Plastic Response of Crown Architecture to Crowding in Understorey Trees of Two Co-dominating Conifers

Crown architecture and growth rate of trunk height, trunk diameterand lateral branches of understorey trees (5–10m tall)were compared between two co-dominating conifers,Abies sachalinensisandPiceaglehnii, in relation to the index of local crowding intensity,W,represented as a function of density, distance and basal areaof taller neighbours. For the two conifers, the growth of trunkheight and diameter was decreased and crowns became flat withincreasingW, keeping crown projection area. Self-pruning oflower branches was more intense inAbiesthan inPiceain crowdedconditions, while both conifers showed similar crown forms inless crowded conditions. These results suggest that the growthin lateral branches exceeded that in height in crowded conditions,especially inAbies. Tree age of both conifers increased withincreasingW, resulting from the low growth rate in crowded conditions.The age of the longest and lowest branch ofPicea, up to 150years, was positively correlated with the tree age ranging from70 to 250 years, whereas that ofAbieswas constant at around30 years irrespective of tree age varying from 40 to 140 years.This result agrees with the observation that agedAbieshad moreflat-shaped crowns than in agedPiceain crowded conditions. Theseresults suggest that each conifer adapted to crowding in differentways: high elongation of branches with high turnover rate forAbiesandviceversaforPicea. Abies; crown form; neighbourhood interference; Picea; plasticity     

中国两个气候过渡区森林土壤线虫群落的比较研究

为比较不同气候过渡区地带性森林土壤线虫群落结构和多样性,以南亚热带向中亚热带气候过渡区的石门台常绿阔叶林和北亚热带向暖温带气候过渡区的鸡公山落叶阔叶林为样地,探讨不同气候区土壤微食物网能流方式的差异。结果表明,石门台土壤线虫群落属数(S)、生物量(Biomass)、多样性指数(H')、丰富度指数(SR)、成熟度指数(MI)和结构指数(SI)在表层土壤(0~10 cm)均显著高于鸡公山。石门台的土壤线虫通路指数(NCR)均值高于0.5,而鸡公山的NCR均值小于0.5,说明前者土壤食物网可能偏向于细菌能流通道,而后者偏向于真菌能流通道,这也与食细菌线虫、食真菌线虫生物量的计算结果一致。可见线虫群落结构确实存在明显的南北差异,并较好地指示了土壤能流和养分循环状况。     

Phylogenetic Structure of Tree Species across Different Life Stages from Seedlings to Canopy Trees in a Subtropical Evergreen Broad-Leaved Forest

Investigating patterns of phylogenetic structure across different life stages of tree species in forests is crucial to understanding forest community assembly, and investigating forest gap influence on the phylogenetic structure of forest regeneration is necessary for understanding forest community assembly. Here, we examine the phylogenetic structure of tree species across life stages from seedlings to canopy trees, as well as forest gap influence on the phylogenetic structure of forest regeneration in a forest of the subtropical region in China. We investigate changes in phylogenetic relatedness (measured as NRI) of tree species from seedlings, saplings, treelets to canopy trees; we compare the phylogenetic turnover (measured as β_NRI) between canopy trees and seedlings in forest understory with that between canopy trees and seedlings in forest gaps. We found that phylogenetic relatedness generally increases from seedlings through saplings and treelets up to canopy trees, and that phylogenetic relatedness does not differ between seedlings in forest understory and those in forest gaps, but phylogenetic turnover between canopy trees and seedlings in forest understory is lower than that between canopy trees and seedlings in forest gaps. We conclude that tree species tend to be more closely related from seedling to canopy layers, and that forest gaps alter the seedling phylogenetic turnover of the studied forest. It is likely that the increasing trend of phylogenetic clustering as tree stem size increases observed in this subtropical forest is primarily driven by abiotic filtering processes, which select a set of closely related evergreen broad-leaved tree species whose regeneration has adapted to the closed canopy environments of the subtropical forest developed under the regional monsoon climate.     

百山祖北坡常绿阔叶林多脉青冈种群结构和分布格局

本研究应用理论分布模型和5个聚集强度指标,研究百山祖北坡中山常绿阔叶林多脉青冈种群分布格局。结果表明：多脉青冈种群结构呈基部和中部宽、顶部窄的形状,龄级完整,属于稳定型,但存在波动性;从整个种群和不同发育阶段来看,多脉青冈的分布格局主要呈聚集分布,且随年龄增长,聚集度逐渐降低,呈现扩散趋势,到大树期为随机分布。种群自身生物学特性、种群生境以及环境资源等综合因素影响多脉青冈的年龄结构和分布格局。     

泉州常绿阔叶林的特征与分布

泉州的常绿阔叶林包括南亚热带雨林和南亚热带山地照叶林。通过对这两种植被类型的区分成分、生活型、叶的性质以及群落的结构与分布的分析,说明海拔450m以下具有较明显的以厚壳桂、红楠等为优势种的南亚热带雨林的特征和景观;海拔450～900m主要以米槠等拷类为优势种的群落,但仍有南亚热带雨林的某些特征;海拔900～1400m以甜槠为主要建群种的群落,属于中亚热带照叶林的群落特征。     

亚热带常绿阔叶林栲树与薯豆不同龄级种群生态位特征

种群不同年龄组的生态位是种群资源利用随时间变化的一种重要形式。根据高度将植物种群分为乔木组、幼树组和幼苗组3个年龄梯度,对重庆缙云山自然保护区常绿阔叶林优势树种—栲树与薯豆生态位特征进行了比较研究。结果表明：(1)栲树与薯豆3个龄级的实际生态位宽度均较大,但资源利用能力都不强;它们的生态位宽度与资源利用能力随龄级增加而增大趋势很明显。(2)栲树与薯豆幼苗组生态位特化程度高,幼树组与乔木组生态位泛化程度不高。(3)薯豆乔木组、幼树组的生态位宽度和资源利用能力均大于栲树,但薯豆幼苗组生态位宽度和资源利用能力却比栲树小。(4)两个种群生态位重叠较高,资源性竞争激烈;生态位重叠随年龄增长而呈“V”字形,幼树组重叠值低与幼苗组的高竞争导致栲树中等龄级的缺失有关。     

鼎湖山季风常绿阔叶林大气降雨、穿透雨和树干流的养分特征研究

对鼎湖山季风常绿阔叶林大气降雨、穿透雨和树干茎流中的5种养分元素K、Ca、Mg、N、P进行了测定,结合水量分配规律,研究了森林降雨过程中养分在水相中的含量变化特征和输入规律。结果表明：(1)所有离子浓度均为大气降水<穿透雨<树干流,且增幅较大,而平均浓度以K+和总氮(TN)含量最高;总磷(TP)、磷酸盐(HPO42-)、总有机磷(TOP)含量均最低。(2) 大气降雨中的离子平均浓度中以总有机氮(TON)的变异系数最大,为1.282;最小的是NO3-(0.502);穿透雨中变异系数最大的是TOP(2.357);最小的是TN(0.621)。树干流中各养分元素浓度与树种的相关性不显著(P>0.05)。(3) 季风常绿阔叶林树干流和穿透雨各养分对森林土壤的年输入量为TN>K+>Ca2+>Mg2+>TP,树干流和穿透雨对森林土壤层Ca2+的输入大于凋落物分解输入。因此,大气降雨是养分从林冠层转移到土壤层的重要因素。     

无量山半湿润常绿阔叶林的区系特征及保护生物学意义

无量山半湿润常绿阔叶林是其垂直带上重要的植被类型,目前面临被彻底毁灭的危险,从这类森林及相应地段的177种优势和常见植物的种类结构分析看,只有热带亚洲的成分,东亚中的中国－喜马拉雅成分和中国特有成分贯穿乔木A,B,C层,灌木层,草本和层外植物几大类中,而中国特有种的进一步分析表明了它的区系成分的亚热带性质,温带性质不是很显著,在无量半山湿润常绿阔叶林地段,还存在一些原生植被破坏后产生的次生落叶阔叶加以保护,因之有这么多的特点,加之其为重要特有类群和保护种类聚集的场所,该类植被明显具有不同层次的保护生物学意义。     

择伐强度对中亚热带天然针阔混交林林分空间结构的影响

利用混交度、大小比数和角尺度3个结构参数,研究4种不同择伐强度（弱度13.0%、中度29.1%、强度45.8%、极强度67.1%）对中亚热带天然针阔混交林林分空间结构的影响。结果表明：弱度择伐后林木的平均混交度最大,中度择伐次之,极强度择伐林木单种聚集的比例最高;不同择伐强度对林木的大小分化程度影响不大,但各主要树种的地位都有一定程度变化;择伐并未改变林木的空间分布格局,各样地林分整体和主要树种均为聚集分布,极强度择伐林木多呈团状分布,而弱度、中度择伐树种大多处于不均匀和随机分布。总的来说,弱度和中度择伐有利于林分空间结构的优化。     

中国亚热带常绿阔叶林优势种常见种分布与气候的相关分析

 广泛收集植物的分布资料,包括杨梅科、胡桃科、壳斗科、木兰科、樟科、山茶科、金缕梅科、交让木科、杜英科、五加科、安息香科、冬青科、杜鹃花科、山矾科的优势种和常见种112个,利用目前在国际上被认为是较好的几种研究植被—气候相互关系的指标和方法,包括：Kira方法;Penman公式;Thornthwaite方法与分类;Holdridge生命地带分类系统指标与方法,分析中国亚热带常绿阔叶林优势种及常见种分布与气候的生态关系,找出它们的地理分布特征和气候指标特征,建立现代植被与气候的关系。(1)利用Kira的温暖指数(WI)和寒冷指数(CI)及徐文铎的湿润指数(HI),计算了中国亚热带常绿阔叶林112个优势种及常见种的水热指标值,分析了树种分布与气候的关系,并将优势种及常见种划分为5个Kira水热指标分布类群。(2)计算了112个优势种及常见种的Penman可能蒸散(PET)和干燥度(A)值,划分了5个优势种及常见种的Penman水热指标分布类群。(3)计算了树种的Thornthwaite潜在可能蒸散(APE)及湿润指数(IH)、干旱指数(IA)和水分指数(IM),划分了优势种及常见种的Thornthwaite水热指标分布类群。(4)计算了树种的Holdridge生物温度(BT)、可能蒸散(PE)、降水量(P)及可能蒸散率(PER),划分了优势种及常见种的Holdridge水热指标分布类群。     

中亚热带喀斯特常绿落叶阔叶林空间结构特征

喀斯特常绿落叶阔叶林是中国西南喀斯特地区非地带性顶极森林群落,该研究基于相邻木关系的角尺度、混交度和大小比数3个结构参数,对木论国家级自然保护区常绿落叶阔叶林25 hm^(2)大型固定监测样地整体、上木层、下木层及其优势物种的空间结构特征进行了分析,以期揭示其森林空间结构现状,为喀斯特植被恢复重建提供依据。结果表明:(1)样地群落整体为轻度聚集分布格局,接近随机分布,物种高度混交且个体间大小分化程度相近,上木层呈现随机分布、强度混交和中庸偏亚优势状态,下木层呈现聚集分布、强度混交和中庸偏劣势状态。(2)样地内优势物种大多处于轻度聚集分布、强度混交且中庸偏劣势的状态。(3)林木大小比数与胸径、树高均呈显著负相关关系,混交度与胸径、树高均呈显著正相关关系,随林木的生长发育,树种优势度逐渐增大,物种多样性逐渐增强。研究认为,木论常绿落叶阔叶林空间结构尚未完全稳定,正处于演替中后期,具有发育成顶极群落的潜力。     

粤北山地常绿阔叶林自然干扰后冠层结构空间异质性动态

以受2008年冰灾破坏的广东始兴车八岭山地常绿阔叶林为研究对象,采用半球面影像技术、地统计学的空间异质性和空间自相关分析方法,连续3年(2008-2010年)对林冠结构空间异质性动态进行了检测研究.结果表明:(1)从2008到2010年,林冠开度的平均值、标准差、变异系数、最大值、最大值和最小值的差值以及林冠结构的空间异质性均在逐渐减小,且后两年较为接近;(2)受灾当年冠层结构由随机因素造成,其半方差拟合函数属纯块金模型,后两年冠层结构则由结构性因素引起,其半方差拟合函数属球状模型;(3)受灾当年冠层结构不存在空间自相关;随着时间推移其空间自相关越来越强.说明冰灾后常绿阔叶林冠层结构在没有人为干预的情况下会逐渐恢复到灾前水平,体现出天然的空间分布状况.     

实生和嫁接槐树的枝梢生长与光合特性

测定槐树实生树和嫁接树叶片的光合光响应特性、比叶重和叶绿素含量及枝梢生长的结果表明,嫁接树枝梢基径和高度增长趋势与实生树一致,但嫁接树一次、二次梢基径和高度增长量均大于实生树。嫁接树的最大净光合速率、光饱和点、比叶重和单位重量的叶绿素含量均显著高于实生树,高的光合能力与其单位面积叶片重量增加和单位重量叶绿素含量增高有关。嫁接槐树的类胡萝卜素与叶绿素比值高于实生槐树,叶绿素a,b比值和单位重量类胡萝卜素含量显著高于实生槐树,表明其对强光的适应性强。     

广东石门台亚热带典型常绿阔叶林和亚热带山顶矮林群落特征

为了研究亚热带典型常绿阔叶林和亚热带山顶矮林的物种组成和群落结构,在广东石门台国家自然保护区内分别建立了1 hm2亚热带典型常绿阔叶林样地和1 hm2亚热带山顶矮林样地,以样地内所有胸径（DBH）≥1 cm的乔木、灌木和藤本为研究对象,分析两种森林类型的物种组成、密度、径级和株高结构。结果显示：（1）两种森林的Srensen物种相似性指数为0.41,优势种不同,但优势科却较相似;其中,茶科和杜鹃花科在两种森林中所占比例较高;（2）亚热带典型常绿阔叶林的幼苗（1 cm≤DBH〈2.5 cm）和幼树（2.5 cm≤DBH〈12.5 cm）密度都显著小于亚热带山顶矮林,但两种森林的小树（12.5 cm≤DBH〈25 cm）和大树（DBH≥25 cm）密度均无显著差异;亚热带典型常绿阔叶林幼苗和大树的平均胸径都显著大于亚热带山顶矮林,而幼树的平均胸径则显著小于亚热带山顶矮林,小树的平均胸径无显著差异;亚热带典型常绿阔叶林中小树和大树的平均高度都显著大于亚热带山顶矮林,而幼苗的平均高度显著小于亚热带山顶矮林,幼树的平均高度无显著差异。综合分析表明,亚热带典型常绿阔叶林和亚热带山顶矮林的物种组成、密度、胸径和高度结构差异较大,亚热带典型常绿阔叶林群落稳定性强于亚热带山顶矮林。     

Effect of Purine Analogs and Their Interactions with Benzyladenine on Bud Burst and Shoot Growth in Apple Bud Explants

The purine analogs 8-azaadenine, 8-azaguanine, 4-aminopyrazolo [3,4-d] pyrimidine, 2-fluoroadenine and 6-methylpurine inhibited bud burst in non-dormant vegetative axillary bud explants obtained from apple (Malus domestica Borkh.) seedlings. The reversal of inhibition was attempted by incorporating increasing concentrations of benzyladenine (BA) in the culture medium. The inhibition caused by 8-azaadenine and 8-azaguanine was reduced especially when BA was added to the media at equimolar ratios along with the inhibitors. The inhibition due to 4-aminopyrazolo [3,4-d] pyridine was reduced only with equimolar BA, BA was ineffective or only minimally effective in reducing inhibition due to 2-fluoroadenine and 6-methypurine. Short pretreatment with 8-azaadenine and 8-azaguinine failed to cause any inhibition when explants were subsequently transferred to BA -containing medium. The effectiveness of 2-fluoroadenine and 6-methylpurine was maintained or only slightly reduced, indicating their long-term inhibitory action.     

喷施烯效唑对苹果顶芽激素水平和花芽分化的影响

用烯效唑(uniconazol,S3307)1 g/L喷洒“红富士“苹果树降低了顶芽IAA、GA1,3,4,7含量,提高了ZR、ABA含量,从而提高了ZR/IAA、ZR/GA1,3,4,7、ABA/IAA和ABA/GA1,3,4,7比值.烯效唑处理增加了花芽形成百分率,加速了花芽分化的进程,缩短了花芽形成的延续时期,但对花芽生理孕育临界时期长短没有影响.烯效唑处理对花芽的节位数没有影响,但使叶芽节位数增加了1节.     

Understanding Fluctuations in Bobcat Harvest at the Northern Limit of Their Range

ABSTRACT In Quebec, Canada, harvest of bobcats (Lynx rufus) started to decline in 1985 and by 1991, harvest seasons were closed due to concerns of a perceived population decline. Since the closing of harvest season in 1991, the average temperature has increased, snow quantity has decreased, and important changes in agriculture and forest management have occurred. In light of changing conditions, the situation of Quebec bobcats needed reassessment. Thus, we analyzed harvest data to clarify the current status of bobcat populations in Quebec. From 1980 to 1991, bobcat harvest in Quebec was strongly correlated with bobcat harvest in Maine (USA), Nova Scotia (Canada), Ontario (Canada), and Vermont (USA). Extrapolations of harvest in Quebec relative to harvest in Maine, Ontario, Vermont, and Nova Scotia suggested an increase in number of bobcats after 1991. Mass of male and female bobcats before 1991 was less than mass of animals captured after 1991. Percentage of juveniles in the reported harvest before 1991 was higher than after 1991. However, percentage of males and litter sizes in the harvest did not differ before and after 1991. The geographic distribution of bobcats captured has gradually expanded after the closure of the harvest season. Our findings suggest that bobcat populations in Quebec have recovered from the 1985–1991 decline, and that the harvest season for this species could resume. This study also illustrates how managers can rely on data from neighboring jurisdiction to manage species when local harvest data is unavailable.     

八大公山中亚热带山地常绿落叶阔叶混交林物种组成与结构

山地常绿落叶阔叶混交林在我国主要分布在中亚热带1000～2000 m中山地带。八大公山位于武陵山系北端,中亚热带北缘,具有保护较好的典型山地常绿落叶阔叶混交林。为了研究常绿落叶阔叶混交林动态和川东-鄂西植物多样性形成及维持机制,按照CTFS（Center for Tropical Forest Science）样地建设标准,中国科学院武汉植物园于2010-2011年在湖南八大公山（Badagongshan,BDGS）国家级自然保护区建立了一个25 hm2（500 m×500 m）中亚热带山地常绿落叶阔叶混交林动态监测样地（Forest Dynamic Plot）。本研究以样地内所有胸径（DBH）≥1 cm的木本植物（不含竹藤）为研究对象,分析该样地区系成分、群落组成、垂直结构、径级结构和空间分布。结果表明：八大公山样地属于典型的山地常绿落叶阔叶混交林,植物以泛热带分布科（24.50%）和北温带分布属（24.56%）占优势,包括9种珍稀濒危植物。样地内木本植物合计53科、114属、238种（含种下分类单位）,186556株存活个体。落叶树144种,常绿树94种。壳斗科（Fagaceae）、杜鹃花科（Ericaceae）、樟科（Lauraceae）和山茶科（Theaceae）占据优势;个体数超过1000的有38个物种,以常绿树种（63.16%）为主;稀有种（〈25株）103个（占样地物种总数43.28%）。群落垂直结构可分为乔木层（优势树种多脉青冈Cyclobalanopsis multinervis和亮叶水青冈Fagus lucida）、亚乔木层（优势种长蕊杜鹃Rhododendron stamineum和黄丹木姜子Litsea elongata）和灌木层（优势种短柱柃Eurya brevistyla和薄叶山矾Symplocos anomala）。个体数超过1000的树种和稀有种主要来自灌木层。由于生长型限制,样地内树种平均胸径较小（5.41 cm）,DBH〈5 cm的个体占优势（68.40%）。主要优势树种的径级结构呈现倒J型。