海拔对天宝岩长苞铁杉林粗死木质残体分布的影响   总被引：2，自引：0，他引：2  

游惠明  何东进  洪伟  游巍斌  刘进山  蔡昌棠  王磊  叶贤双 《福建农林大学学报(自然科学版)》2011,40(4)

对天宝岩国家级自然保护区不同海拔长苞铁杉林粗死木质残体(coarse woody debris,CWD)的直径、数量、体积、高度及腐烂等级的分布特征进行对比研究.结果表明:(1)不同海拔的CWD主要分布在0-20 cm的小径级范围,数量和体积随径级的增加呈下降趋势;(2)海拔对倒木数量分布有极显著影响(df=2,P=0.006),倒木的数量随海拔上升而减少;枯立木的数量、体积随海拔的上升而增加;(3)不同海拔CWD主要分布在0-5 m高度级,且此高度级内CWD的数量分布随海拔的下降而增加;(4)倒木数量在不同腐烂等级上的分布差异显著(df=4,P=0.033).  相似文献   

Evaluation of ELISA for imidacloprid detection in eastern hemlock (Tsuga canadensis) wood and needle tissues     

Eisenback BM  Mullins DE  Salom SM  Kok LT 《Pest management science》2009,65(2):122-128

BACKGROUND: Imidacloprid is the primary insecticide used against the exotic invasive insect hemlock woolly adelgid, Adelges tsugae Annand, a pest of eastern hemlock [Tsuga canadensis (L.) Carrière] trees in the eastern United States. A competitive enzyme-linked immunosorbent assay (ELISA) was evaluated for quantification of imidacloprid in eastern hemlock wood and needle tissues.RESULTS: Matrix effects in the form of false positives and overestimated imidacloprid concentrations were observed in both wood and needle extracts. Tissues required a 100-1000-fold dilution with water in order to reduce matrix effects. Standard curves in 1% wood or needle extract were not significantly different from standard curves prepared in water. Matrix effects were more pronounced at concentrations in the lower working range of the kit, with recovery of 5 microg L(-1) imidacloprid more accurate than recovery of 0.2 microg L(-1).CONCLUSION: ELISA remains a valuable tool for semi-quantitative imidacloprid detection within the hemlock system because of its sensitivity, cost and ease of use. However, a 1000-fold dilution of hemlock tissue extract is recommended to ensure accurate imidacloprid determinations.  相似文献   

莽山南方铁杉种群格局分布格局研究   总被引：3，自引：0，他引：3  

王大来 《中国农学通报》2010,26(1):74-77

采用方差/均值比率法对10个南方铁杉种群的分布格局类型进行了分析,同时,采用负二项式参数、扩散性指数、丛生指数、平均拥挤度指数和聚块性指数计测这些种群的空间聚集强度。结果表明:南方铁杉种群的分布格局呈集群分布,不同种群的聚集强度有所差异。对这种分布格局的原因进行了分析。  相似文献   

莽山南方铁杉群落种间关系研究   总被引：2，自引：1，他引：1  

赵峰 《中国农学通报》2011,27(31):68-72

为了研究莽山南方铁杉群落种间关系,以便更好地保护这种植物,笔者采用方差比率法（VR）,应用Jaccard指数、Dice指数和Pearson相关系数、Spearson秩相关系数,对莽山自然保护区南方铁杉群落种间关系进行分析。结果表明：（1）南方铁杉群落中主要种群总体上表现出正关联;（2）群落中种间联结的显著度较低,其中有显著正相关2对,显著负相关4对,极显著正负相关各1对,南方铁杉与水青树呈显著负联结,与香樟呈极显著负联结;（3）大多数种对间关联程度较低,存在极大排斥性的种对较少,表明目前南方铁杉群落处于较成熟阶段。研究种间关系时,结合多种方法共同分析,能够更有效地寻找种间潜在的联结关系,最后对南方铁杉的保护提出了一些建议。  相似文献   

Transformation of western hemlock (Tsuga heterophylla) tree crowns by dwarf mistletoe (Arceuthobium tsugense,Viscaceae)     

Stephen J. Calkins  David C. Shaw  Yung‐Hsiang Lan 《Forest Pathology》2021,51(1):e12664

Dwarf mistletoes (Arceuthobium species) are arboreal, hemiparasitic plants of conifers that can change the structure and function of the tree crown. Hemlock dwarf mistletoe (Arceuthobium tsugense subsp. tsugense) principally parasitizes western hemlock (Tsuga heterophylla) and effects 10.8% of all western hemlock trees in Oregon, USA. In this study, we climbed 16 western hemlock trees (age 97–321 years, height 33–54.7 m) across a gradient of infection (0%–100% of branches infected) and measured occurrence of all dwarf mistletoe infections, dwarf mistletoe caused deformities, foliage, branch and crown metrics, and sapwood area. We then modelled over 25 different response variables using linear and generalized linear models with three metrics of severity as explanatory variables: total infection incidence, proportion of all live branches infected, and proportion of all live, infected branches with 33 per cent or more foliage distal to infection. A strong effect of dwarf mistletoe intensification was the reduction of branch foliage and an increase in the proportional amount of foliage distal to infections, with severely infected trees having the majority of foliage distal to infections. Increasing severity led to an apparent crown compaction as crown volumes decreased and became increasingly comprised of deformities. Sapwood area was unrelated to infection severity. Branch length and diameters were unrelated to increasing infection severity despite severely infected branches supporting 1–70 infections. The most severely infected tree had 3,615 individual plants in the crown. Our results suggested that shifts in crown structure and branch deformation, foliage amount, and foliage distal to infection, reflected a likely reduction of capacity for tree growth that coincided with a hypothesized increase in resource demand by dwarf mistletoe plants as infection severity intensified.  相似文献   

天宝岩珍稀濒危植物长苞铁杉的生长规律   总被引：1，自引：2，他引：1  

张彩云  吴承祯  洪伟  范海兰  洪滔  宋萍  夏鑫 《福建林学院学报》2007,27(2):118-122

采用4种数学模型拟合天宝岩长苞铁杉胸径、树高、材积生长过程,并分析其生长规律。结果表明,天宝岩长苞铁杉胸径生长旺盛期在3-36 a;树高在前7 a生长较快,以后逐年下降;材积生长逐年增加,数量成熟期在139-140 a。通过与永泰、连城长苞铁杉生长过程的对比,天宝岩长苞铁杉在第3年就有胸径生长,树高在70 a时达19.27 m。  相似文献   

珍稀植物长苞铁杉种群空间分布的Weibull模型及其应用研究   总被引：13，自引：4，他引：9  

吴继林  吴承祯 《江西农业大学学报》1999,21(4):602-605

首次将连续型Ｗｅｉｂｕｌｌ分布用于珍稀淑危植物长苞铁杉种群空间分布格局的研究,取得理想效果,长苞铁杉种群分布符合Ｗｅｉｂｕｌｌ分布。并根据Ｗｅｉｂｕｌｌ分布建立了长苞铁杉种群最知抽样式,为长苞铁杉种群抽样技术和取样数量确定提供了理论依据。  相似文献   

长苞铁杉天然林水源涵养功能研究   总被引：18，自引：4，他引：14  

钟祥顺 《福建林学院学报》1999,19(3):261-264

研究了闽西邱家山长苞铁杉天然林、常绿阔叶林和杉木人工林的林冠层、林下植被层和凋落物层的持水量、土壤蓄水能力和渗透性能,结果表明：长苞铁杉天然林地上部分持水量与常绿阔叶林接近,分别为２５８．４２６Ｔ／ｈｍ２和２７７．２４２Ｔ／ｈｍ２,林地土壤的稳渗值亦相近,分别为６．６８ｍｍ／ｍｉｎ和６．９１ｍｍ／ｍｉｎ,是杉木人工林的１．８倍和１．９倍．说明了长苞铁杉天然林具有较好的水源涵养功能．  相似文献