树种组成决定联合抗性或易感性:以昆嵛山腮扁叶蜂发生为例

以昆嵛山天然赤松(Pinus densiflora)林和寡食性食叶昆虫-昆嵛山腮扁叶蜂(Cephalcia kunyushanica)为研究对象,对比树种组成类型、多样性、立地和林分因子对昆嵛山腮扁叶蜂种群密度的影响,分析了2009-2011年昆嵛山腮扁叶蜂在不同林分类型中种群年度波动变异系数.结果表明:林分类型是影响昆嵛山腮扁叶蜂虫口密度最重要的解释变量,随着赤松与混交亲缘关系越远,虫口密度越小.不同林分类型中,Shannon指数和赤松株虫口密度存在差异,但两者变化趋势完全不同.赤松纯林中赤松株虫口密度均为最高,与赤松-同属混交林没有显著差异,显著高于赤松-同目和阔叶树种组成的混交林;赤松纯林和赤松-同属混交林中昆嵛山腮扁叶蜂种群年度波动大于其他两种林分类型.表明相比树种多样性,树种组成对昆嵛山腮扁叶蜂种群的影响更为重要,赤松与其亲缘关系较近树种混交,昆虫种群稳定性较差,赤松与相邻树种形成对昆嵛山腮扁叶蜂联合易感作用,而与其他亲缘关系较远的树种混交,使害虫种群稳定性增强,进而形成联合抗性作用.     

昆嵛山腮扁叶蜂发生与赤松纯林林分因子的关系

为了解林分因子与昆嵛山腮扁叶蜂发生的关系,为昆嵛山赤松纯林的营林措施和昆嵛山腮扁叶蜂的防控技术提供理论指导,本研究在昆嵛山区域选取林龄相对一致(34±2 a)的赤松纯林为对象,调查林分密度、郁闭度、草本盖度、树高、枝下高、胸径、冠幅7个林分因子以及昆嵛山腮扁叶蜂虫巢数。依据虫情指数的分布范围,将样地分为4组,通过方差分析和多重比较研究了4组样地中各项林分因子的差异性。采用逐步回归法,筛选出影响昆嵛山腮扁叶蜂虫情指数的关键因子,在此基础上通过偏相关分析和单因素方差分析法进一步阐明关键因子与虫情指数之间的关系。结果表明,7个林分因子在4组样地中均存在极显著的组间差异。逐步回归筛选出冠幅、枝下高和林分密度为影响昆嵛山腮扁叶蜂发生的关键因子,根据关键因子建立了虫情指数的线性预测方程。冠幅和枝下高对昆嵛山腮扁叶蜂虫情指数的影响均达到极显著正相关水平(P0.01),林分密度对昆嵛山腮扁叶蜂虫情指数的影响为极显著负相关(P0.01)。影响虫情指数的关键因子可能会因林分的不同而不一致,因此要根据关键因子调整林分结构,以达到控制虫害流行的目的。     

赤松林上调力及群落结构对昆嵛山腮扁叶蜂的调控机制及作用

赤松作为昆嵛山腮扁叶蜂的主要寄主,赤松林上调力及群落结构对该食叶害虫种群密度的调控机制一直是昆嵛山区森林生态系统研究的核心问题之一,也是有害生物可持续控制的重要理论基础。本文把昆嵛山赤松林生态系统作为研究对象,以赤松林林分特征和以寄主植物的多样性、树种组成、邻近木和物种联结性为主的群落结构为主线,阐明了赤松林上调力及群落结构调控昆嵛山腮扁叶蜂的作用和机制,为研究昆嵛山腮扁叶蜂与寄主植物及其群落结构的关系开辟新思路和新领域,进而为真正实现森林食叶害虫的可持续控制提供依据。     

基于物种多样性和空间格局的林分稀疏

为了解影响热带天然次生林稀疏的因素,本研究应用地上生物量模型、多样性指数和O-ring统计对固定样地中植物的地上生物量、物种多样性和空间分布格局进行定量研究,并结合Yoda自疏模型计算林分稀疏指数,分析物种多样性与空间格局对林分稀疏的影响。结果表明:林分地上生物量随着林分密度的减小呈现先增大,后减小,再增大的趋势,在径级Ⅲ或径级Ⅳ处,出现变化拐点,在天然林管理时应加以注意。多样性指数与林分稀疏指数总体上无显著的相关性,但中等多样性指数值却对应最大的稀疏指数。说明物种多样性中等情况下,林分稀疏最为强烈。植物个体聚集分布的最大强度与稀疏指数呈显著线性负相关,二者的回归方程为:α=-1.7873O11(r)max+2.3451(R2=0.798,P=0.003)。结果表明,在热带常绿季雨矮林中,过大的聚集强度不但不能促进稀疏过程的进行,反而会对其产生阻碍作用。     

昆嵛山腮扁叶蜂与林下植物的物种联结性

为明确昆嵛山腮扁叶蜂(Cephalcia kunyushanica)的出现与林下植物是否关联,本研究在昆嵛山林区设置的50块永久样地内,应用样圆法进行了灌草层植物调查,并基于2×2联表,应用总体方差分析、χ2统计检验、Ochiai关联度指数、Dice指数、联结系数、共同出现百分率、点相关系数以及Cramer指数等指标,分别对昆嵛山腮扁叶蜂与邻近环境中所有195种林下植物种群的总体相关性、该昆虫与各植物构成的物种对之间联结显著性以及联结强度进行了测度。结果表明:(1)昆嵛山腮扁叶蜂与195个植物物种种群总体存在极显著的正相关;(2)该食叶昆虫与83个物种分别构成的物种对呈正联结关系,与另外112个物种分别构成的物种对呈负联结关系,负联结的比例高于正联结;(3)该昆虫与羊胡子草(Carex rigescens)等11种植物具有极显著的正联结关系,与宽叶苔草(C.siderosticta)等16种植物具有极显著的负联结关系。     

林分密度对尾赤桉人工林群落结构与生态效应的影响研究

对永安市不同经营密度下尾赤桉(Eucalyptus urophylta×E. eamalducensis)人工林的林分结构、群落组成以及林下枯落物和土壤持水性能进行了分析,探讨造林密度对闽西北地区桉树人工林生态效应的影响。结果表明,密度对尾赤桉人工林林分径级结构有极显著影响,密度与平均胸径、树高间存在极显著的负相关,相关系数分别为-0.99和-0.93,对林分蓄积量也存在显著影响(r=0.84)。密度对林下灌草层物种多样性的影响呈现分异现象,与灌木层的相关性达到极显著水平(r=0.94),但与草本层的相关不显著(r=-0.52)。不同密度林分的林下植物种类有较大差异,但低密度林分的林下植被收获量最大。林分密度对枯落物持水率的影响较大(r=0.94)。     

小兴安岭谷地云冷杉林粗木质残体碳密度特征

以小兴安岭谷地云冷杉林9.12 hm~2固定样地为研究对象,分析粗木质残体(CWD)碳密度的基础特征,揭示其与林分因子和物种多样性的关系。结果表明:(1)谷地云冷杉林CWD碳密度为13.25 t C/hm~2,其中云杉(Picea spp.)、冷杉(Abies nephrolepis)、兴安落叶松(Larix gmelinii)和未知种的CWD碳密度分别为3.59、2.61、3.06和2.85 t C/hm~2。(2)不同腐烂等级下CWD碳密度呈近正态分布,多集中在Ⅱ和Ⅲ等级,分别占总量的42.7%和35.4%。不同径级的CWD碳密度也呈近正态分布,主要分布在30—40 cm和40—50 cm径级上。干中折断、拔根倒、枯立木和干基折断为谷地云冷杉林CWD碳密度的主要存在方式。腐烂等级为Ⅰ和Ⅴ的CWD中,拔根倒的碳密度最高,其他腐烂等级中均为干中折断的碳密度最高。(3)CWD碳密度表现出较强的空间异质性,其随着林分平均胸径、最大胸径和胸高断面积的增加而下降,呈显著负相关关系(P0.05);而与林分密度、多样性指数和均匀度指数均无显著相关性(P0.05)。     

放牧干扰下高原鼢鼠栖息地选择因素

以祁连山东段高寒草甸栖息的高原鼢鼠(Myospalax baileyi)为研究对象,探讨放牧干扰下高原鼢鼠适合栖息地选择的影响因素,为合理控制草原鼠害和保护生物多样性提供科学依据。在5个不同放牧强度小区中,连续3年监测高原鼢鼠相对种群密度变化,同时获取植被和土壤的变化数据。分析高原鼢鼠相对种群密度、植被(盖度、高度、频度、植被生物量、植被均匀度、丰富度、多样性和地下根系生物量)和土壤(紧实度、容重、水分)之间的关系。中度放牧干扰下,高原鼢鼠相对种群密度最低,不利于对栖息地的选择,轻度、次轻度放牧区的高原鼢鼠相对种群密度高于重度、次重度放牧区的;轻度放牧干扰的草地有利于高原鼢鼠种群数量的增加。高原鼢鼠相对种群密度与土壤紧实度、容重呈显著负相关(R=﹣0.921、﹣0.883,P0.05);与土壤水分呈显著正相关(R=0.879,P0.05);高原鼢鼠相对种群密度与地下根系生物量呈极显著正相关(R=0.982,P0.01),与植被丰富度呈显著正相关(R=0.921,P0.05),与地上植被总盖度呈显著正相关(R=0.909,P0.05),与地上生物量、均匀度、多样性呈不显著正相关(P0.05)。在草地放牧干扰系统中,非生物因素土壤紧实度、水分可能是高原鼢鼠栖息地选择的首要选择因素,食物资源也许是次要选择因素。     

不同林分密度杉木林生态系统碳密度及其垂直空间分配特征

以不同林分密度(1800、3000、4500株/hm~2)杉木林为研究对象,通过野外调查、样品采集和室内分析,研究不同林分密度杉木林生态系统碳密度及其分配特征。结果表明:1)三种林分密度杉木林生态系统碳密度分别为131.54、161.42、172.69 t/hm~2,随林分密度增大而升高,且具有显著差异(P<0.05)。杉木林碳密度表现为土壤层>乔木层>林下地被物层。土壤有机碳储量占总碳储量的比例最大(53.11%—67.37%),其次是树干、树根、树皮(25.89%—35.74%),高密度杉木林分有利于树干、树皮、树根碳密度分配比例的增加。2)乔木层,树干、树皮、宿留枯枝及宿留枯叶碳密度随林分密度增大而升高,鲜枝及鲜叶碳密度随林分密度增大先升高后降低,且均具显著差异(P<0.05);树干、树皮碳密度随树体高度的升高而降低,鲜枝鲜叶碳密度集中于树体中上部(8 m≤h≤10 m),宿留枯枝枯叶碳密度集中分布于树体中部(4 m≤h≤8 m)。3)随着林分密度的增大,不同径级根碳密度呈上升趋势,且不同径级根碳密度随林分密度变化差异达显著水平(P<0.05);不同...     

光肩星天牛虫口密度和空间分布型与抽样方法的数量化分析

一、问题的提出选择最佳抽样方案对判定昆虫种群空间分布型和提高虫口密度的统计精度具有重要意义.通过在试验林分中,设计若干目标抽样方案,进行多种算法筛选,逼近林分实测值,     

Carbon and nitrogen dynamics in a Pinus densiflora forest with low and high stand densities

Aims Understanding carbon (C) and nitrogen (N) dynamics and their dependence on the stand density of an even-aged, mature forest provides knowledge that is important for forest management. This study investigated the differences in ecosystem total C and N storage and flux between a low-density stand (LD) and a high-density stand (HD) and examined the effects of stand density on aboveground net primary productivity (ANPP), total belowground C allocation (TBCA) and net ecosystem production (NEP) in a naturally regenerated, 65- to 75-year-old Pinus densiflora S. et Z. forest.Methods LD (450 trees ha^-1) and HD (842 trees ha^-1) were established in an even-aged, mature P. densiflora forest in September 2006. The forest had been naturally regenerated following harvesting, and the stand density was naturally maintained without any artificial management such as thinning. The diameter at breast height (DBH ≥ 5.0cm) of all live stems within the stands was measured yearly from 2007 to 2011. To compare C and N storage and fluxes in LD and HD, C and N pools in aboveground and belowground biomass, the forest floor, coarse woody debris (CWD) and soil; soil CO₂ efflux (R S); autotrophic respiration (R A); litter production; and soil N availability were measured. Further, ANPP, TBCA and NEP were estimated from plot-based measurement data.Important findings Ecosystem C (Mg C ha^-1) and N (Mg N ha^-1) storage was, respectively, 173.0±7.3 (mean ± SE) and 4.69±0.30 for LD and 162±11.8 and 4.08±0.18 for HD. There were no significant differences in C and N storage in the ecosystem components, except for soils, between the two stands. In contrast, there were significant differences in aboveground ANPP and TBCA between the two stands (P < 0.05). Litterfall, biomass increment and R S were major C flux components with values of, respectively, 3.89, 3.74 and 9.07 Mg C ha^-1 year^-1 in LD and 3.15, 2.94 and 7.06 Mg C ha^-1 year^-1 in HD. Biometric-based NEP (Mg C ha^-1 year^-1) was 4.18 in LD and 5.50 in HD. Although the even-aged, mature P. densiflora forest had similar C and N allocation patterns, it showed different C and N dynamics depending on stand density. The results of the current study will be useful for elucidating the effects of stand density on C and N storage and fluxes, which are important issues in managing natural mature forest ecosystems.     

昆嵛山天然赤松种群的数量特征及更新动态

1　前　言赤松(ＰｉｎｕｓｄｅｎｓｉｆｌｏｒａＳｉｅｂ.ｅｔＺｕｃｃ.)天然分布于朝鲜、日本和中国,它在我国的天然分布从黑龙江东南部(宁安、东宁)、吉林东部(长白山)、辽东半岛经山东半岛(昆嵛山、崂山、沂山东部)到江苏东北部云台山区,是我国暖温带沿海地区温性针叶林的主要建群种之一[1]。昆嵛山地处山东半岛东端,位于Ｎ37°16′,Ｅ121°43′附近,是赤松在山东半岛的最集中分布地。赤松林在该地区从山麓一直到海拔800ｍ左右都有分布,并与落叶栎林共同组成该地区的地带性天然次生森林植被[2],在调节生态系统结构与功能方面起到重要作用…     

利用I&和*m指标法对山东赤松种群空间分布格局纹理的研究

赤松 (Ｐｉｎｕｓｄｅｎｓｉｆｌｏｒａ)是重要的造林先锋树种 ,在我国主要分布于辽东半岛南部至江苏北部云台山之间的温带沿海地区 ,山东为其主要分布区。赤松林作为我国暖温带落叶阔叶林区域的温性针叶林类型 ,是山东最主要的针叶林 ,总面积达 2 .6 6 7×10 5ｈａ以上 ,木材蓄积量为 1.2× 10 6ｍ3 ,分别占全省森林总面积的 2 0 .19%及木材蓄积量的 14.4 9%。但自 2 0世纪 70年代以来 ,赤松受到“两虫”(松毛虫、松干蚧 )的严重危害 ,加上纯林太多和物种多样性指数低等原因 ,以至目前在山东难以找到大片的成年赤松林[1] 。为保护和发展这…     

林分因子对神木垒不同森林群落林下植物多样性的影响

为探究神木垒不同森林群落林下植物多样性的差异,本研究采用典型样地法,以夹金山神木垒的5种主要森林群落：云杉林、丽江云杉林、红杉林、针阔混交林、阔叶林为研究对象,对不同森林群落林下植物物种组成和物种多样性进行比较,并对林分因子和林下植物多样性进行冗余分析,确定影响林下植物多样性的主要林分因子,为当地森林经营管理提供理论依据。结果表明：（1）在研究区内共记录林下植物147种,隶属于61科,108属;云杉林群落林下植物的科属种组成最丰富。（2）各类型群落的H值、H"值、D值、JSW值均为：草本层＞灌木层;灌木层多样性最高的群落为云杉林群落,草本层多样性最高的群落为丽江云杉林群落,针阔混交林群落、阔叶林群落林下植物多样性较差。（3）平均枝下高与林分密度是影响灌木层物种多样性的主要林分因子（P<0.01）,平均枝下高与灌木层的D值、H值、H"值呈负相关关系,林分密度与灌木层4个多样性指数均呈正相关关系;平均枝下高是影响草本层物种多样性的主要林分因子（P<0.01）,平均枝下高与草本层H值、H"值、JSW值呈正相关关系。本研究认为,云杉林群落与丽江云杉林群落的林下植物多样性水平较高,平均枝下高与林分密度是影响神木垒不同森林群落林下植物多样性的主要林分因子。     

基于空间结构指数的不同森林群落稳定性研究

以长白山杨桦次生林、云冷杉针阔混交林、云冷杉近原始林为研究对象,基于微观经济学中的柯布—道格拉斯生产函数相关理论,以3个常用的空间结构指标(混交度、大小比数、角尺度)为"投入",林分整体空间结构为"产出",构建林分空间结构生产函数,定义了林分空间结构指数(FSSI)并计算了林分空间结构距离(FSSD)。利用这5个指标分析比较不同演替阶段森林群落的空间结构特点,从而评价各演替阶段的稳定性。结果表明:不同演替阶段森林群落的混交度值均不相同,云冷杉近原始林平均混交度最大,云冷杉针阔混交林次之,杨桦次生林最小;大小比数对不同森林群落空间结构影响较小,其值基本为0.49~0.52;3种森林群落水平分布状态为云冷杉针阔混交林和云冷杉近原始林随机分布,杨桦次生林聚集分布;其空间结构指数大小及与理想结构接近程度排序为:云冷杉近原始林云冷杉针阔混交林杨桦次生林。因此,云冷杉近原始林空间结构较好,稳定性最佳。     

山东赤松种群的个体生长规律

利用Logistic增长模型对山东赤松 (PinusdensifloraSieb .etZucc .)种群个体生长规律进行了初步研究。结果表明 ,赤松个体生长密切符合Logistic方程 ;人工林个体生长好于天然次生林 ;人工林与次生林个体生长规律一致 ;树高成熟龄和连年生长量最大时年龄出现最早 ,胸径成熟龄和连年生长量最大时年龄出现较晚 ,材积成熟龄和连年生长量最大时年龄出现最迟     

Differences in bird communities in postfire silvicultural practices stands within pine forest of South Korea

We examined differences in bird communities in relation to characteristics of habitat structure in a pine forest, Samcheok, South Korea. An unburned stand, a stand burned 7 years earlier and then naturally restored, and a stand where Japanese red pine Pinus densiflora seedlings were planted after the fire were used for the survey. Habitat structure was dramatically changed by postfire silvicultural practices. Number of stand trees, shrubs, seedlings, snags, and vegetation coverage were significantly different among study stands. We made 1,421 detections of 46 bird species during 23 separate line transect surveys per stand between February 2007 and December 2008. The mean number of observed bird species and individuals, bird species diversity index (H′), and Simpson’s diversity index (D _s) were highest in the unburned stand and lowest in the pine seedling stand. There were more species and individuals of forest-dwelling birds in the unburned stand than both burned stands. Canopy and cavity nesters, foliage searchers, bark gleaners, and timber drillers were significantly higher in the unburned stand. In the pine seedling stand, densities of birds that prefer open field and shrub cover were higher. Stand structure was simplified in the pine seedling stand by postfire practices. Because of differences in habitat structure and bird communities, postfire practices in the burned stand should be re-evaluated. Also, management strategies for pine forest after forest fires are needed based on results of long-term experiments.     

Tree diversity drives diversity of arthropod herbivores,but successional stage mediates detritivores

The high tree diversity of subtropical forests is linked to the biodiversity of other trophic levels. Disentangling the effects of tree species richness and composition, forest age, and stand structure on higher trophic levels in a forest landscape is important for understanding the factors that promote biodiversity and ecosystem functioning. Using a plot network spanning gradients of tree diversity and secondary succession in subtropical forest, we tested the effects of tree community characteristics (species richness and composition) and forest succession (stand age) on arthropod community characteristics (morphotype diversity, abundance and composition) of four arthropod functional groups. We posit that these gradients differentially affect the arthropod functional groups, which mediates the diversity, composition, and abundance of arthropods in subtropical forests. We found that herbivore richness was positively related to tree species richness. Furthermore, the composition of herbivore communities was associated with tree species composition. In contrast, detritivore richness and composition was associated with stand age instead of tree diversity. Predator and pollinator richness and abundance were not strongly related to either gradient, although positive trends with tree species richness were found for predators. The weaker effect of tree diversity on predators suggests a cascading diversity effect from trees to herbivores to predators. Our results suggest that arthropod diversity in a subtropical forest reflects the net outcome of complex interactions among variables associated with tree diversity and stand age. Despite this complexity, there are clear linkages between the overall richness and composition of tree and arthropod communities, in particular herbivores, demonstrating that these trophic levels directly impact each other.     

Boreal Fire Effects on Subsistence Resources in Alaska and Adjacent Canada

Rural communities in the northern boreal forest depend on a suite of wild species for subsistence, including large game animals, furbearers, fish, and plants. Fire is one of the primary ecological disturbances and determinants of landscape pattern in the northern boreal forest. We review responses of key boreal subsistence species to variation and change in post-fire stand age and other characteristics. Available data for 17 species indicate highly varied post-fire habitat requirements. Mosaics of differing stand ages generated by fire could therefore be most effective in supplying a suite of subsistence species to hunting-and-gathering communities. Recent and projected increases in frequency of large-fire years might produce a more homogeneous landscape dominated by younger stand ages. Increases in fire suppression around communities might also produce a more homogenous landscape, but dominated by older stand ages. Neither of these scenarios provides mixed habitats for a diverse suite of subsistence species. We suggest that one aspect of the complex suite of human–fire interactions is an understanding of wildlife and plant species’ response to fire in a subsistence region, in an effort to sustain ecosystem services critical to human well-being.     

Influence of Tree Species Composition and Community Structure on Carbon Density in a Subtropical Forest

We assessed the impact of species composition and stand structure on the spatial variation of forest carbon density using data collected from a 4-ha plot in a subtropical forest in southern China. We found that 1) forest biomass carbon density significantly differed among communities, reflecting a significant effect of community structure and species composition on carbon accumulation; 2) soil organic carbon density increased whereas stand biomass carbon density decreased across communities, indicating that different mechanisms might account for the accumulation of stand biomass carbon and soil organic carbon in the subtropical forest; and 3) a small number of tree individuals of the medium- and large-diameter class contributed predominantly to biomass carbon accumulation in the community, whereas a large number of seedlings and saplings were responsible for a small proportion of the total forest carbon stock. These findings demonstrate that both biomass carbon and soil carbon density in the subtropical forest are sensitive to species composition and community structure, and that heterogeneity in species composition and stand structure should be taken into account to ensure accurate forest carbon accounting.