广西弄岗五桠果叶木姜子群落木质藤本空间格局及其与树种间的关系

木质藤本是生物多样性的重要组成,木质藤本通过影响支持木进而影响群落的结构和功能,但在生物多样性丰富的北热带喀斯特森林中,木质藤本与支持木的关系鲜为人知。以喀斯特季节性雨林的五桠果叶木姜子（Litsea dilleniifolia）群落为研究对象,对木质藤本的密度、分布格局及其与主要树种的关系进行调查研究,分析木质藤本对树木的影响。结果显示：（1）五桠果叶木姜子群落内木质藤本平均密度为0.0913株/m²,木质藤本在0-20m空间尺度整体表现为聚集分布,且随着尺度增大,聚集强度逐渐减弱;不同径级木质藤本在不同尺度上的分布格局不同。（2）木质藤本对不同径级、不同种类、不同聚集强度的支持木选择表现以下体征：随着支持木径级增加,木质藤本攀附的比例和每木藤本数有增加趋势,且木质藤本胸径与支持木胸径呈极显著正相关;附藤率较高的支持木有紫葳科（Bignoniaceae）种类和东京桐（Deutzianthus tonkinensis）,单木附藤数量多的是南方紫金牛（Ardisia thyrsiflora）;物种的聚集强度与附藤率、附藤数量呈负相关。（3）木质藤本的密度与支持木死亡率关系不显著,而物种的附藤率与死亡率呈极显著负相关。以上结果表明,木质藤本密度在原生性喀斯特季节性雨林中并不高,且木质藤本对支持木具有选择性,但其对五桠果叶木姜子群落的死亡率并未产生显著影响。该研究可为喀斯特原生性季节性雨林的物种共存、极小植物种群保育提供理论依据,也可为石漠化区域的植被修复提供科学参考。     

桂西南喀斯特季雨林木本植物的水力安全

桂西南喀斯特地区生物多样性丰富、特有种多, 同时也是石漠化问题较为严重的区域。由于该喀斯特地区土层浅薄、岩石裸露、表层储水能力差, 植物在干旱季节经常会受到水分胁迫。植物水力学特征不仅是探讨喀斯特地区植物的生理生态适应性的关键, 还能够为石漠化地区的植被恢复提供重要参考。该研究测定了桂西南喀斯特季雨林17种代表性木本植物(包括不同生活型、叶片习性和生境)的木质部脆弱性曲线、最低水势、叶片膨压丧失点和边材密度等水力性状, 结果发现: (1)喀斯特植物木质部导水率丧失50%时的水势值(P₅₀)的种间差异较大(-0.51- -2.51 MPa), 其中常绿种的抗栓塞能力比落叶种强; (2)喀斯特植物的木质部水力安全边界值(最低水势与P₅₀之间的差值)的均值为0.36 MPa, 说明喀斯特森林植物在自然最低水势状况下木质部发生栓塞的程度较高; 但是不同植物种间存在显著差异, 这可能与喀斯特峰丛洼地生境的复杂性以及物种不同的抗旱策略有关; (3)由于喀斯特植物水分适应机制的多样化, 导致木质部水力安全边界与叶片膨压丧失点、边材密度的相关性并不显著。在区域气候干热化的背景下, 结合喀斯特植物的栓塞脆弱性和长期水势监测(尤其极端干旱事件)分析它们的水力安全, 对预测未来喀斯特森林物种分布和群落动态具有重要的指示作用。     

滇南勐宋热带山地雨林的物种多样性与生态学特征

 研究了鲜为人知的滇南勐宋地区的原始山地雨林植被, 根据分布生境、群落结构和种类组成特征,可将该山地雨林区分为沟谷和山坡两个类型, 分别定义为八蕊单室茱萸(Mastixia euonymoides)-大萼楠(Phoebe megacalyx)林和云南拟单性木兰(Parachmeria yunnanensis)-云南裸花(Gymnanthes remota)林。该山地雨林的外貌仍以单叶、革质、全缘、中叶为主的常绿中、小高位芽植物组成为特征,层间木质藤本植物仍较丰富,草本高位芽植物和附生植物丰富,但板根和茎花现象少见,属于热带山地垂直带上低山雨林或山地雨林植被类型。与该地区的典型热带季节雨林和赤道热带雨林相比, 勐宋的山地雨林群落中的大、中高位芽植物和藤本高位芽植物比例相对减少, 小、矮高位芽植物和草本高位芽植物比例相对增加,单叶、革质、非全缘叶和小叶比例相对增加,板根现象少见。与中国热带北缘-南亚热带地区（季风）常绿阔叶林比较, 勐宋的山地雨林有较多的附生植物和草本高位芽植物,相对较少的小高位芽植物和矮高位芽植物,小叶比例亦较少,非全缘叶和革质叶比例相对较低。故勐宋山地雨林是滇南热带北缘山地的一种较湿润生境的植被类型, 与所谓的季风常绿阔叶林不同。在物种多样性上,勐宋热带山地雨林在单位面积植物种数上并不比该地区的热带季节雨林低, 物种多样性指数与低丘季节雨林相当,比沟谷季节雨林低, 明显高于季风常绿阔叶林。     

Fruit types and seed dispersal modes of plants in different communities in Shilin Geopark,Yunnan, China

喀斯特植物群落果实类型和种子散布特征的研究, 对于理解喀斯特植物群落更新与拓展特征, 进而揭示喀斯特石漠化地区恢复植被的自然扩展机制及制定植被恢复规划具有重要意义。该研究以石林地质公园不同群落类型为对象, 研究不同群落的果实类型谱与种子散布谱, 以揭示果实类型与种子散布方式对恢复植被的影响。采用石林地质公园不同群落各1 hm ²样地记名计数法调查的维管束物种名录, 依据Flora of China对物种果实的描述确定其果实类型; 根据文献、数据库以及果实、种子形态性状确定种子散布方式。结果表明: (1)石林地质公园282种维管束植物共16种果实类型(含孢子), 其中瘦果、蒴果、浆果和核果的物种比例均大于10%。木本植物、草本植物、藤本植物的优势果实类型分别为核果、瘦果和浆果。石林地质公园各群落的木本植物、草本植物和藤本植物的果实类型谱差异不显著。在原生林、次生林、灌丛、灌草丛和人工辅助云南松林不同群落中, 浆果和核果的物种比例减少, 瘦果、颖果和蒴果的物种比例增加。(2)石林地质公园植物种子以动物传播为主, 其次为风传播。在原生林、次生林、灌丛、灌草丛和人工辅助云南松林不同群落中, 风传播的物种比例增加了73%-87%, 动物传播(包括鸟类传播)减少了31%-36%。(3)物种的种子散布方式直接影响到植被恢复物种和恢复策略的选择。基于恢复目标, 选择自然传播能力强的乡土物种或地带性植被关键种, 辅以传播廊道, 有助于喀斯特的植被恢复。     

Impacts of nitrogen addition on foliar nitrogen and phosphorus stoichiometry in a subtropical evergreen broad-leaved forest in Mount Wuyi

Aims Our purpose was to explore the effects of nitrogen addition on foliar nitrogen (N), phosphorus (P) and N:P stoichiometry and to assess their differences among different species and functional groups.
Methods N addition experiment has been conducted in a subtropical evergreen broad-leaved forest in Mount Wuyi, Fujian Province since 2011. Foliar concentrations of nitrogen and phosphorus were measured and foliar stoichiometry was estimated in tree, shrub, herb, fern and moss species following the N addition treatments from 2013 to 2015.
Important findings Generally, foliar N increased for almost all species and herbaceous plants are much more sensitive than trees and shrubs under N addition. Foliar N of Castanopsis carlesii, Amomum villosum, Woodwardia japonica increased significantly under N addition. Foliar P for most species was sensitive to the N addition. Foliar P of herbaceous plants increased significantly but foliar P of Leucobryum chlorophyllosum decreased significantly. The results showed the subtropical evergreen forest in Mount Wuyi was mainly limited by P and mean foliar N:P ratios enhanced from 18.67 to 19.72 under N addition, indicating that the strength of P limitation was enhanced by N addition. N:P ratios of the dominant arboreal species in the communities tended to be stable, while N:P ratios of herbaceous plants and shrubs increased. The changes in N:P ratios were mainly determined by P dynamics instead of N dynamics under N addition, and our results confirmed that increasing N availability can affect P cycling.     

Reproductive phenology of Melastomataceae species with contrasting reproductive systems: contemporary and historical drivers

• Flowering and fruiting are key events in the life history of plants, and both are critical to their reproductive success. Besides the role of evolutionary history, plant reproductive phenology is regulated by abiotic factors and shaped by biotic interactions with pollinators and seed dispersers. In Melastomataceae, a dominant Neotropical family, the reproductive systems vary from allogamous with biotic pollination to apomictic, and seed dispersal varies from dry (self‐dispersed) to fleshy (animal‐dispersed) fruits. Such variety in reproductive strategies is likely to affect flowering and fruiting phenologies.
• In this study, we described the reproductive phenology of 81 Melastomataceae species occurring in two biodiversity hotspots: the Atlantic rain forest and the campo rupestre. We aim to disentangle the role of abiotic and biotic factors defining flowering and fruiting times of Melastomataceae species, considering the contrasting breeding and seed dispersal systems, and their evolutionary history.
• In both vegetation types, pollinator‐dependent species had higher flowering seasonality than pollinator‐independent ones. Flowering patterns presented phylogenetic signal regardless of vegetation type. Fruiting of fleshy‐fruited species was seasonal in campo rupestre but not in Atlantic rain forest; the fruiting of dry‐fruited species was also not seasonal in both vegetation types. Fruiting showed a low phylogenetic signal, probably because the influence of environment and dispersal agents on fruiting time is stronger than the phylogenetic affinity.
• Considering these ecophylogenetic patterns, our results indicate that flowering may be shaped by the different reproductive strategies of Melastomataceae lineages, while fruiting patterns may be governed mainly by the seed dispersal strategy and flowering time, with less phylogenetic influence.

     

Cattle change plant reproductive phenology,promoting community changes in a post-fire Nothofagus forest in northern Patagonia,Argentina

Aims Variations in rates and length of flowering and fruiting not only affect the reproduction of a given plant species but also the behavior and reproduction of associated taxa. Flowering and fruiting variations may be influenced by herbivory, especially by large mammals. The aim of this study was to determine the effects of cattle browsing on the reproductive phenology of understory species in a subalpine post-fire Nothofagus forest in Patagonia.Methods The effects of herbivory on plant reproductive phenology were studied in a set of experimental exclosures (fenced plots) installed since 2001 in a post-fire N. pumilio forest, located in Nahuel Huapi National Park (NHNP), Argentina. We monitored the beginning and duration of each reproductive phenological stage: floral bud, open flower, immature fruit and mature fruit. We also counted the number of flowers, fruits, seeds and viable seeds of the dominant plants to assess whether browsing modifies temporal patterns of the flowering and fruiting periods.Important findings Cattle reduced the total number of species flowering and fruiting and changed the reproductive phenology of some species. We found that palatable species seem to be negatively affected by browsing in terms of reduced fitness due to changes in flowering and fruiting periods. In contrast, cattle benefitted the reproduction of non-palatable species and could promote the invasion of shade-intolerant exotic forbs such as Cirsium vulgare. The effects of livestock reported in this study are important to understanding how browsing could alter native species establishment and possibly alter successional trajectories during recolonization after fire.     

湖北星斗山地形变化对不同生活型植物叶功能性状的影响

探究地形变化对不同生活型植物叶功能性状的影响有助于深入理解森林群落物种组成的维持特征。该研究以湖北星斗山常绿落叶阔叶混交林为研究对象, 测量了50个样地中224种木本植物的叶面积、叶厚度、叶干质量、叶干物质含量和比叶面积, 运用单因素方差分析揭示了乔木、灌木和木质藤本的叶功能性状变异特征, 并采用偏曼特尔检验分别从群落水平和物种水平分析了地形变化对不同生活型木本植物叶功能性状的影响。研究发现: 不同生活型植物叶性状变异系数分布范围为23.42%-110.45%; 不同生活型之间的植物叶功能性状差异明显。群落水平上, 海拔与乔木叶干质量、灌木叶面积和木质藤本叶厚度显著正相关, 坡度仅对灌木和木质藤本比叶面积具有显著影响, 坡向与灌木叶厚度、叶干质量和比叶面积显著正相关。物种水平上, 海拔比坡度和坡向对植物叶功能性状影响更为显著, 且不同物种对地形变化的敏感度不一致; 在控制空间结构影响后, 地形因子对植物叶功能性状的影响降低。该研究结果表明, 不同生活型植物的叶功能性状对地形变化的响应格局不同, 这可能是星斗山常绿落叶阔叶混交林植物多样性的主要维持机制。     

Growth-form regulates the altitudinal variation of interspecific seed mass of woody plants in Mt. Dalaoling,the Three Gorges Region,China

Aims Seed size is one of the most important characteristics of plant seeds, and has significant implications in plant ecological functions. Exploring the altitudinal pattern of seed size would help to detect environmental constraints on species distribution and understand the linkage between plant ecological function traits Methods The present study measured the quantitative features of seed size, including weight of 1 000 grain seeds, lengths of longer and shorter axes, and analyzed the relationships between seed size and altitude, as well as the influence of growth form. Seed samples were all collected from 201 locally common woody plants (belonging to 59 families and 87 genera) in the Dalaoling Natural Reserve in Yichang City, Hubei Province.Important findings Measured values of the seed mass, the longer axis, and the shorter axis of the 201 woody plant species all follow the lognormal distribution. Measurements of seed mass vary across five orders of magnitude. Significant correlation was found between seed mass, seed length of the longer and shorter axes (R² = 0.755; 0.819; 0.630, p < 0.01). Moreover, seed mass of trees and small trees are significantly heavier than those of shrubs and woody vines. Seed mass values of evergreen broad leaved species are significantly heavier than those of deciduous broad leaved species and needle leaved species. Seed mass of all 201 species shows a slightly but statistically significant decreasing trend with the increase of altitude. In addition, altitudinal patterns of seed mass varied between species with different growth form. Our results indicated the variation of altitudinal trends of seed mass for different structural components of plant communities, implying the local community structure as a critical aspect of variation in macro-ecological patterns.     

北热带喀斯特森林木本植物花性状及其生境分异

植物花性状的多样化是植物长期进化及自然选择的结果, 不同植物种间花性状的变异与生境存在一定的相关性。北热带喀斯特季节性雨林具有生境异质性强、群落结构复杂、特有成分丰富等特点, 分析该森林植物性状的变化特征及其与生境的关联性, 有助于理解物种共存、协同进化过程和对生境的适应, 可为阐明喀斯特植物的生态适应性、理解生物多样性维持机理提供依据。本研究在弄岗15 ha森林动态监测样地木本植物开花相对集中的时间段进行, 记录并分析了21个物种花性状的变化。根据物种空间分布及其与生境的关联特性, 将21个物种分成偏好谷底、山坡、山顶的3种类型, 分析了这3种类型植物的花性状差异; 另外又根据花性状对21个物种进行聚类分析, 探讨了聚类分组结果和根据偏好生境分组结果的异同。结果表明: 花大小、花色鲜艳度均与物种优势度存在显著的负相关关系, 花小而不鲜艳的物种在群落中更有优势, 表现出更好的适应性; 不同偏好生境的植物花色明度有显著差异, 其他的花性状差异不显著; 聚类分组与根据偏好生境的分组有较好的一致性, 反映出物种的花性状变化响应了生境的变化。综上结果, 我们认为北热带喀斯特季节性雨林植物花性状与物种的优势度及生境条件有密切联系, 在该区域中生境对花性状的影响可能比传粉者更为深刻。     

Life History Traits of Lianas During Tropical Forest Succession

Tropical secondary forests form an important part of the landscape. Understanding functional traits of species that colonize at different points in succession can provide insight into community assembly. Although studies on functional traits during forest succession have focused on trees, lianas (woody vines) also contribute strongly to forest biomass, species richness, and dynamics. We examined life history traits of lianas in a forest chronosequence in Costa Rica to determine which traits vary consistently over succession. We conducted 0.1 ha vegetation inventories in 30 sites. To examine the establishment of young individuals, we only included small lianas (0.5–1.5 cm diameter at 1.3 m height). For each species, we identified seed size, dispersal mode, climbing mode, and whether or not the seedling is self‐supporting. We found a strong axis of variation determined by seed size and seedling growth habit, with early successional communities dominated by small‐seeded species with abiotic dispersal and climbing seedlings, while large‐seeded, animal‐dispersed species with free‐standing seedlings increased in abundance with stand age. Contrary to previous research and theory, we found a decrease in the abundance of stem twiners and no decrease in the abundance of tendril‐climbers during succession. Seed size appears to be a better indicator of liana successional stage than climbing mode. Liana life history traits change predictably over succession, particularly traits related to seedling establishment. Identifying whether these trait differences persist into the growth strategies of mature lianas is an important research goal, with potential ramifications for understanding the impact of lianas during tropical forest succession.     

Variations of plant functional traits and adaptive strategy of woody species in a karst forest of central Guizhou Province,southwestern China

性状变异反映了植物的生活史对策。该研究以贵州普定县天龙山10种木本植物为对象, 通过分析枝叶和根系9个功能性状的种间与种内变异, 揭示植物对喀斯特生境的适应策略。结果表明: (1) 9个性状变异程度不同, 细根组织密度的种间和种内变异系数最大, 分别达96.47%和51.44%, 小枝干物质含量的种间与种内变异最小, 分别为11.67%和6.83%。(2)种间水平的细根组织密度在不同物种中没有显著的差异, 比根长、叶厚度、叶面积、比叶面积、叶干物质含量、叶组织密度、小枝干物质含量和小枝组织密度均表现出显著的差异。在种内, 比叶面积差异显著, 其他性状差异不显著。(3)绝大多数叶和枝性状间显著相关, 比根长与比叶面积显著负相关, 其他根系性状与枝叶性状相关性不显著。总之, 与同纬度非喀斯特地区植物相比, 普定喀斯特地区植物具有较小的叶面积和比根长度, 较大的叶干物质含量、叶组织密度等一系列有利于减小蒸腾和储存养分的功能性状组合, 这可能是其适应干旱贫瘠的喀斯特环境的主要生态策略。     

Reconstitution d'un « paysage de l'époque houillère » revue à la lumière des découvertes récentes sur les cuticules végétales fossiles

To date, plants with a climbing or scrambling growth habit are widely represented in equatorial forest ecosystems, with a warm and humid climate, with a variety of different species. Although it has been speculated repeatedly that several Late Carboniferous seed ferns applied the same growth strategies as modern vines and /or lianas, only few examples have been substantiated in sufficient details. Most Paleozoic seed ferns are reconstructed as free-growing erect trees. However, these last years, new discoveries about the growth habits of fossil plants have been highlighted on the basis of cuticular material. In this way, different types of climbing organs of seed ferns, reported on pteridosperm cuticles collected from the Stephanian basin of the Blanzy-Montceau (central France), have revolutionized the stereotype of “free-growing erect trees” that we had about these plants. These discoveries demonstrate the potential of cuticular analysis for the reconstruction of growth habits of fossil plants. Moreover they exemplify that climbing and scrambling became common life strategies among Late Carboniferous seed ferns. The increasing proportion of climbing seed ferns in the Stephanian, interpreted as an expression of changing structures of Late Paleozoic coal swamp forests, lead to modify the “classical” reconstructions of the Late Carboniferous landscapes.     

神农架常绿落叶阔叶混交林碳氮磷化学计量比

生态化学计量学是研究生态过程中化学元素平衡的科学, 碳(C)、氮(N)、磷(P)化学计量比是生态系统过程及其功能的重要特征。该研究测定了神农架常绿落叶阔叶混交林植物器官、凋落物及土壤的C、N、P含量, 利用生物量加权法计算其化学计量比, 并分析该生态系统不同组分间及不同器官间化学计量比的差异。研究结果发现: 在不同组分之间, C含量、C:N及C:P表现为植物>凋落物>土壤; N、P含量及N:P表现为凋落物>植物>土壤。在不同植物器官间, C含量的差异较小, 其变异系数相对N、P含量较低且保持稳定; N、P含量为叶片最高且变异系数最低; N:P为树皮最高, 而枝的变异系数最低。常绿与落叶树种的叶片N、P含量差异显著。与不同森林类型的化学计量比相比, 该常绿落叶阔叶混交林植物群落的C:P及N:P较低, 凋落物的C:P及N:P较高, 土壤的C、N、P化学计量比与亚热带常绿阔叶林基本一致, 生态系统的C:N相对较低。利用生物量加权法计算得到的该森林生态系统不同组分的C、N、P化学计量比的大小关系与前人利用枝叶取样算术平均的结果存在较大差异。C、N、P含量及其化学计量比在不同器官的分配及内稳性与器官的生理功能关系密切。     

Effects of seasonal snow cover on decomposition and carbon,nitrogen and phosphorus release of Picea schrenkiana leaf litter in Mt. Tianshan,Northwest China

季节性雪被下显著的冻融格局差异可能对干旱区山地森林凋落叶分解过程产生重要影响, 但一直未见深入研究。2015年10月至2016年10月, 采用凋落物分解袋法, 研究了天山典型树种雪岭云杉(Picea schrenkiana)凋落叶在季节性雪被覆盖下的3个关键时期(冻融期、深冻期、融冻期)以及生长季(生长季早期和生长季末期)的分解动态和碳、氮、磷释放特征。结果表明: (1)经过一年的分解, 不同雪被厚度下雪岭云杉凋落叶分解率为24.6%-29.2%, 且存在显著性差异。分解系数k值厚雪被覆盖最大, 无雪被覆盖最小。(2)冬季雪被覆盖期雪岭云杉凋落叶分解对当年分解总量的贡献达46.0%- 48.5%, 其中对冻融期凋落叶分解影响较为明显。(3)随着凋落叶的分解, 雪岭云杉凋落叶氮含量总体呈增加趋势; 碳含量和碳氮比大致呈下降趋势, 在深冻期和生长季末期不同雪被处理下碳含量呈显著性差异; 而凋落叶磷含量呈不规则变化趋势, 且在冻融期和融冻期不同雪被厚度下呈显著性差异。(4)整个雪被覆盖季节凋落叶氮元素表现为富集, 碳和磷元素表现为释放; 其中, 在融冻期薄雪被和中雪被处理下碳元素富集率最大, 在冻融期薄雪被、中雪被和厚雪被处理下, 融冻期无雪被和厚雪被下以及生长季早期中雪被和厚雪被下氮元素富集率最大, 而雪被对凋落叶磷释放的影响不显著。     

Associations between litterfall dynamics and micro-climate in forests of Putuoshan Island,Zhejiang, China

Aims Seasonal litterfall production plays an important role in the carbon and nutrient cycling in forest ecosystems. This study examines the effects of micro-environmental factors on seasonal litterfall dynamics in the forests of Putuoshan Island, Zhejiang Province of eastern China.
Methods The study covers five forest types, including Liquidambar formosana forest, Cinnamomum japonicum and Machilus thunbergii forest, Pinus massoniana forest, Cyclobalanopsis glauca forest, and Distylium gracile forest, in Putuoshan Island. We collected micro-meteorological data, and measured monthly litterfall in stands of the five forest types over one year. Redundancy analysis (RDA) was performed to determine the effects of micro-climatic factors on litterfall production．
Important findings The average annual litterfall production ranged from 3.45 to 5.36 t·hm^-2·a^-1 across five types of forests, albeit no effect of forest types on the litterfall production. The partitioning of litterfall components differed among the five forest types. The seasonal litterfall production exhibited two contrasting patterns, i.e. double climax curve and triple peaks, and varied significantly among the five forest types. Moreover, the peak in the litterfall production mostly occurred in the windy months of the year, such as in April, July and December, which was consistent with the dynamics of wind speed. RDA results showed that components of litterfall production in different months were controlled by different micro-climatic factors. The total, leaves, fruits, and miscellaneous litterfall productions were directly and positively affected by air temperature. Twig litterfall production was positively affected by the overstory wind velocity. Flower litterfall production was negatively affected by air humidity. In summary, forest types had no effects on litterfall production. However, variations in litterfall productions were explained by air temperature, air humidity, and overstory wind velocity in the forests studied.     

Reproductive Traits and Phenology of Plants in Tropical Dry Evergreen Forest on the Coromandel Coast of India

Qualitative reproductive traits of 84 plant species belonging to 41 families were studied in tropical dry evergreen forest on the Coromandel coast of India. Majority of species had rotate type, white-coloured, scented flowers, rewarding nectar and pollen and pollinated chiefly by bees. An association between floral traits and pollination spectrum is evident. Bee pollination was prevalent in pollination systems. Among the fruit types, drupe and berry were common in black and red colour respectively, and dispersed by zoochorous mode. Seeds of brown- and green-coloured dry fruits, without any reward were disseminated by wind and explosion. The reproductive phenophase of trees and lianas occurred mostly during the dry period from January to June, which receives rainfall of less than 50 mm a month. However, shrubs showed a peak in flowering and fruiting in wet period. Detailed phenological observations of 22 woody species revealed a seasonal and unimodal pattern in flowering. Although some species were in flower round the year, flowering activity was skewed towards the dry season. The fruiting activity showed a bimodal pattern, one peak in dry season and another in wet season. Many species displayed a temporal aggregation in flowering and fruiting. The significant relation was obtained between reproductive traits and phenology of plants in the tropical dry evergreen forest.     

Relationships between species diversity or community structure and productivity of woody-plants in a broad-leaved Korean pine forest in Jiaohe,Jilin, China

Aims Based on the dataset of a broad-leaved Korean pine forest in Jiaohe, Jilin Province, this research compared the influences of species diversity and community structure on productivity. We aim to explain the relationship between diversity and productivity for better forest management. Methods We used the data of 10 973 woody-plants in a 11.76 hm² large sample plot and analyzed the correlations between 7 different indices of species diversity or community structure and productivity. Structural equation model was used to compare the effects of species diversity and community structure on productivity. Important findings The results showed that: (1) Both species diversity and community structure had significant effects on productivity when they were considered separately in linear regression analysis, i.e. species evenness was negatively correlated with productivity, the Shannon index of community structure was positively correlated with productivity and the Gini index was negatively correlated with productivity. (2) In the structural equation model, when simultaneously considered, community structure had stronger influence on productivity than species diversity. Our research suggests that, the effects of community structure on productivity are greater than species diversity and it is important to increase community structure complexity to improve forest productivity during forest management.     

喀斯特季节性雨林蚬木种群的增长模型

蚬木是喀斯特季节性雨林的优势种和特征种,研究蚬木种群的增长过程将为深入理解喀斯特季节性雨林动态提供基础。根据一个15hm2固定样地的调查数据,采用logistic模型及其4种改进模型对蚬木种群的增长过程进行了拟合,用残差平方和、决定系数和AIC准则对拟合的模型进行评价。结果表明:李新运模型和刘金福模型的拟合效果较好,但综合考虑模型的拟合效果和模型的简洁性,logistic模型和S形增长过程模型为较优模型。用logistic模型对蚬木种群的增长过程进行深入分析发现,种群增长最快的时期为50a左右,而在150a后,种群逐渐进入增长饱和期。种群目前接近增长饱和期,所以应加强保护,以维持蚬木群落的稳定发展。