常绿阔叶树种栲树开花物候动态及花的空间配置

 基于定株观测和随机枝取样法,对浙江天童常绿阔叶林内栲树（Castanopsis fargesii）的开花物候动态及其雌花、雄花的空间配置进行了研究。结果表明：在栲树的生殖枝上,并非所有的芽都分化、萌发生成花序,栲树花芽的分化和发育集中在一级生殖枝上。生殖枝上花芽的分化与该枝的空间位置密切相关。栲树花期明显晚于春季的展叶期,与叶片生长时间重叠。盛花期集中于5月下旬,约持续8 d左右,属于同步发生的花期。栲树雄花序的数量明显高于雌花序,雄花序约占花序总数的77.88%,雌花序仅占22.12%。大量雄花和花粉的存在是保证雌花接受花粉和完成受精的基础。花序在植冠层中的空间配置明显不同：在同一植冠内,向阳面和背阴面生殖枝上芽萌发成花序的比率存在明显差异(p<0.01),阳面生殖枝上顶芽萌发成花序的比率高于阴面生殖枝的比率,并且,阳面的每个生殖枝上平均花序数和雄花数量均高于阴面生殖枝,花序的分化和发育与枝系的生长发育状况有密切关系。     

濒危植物金花茶开花物候和生殖构件特征

对桂林雁山迁地保护的金花茶(Camellia nitidissima)开花物候和生殖构件特征进行了研究.结果表明:(1)单花开放过程可分为蕾松、初开、盛开、落花4个阶段,单花寿命约2～8 d;(2)个体花期长,始花时间变异大,单株花期平均为37 d,始花时间可相差2个多月,种群始花时间为1月上旬,3月上旬达到开花高峰期,花期持续近3个月;(3)生殖构件的数量与个体径级和树冠层次有一定关系,地径大于6 cm的个体,其单株花数、生殖枝数、生殖枝比率显著高于地径小于4 cm和4～6 cm个体,而每生殖枝花数则无显著差异;不同树冠层次之间,平均生殖枝数和生殖枝比率,以中、下层显著高于上层,而每生殖枝花数以上层最高,花数在不同冠层之间无显著差异;(4)花芽期败育率为16.33%,花期败育率为63.05%,果期败育率为44.09%,败育率在不同径级个体和不同冠层之间有一定差异;败育率高,结实率低,种子产量少,是金花茶濒危的一个主要原因;(5)开花数目与花期长度呈正相关,个体始花时间与花期长度、座果率之间存在显著的负相关关系.     

荒漠植物白刺属4个物种的生殖分配比较

选定乌兰布和沙漠地区白刺属4种植物为研究对象,通过对其样株在花期的各生殖构件的数量特征及生物量调查,系统研究了唐古特白刺(Nitraria tangutorum Bobr.)、西伯利亚白刺(Nitraria sibirica Pall.)、大白刺(Nitraria roborowskii Kom.)和泡泡刺(Nitraria sphaerocarpa Maxim.)4种白刺属植物在生殖枝水平上的生殖分配。结果表明:不同白刺属植物在分株高度、生殖枝长、生殖枝基径、单枝花数、花序干重、枝叶干重等生殖构件的数量性状方面均有显著差异,其中泡泡刺的各生殖构件的数量均最小;除了西伯利亚白刺的生殖分配值达到44.51%外,其余3种白刺的生殖分配值均没有超过20%。经统计分析,4种白刺种群的生殖枝长分别与分株高度呈显著(P<0.05)的直线性正相关关系;生殖枝花序干重与分株高显著正相关;4种白刺的生殖分配随着分株生殖枝生物量的增加而减少,即白刺的个体大小与生殖分配之间呈现负相关关系。这种生殖分配特点反映了不同白刺植物对生长环境的资源利用、与克隆繁殖的权衡及对生态适应的策略。     

濒危植物长柄双花木自然种群生殖构件的时空动态

根据野外观测数据,研究了濒危植物长柄双花木(Disanthus cercidifolius var.longipes)在不同生境条件下自然种群开花物候变异以及生殖构件的时空动态.结果表明,不同群落类型中长柄双花木开花物候存在一定差异,在纯林中个体的平均花期最长,达75d,而个体间开花同步性最低,仅为0.717;竹林中的个体花期最短,只有47d,而同步指数最高,达0.968.生殖枝数量及花序数均随个体年龄增长而增加,在年龄为30～35年时达最高,此后又呈下降趋势;在海拔为810m左右处,个体生殖枝数及着生的花序数均达最大值,且冠层间差异明显.纯林中个体着生的生殖枝数及每生殖枝上着生的花序数均最高,分别为411.39和7.857;竹林中个体每生殖枝着生的花序数显著低于其它群落.年龄小的个体,各时期生殖构件败育率均高于年龄大的个体;另外,生殖构件的败育与海拔高度间无相关性,而与构件发育时间、分布的树冠层次以及所处的群落类型相关.影响生殖构件败育的主要因子是光照条件.     

间伐强度对黄桥林区辽东栎生殖构件的影响

为了阐明抚育间伐强度对辽东栎生殖构件的影响,以黄土高原南部黄龙和桥山林区辽东栎中龄林为研究对象,对不同间伐强度(对照、10%、20%、30%)下近自然经营抚育间伐5年后的辽东栎平均单株个体大小、生殖构件产量、比率及空间分布格局特征等进行研究.结果表明: 间伐强度对辽东栎林分平均树高、胸径影响不显著,而与冠幅面积、冠幅体积呈显著正相关;辽东栎标准株的生殖枝、幼果、成熟果实产量随间伐强度的增大而增大,而营养枝、雄花序、雄花、雌花的产量变化不大.当间伐强度达到20%时,生殖枝、幼果、成熟果实产量显著提高,30%间伐下达到最大.生殖枝比例和座果率随间伐强度增大而增大,在20%、30%间伐强度时与对照的差异达到显著水平.约3/4的生殖枝、雌花、雄花集中分布于树冠上层,1/4分布于下层;树冠阳面生殖构件数量占65%,树冠阴面占35%.树冠下层、阴面生殖枝、雌花、雄花序的空间分布比例随着间伐强度的增大而增大;树冠上层、阳面生殖枝、雌花、雄花序分布比例随间伐强度的增大呈递减趋势.因此,选择30%间伐强度(保留郁闭度0.6)最佳,可以大幅提高辽东栎的座果率和成熟率,有效提高结实量和品质,为辽东栎林的采种及天然更新提供保证.     

金沙江干热河谷车桑子生殖枝生物量分配的性别差异

以车桑子生殖枝为材料,通过野外调查、取样以及各器官生物量的测定,研究金沙江干热河谷地区车桑子不同性别植株生殖枝生物量分配特征。结果表明：（1）金沙江干热河谷地区车桑子种群雄∶雌性别比为0.11,极显著的偏离1∶1（P<0.001）,种群偏雌性。（2）车桑子生殖枝的形态特征和生物量分配特征均具有显著的性别差异;雌性植株生殖枝花朵生物量和总生物量显著高于雄性和两性植株（P <0.05）,而后两者之间无显著差异;生殖枝生殖分配具有显著的性别差异（P <0.05）,但生殖枝叶生物量无性别差异。（3）生殖枝生物量大小与花朵生物量、营养生物量均呈极显著正相关关系（P <0.001）。营养生物量与花朵生物量之间为显著正相关关系(P <0.01),生殖分配与生殖枝大小无相关关系。研究认为,车桑子生殖枝营养生长与生殖生长不具有权衡关系,且生殖分配不具有个体大小依赖性,特定生物量分配模式可能是对金沙江干热河谷区资源利用、环境适应的一种特殊形态模式。     

两种生境条件下西南桦的生殖构件及其空间格局

在广西靖西土石山生态交错区调查了西南桦(Betula alnoides)生殖植株的生长状况,并研究土山和石山两种生境条件下西南桦的生殖构件及其在冠层的分布格局.结果表明:石山西南桦开始开花结实的林木胸径明显小于土山;两种立地上西南桦植株的花芽、花序数以及雄花序比率与其胸径、树高均不显著相关(P>0.05);土山和石山的西南桦雄花序数随着总花序数的增加均呈对数曲线增长趋势,在生殖投资较小的情况下植株趋向于优先发育雄花序,而在生殖投资较大时主要增加雌花序的数量;西南桦生殖构件在两种生境间存在显著差异,石山植株的雄花芽数、每个雄发芽发育出的雄花序数均显著低于土山(P<0.05),雄花序少于雌花序的植株比例远高于土山,生殖枝比率亦显著低于土山(P<0.05);尽管石山雄花序、雌花序和总花序数量以及雄花序比率低于土山,其雌花序比率高于土山,但是由于两种立地上单株间变异幅度大,独立t检验表明其差异均未达到显著水平;两种立地上西南桦花序大多着生于树冠上、中层,且90%以上的生殖枝居于树冠外层.     

四合木种群生殖对策的研究

 通过研究四合木(Tetraena mongolica Maxim)种群的生殖对策,发现四合木既可进行有性生殖,又可进行营养繁殖,以有性生殖为其主要的生殖方式。有性生殖过程中具以下特征：1)具有自交和异交相结合的交配系统,异交比例(50％)高于自交比例(15％);2)具有花多果少的生殖格局,其开花率与生境、降水、植株年龄关系密切,不同种群的开花率有一定差异,种群的年龄结构对开花率有较大影响。在3～5月降水丰富的情况下,不仅开花比例高(40％～80％),且每一植株的花量很大。不同年份种群结实率普遍偏低,3～5月降雨较少的1996年平均结实率为19.8％;3～5月降雨较多的1998年为12.2％。只是由于开花基数大,对四合木种群种子的总产量不会造成较大威胁;3)胚胎发育过程中败育比率极高,只有约10％～20％的胚能发育成熟。     

白桦的开花时间及生殖构件的数量与树龄和树冠层次的关系

白桦的初始开花结实年龄在不同生境、不同起源情况下是有很大差别的。在相同地生境下,实生苗比萌生苗的始花年龄晚６ａ以上,中生生境的林分始花期要早于湿生生境的林分,在同一年中花期的早晚因林龄而异。花序构件种群、生殖技构件种群以及生殖枝花序数量都与树龄直接相关。花序构件数量壮年期〉老龄期〉结实初期。在同一生殖个体上,构件数量雄花序为中层〉上层〉下层,雌花序数量为土层〉中层〉下层,每个生殖枝平均的花序构件数     

基于液流格型特征值和标准化方法分析胸径和土壤水分对荷木液流的影响

基于液流格型特征值-偏度和峰度分析了不同胸径荷木在水分利用方面的差异,并利用标准化的方法消除强影响因子(光合有效辐射,PAR)对液流的影响,研究了弱影响因子(土壤湿度)与液流的关系.结果表明：荷木胸径越大,偏度越小,液流密度峰值越靠后,相应的液流峰值越大,蒸腾量也越大.与旱季相比,荷木大树在湿季偏度较小,液流密度到达峰值时间靠后,峰值大,蒸腾量也大;而小树偏度在旱、湿季的差异不明显,蒸腾量差异也不大.用PAR峰值对荷木个体蒸腾和土壤湿度进行标准化后,荷木个体蒸腾与土壤湿度呈更明显的正相关关系.在土壤湿度较大的季节,荷木大树的蒸腾量随土壤湿度增加而上升的速率基本稳定;而中等木和小树的某些个体则明显下降,说明这些树木的蒸腾和吸收土壤水分的能力可能接近极限.     

Size and crown shape predict reproductive maturity of Carapa guianensis in upland and floodplain forests in the northeastern Amazon

Comprehending the size distribution within a population and grasping its connection to tree maturation (onset of reproductive phase) is pivotal for formulating sustainable management strategies and conserving numerous tree species. The objective of this study was to compare the structure and probability of fruit production of Carapa guianensis in two types of forest (varzea, or floodplain, vs. terra firme, or upland) in the northeastern Amazon, Brazil. The study was conducted in four permanent plots of 300 × 300 m (two for each type of forest). All individuals ≥10 cm in diameter at breast height (DBH) were mapped and measured for DBH, height, and canopy characteristics (shape and position), and liana infestation. Sixty-seven trees were inventoried in the upland forest and 297 in the floodplain forest. The trees were larger in the upland (33.36 ± 1.84 cm) than in the floodplain (21.92 ± 1.5 cm) and more than half (56%) of the upland trees and more than two thirds (67%) of floodplain trees were reproductive. The minimum diameter for fruit production in the floodplain (10.2 cm of DBH) was more than two times smaller than in the upland (25.5 cm of DBH). The probability of fruit production of a tree of the same size was twice as high in the floodplain compared with the upland, and trees with rounded canopies had a higher probability of fruit production in the upland. Our results showed that the probability of fruit production can be modeled with variables of tree size and canopy shape, and that intrinsic factors of the forests influence the reproductive maturity of C. guianensis which presents greater precocity and productive potential of seeds in the estuarine floodplain forest of the Amazon River.     

Impacts of El Niño related drought and forest fires on sun bear fruit resources in lowland dipterocarp forest of East Borneo

Droughts and forest fires, induced by the El Niño/Southern Oscillation (ENSO) event, have increased considerably over the last decades affecting millions of hectares of rainforest. We investigated the effects of the 1997–1998 forest fires and drought, associated with an exceptionally severe ENSO event, on fruit species important in the diet of Malayan sun bears (Helarctos malayanus) in lowland dipterocarp forest, East Kalimantan, Indonesian Borneo. Densities of sun bear fruit trees (≥10 cm DBH) were reduced by ～80%, from 167±41 (SD) fruit trees ha^?1 in unburned forest to 37±18 fruit trees ha^?1 in burned forest. Densities of hemi-epiphytic figs, one of the main fallback resources for sun bears during periods of food scarcity, declined by 95% in burned forest. Species diversity of sun bear food trees decreased by 44% in burned forest. Drought also affected sun bear fruit trees in unburned primary forest, with elevated mortality rates for the duration of 2 years, returning to levels reported as normal in region in the third year after the ENSO event. Mortality in unburned forest near the burn-edge was higher (25±5% of trees ≥10 cm DBH dead) than in the forest interior (14±5% of trees), indicating possible edge effects. Combined effects of fire and drought in burned primary forest resulted in an overall tree mortality of 78±11% (≥10 cm DBH) 33 months after the fire event. Disturbance due to fires has resulted in a serious decline of fruit resources for sun bears and, due to the scale of fire damage, in a serious decline of prime sun bear habitat. Recovery of sun bear populations in these burned-over forests will depend on regeneration of the forest, its future species composition, and efforts to prevent subsequent fire events.     

胡桃楸个体有性生殖过程研究

胡桃楸是东北东部山地阔叶红松林的重要组成树种。以胡桃楸个体有性生殖过程为研究对象,通过定株定枝调查,研究了胡桃楸芽种群分化、物候及散粉规律、颗粒生长发育过程及环境影响因子。结果表明：１．胡桃楸壮龄树芽种群分化简单。２．胡桃楸个体间花期物候差异很大,并具有典型的雌雄异熟现象。３．胡桃幼果期生长速度快,生长分化现象严重,疏果率高;进入果实生长后期之后,生长速度及疏果率均显著降低。     

Resource patch size and flexible foraging in white-faced capuchins (Cebus capucinus)

White-faced capuchins (Cebus capucinus)on Barro Colorado Island, Panama, have a flexible foraging strategy. Typically, foraging party size is small and individuals feed dispersed from one another. When seasonal fruiting of large volume trees occurs, the majority of the group forages simultaneously. As C. capucinusdo not display a rigorous dominance structure and there are few indications that individuals or coalitions monopolize food patches,individuals are expected to display scramble strategies instead of high frequencies of contest competition. I recorded foraging party size (simultaneous foragers), the total number of animals to feed successively, and the diameter at breast height (DBH) of fruit trees used in two habituated troops. Individuals in each group spent a substantial amount of time — 65 and 48% of foraging time for each group — foraging in party sizes of one. Monkeys predominantly foraged alone in small trees (0- to 20- cm DBH), successively in medium trees (21- to 60- cm DBH), and simultaneously in large trees (>61- cm DBH). They used small trees more frequently than all other tree classes. In medium-sized trees, although fruit was plentiful, space was limited. In these trees Cebusforaged successively. In large-volume trees, space and fruit were abundant and several individuals fed together. As the DBH of fruiting trees increased, the average foraging party size increased exponentially. Cebus capucinusat Barro Colorado Island modify their foraging party size to adapt to the seasonal patterns of fruit production.     

栲树不同生长发育阶段的枝系特征分析

对浙江天童国家森林公园内常绿阔叶优势树种栲树(Castanopsis fargesii)不同发育阶段植冠内的分枝式样特征进行了统计分析。结果表明：栲树在不同发育阶段的总体分枝率和逐步分枝率有显著变化,幼苗和幼树阶段的分枝率较低,而成株阶段的分枝率较高;幼树阶段的枝条长度、枝倾角和叶倾角明显大于幼苗和成株阶段,表现为明显的高生长对策;叶片配置在不同枝系上有较大差异,叶片主要集中于植冠内一级枝和二级枝上;叶片的大小从幼苗、幼树到成株阶段逐渐增大。研究结果表明栲树在生活史的不同生长发育阶段,分枝式样表现出一定的可塑性,反映了不同的适应对策。     

福建和浙江乡村人居林结构特征比较

对位于福建省和浙江省8个地区39个村庄的乡村人居林4种林型(庭院林、道路林、水岸林和游憩林)的树木结构特征进行了调查和分析.结果表明:两省的乡村人居林共有乔木61科130属201种,共有灌木34科52属76种;福建省乡村人居林中乔木种类较为丰富;浙江省乡村人居林中灌木种类较为丰富.4种林型中,庭院林树种数最多,道路林树种数最少;组成庭院林的乔木树种和单株数均最多,而组成道路林的乔木树种及单株数均最少;组成庭院林和游憩林的灌木树种和单株(丛)数均较多,组成水岸林的灌木树种及单株(丛)数最少.在福建省和浙江省乡村人居林中,常绿树种、乡土树种和2003年以前种植的树种株数较多,分别占两省乡村人居林树木总株数的71.05％、85.57％、61.20％和65.95％、76.02％、61.43％;栽植截干和管护截干株数均较少,但浙江省乡村人居林中栽植截干和管护截干的株数均多于福建省.福建省乡村人居林中乔木的胸径、树高、冠幅和枝下高的均值均明显大于浙江省,而两省灌木的地径、树高、冠幅和枝下高的均值差异较小.福建省的游憩林及浙江省的水岸林中乔木的胸径最大,而福建省的水岸林及浙江省的庭院林中灌木的地径最大;福建省乡村人居林中胸径10.0 cm以上的乔木所占比例高于浙江省,其中福建省的4种林型中胸径在30.0 cm以上的乔木树种的平均胸径、种类数及株数均高于浙江省.两省乡村人居林中频度最高的10个树种明显不同,仅香樟[ Cinnamomum camphora (L.)Presl]共存于两省所有林型中.     

The pollination seesaw of Rhynchospora cephalotes (L.) Vahl (Cyperaceae): Influence of plant location on the role of wind and insects as pollen vectors

Ambophily (wind and insect pollination) has been reported for some genera of the typically wind-pollinated family Cyperaceae, including the genus Rhynchospora. The significance of wind and insect pollination can vary, depending on local microclimatic conditions. Rhynchospora cephalotes is an ambophilous species that can grow under different environmental conditions, either along forest edges or inside forest fragments. This study, therefore, tests the hypothesis that (a) there is greater contribution by wind than insects to fruit set of the individuals at the forest edge and (b) there is greater contribution by insects than wind to fruit set of the individuals inside the forest. Field work was carried out in a fragment of Atlantic Forest in northeastern Brazil. We quantified the number of visits by insects, wind velocity and the reproductive success (fruit set) of R. cephalotes provided by wind and insects through exclusion experiments performed at the edge of and inside the forest. We observed a greater number of visits per day by pollinating bees to individuals inside the forest (36.83 ± 7.46) than to individuals at the edge (16.66 ± 6.53). The wind speed was significantly higher at the edge (1.71 ± 0.46 m/s) than inside the forest (0.97 ± 0.18 m/s). Bees and wind are both pollen vectors of R. cephalotes, but bees were the pollen vector that contributed most to fruit set (63.3%) for individuals inside the forest, whereas wind was the primary vector for individuals at the forest edge (76.6%). This seesaw in importance of each pollen vector in the two different environments guarantees high fruit set in R. cephalotes under different microclimatic conditions.     

'Nucleating’ succession in recovering neotropical wet forests: The legacy of remnant trees

Question: What is the influence of remnant trees on secondary forest structure and composition in tropical pastures many years after abandonment? Location: Neotropical lowland wet forest, La Selva Biological Station, Costa Rica. Methods: Tree and sapling density, basal area, and species richness were quantified at three distances from remnant trees, 0–10 m (inner), 20–30 m (intermediate), and ca. 50 m (distal) zones. A total of 15 remnant trees were sampled in pastures ~23 years after abandonment. Results: Tree density decreased along a gradient from inner (1117 ± 377 individuals/ha) to distal (592 ± 282 individuals/ha) zones, and the number of large‐seeded individuals (seeds > 1 cm diameter) was significantly greater in the inner zone. Basal area of tree individuals was greater in the inner (25.6 ± 12 m²/ha) and intermediate (28.3 ± 15.6 m²/ha) zones than the distal zone (14.7 ± 7.2 m²/ha), but there were no differences between inner and intermediate zones. Similar patterns are reported for species richness. Additionally, saplings (1 ‐ 5 cm DBH) had higher density directly beneath and adjacent to remnants, suggesting that remnant trees can affect recruitment even many years after pasture abandonment and the formation of a surrounding secondary forest. Conclusions: Results indicate that remnant trees facilitate forest recovery over a broad temporal range, and appear to ‘nucleate’ forest regeneration by expanding their sphere of influence outward over time.