广东省森林群落草本多样性研究

结合广东省森林资源清查第七次复查样地调查资料,以广东省不同气候带草本植物群落为研究对象,探讨了其区系组成及草本物种多样性在不同气候带内的变化规律。结果表明:广东省中亚热带草本植物有67科147属190种;南亚热带有65科143属179种;北热带有15科41属42种。其中禾本科在草本层中占重要地位;从数量特征来看,芒萁(Dicranopteris dichotoma)在中亚热带和南亚热带占有显著的优势,在北热带则为飞机草(Eupatorium odoratum)和小蓬草(Conyza canadensis);人工林草本层物种丰富度指数在1.313~1.459之间,多样性指数在1.260~1.328之间,均随纬度降低呈倒"V"形变化,而天然林、竹林和灌丛林草本层物种丰富度指数和多样性指数均随纬度降低而逐渐增加;总体而言,广东省森林草本植物多样性水平偏低。     

鹅掌楸天然林与人工林群落特征及物种多样性研究

利用物种丰富度、多样性、均匀度等物种多样性指标,对邛崃天台山的鹅掌楸人工林和通江县海鹰寺林场的鹅掌楸天然林群落的物种多样性进行了调查研究。结果表明:1)鹅掌楸两种不同起源林分群落中合计有31种植物,隶属于26科30属,其中蕨类植物3科3属3种,裸子植物3科3属3种,被子植物20科24属25种,天然林群落的物种丰富度高于人工林;2)群落区系属级成分中,北温带分布类型的属占20.0%,其次是世界分布类型和旧世界热带分布类型各占13.33%,热带亚洲和热带美洲洲际间断分布类型和东亚-北美间断分布类型的属各占10.0%;3)在不同起源的鹅掌楸林分中,天然林群落乔木层、灌木层与草本层的物种丰富度和物种多样性指数均高于人工林群落;4)在同一林分群落中,各物种多样性指数在群落层次间变化幅度,均为草本层灌木层乔木层。     

山西省二郎山国家森林公园主要森林群落植物多样性研究

对山西省二郎山国家级森林公园4种主要森林群落进行了实地调查,采用丰富度指数、均匀度指数和多样性指数等指标,对二郎山森林群落的植物多样性进行了研究。结果表明:4种群落共有植物40种,分别属于22科31属;油松林和油松+山楂林的均匀度指数和多样性指数均较大;林分起源、坡度、群落垂直结构和林分密度等对群落的植物多样性均有较大影响:天然林的植物多样性大于人工林;多样性指数随坡度增大而减小;灌木层多样性高于乔木层和草本层;林分密度过大,群落物种丰富度和多样性降低。通过研究,以期为二郎山国家级森林公园经营与植物资源的可持续发展提供理论依据。     

西双版纳加勒比松人工林群落特征研究

采用样方法对西双版纳加勒比松人工林开展了群落学调查。结果表明:(1)加勒比松人工林有维管束植物43种,分属22科41属;(2)乔木层、灌木层和草本层的的香农威纳指数分别为2.71、1.52和2.69;(3)其群落垂直结构明显,可分为乔木层Ⅰ层、乔木层Ⅱ层、灌木层和草本层4层;(4)加勒比松人工林群落的物种丰富度和乔灌层的多样性指数低于天然次生林,而群落垂直结构较天然次生林复杂。     

茂名森林公园人工林群落林下物种多样性分析

对茂名森林公园人工林群落进行典型样地调查,结果表明:公园内人工林群落共有植物64种34科55属,其中蕨类植物10种7科8属、裸子植物1种1科1属、双子叶植物48种24科41属、单子叶植物5种2科5属.园内人工林灌木层物种组成以桃金娘、九节、银柴、大青、白背叶、鬼灯笼、酸藤果、土密树为主;草本层植物主要有芒萁、蔓生莠竹、飞机草、弓果黍等10种.不同人工林群落林下物种在丰富度和Shannon-Wiener指数方面均表现为灌木层草本层,但均匀度表现不一.3个多样性指数的变化趋势表现为Shannon-Wienner指数与均匀度指数呈正相关,而两者与丰富度指数呈负相关.     

深圳市主要植被群落类型划分及物种多样性研究

采用组间平均联结法对深圳市主要植被群落进行划分,并应用Gleason丰富度指数、Shannon-Wiener指数、Simpson指数和Pielou指数对主要植被群落的物种多样性水平进行比较分析。结果表明:深圳市城市森林可以划分为5个群系组和31个群落类型;各群落类型的物种多样性均表现为灌木层>乔木层,常绿阔叶人工林的乔木层和灌木层的生物多样性指数均最低,常绿落叶阔叶人工林乔木层丰富度指数、Shannon-Wiener指数、均匀度指数均最高,常绿阔叶人工林的乔木层优势种比较明显。     

北京八达岭植物群落多样性特征分析

根据34个样地的调查资料,分析了该地区森林植物群落物种多样性的特征:群落内各层物种丰富度指数的大小为草本层>灌木层>乔木层;多样性指数的大小为乔木层<灌木层和草本层。灌木层与草本层的多样性指数随林分郁闭度变化而变化,在林分郁闭度为25%的侧柏黄栌混交林中,灌木层的多样性指数和丰富度指数小于草本层;在郁闭度53%的杂木林中,灌木层和草本层的多样性指数接近;在郁闭度53%以上的各个群落内,草本层的多样性指数和丰富度指数基本上都大于灌木层。人工林中的物种多样性变化多样,明显低于天然林,林分层次单一,更新不良,缺乏灌木层和地被植物,生态系统很不稳定。     

不同海拔高度对周公山柳杉人工林植物多样性及土壤养分的影响

【目的】研究海拔高度对周公山柳杉人工林林下植物多样性及土壤养分的影响,对人工林的抚育及合理经营有着重要意义,旨在为人工林近自然改造以及利用山地造林、恢复森林生态提供科学依据。【方法】采用代表性样地法和随机取样法相结合的方法,在800、1 000和1 200 m 3个海拔高度对周公山柳杉人工林林下的物种组成、物种重要值、物种多样性和土壤养分进行了初步研究和对比分析。【结果】1)林下草本层共发现植物33种,属于19科32属;林下灌木层共发现植物49种,隶属于39属26科。2)草本群落Shannon-Wiener多样性指数(H)、Simpson优势度指数(H’)和Pielou均匀度指数(JSW)均随着海拔的升高表现为先升高后降低的趋势,符合"中度膨胀"理论,而草本层物种丰富度指数(D)以及灌木层群落各多样性指数则符合负相关关系理论。3)林下植被0~40 cm深度土壤养分随土层深度增加,全氮、全磷、有效磷、速效钾、有机碳、有机质含量均降低。4)物种多样性指数与有机质、全氮(TN)、全磷(TP)、有效磷(AP)的含量呈显著负相关。【结论】应控制人为干扰的强度,保持合理的林分密度,改善柳杉人工林的物种组成和群落结构,使人工林处于一种天然更新状态。     

黄土半干旱区白榆人工林密度与林下物种多样性的关系研究

选取半干旱黄土丘陵沟壑区相似气候、土壤和立地条件下的4种密度白榆人工林为研究对象,通过调查林下物种组成和结构,比较不同密度人工林下的物种组成、结构特征及其差异,评价人工林林下植被的发育状况．结果表明：白榆林下共有维管柬植物43种,分属18科35属;群落乔木层结构比较简单,灌木层优势种主要以建群种的幼苗和达乌里胡枝子为主,草本层物种较多,优势种为菊科、禾本科;当林分密度为1667株／hm^2时,乔木、灌木及草本层的物种丰富度、多样性、均匀度指数均较高．     

中国森林生态系统植物多样性的空间变化格局

利用中国国家生态系统研究网络(CNERN)的监测数据,分析我国森林生态系统中乔木层、灌木层、草本层的植物多样性随纬度、经度和海拔的空间变化格局。植物多样性指标包括物种丰富度指数(Patrick指数)、多样性指数(Shannon-Weiner和Simpson指数)和均匀度指数(Pielou)。结果表明:沿纬度梯度(从南向北),我国森林生态系统中乔木层和灌木层的物种丰富度指数呈下降趋势,草本层无明显的变化趋势;乔木层多样性指数先下降后升高。沿经度梯度(自西向东),乔木层、灌木层和草本层的物种丰富度指数呈下降趋势;乔木层的多样性指数均表现为先减小后增大的趋势,灌木层的变化趋势与乔木层相反,草本层的变化趋势不明显;3个层次的均匀度指数与多样性指数的变化趋势一致。在海拔垂直梯度上,随着海拔的升高,乔木层,灌木层和草本层物种丰富度指数呈先升高后降低趋势,峰值偏向于低海拔;乔木层多样性指数与物种丰富度指数的变化趋势相似,灌木层和草本层的变化趋势不明显。     

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。     

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.     

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.