Gap phase regeneration recruitment of mixed conifer-broadleaf forests in Wolong Nature Reserve

Wolong Nature Reserve is the largest reserve for protecting the endangered wild giant panda. Due to historical factors, even in many sections of the core protection area, the forests have been seriously destroyed and natural forests are poorly restored. However, the relative importance of the determinants for recruitment of communities under disturbance is rarely explored. In our study the endogenous and exterior factors in a forest gap that affect the conifer-broad-leaved mixed forest regeneration were investigated near Wuyipeng, one of the observation stations at Wolong, to explore which determinant had the greatest effect on gap regeneration and to discover the recruitment of seedling establishment in forest gaps. With a linear sampling method, environmental factors, gap characteristics and recruitment of new individuals were measured and examined in every forest gap along three sampling lines. Data of environmental factors in the gaps were collected for a Pearson correlation analysis in order to explore the disturbance and preprocessed characteristics of the gaps, using principal component analysis in SPSS. Correlation analysis was applied to further explore the relationship between changes in the gaps and the response of the regenerating seedlings. The results show that a range of natural and human disturbances affected the pattern and characteristics of the forest gaps in this area. The richness in the composition of the seedlings was higher than that of gap makers, but the order of dominance of the composition was different between seedlings and gap makers. The success of dominant species in establishing themselves was affected by different environmental factors. For instance, the establishment of Betula spp. was correlated significantly with topographic factors, while that of Abies faxoniana was affected by soil characteristics and that of Rhododendron spp. correlated significantly with topographic factors and characteristics of gap makers. Moreover, all the biodiversity indices of regenerating seedlings were significantly correlated with environmental principle components mostly reflecting soil properties. From this we can infer that soil characteristics are the most important factors affecting the regeneration of dominant species and seedling diversity under gap disturbances. __________ Translated from Journal of Plant Ecology (Chinese Version), 2007, 31 (3): 425–430 [译自: 植物生态学报]     

Native woody species regeneration in exotic tree plantations at Munessa-Shashemene Forest,southern Ethiopia

Regeneration of native woody species was studied in the plantations and the adjacent natural forest at Munessa-Shashemene Forest Project Area, Ethiopia. The aim of the study was to test the hypothesis that tree plantations foster regeneration of native woody species. A total of 60 plots, having 10 × 10 m area each, were studied in monoculture plantations of 4 exotic species (Cupressus lusitanica, Eucalyptus globulus, E. saligna, Pinus patula) and an adjacent natural forest. Ages of the plantations ranged between 9 and 28 years. Soil seed bank analysis was also undertaken from soil samples collected in each of the 60 plots to examine the similarity between the soil seed flora and aboveground vegetation. A total of 56 naturally regenerated woody species were recorded beneath all plantation stands with densities ranging between 2300 and 18650 individuals / ha in different stands. There was a significant difference among plantation stands with regard to understorey density (standard deviation: 4836 ± 1341). Vegetation diversity was assessed through analyses of floristic composition, species richness and abundance. Generally, seedling populations were the most abundant components of the regeneration in most of the plantation stands, forming 68 % of the total regeneration count in all stands. A total of 77 plant species represented by 44 herbs, 13 woody species, 8 grasses and 12 unidentified species were recorded in the soil seed bank from all stands. Similarity between the soil seed bank and aboveground flora was very low implying that the role of soil seed banks is negligible rather dispersal plays an important role in the process of regeneration. These results support the concept that forest plantations can foster the regeneration of native woody species, thereby increasing biological diversity, provided that there are seed sources in the vicinity of the plantations.     

长白山北坡森林群落交错区优势树种动态

基于28个20mx90m样地的调查数据,利用Lotka-Volterra模型,本文分析了长白山北坡阔叶红松(Pinuskoraiensis)林和云冷杉林(也叫暗针叶林)群落交错区优势树种之间的竞争及动态。结果显示:在自然条件下,群落将向两个方向分化,一是以云杉(PiceajezoensisandP.koraiensis)和冷杉(Abiesnephrolepis)为优势的群落,并在达到平衡时冷杉占绝对优势(相对优势度的77.1%):另一种是以红松或云冷杉和阔叶树占绝对优势的针阔混交林,并在达到平衡时,阔叶树在阔叶红松林中占相对优势度的50%,在云冷杉一阔叶林类型中占66%。同时,本研究说明:(1)阔叶红松林和云冷杉林都是长白山气候顶极群落:(2)交错区具有过渡性质:(3)森林群落的分化结果说明演替的方向受局部生境的影响。图1表3参24。     

Tree and stand structure of the non-native Pinus contorta in relation to native Pinus sylvestris and Picea abies in young managed forests in boreal Sweden

Managed forest stands are typically younger and structurally less diverse than natural forests. Introduction of non-native tree species might increase the structural changes to managed forest stands, but detailed analyses of tree- and stand-structures of native and non-native managed forests are often lacking. Improved knowledge of non-native forest structure could help clarify their multiple values (e.g. habitat for native biodiversity, bioenergy opportunities). We studied the structural differences between the introduced, non-native Pinus contorta and the native Pinus sylvestris and Picea abies over young forest stand ages (13–34 years old) in managed forests in northern Sweden. We found that P. contorta stands had greater mean basal areas, tree heights, diameters at breast height, and surface area of living branches than the two native species in young stands. The surface area of dead attached branches was also greater in P. contorta than P. abies. Although this indicates greater habitat availability for branch-living organisms, it also contributes to the overall more shaded conditions in stands of P. contorta. Only one older 87 years old P. contorta stand was available, and future studies will tell how structural differences between P. contorta and native tree species develop over the full forestry cycle.     

Colonisation of native and exotic conifers by indigenous bark beetles (Coleoptera: Scolytinae) in France

Planting exotic conifers offers indigenous forest insects an opportunity to extend their host range and eventually to become significant pests. Knowing the ecological and evolutionary modalities driving the colonisation of exotic tree species by indigenous insects is thus of primary importance. We compared the bark beetle communities (Coleoptera: Curculionidae, Scolytinae) associated with both native and introduced conifers in France. The aim of our study was to estimate the influence of both host- and insect-related factors on the beetles’ likelihood to shift onto new hosts. We considered the influence of host origin (i.e. native vs. exotic), host tree species identity, tree bark thickness and tree taxonomic proximity, as well as insects’ host specificity. A field inventory using trap trees was carried out in two regions in France (Limousin and Jura) during two consecutive years (2006 and 2007) on three European native conifer species [Norway spruce (Picea abies); Scots pine (Pinus sylvestris) and European Silver-fir (Abies alba)] and five North American [Sitka spruce (Picea sitchensis); Eastern white pine (Pinus strobus); Grand fir (Abies grandis); Douglas fir (Pseudotsuga menziesii) and Western red cedar (Thuja plicata)]. A total of 18 indigenous and 2 exotic bark beetle species were collected. All exotic conifer species were colonised by indigenous bark beetle species and no significant difference was observed of the cumulated species richness of the latter between native and exotic tree species (13 vs. 14, P < 0.05). The ability of indigenous bark beetles to shift onto exotic conifers appeared to strongly depend on host species (significantly structuring bark beetle assemblages), the presence of phylogenetically related native conifer species and that of similar resources, in combination with insect host specificity. Host tree species status (native or exotic) also seemed to be involved, but its effect did not seem as essential as that of the previous factors. These findings are discussed in terms of adaptation, plasticity and practical aspects of forest management.     

印度加瓦尔喜马拉雅山的亚热带的宽叶榆绿木(Anogeissus latifolia)林恢复状况(英文)

研究了位于印度加瓦尔海平面(950～1100m)上的亚热带森林的再生生长状况。对生长在不同方位(东、西、北、南)研究地的植被进行了定量分析。研究结果表明:宽叶榆绿木(Anogeissus latifolia)的树木、幼树和幼苗层在研究地点的所有方位显生长优势。长叶松(Pinusroxburghii)和毛白杨(Terminalia tomentosa)的树木、小树在研究地点的北部显生长优势。树木层的最高(380株·ha-1)和最低密度(260株·ha-1)分别出现在南坡和北坡。幼树的最高(1790株·ha-1)和最低密度(970株·ha-1)分别出现在东坡和西坡。树木和灌木层的多样性分别为0.846～1.710和1.943-2.847。与其它种的相比较(4%～33%),宽叶榆绿木(Anogeissus latifolia)的相对剪枝强度较高(45%-57%),此种是在北坡中最重要的树种。目前研究表明,如果不合理开采继续进行,宽叶榆绿木(Anogeissus latifolia)就有可能被其他种代替,在树种的成分和森林重建方面会发生剧烈的变化。人类活动的压力,地理方位和土壤营养已引起了树种的成分和森林重建方面的变化。     

甘肃小陇山灌木林不同改造模式天然更新研究

用样方法,研究了小陇山林区5种典型灌木林地改造模式的乔木树种天然更新幼苗的密度和多样性。结果表明:5种灌木林地改造模式的乔木树种天然更新情况总体良好,小于50 cm高度级幼苗数量相对较少,大于50 cm高度级幼苗的存活率较高;5种改造模式天然更新树种以锐齿栎为主,其中,全面割灌改造日本落叶松(模式3)更新幼苗物种丰富度最高,全面割灌改造油松模式(模式2)天然更新树种丰富度最小;带状割灌改造模式(模式4和模式5)和全面割灌改造华山松模式(模式1)的更新树种多样性较高,各树种分配均匀,优势树种的集中性较低;改造树种华山松的天然更新能力较油松日本落叶松强,带状割灌改造模式更有利于华山松天然更新。     

The usefulness of a long-term perspective in assessing current forest conservation management in the Apuseni Natural Park, Romania

The forest ecosystem of the Apuseni National Park (ANP) in NW Romania is recognized for its high species and genetic diversity and is protected through various conservation measures. As ANP is the most populated natural park in Romania, the focus is on the need for communities to manage, sustain and prosper by using, exploring and sustaining the natural resources. But what activities are the most appropriate for the conservation of a highly diverse natural forest? This paper presents results from a long-term ecological study using fossil pollen, microscopic and macroscopic charcoal and AMS¹⁴C dating on a site in the ANP in order to examine how the interaction between climate change, human activities and other disturbances have shaped the present protected landscapes over the last 5700 years in this part of the reserve. Results from this study show that the landscape in this region has been continuously forested over the last 5700 years BP, but the forest composition and structure have been dynamic throughout much of the time. In particular, distinct changes in forest composition have occurred over the last 700 years of the record. Fagus sylvatica was the major taxon between 5200 and 200 years BP and its dominance is associated with the highest forest stability. The formation of the current Picea abies forests started 400 years ago and spruce became the dominant forest species during the last two centuries as a result of selective forest clearance, intensive grazing, and more recently, plantations. This led to a large reduction in forest diversity, decline of F. sylvatica and local extinction of several species including Abies alba, Ulmus, Tilia, and Acer. Our results show the high conservation values of A. alba and F. sylvatica in the ANP. Current management practices that allow the anthropogenic activities of timber production and fast tree regeneration, usually involving the plantation of P. abies in this part of the ANP are not in keeping with the NATURA 2000 objectives of ensuring the persistence of the most vulnerable species and habitats.     

Ophiostomatoid fungi associated with bark beetles onAbies veitchii in wave-regenerated forests

Relationships between tree mortality and bark beetle infestation onAbies veitchii at the wave-regenerated forest in Mt. Asahi, Okuchichibu area were investigated. Most of the firs with green needles and newly developed current year’s shoots in the dieback zone were heavily infested by bark beetles before the death of the trees. After heavy infestation of beetles, about half of the infested firs died within the year, and the other half died in the next year. When the species composition of bark beetles and associated ophiostomatoid fungi were investigated in Mt. Asahi and also at a typical wave-regenerated forest in Mt. Shimagare, Yatsugatake area,Cryphalus montanus andC. piceae were dominant beetle species for Mt. Asahi and Mt. Shimagare, respectively.Ophiostoma subalpinum andO. europhioides were dominant fungal species at both wave-generated forests. BecauseO. subalpinum was detected more frequently from deeper areas of sapwood thanO. europhioides, it was suggested that the fungal species may accelerate the death of stressed firs in wave-regenerated forests. Contribution No. 169, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Tree regeneration and seedling survival patterns in old-growth lowland tropical rainforest in Namdapha National Park, north-east India

The tree structure and regeneration was studied in the buffer zone area comprising lowland evergreen and semi-evergreen forests in the Namdapha National Park, one of the largest remaining tract of pristine rainforests in the Eastern Himalayan biodiversity hotspot in India. The investigations were conducted in the three forest stands, viz. Altingia-mixed species, Shorea-Dipterocarp, and Albizia forests that are most dominant forest types in the lowland areas of the park. A total of 98, 54 and 20 species have been recorded at tree stratrum, while 87, 44 and 15 species at regeneration stratum for three stands, respectively. The cumulative regenerating density (seedlings + saplings) was estimated 17,648, 16,110 and 768 individual ha⁻¹ for respective stands. It was interesting to note that of the total regenerating species, 44–47% species were new to different stands, which mainly comprised middle storey species. Low-dominant and rare species also contributed significantly in the regeneration of the forest stands. The expanding population structure of forest stands indicated higher survival of the mid- and the low-canopy species than the top-canopy species. The data revealed that the future composition of these stands will highly depended on the potential regenerative status of species in each of the stand and such information would be crucial for forest management. Since the park contributed significantly to the regional biodiversity by depicting species assemblages for both wet evergreen and semi-evergreen biomes, such last remnants of rainforest should be integrally protected from anthropogenic disturbances.     

Effects of grazing on natural regeneration of tree and herb species of Kheyroud forest in northern Iran

We investigated the effects of grazing on natural regeneration, quantity, and diversity of woody species and dominant herb species in Kheyroud forest in northern Iran. We sampled vegetation in 5m2 plots in custom units, which are demarcated resource areas traditionally used by local livestock producers. The authors quantified number of species, height of seedlings, and diameter of seedlings. Height classes were 0-30 cm, 30-130 cm, and >130 cm, and diameter classes were 0-2.5 cm, 2.5-5 cm and 5-7.5 cm. The density of seedlings declined with distance from corral until reaching the custom unit boundary. Most seedlings had diameters of 0-2.5 cm and heights of 0-30 cm. Predominant species, Carpinus betulus and Acer capadocicum, were in plots near the centers of custom units, Fagus orientalis, Acer velutinum, Quercus castanifolia species were dominant in plots near the custom unit boundary. Plant species such as Oplismenus undulatifolius, Euphorbia amygdaloides, Rubus fruticos and Pteridium aquilinum were dominant in plots nearer to forest corral. Healthy seedlings were more numerous in plots nearest the corral, while defective and deformed seedlings were more abundant away from the corral. We conclude that grazing had negative effects on the quantity and quality of vegetative regeneration. Continuation of overgrazing will not only endanger the sustainability of forest ecosystems, but also will increase the challenge of sustainable forest management.     

Assessment of natural regeneration status and diversity of tree species in the biodiversity conservation areas of Northeastern Bangladesh

A study was conducted at two-biodiversity conservation areas of Northeastern Bangladesh (a part of Sylhet Forest Division) to assess the species composition, diversity and density of natural regeneration of tree species both indigenous and exotic species. Data were collected by stratified random quadrate method during January 2010 to July 2010. Totally 200 circular plots of 2 m×2 m in size had 5 different habitat types of plants namely; forest, roadside, homestead (surrounding forest dwellers house), fallow land and others (canals, streams and tea gardens side), which included a total of 55 regenerating species belonging to 28 families. Meliaceae is the dominant family and shows the highest family importance value (26.3), having six species, followed by Moraceae (24.24). Among the five habitat types, forest (43 species) possess the highest number of species, followed by roadside (23 species). Total 15 exotic species among 9 families and 40 indigenous species with 24 families were recorded. For exotic species, Tectona grandis possess the highest relative density (11.7%) and relative frequency (10.5%); Senna siamea had highest relative abundance (7.83%). In case of indigenous species, Chickrassia tabularis possess the highest relative density (4.23%) and relative frequency (4%); Dipterocarpus turbinatus had the highest relative abundance (3.92%). Tectona grandis (29.66) and Chickrassia tabularis (10.8) had the highest IVI for exotic and indigenous species respectively. Different diversity indices such as Shanon-Winner diversity index, species diversity index, species richness index, species evenness index, Simpson index and species dominance index, etc. were applied to quantify definite diversity. The regeneration of species associated with low levels of disturbance was in the exotic species. Study suggests that proper protection from human disturbances and scientific management of natural regeneration of two-study forests may lead a rich biodiversity site in the country.     

Population Structure and Protective Value of Temperate Forests in a Part of Central Himalaya

Abstract

This study pertains to the density-diameter (d-d) curves, diameter class distribution of dominant species and protective value of temperate forests between 2000 and 3300 m amsl in Pinder catchment of the Central Himalaya. The identified forests were mixed deciduous-evergreen, alder (Alnus nepalensis), mixed evergreen-deciduous, maple (Acer cappadocium), burans (Rhododendron arboreum), silver-fir (Abies pindrow), kharsu oak (Quercus semecarpifolia)and birch (Betula utilis).The d-d curve was inverse curvilinear for all species in the entire study area. The curve assumed an inverse curvilinear slope for the stands of smaller mean diameter, linear for the stands of intermediate mean diameter and bell shaped for the stands of larger mean diameter. The curves for burans, kharsu oak and alder, mixed and silver-fir, and birch forests were slightly convex, bell shaped, curvilinear, straight line and linear, respectively. Two light demanding species, Q. semecarpifoliaand Aesculus indicahave been experiencing regeneration problem, whereas the other two light demanding species, A. nepaiensisand B. utilisexhibited moderate regeneration. Shade tolerant A. pindrow, A. cappado-ciumand R. arboreumexhibited satisfactory regeneration, but conversion of seedlings into trees was not satisfactory for A. pindrow.The relative protective value of 5 different forests was in the order: silver fir > kharsu oak > mixed deciduous-evergreen > mixed evergreen-deciduous > birch.     

川西山地岷江冷杉风景林林分空间结构分析

应用传统林分结构因子配合混交度、角尺度、大小比数和开敞度4个林分空间结构参数,分析了川西山地退化风景林的空间结构特征.结果表明:林分结构较为简单,林分乔木层由7个树种组成,树种密度分布差异较大,树种结构相对单一;林分垂直结构特征明显,可分为3个林层,呈现出典型的复层林结构特征;林分平均混交度为0.46,以中强度混交单元为主,所占比例达61％;平均角尺度为0.483,属于随机分布状态;林木的胸径大小比数为0.286,有接近30％的林木处于优势状态;林分平均敞开度为0.309,林木生长空间基本充足.岷江冷杉种群优势度明显,群落处于相对稳定状态,其他5个树种由于株数较少,且径级分布不连续,自然更新较困难,经过一定时间的演化,将死亡,因此必须切实采取保护措施,保证其顺利生长,以保持物种多样性和群落的稳定性.     

The effects of fire on the regeneration of a Quercus douglasii stand in Quail Ridge Reserve, Berryessa Valley (California)

Wildfire is an important element in the dynamics of the blue oak (Quercus douglasii) stand. We evaluated the effect of fire in the regeneration of a stand in Quail Ridge. This protected area is located on a peninsula formed by the flooding of Berryessa Valley (California) which has helped it maintain many elements of the native flora. Major vegetation types are blue oak woodland and forest (Q. douglasii, Fagaceae), chamise chaparral (Adenostoma fasciculatum, Rosaceae), and grasslands. In the blue oak stand, 14 plots were randomly located: seven in the burned area and seven outside of the burned areas (control). The effect of fire on sexual regeneration, asexual regeneration, mortality and species composition was analyzed. The fire caused changes in canopy cover, soil cover and litter cover. Asexual regeneration was significantly favored by the fire, but the effect on sexual regeneration was not significant. Fire caused a significant reduction in the basal area of Q. wislizeni and Arctostaphylos manzanita and a reduction in the density of Heteromeles arbutifolia. We concluded that fire does not have a significant effect on the sexual regeneration of Q. douglasii or Q. wislizeni. Fire does stimulate asexual regeneration in both species of oaks, but grazing reduces the regenerative effect of fire. Fire increases regeneration of Arctostaphylos manzanita and Heteromeles arbutifolia by stimulating asexual and sexual regeneration. The occupancies of these chaparral species are further enhanced by their lower palatability compared to both species of oaks.     

闽北闽粤栲天然林主要树种幼树器官碳氮磷化学计量特征分析

[目的]选取4种主要优势树种幼树为研究对象,分析其不同器官中C、N、P的生态化学计量特征,为闽粤栲天然林的更新与保护提供理论参考。[方法]应用碳氮分析仪与HNO3-HCl O4消煮法分别测定幼树的干、根、枝、叶中的C、N、P含量的质量分数,在不同器官C、N、P含量差异分析的基础上,通过化学计量比变化的对比分析研究幼树不同器官的C、N、P化学计量特征。[结果]闽北闽粤栲天然林主要优势树种幼树叶片中各元素的含量均高于其他器官,而根与干中的营养元素含量较低;不同器官的C∶P远高于C∶N与N∶P,其中,N∶P最小且因树种不同而有所变化,不同器官的C、N、P含量及化学计量特征均差异极显著。[结论]闽北闽粤栲天然林主要优势树种不同器官对C、N、P的选择与吸收存在差异,其叶片C含量最高且高于全球尺度和全国尺度,但N、P含量较低;幼树不同器官的C∶N、C∶P高于平均水平,而N∶P16;闽粤栲天然林主要优势树种幼树对养分的利用效率与生长速率均较低,幼树的生长更新主要受N、P元素含量的影响,并可能受到P元素缺失的制约。     

次生金钱松林自然化培育前期的恢复特征

对宁波市鄞州区天童林场盘山林区退化金钱松人工林实施择伐、留养和补植先锋树种的近自然化改造,比较不同林分早期恢复生长的差异。结果表明:①改造6年后,山坡上的木荷、青冈和沟谷上的红楠等地带性常绿阔叶树种呈快速的恢复生长,已形成了一个高3~5 m的更新层,林分结构得到改善,已形成松阔异龄混交林,比对照区林分蓄积量分别提高68.3%和18.9%。②通过抚育使山坡和沟谷类型更新层的优势种群密度分别达2 538、3 183株.hm-2,比对照区提高1.8倍、7.2倍;山坡类型更新的木荷和青冈种群的个体数量分布基本上呈正态分布,这表明更新种群都处于恢复中前期增长进程阶段;沟谷类型更新的红楠种群个体数量呈逆J型分布,已成为稳定型种群。③改造后混交林群落结构发生变化,更新优势种群抗胁迫性显著增强。     

我国天然云冷杉针阔混交林结构特征、更新特点及经营管理

天然云冷杉林是世界主要森林类型之一, 具有重要的生态、经济和社会效益。探明天然云冷杉林结构特点和演替规律, 制定科学的经营管理措施, 因地制宜地合理经营云冷杉林意义深远而迫切。文中概述了我国天然云冷杉林的分布、结构和更新演替特征, 分析了经营管理现状及存在的问题, 并提出建议:1)对禁伐区内的云冷杉林分, 坚决杜绝一切采伐活动; 对限伐区要严格控制采伐强度, 一般控制在伐前蓄积量的15%以内; 对商品林经营区可按每公顷蓄积量的大小确定适宜采伐强度, 并按照林分特点进行经营, 做到科学择伐。2)对林地草本植被密集、灌木覆盖度不大、采伐迹地上有种源条件的进行封育、栽植或补植, 人工促进天然更新。3)建立秦岭冷杉、大果青杄、元宝山冷杉等珍稀濒危物种自然保护区和科学试验站, 积极开展就地保护, 减少人为破坏。4)适时采种, 就地建立苗圃, 开展育苗造林, 扩大人工种群, 促进天然更新。     

巴山冷杉-牛皮桦混交林乔木更新及土壤化学性质对更新的影响

调查太白山巴山冷杉-牛皮桦混交林林下与林隙乔木更新及土壤化学性质,分析林隙及土壤化学性质对乔木更新的影响.结果表明:巴山冷杉-牛皮桦混交林乔木更新苗密度较小,为0.059株·m-2,但林下与林隙均以巴山冷杉更新苗为主;林下与林隙乔木更新苗密度差异不显著(P=0.160),但巴山冷杉幼苗密度表现为林隙内显著高于林下(P =0.012);相关分析表明,小林隙更利于巴山冷杉更新(r=- 0.397,P=0.030),而林隙大小对牛皮桦更新没有显著影响(r=0.125,P=0.511);在林下,土壤碱解N、全P含量和pH值与牛皮桦更新苗密度呈显著正相关;在林隙内,土壤全P和有效P含量与巴山冷杉更新苗密度呈显著负相关,全P含量与牛皮桦幼树密度呈显著负相关;林下土壤有机质含量、全N含量和有效P含量及林隙土壤pH值、有机质含量、全N含量和碱解N含量与牛皮桦和巴山冷杉更新苗密度均没有显著相关关系;林下土壤pH值显著高于林隙,而有机质、全N、碱解N、全P和有效P含量显著低于林隙.     

The influence of reproductive traits on liana abundance 10 years after conventional and reduced-impacts logging in the eastern Brazilian Amazon

Balancing timber production and conservation in tropical forests requires an understanding of the impacts of silvicultural manipulations on specific groups of organisms. Lianas are characteristic of many tropical forests, where they contribute to species diversity, ecosystem functioning, and biomass. However, lianas can also impede timber production by increasing logging damage and slowing tree growth. Cutting lianas prior to logging can mitigate the negative effects, but may adversely affect a forest's value for conservation. To evaluate the effects of forest management activities on lianas, this study assessed the impacts of logging, both with and without pre-logging liana cutting, on the relative abundance and population structure of five species of lianas that differed in primary reproductive strategies.Inventories of the five study species were conducted 10 years following logging in 4.4 ha plots in three adjacent treatment areas: (1) an old-growth forest reserve, (2) a selectively-logged forest that used conventional practices for the region, and (3) a forest that was logged using reduced-impact logging (RIL) techniques including complete liana cutting prior to logging. Liana species responses to logging varied according to their primary modes of reproduction. Croton ascendens, a pioneer species with a persistent seed bank, had a higher abundance in the two logging treatments relative to the old-growth forest, while Serjania caracasana, an early successional species lacking a persistent seed bank, showed abundant regeneration following conventional logging but negligible regeneration following RIL. In contrast, Acacia multipinnata, also an early successional species, showed abundant regeneration following RIL owing to the sprouting of persistent prostrate stems present on the forest floor prior to logging. In both logged areas, Bauhinia guianensis recruited abundant climbing stems from self-supporting seedlings that were present prior to logging, but it showed greatly reduced seedling density following RIL. By sprouting profusely from both fallen stems and stumps, Memora schomburgkii recruited abundant small-diameter climbing stems in both of the logging treatments. The results of this study demonstrate that there are interspecific differences in liana responses to different types of logging and that knowing species’ primary modes of reproduction is a valuable first step toward predicting those responses.