马占相思开花生物学特征研究

利用光学显微镜和扫描电子显微镜（SEM）,对马占相思开花物候、花部形态和传粉效率等进行了研究。结果表明：马占相思于9-11月开花,整个群体花期有6 7个小花期;单株开花同步性强,呈现“集中开花”模式;穗状花序由172.7±27.1朵花组成,每个花序平均有（10.35±7.78）%的雄花,两性花具有雌蕊１枚,含14.11±1.05粒胚珠;柱头凹陷,大小可容纳1 2粒直径为29 35 μm的16合花粉粒,P/O’为1.13/1;马占相思开花时,雌蕊先于雄蕊伸展并成熟,为雌蕊先熟;SEM结果显示：花药在开花第2、3阶段仅有开裂线,在第4阶段之后才开裂,即7：00－9：00开裂,9：00－12：00大量散粉;柱头在开花第1天上午可观察到分泌物,预示柱头可授。此研究结果将为今后加强相思种子园的管理及开展相思杂交育种奠定重要基础。     

马占相思扦插繁殖技术研究

Effects of substrates, type of auxin, treatment concentration and time on rooting ability of Acacia mangium were systematically studied, and the change trend of rooting ability over time were analyzed. The results obtained from the experiment indicated that the substrate of yellow subsoil could improve the rooting rate of the cuttings significantly. IBA was superior to other auxins in increase the number of mean roots and the longest root length. And general rooting effect for different treatments was evaluated based on subordinate function values analysis. The optimized combinations were the cutting treated by IBA 400 mg·L^-1 soaked for 2 hours. Callus were occurred in 5 d after cutting, and higher rooting period occurred in 10—15 d and 25—30 d after cutting.     

Soil changes induced by Acacia mangium plantation establishment: Comparison with secondary forest and Imperata cylindrica grassland soils in South Sumatra,Indonesia

Acacia plantation establishment might cause soil acidification in strongly weathered soils in the wet tropics because the base cations in the soil are translocated rapidly to plant biomass during Acacia growth. We examined whether soils under an Acacia plantation were acidified, as well as the factors causing soil acidification. We compared soils from 10 stands of 8-year-old Acacia mangium plantations with soils from 10 secondary forests and eight Imperata cylindrica grasslands, which were transformed into Acacia plantations. Soil samples were collected every 5–30 cm in depth, and pH and related soil properties were analyzed. Soil pH was significantly lower in Acacia plantations and secondary forests than in Imperata grasslands at every soil depth. The difference was about 1.0 pH unit at 0–5 cm and 0.5 pH unit at 25–30 cm. A significant positive correlation between pH and base saturation at 0–20 cm depth indicated that the low pH under forest vegetation was associated with exchangeable cation status. Using analysis of covariance (ANCOVA), with clay content as the covariate, exchangeable Ca (Ex-Ca) and Mg (Ex-Mg) stocks were significantly lower in forested areas than in Imperata grasslands at any clay content which was strongly related to exchangeable cation stock. The adjusted average Ex-Ca stock calculated by ANCOVA was 249 kg ha⁻¹ in Acacia plantations, 200 kg ha⁻¹ in secondary forests, and 756 kg ha⁻¹ in Imperata grasslands at 0–30 cm. Based on a comparison of estimated nutrient stocks in biomass and soil among the vegetation types, the translocation of base cations from soil to plant biomass might cause a decrease in exchangeable cations and soil acidification in Acacia plantations.     

金合欢属植物的生殖生物学研究进展

金合欢属植物具有较高的经济价值,我国引入已近百种。自引入以来,种子园经营及管理出现诸多问题,加之林木经营者对本属植物生殖学了解欠缺,迫切需要加深这方面的认识。笔者对半个世纪国外在金合欢属植物生殖生物学方面的研究成果进行整理,对其生殖生物学研究进行综述,包括花部生物学特征、雄蕊的发育、开花传粉及繁育体系;同时讨论了种子园座果率及种子产量低下的原因,并对以后的研究提出了展望,以期为生产中提高种子园的管理效率起到指导意义。     

Mixed-species plantations of Acacia mangium and Eucalyptus grandis in Brazil: 1. Growth dynamics and aboveground net primary production

Nitrogen fertilizer inputs increased sharply over the last decade in Brazilian eucalypt plantations. Due to the economic and potential environmental cost of fertilizers, mixed plantations with N-fixing species might be an attractive option to improve the long-term soil N status. A randomized block design was set up in southern Brazil, including a replacement series and an additive series design, as well as a nitrogen fertilization treatment. The development of mono-specific stands of Eucalyptus grandis (0A:100E) and Acacia mangium (100A:0E) was compared with mixed plantations in proportions of 1:1 (50A:50E), and other stands with different densities of acacia for the same density of eucalypts. The objective was to assess the effect of inter-specific interactions on the early development of the two species. Aboveground biomass was measured 6, 12, 18 and 30 months after planting, sampling 6–10 trees of each species per treatment at each age, and allometric equations were established in 0A:100E, 100A:0E, 50A:50E and 50A:100E. The height and basal area of E. grandis seedlings were enhanced by 12% and 30%, respectively by N fertilization at age 1 year. Inter-specific competition led to a stratified canopy, with suppression in acacia growth earlier for basal area than for height. The mean number of stems per acacia tree at 36 months after planting was significantly higher in pure stands (3.7), than in 50A:50E (2.7) and in the additive series (between 1.6 and 1.8). H/D ratios were highly sensitive to inter-tree competition for the two species. The suppressed acacia understorey in mixed-species stands did not influence biomass production and partitioning within eucalypts. This pattern led to biomass accumulation combining the two species in 50A:100E that was about 10% higher than in 0A:100E, from age 12 months onwards. Aboveground net primary production (ANPP) amounted to 25 Mg ha⁻¹ and 37 Mg ha⁻¹ from age 18 to 30 months in 100A:0E and 0A:100E, respectively. Acacia ANPP in 50A:100E amounted to 2 Mg ha⁻¹ over the same period, as a result of substantial inter-specific competition. An increment in biomass production in these very fast-growing eucalypt plantations was achieved introducing acacia as an understorey and not in the 50A:50E design, as observed in other studies.     

金合欢属植物组织培养研究进展

金合欢属植物生长速度快、产量高、材质好、适应性强、用途广,在我国南方林业生产中占据重要地位。掌握该属植物的组织培养技术,对促进其产业发展具有重大意义。文中从外植体、基本培养基、培养条件、植物生长调节剂、组培苗移栽等方面简述20世纪80年代以来金合欢属植物组织培养技术的研究进展,并就组培快繁中存在的主要问题提出相应的解决方法,同时提出今后的研究展望,以期为建立金合欢属植物高效组培体系及工厂化育苗提供参考。     

Effect of species and spacing of fast-growing nurse trees on growth of an indigenous tree, Hopea odorata Roxb., in northeast Thailand

We tested the effects of species and spacing of nurse trees on the growth of Hopea odorata, a dipterocarp tree indigenous to Southeast Asia, in a two-storied forest management system in northeast Thailand. Eucalyptus camaldulensis, Acacia auriculiformis, and Senna siamea were planted as nurse trees in 1987 at spacings of 4 m × 8 m, 2 m × 8 m, 4 m × 4 m, and 2 m × 4 m in the Sakaerat Silvicultural Research Station of the Royal Forest Department, Thailand. Seedlings of H. odorata were planted in the nurse tree stands at a uniform spacing of 4 m × 4 m and in control plots (no nurse trees) in 1990. Stem numbers of some nurse trees were thinned by half in 1994. The stem diameter and height of all trees were measured annually until 1995 and again in 2007. The mean annual increment (MAI) in volume was estimated as 8.2–10.1 m³ ha⁻¹ year⁻¹ for E. camaldulensis and 0.9–1.2 m³ ha⁻¹ year⁻¹ for S. siamea, smaller than reported elsewhere. This suggests that the site properties were not suitable for them. The MAI of A. auriculiformis was 7.9–9.8 m³ ha⁻¹ year⁻¹, within the reported range. Survival rates of H. odorata in the S. siamea stands and the control plots decreased rapidly during the first 2 years but then stayed constant from 1992. In contrast, survival rates of H. odorata in the E. camaldulensis and A. auriculiformis stands were initially high (>70%), but then decreased after 1995. Stem diameter, tree height, and stand basal area of H. odorata were large in both the S. siamea stands and the control plots from then. The growth of H. odorata was largest in the 2 m × 8 m S. siamea stands. In contrast, it was restricted in the E. camaldulensis and A. auriculiformis stands owing to strong shading by their canopies. Thinning by 50% tended to facilitate the growth of H. odorata temporarily in the E. camaldulensis and A. auriculiformis stands. The stand basal areas of nurse trees and of H. odorata showed a trade-off. These results suggest that the growth of H. odorata was maximized in the S. siamea stands. We assume, however, that the growth of H. odorata could be improved even in the E. camaldulensis and A. auriculiformis stands by frequent or heavy thinning.     

中国广义金合欢属植物亲缘关系的分子分析

通过ITS-rpl16序列和mat K序列的分子分析,对中国现有金合欢属的各亚属间的亲缘关系进行了研究,结果表明:我国现有广义金合欢属的14个种大致被聚为相思亚属、皮刺亚属和金合欢亚属3大类,原产中国的3种皮刺亚属的种聚成1支,表明印度金合欢和羽叶金合欢关系更近,二者再与儿茶形成姐妹类群。基于选自美洲、非洲、澳大利亚和中国乡土种(印度金合欢、羽叶金合欢和儿茶)共40个金合欢属种和1个外类群的mat K序列建立的系统发育树表明:皮刺亚属和相思亚属的亲缘性关系比与金合欢亚属的亲缘关系更近,相思亚属和金合欢亚属均是单系类群,而皮刺亚属属于并系类群;中国的几个乡土种都与非洲一些种的亲缘关系较近,聚为1支。     

Early seedling establishment of two tropical montane cloud forest tree species: The role of native and exotic grasses

Tropical montane cloud forest has been undergoing a drastic reduction because of its widespread conversion to pastures. Once these forests have been cleared exotic grasses are deliberately introduced for forage production. Exotic grass species commonly form monodominant stands and produce more biomass than native grass species, resulting in the inhibition of secondary succession and tree regeneration. The purpose of this study was to assess the effect of native vs. exotic grass species on the early establishment of two native tree seedlings (Mexican alder, Alnus acuminata and Jalapa oak, Quercus xalapensis) on an abandoned farm in central Veracruz, Mexico. Seedling survival and growth were monitored (over 46 weeks) in relation to grass cover and height, and available photosynthetic active radiation (PAR). More seedlings survived in the presence of the native grass Panicum glutinosum than those growing with the exotic grass Cynodon plectostachyus (92% vs. 48%). The causes of seedling mortality varied between species; Q. xalapensis was affected by herbivory by voles but mainly in the exotic grass-dominated stands, whereas A. acuminata seedlings died due to competition with the exotic grass. A. acuminata seedlings increased more in height in the exotic grass-dominated stands (102 ± 7.8 cm) compared to native grass-dominated stands (51 ± 4.7 cm). Grass layer height, cover and available PAR were correlated (Pearson; p < 0.05). In the exotic grass dominated plots, grass layer height was correlated with the relative height growth rates of Q. xalapensis (Pearson; p < 0.05). These results indicate that the exotic grass may be affecting tree regeneration directly (grass competition) and indirectly (higher herbivory). Passive restoration may occur once P. glutinosum dominated pastures are abandoned. However, when C. plectostachyus dominates, introduction of early and mid successional tree seedlings protected against vole damage is needed.     

干热河谷大叶相思树干液流季节动态及其与气象因子的关系

应用热扩散式探针法(TDP)对干热河谷主要造林树种大叶相思的树干液流进行了湿季(7-8月)和干季(1-3月)典型月连续监测,并结合自动气象站对周围气象要素进行同步测定,据此分析液流速率的昼夜、季节变化规律及其与气象因子的关系.结果显示:(1)无论是干季还是湿季,大叶相思树干液流均表现出明显的昼夜变化规律,即呈现“昼高夜低”典型的液流单峰曲线;(2)树干南面液流速率均高于北面,干季南、北方位液流速率最大相差0.0037 cm· s-1,湿季最大相差0.0014cm·s-1;(3)干、湿季液流平均值和最大值具显著差异,湿季树干液流速率平均值和峰值约为干季的2.8倍和2.5倍;(4)大叶相思树干液流速率与光合辐射强度、水汽压亏缺、大气温度、风速呈极显著的正相关关系,而与相对湿度呈极显著负相关关系,按相关程度排序为光合辐射强度＞大气温度＞水汽压亏缺＞相对湿度＞风速,其中,光合有效辐射、相对湿度、水汽压亏缺是影响液流速率的主导因子.     

我国杉木组织培养技术研究进展

杉木是我国南方特有的速生用材树种,具有生长快、产量高、材质好和用途广的特点,在南方林业生产中占据重要地位。熟悉和掌握杉木的组织培养技术,对促进杉木产业的发展具有重要意义。文中从叶、茎尖、茎段和离体胚等外植体的选择,外植体消毒,愈伤组织和芽的诱导分化,继代增殖培养以及壮苗与生根等方面简述近几年我国杉木组织培养技术的研究进展,对杉木组培快繁中的灭菌技术、培养基筛选和生长调节物质使用水平等技术环节进行评述,同时提出目前研究中存在的几个主要问题和今后的发展方向。     

Tree age and soil phosphorus conditions influence N2-fixation rates and soil N dynamics in natural populations of Acacia senegal

Acacia senegal, an important leguminous tree in arid and semi-arid environments, has shown promise as a multipurpose species, including gum production and soil fertility improvement, linked with N₂-fixation capabilities. Of particular interest are ontogenetic and edaphic effects on A. senegal performance in natural populations. Our research objectives were to investigate the effect of tree age and site phosphorus conditions on (1) tree N₂-fixation and (2) soil N and C dynamics in natural stands of A. senegal var. senegal, Baringo District, in the Rift Valley, Kenya. Sites consisted of A. senegal saplings (9 months) and mature A. senegal trees (7 years) along an edaphic gradient of soil P availability. A single-tree neighborhood approach was employed using a two by two factorial design: site conditions [high and low soil P contents] and tree age class [juvenile and mature]. Soil (N and C pools and fluxes) and plant metrics were quantified. A soil transfer experiment was also employed to confirm age and site effects on soil N mineralization. On the high soil P site, A. senegal had significantly lower foliar (¹⁵N levels than neighboring non-leguminous species (Balanites aegyptiaca), while foliar δ¹⁵N values in A. senegal on the low P site exhibited no significant difference with our reference plant, B. aegyptiaca. Across P sites, B. aegyptiaca had similar foliar δ¹⁵N values. These results indicate that the rate of N₂-fixation of A. senegal trees, as determined with foliar ¹⁵N natural abundance methodology, increased with increasing soil P availability in these natural populations. However, N₂-fixation rates declined with age. Although soil texture and soil CO₂ efflux did not differ between sites or across ages, soils under mature A. senegal at the high P site exhibited significantly greater total N content and total C content in comparison to soils at the low P site and under juvenile plants. Furthermore, under mature A. senegal trees, soil N mineralization rates were significantly greater as compared to under saplings. Soil transplants confirmed that soil microbial activity may be stimulated under mature trees as N mineralization rates were 2-3 fold greater compared to under A. senegal saplings. Our findings suggest that tree age and soil P availability are important factors in the nitrogen budget of natural populations of A. senegal, determining N₂-fixation rates, and potentially influencing soil total N and C pools and soil mineral N. This study provides information regarding the adaptation of A. senegal under differing edaphic conditions thus increasing accuracy of management support for A. senegal populations as productive agroforests.     

中国漆树资源与品种现状及产业发展前景

漆树是指漆树科(Anacardiaceae)漆树属(Toxicodendron)的一类植物,是原产于我国的重要经济树种.在世界的漆产业中,中国资源丰富,历史悠久,有着举足轻重的作用.中国漆树品种数量繁多,20世纪80年代筛选出农家品种97个、优良品种46个、特优品种14个,具有产量高、漆质优良的特点,其中大红袍、灯台小木漆是值得开发的品种,具有较好的研究及产业发展前景.目前,我国漆树资源不到2亿株,国内年产生漆达2500t.文中从漆树特性、经济价值、资源状况、科研现状、产业发展和前景展望等5个方面概述了国内漆树现状,重点介绍了我国西南地区云南省的漆树产业发展前景,以期为漆产业发展提供科学参考.     

Regeneration of Rocky Mountain bristlecone pine (Pinus aristata) and limber pine (Pinus flexilis) three decades after stand-replacing fires

Rocky Mountain bristlecone pine (Pinus aristata) and limber pine (Pinus flexilis) are important high-elevation pines of the southern Rockies that are forecast to decline due to the recent spread of white pine blister rust (Cronartium ribicola) into this region. Proactive management strategies to promote the evolution of rust resistance and maintain ecosystem function require an improved understanding of the role of disturbance on the population dynamics of both species and environmental conditions that favor seedling establishment. We examined patterns of bristlecone and limber pine regeneration across the perimeters of three, 29-year-old, high-severity burns in northern, central, and southern Colorado: Ouzel, Badger Mountain, and Maes Creek, respectively. Both species exhibited a very protracted regeneration response to these fires. Bristlecone pine regeneration was concentrated near burn edges and beneath surviving seed sources. This spatial pattern is consistent with limitations incurred by wind-dispersal, also borne out by the low occurrence of seedling clusters. Relative to unburned stands, the absolute abundance of bristlecone pine generally increased only on plots retaining some surviving trees. Limber pine regeneration pattern varied between sites: high in the burn interior at Ouzel, concentrated at burn edges at Badger, and mostly in unburned stands at Maes. Clark’s Nutcracker dispersal of limber pine in each study area was indicated by high seedling distance from possible seed sources and high frequencies of clustered stems. Except at Ouzel, the absolute abundance of limber pine decreased in burns. Across sites, establishment by both species was boosted by nearby nurse objects (rocks, fallen logs, and standing tree trunks), a relationship that extended out at least as far as the closest three such objects, usually found within 50 cm. Fire decreased the frequency of Pedicularis but increased Castilleja and Ribes species (alternate hosts of white pine blister rust), though only one species, R. cereum, was positively associated with either pine species. We conclude that regeneration of bristlecone and limber pine may benefit from natural disturbance or proactive management creating appropriately sized openings and microtopographic structure (e.g., abundant fallen logs); however, beneficial responses may require many decades to be achieved.     

模拟外源性氮磷对马占相思凋落叶分解及土壤生化特性的影响

[目的]研究外源性氮和磷对马占相思凋落叶的分解速率、分解过程中N、P、K含量和土壤生化特性的影响,以便为森林土壤养分管理提供参考。[方法]以广东省云勇林场马占相思林下凋落叶为试验材料,采用尼龙网袋分解法,设置对照(CK)、施N(10 g·m~(-2))、施P(5 g·m~(-2))、施N+P(N 10 g·m~(-2)+P 5 g·m~(-2))4种处理,每隔3个月取样1次,并测定凋落叶残留量和N、P、K含量。[结果]表明:施N、P和N+P处理对马占相思凋落叶的分解均为促进作用。各处理马占相思凋落叶的N含量在分解过程中大致保持稳定,施P和N+P处理的凋落叶P含量在分解过程中总体呈波动性上升,而各处理的凋落叶K含量变化规律不明显。施N、P和N+P处理提高了马占相思林土壤的有机质和全N含量,促进脲酶、磷酸酶及过氧化氢酶的活性。[结论]施N、P和N+P处理促进了马占相思凋落叶的分解,有利于马占相思林的养分循环。     

Environmental effects on morphology of Acacia tortilis group in the Red Sea Hills,North-Eastern Sudan and South-Eastern Egypt

Acacia tortilis is a drought-resistant species. Its survival and existence in the arid and semi-arid area of Northern Africa and Arabian Peninsula is due to its ability to endure the harsh condition and therefore, it is generally forms open pure stands or mixed stands in these drylands. Wherever it grows, it plays an important role in human, animal and other plant species lives. Yet the relation between its adaptive features and their relation to the environmental conditions is not studied in a large scale of environmental variation. The main objective of this study is therefore to examine if the immediate environmental factors, other than human utilization, are associated to the expressed morphological variables among the A. tortilis sub-taxa. Three subspecies are collectively reported in the study area, Red Sea Hills of Sudan and Egypt. According to different literatures, they are distinguished by features of high plasticity under the variable pressure of human activity and climate. Such features are hair density in some parts of the plant, crown shape and number of stems. In the current study, the result of analysing 520 samples of A. tortilis – collected from 25 different localities representing various altitudinal gradients – showed a correlation between the expressed morphological studied and the immediate environment. When data from both regions studied as one data set, elevation, above sea level, was the only significant response variable and higher hair density was associated to plants growing in Sudan. However, when only data from Sudan was studied separately, elevation, hillside and lower part of the catchment were the statistically significant response variables. In the Egyptian data set, the statistically significant response variables were elevation, khor bank and the upper, mid, and lower part of the catchment. An intra-morphological correlation was also shown. These results may suggest that the current A. tortilis sub-taxa are ecotype. Genetic and anthropogenic studies are needed to verify this assumption.     

我国栓皮栎分布及其生态学研究

栓皮栎作为广泛分布的树种之一,在全球气候变化的大环境下,成为研究树木生长应对气候变化的重要树种。文中分析了我国栓皮栎水平分布和垂直分布的特点及其与气候的关系,栓皮栎在不同地区的森林类型,主要包括栓皮栎纯林、松栎混交林、栎类混交林等类型;综述了我国对栓皮栎生态学、群落结构、更新等研究的最新进展和主要结论;提出今后开展栓皮栎研究的重点和方向,以期为栓皮栎生理生态学及其对气候变化响应研究提供参考。     

Bird community assembly in Bornean industrial tree plantations: Effects of forest age and structure

Plantations of exotic trees for industrial and agricultural purposes are burgeoning in the tropics, and some of them offer the opportunity to study community ecology of animals in a simplified forest setting. We examined bird community assembly in different aged groves of the industrial tree mangium (Acacia mangium) at two plantations in Malaysian Borneo: Sabah Softwoods near Tawau, Sabah, and the Planted Forest Project, near Bintulu, Sarawak. Bird communities were compared among three age-groups of mangium (2-, 5-, and 7-years old) and logged native forest. Mangium rapidly developed into a secondary forest consisting of a wide diversity of understory trees and shrubs. The bird community correspondingly increased in species richness and diversity, and we were able to relate these increases specifically to canopy height, secondary canopy development, and shrub cover. Species of common, small bodied frugivores, nectarivores, and insectivores were diverse in older plantation groves, as were common mid-sized insectivores. However, large, specialized, and normally uncommon taxa (e.g., galliforms, pigeons, hornbills, barbets, midsized woodpeckers, muscicapine flycatchers, and wren babblers) were rare or nonexistent in the plantations. Because we lacked species-specific data on foraging, nesting, and other behaviors of most groups of birds, it was difficult to explain the precise causes of seral diversification in any group except woodpeckers, which have been well studied in Southeast Asia. Thus, in future, particular emphasis needs to be placed on obtaining such data. Industrial plantations, by virtue of their simple structure, variably aged groves, and bird community richness, are good places to gather such data.     

Comparison of depth- and mass-based approaches for estimating changes in forest soil carbon stocks: A case study in young plantations and secondary forests in West Java, Indonesia

Soil carbon (C) stocks in forest ecosystems have been widely estimated to a fixed soil depth (i.e., 0-30 cm) to clarify temporal changes in the C pool. However, surface elevations change as a result of compaction or expansion of the soil under forest management and land use. On the other hand, the calculation of soil C stocks based on “equivalent soil mass” is not affected by compaction or expansion of forest soil. To contribute to the development of a forest C accounting methodology, we compared changes in soil C stocks over 4 years between depth- and mass-based approaches using original soil data collected at 0-30 cm depths in young plantations and secondary forests in West Java, Indonesia. Our methodology expanded on the mass-based approach; rather than using one representative value for the mass-based calculation of soil C stocks, we adjusted individual values, maintaining the coefficient of variance in soil mass. We also considered the effect of an increase or decrease in soil organic matter on equivalent soil mass. Both increasing and decreasing trends in soil C stocks became clearer when the mass-based approach was used rather than the depth-based approach. The trends in soil C stocks based on equivalent soil mass were particularly evident in the surface soil layers (0-5 cm) and in plantation sites, compared with those for soil profiles including subsurface soil layers (0-30 cm) and in secondary forests. These trends in soil C stocks corresponded with temporal trends in litter stocks. We suggest that equivalent mass-basis soil C stock for the upper 30 cm of soil be calculated based on multiple soil layers to reduce estimation errors. Changes in soil organic matter mass had little effect on the estimation of soil C stock on an equivalent mass basis. For the development of a forest C accounting system, the mass-based approach should be used to characterize temporal trends in soil C stocks and to improve C cycle models, rather than simpler methods of calculating soil C stocks. These improvements will help to increase the tier level of country-specific forest C accounting systems.     

藏东南川滇高山栎群落物种多样性格局

通过样方调查,采用物种多样性指数和DCCA排序方法,并结合种间联结、种间协变和系统聚类分析,对藏东南川滇高山栎(Quercus aquifolioides)群落的物种多样性及其分布格局进行了研究。结果表明:1)川滇高山栎群落物种数(丰富度)随海拔增高而降低,一定程度的人为干扰(即中度干扰)、较大的林分郁闭度和较矮的林冠层有利于群落物种多样性的增加;另外干旱河谷现象对群落物种多样性格局也有影响。2)群落各层次间物种多样性呈现出草本层>灌木层>乔木层的特征。3)群落种间较高的正负关联比理论上说明川滇高山栎群落结构较为稳定,生态习性和分布差异造就了种间的联结和协变格局。海拔梯度和年均降水量是影响各种群空间分布的主要因素。4)结合种-环境DCCA排序结果、种间关系和聚类分析结果可将川滇高山栎群落中除川滇高山栎之外的48个主要物种划分为4个生态种组。