹生物学影响因子看,年龄和胸径对受灾程度的影响不大;而从各林地状况因子与毛竹受灾程度的关系看,海拔、地形、坡向和立竹度对毛竹受损率影响显著,T检验P值分别为0.008,0.000,0.045和0.052,并呈现出不同的主要受损类型,经营状况和树种组成的影响程度不明显.     

受雨雪冰冻危害后毛竹的繁衍特点

通过对受雨雪冰冻危害的毛竹林受损数量和经一个春笋大年的新竹留养数量,分析了受害后毛竹的繁衍恢复特点。结果显示:与灾前相比,毛竹平均株数增加29.8%,春笋产量减少21.7%;新竹平均株数t值=4.22>t(14)0.01(2.977),增加14.2株;毛竹受损率与留养新竹之间,其相关方程为y=0.414 1x+21.978,R2=0.300 9,没有紧密的相关性;新竹大径材减少4.4%~12.1%,没有达到灾前比例。     

幼竹摇梢防雪压效果的商讨

冬季冰雪,特别是冻雨危害,造成毛竹断裂、拔倒,给毛竹生产带来重大损失,受害严重时高达60％以上,轻的也有5％左右。近年来介绍幼竹摇梢防雪压,为检验其效果,我们于1977年进行了对比试验。     

毛竹冰雪灾害后的施救方法

冬季如遇持续雨雪冰冻天气,对毛竹林造成了严重危害:轻者竹竿弯曲、折断,重者导致竹竿破裂甚至整株倒伏翻兜,对竹林的破坏极大.为了尽可能减少冰冻对毛竹林的影响程度,宜采取如下补救管护措施. 一、及时清理.冰雪过后,要尽快对竹林进行清理,并根据竹株受害程度不同而区别对待,以减少冰雪灾害对竹林造成的损失. 1、对严重妨碍交通或竹林管理的少量翻兜竹、劈裂竹,在雪停后立即予以砍伐. 2、对竹梢受损严重的、梢部折断且断裂部位高的毛竹,可将其梢部砍去,以减轻竹竿的压力,使其逐渐恢复.砍去的梢长度尽量不要超过竹冠总长度的1/3,留枝不得少于15盘.     

冰雪灾害对毛竹出笋及生长的影响

设置标准地调查毛竹林在冰雪灾害后的出笋及生长情况,采集土壤样品和毛竹叶子样品并分析其N、P、K含量等.结果表明,冰雪灾害后毛竹的出笋数量提高,新竹比例提高10个百分点;新竹平均高减少1.6 m,胸径减少2.2 cm;新竹叶片全N、全P含量差异不显著,全K含量1.400%比对照的1.734%减少了0.334个百分点,粗灰...     

天目山近自然毛竹纯林空间分布格局研究

近自然毛竹纯林是浙江省天目山国家级自然保护区内特殊的植被类型,研究近自然毛竹纯林的空间分布格局,不仅可以揭示近自然毛竹纯林的生态学意义,而且也可以为人工经营毛竹林的管理提供科学依据.在浙江省天目山国家级自然保护区内,选择近自然毛竹纯林设置样地,样地大小100 m×100 m,用全站仪测定每株毛竹坐标(x,y,z).首先对自然状态毛竹进行分类,再运用方差/均值比(t检验)、丛生指数、Cassie指数、聚块性指数、Moristia指数5种格局研究方法,对不同状态毛竹的分布格局进行分析.结果表明:近自然毛竹纯林中,活竹占绝对优势,且多呈弯曲状态.而死竹以受损居多.折断和倒伏是活竹和死竹受损的主要原因.近自然毛竹纯林的活立竹、枯死竹和整个林分的分布格局均为聚集分布.     

毛竹在冰冻灾害后的管理

去年初的强冷空气，使广西遭遇了罕见的冰雪灾害，竹林（主要为毛竹）是受害最为严重的森林类型之一。随着海拔的增高，受灾越来越严重，被雪压弯、压断，竹竿破裂的越来越多。据统计，海拔350—400米处，毛竹受损在50％-60％；海拔500米以上，毛竹倒伏受损达到80％～90％。受损的毛竹中约有一半的断裂、破裂倒伏的竹子，大多在竹竿高1～1．5米处折断；另一半为雪压倒竹，弯曲低垂。严重的地块，约有5％连蔸拔起倒伏的。     

冰雪灾害对大关县4种竹林损害的调查研究

对云南省大关县4种竹林经2008年1月特大强降温冰雪天气过程后的受其冰雪灾害损害的情况进行了调查研究.结果表明:(1)慈竹林受损比水竹林、斑竹林和筇竹林严重;(2)随海拔高度的升高4种竹林的受损随之严重;(3)慈竹、斑竹和水竹3种竹林的受损率与其竹林立竹密度的大小呈正相关,而筇竹林的受损率则随其竹林立竹密度的增加而下降;(4)同一竹林胸径大的竹子比胸径小的竹子更容易受损害而折断和破裂.     

文竹镇全面护理竹林

盛产毛竹的昭平县文竹镇,共有毛竹林2.7万多亩,最高年产毛竹上百万条。1992年,该镇的毛竹林发生蝗虫灾害,受害严重的竹叶脱落,不发笋,产量下降,这几年,年产毛竹不到30万条,竹子短小。     

众斗冰魔 重建家园——黄冕林场抗击雨雪冰冻灾害纪实

2008年1月中旬至2月上旬,一场百年一遇的雨雪冰冻肆虐着地处桂中偏北的广西国营黄冕林场。海拔260米以上林区发生大面积冻雨、冰冻雪灾,树木毁倒、交通、通讯、供水及供电中断;苗圃、茶园受损;70名民工被冰雪困在山上。18万亩林木受害,经济损失达1.68亿元。林场面临着前所未有的严峻挑战与考验。     

Armillaria ostoyae in managed coniferous forests in Kastamonu in Turkey

Although several Armillaria species have been reported in Turkey, there is little information about their ecology in Turkish forests. In this study, we investigated five forest stands, approximately 5–74 ha in size, in Kastamonu province in the Black Sea Region of Turkey for the presence of Armillaria species in stumps and logs. The stands were mixed Abies nordmanniana ssp. bornmülleriana and Pinus sylvestris forests managed using a selective cuttings system; the proportion of fir in the total number of stems and stumps ranged from 36 to 98%. Based on sequence analysis of the internal transcribed spacer and intergenic spacer regions of the rDNA, all rhizomorphs sampled from the stumps and logs were of Armillaria ostoyae. The size of the genets was estimated with random amplified microsatellites analysis of the isolates and ranged from single stumps to approximately 450 m². One to seven genets were found in each stand. These results indicate that the genets had arisen from spores and vegetative spread was limited on most sites.     

上海中央公园特大银杏树白蚁防治探讨

通过对上海松江中央公园内65株特大银杏树白蚁为害情况的调查,发现该公园银杏受害率为100%,其中存在活白蚁的银杏占总量的56.9%,采用毒土处理、粉剂疗法、建立白蚁监测点等措施,经过两次灭杀,活白蚁的灭杀率达到92.3%和93.3%,从而使存在活白蚁银杏树的比例从56.9%下降到2.7%,白蚁发生情况明显降低。       

我国食品中农药残留研究进展

随着人们安全健康意识提高,食品中农药残留问题更加受到重视,本文综述了样品预处理研究进展及农药残留快速检测技术研究进展,并简单分析介绍各种方法的优缺点。     

建平半干旱地区石质山地造林技术研究

研究了不同植物在石质山地的造林成活率、土壤化学性质随造林年限的变化和造林措施对土壤化学性质和植物胸径、树高年净生长量的影响。结果表明：不同植物在石质山地的成活率在21%～85%之间,其中白榆和沙打旺的成活率分别为81%和85%,而小叶杨、刺槐、栾树的成活率均在70%左右;植被能明显提高石质山地不同土层的有机质、全N、P2O5含量,但提高程度随土层深度、养分种类和造林年限的不同而不同;在同一土层,生物复合肥料、菌剂和保水剂均显著提高土壤有机质含量（p〈0.01）并显著降低土壤P2O5含量（p〈0.01）;只有保水剂可引起土壤全K含量的明显升高;生物复合肥料、菌剂和保水剂均显著提高白榆、小叶杨、刺槐、栾树树高和胸径的年净生长量,但保水剂的提高程度最高。     

植物DNA甲基化研究进展

植物经常暴露在各种生物和非生物的胁迫之下,这些胁迫会影响植物的生长发育和繁殖并最终导致植物死亡。为了抵御不利的环境条件,植物已经进化出复杂而精细的网络来感知胁迫并激活防御系统。为此,植物激活许多信号转导通路,这些信号转导通路可以改变一些胁迫响应基因的表达,从而引起植物形态、生理和生化的改变以适应逆境。DNA胞嘧啶甲基化是高等真核生物的主要表观遗传机制之一,在维持基因组稳定性和调节基因表达方面起着关键作用。表观遗传变异比遗传变异更为灵活。一旦环境条件发生变化,为了适应新的环境植物都会发生表观遗传的改变。许多研究表明DNA甲基化参与植物的发育和应激反应。基于相关研究对DNA甲基化进行了综述,对植物逆境胁迫有重要意义。     

木材碳封存研究进展

碳封存可以分工业封存和生物封存, 工业封存包括地质封存、海洋封存、矿石碳化以及工业循环利用, 这些方法能快速回收CO₂, 但工艺流程技术复杂, 成本较高。木材碳封存是生物碳封存的一种类型, 树木光合作用吸收的碳主要存贮在木材中。运用木材密度、微密度等检测仪器, 通过确定木材密度变化, 结合其含碳率来计量木材的碳封存过程以及封存过程中碳的分配格局, 同时研究其与环境因子的相关性, 可以为研究森林的碳吸收动态提供便捷的方法和科学的依据。     

Tree regeneration in patch cutting in Norway spruce stands in northern Finland

The study focused on the success of regeneration on patch cuts in spruce-dominated stands in terms of stocking and tree height. It was based on an experiment in the Kainuu region in northern Finland. The experimental design included 8 stands with 58 clearcut patches of variable size (0.09–0.37?ha), on which either natural regeneration without site preparation or site preparation and planting of Scots pine was applied. A regeneration survey was conducted 13–15 growing seasons after treatments. Patches without site preparation had been restocked quite well from natural seed sources. The average number of trees was about 11,000?ha^?1, of which 1700?ha^?1 crop trees. With site preparation and planting, the stocking levels were also very high, 25,000 and 2100?ha^?1, respectively. One hundred percent of the planted patches and 75% of the naturally regenerated patches had an acceptable density. Restocking was equally good across the range of patch sizes. Tree growth had been somewhat slower in the smallest patches than in the largest ones in the range. Natural regeneration was capable of yielding good regeneration results in most patches, especially when site preparation was applied. Stocking levels and height development were higher yet in the planted patches.     

Changes in micropores in dry wood with elapsed time in the environment

To investigate the changes in microstructures of wood with elapsed time in the environment, CO₂ adsorption onto dry wood was measured at ice-water temperature (273 K) for samples aged from 0.1 years to over 1000 years. The micropore size distribution was obtained using the Horvath-Kawazoe method. Micropores smaller than 0.6 nm in wood decreased in number with elapsed time in the environment, and a negative correlation was found between cumulative pore volume for pores smaller than 0.6 nm and elapsed time in the environment. Cumulative pore volume in the 1000-year sample was almost half of that in the 0.1- year sample. Micropores smaller than 0.6 nm in wood with a few decades or more of elapsed time increased in number after rewetting and drying. Consequently, microstructures of wood with longer time elapsed in the environment were considered to be more stable, because of longer-term thermal motion and possibly more repeated moisture adsorption and desorption and/or temperature variation in the environment.     

Natural regeneration in patch clear-cutting in Picea abies stands in Southern Finland

Abstract

The success of natural regeneration on patch clear-cuts in Norway spruce stands in Southern Finland was examined in terms of stocking and tree height. The experiment was established in mature spruce stands in the submesic Myrtillus (MT) site type. In each of the eight study sites, three plots were treated with clear-cutting and planting, clear-cutting with partial tree retention and planting, and patch clear-cutting without site preparation, respectively. In three of the study sites, one plot with patch clear-cutting and site preparation was established. Each plot was 1 ha, out of which three patches of 40×40 m were clear-cut in the patch treatments. 10–11 years after cutting, the patches had on average 1316 crop trees ha^–1, of which 91% were spruces. Some 27% of the stands were up to the target stocking level (≥1600 ha^?1), and 36% were at least satisfactory (≥1300 ha^?1). Site preparation did not yield greater stocking levels on patches, but that result is ambiguous due to a difference in initial stocking. The average spruce tree height in the patches (0.76 m) was much smaller than in the case of clear-cutting and planting (2.42 m). In conclusion, the patches had been restocked tolerably well with spruce and birch for practical purposes during the 10- to 11-year period, but the regeneration process had been very slow compared to clear-cutting and planting.