Forest Community Types Research Articles

Landscape biogeochemistry reflected in shifting distributions of chemical traits in the Amazon forest canopy

Tropical forest functional diversity, which is a measure of the diversity of organismal interactions with the environment, is poorly understood despite its importance for linking evolutionary biology to ecosystem biogeochemistry. Functional diversity is reflected in functional traits such as the concentrations of different compounds in leaves or the density of leaf mass, which are related to plant activities such as plant defence, nutrient cycling, or growth. In the Amazonian lowlands, river movement and microtopography control nutrient mobility, which may influence functional trait distributions. Here we use airborne laser-guided imaging spectroscopy to develop maps of 16 forest canopy traits, throughout four large landscapes that harbour three common forest community types on the Madre de Dios and Tambopata rivers in southwestern Amazonia. Our maps, which are based on quantitative chemometric analysis of forest canopies with visible-to-near infrared (400–2,500 nm) spectroscopy, reveal substantial variation in canopy traits and their distributions within and among forested landscapes. Forest canopy trait distributions are arranged in a nested pattern, with location along rivers controlling trait variation between different landscapes, and microtopography controlling trait variation within landscapes. We suggest that processes of nutrient deposition and depletion drive increasing phosphorus limitation, and a corresponding increase in plant defence, in an eastward direction from the base of the Andes into the Amazon Basin. The controls on plant functional diversity are unclear. Analysis of spectral data from the tree canopy in the Amazonian lowlands implies that plant functional traits are influenced by nutrient supply, which in turn varies with topography.

Biogeographic Patterns of Forest Diversity at Mount Kasigau, Kenya

ABSTRACT Mount Kasigau, the most northeastern mountain in the Eastern Arc, rises steeply from arid plains to a moist summit at 1641 m. This paper examines the diversity contributions of this afromontane setting by compiling a chorological analysis of tree species richness, measuring ecological differences among forest community types, and interpreting physical-environmental and human-historical factors that influence diversity patterns. Between 2002 and 2006, stem densities and basal areas of woody plants > 10 cm dbh were measured in 55 (0.1 ha) plots placed at different elevations. The study reports 140 species, 46 were measured in only one plot, and affinities for 75 species to the Somalia-Masai (43%), Afromontane (29%), and Zanzibar-Inhambane (Coastal, 28%) floristic regions. Cluster and Indicator Species Analyses identified eight community types. Mount Kasigau uniquely conserves much forest cover and a diversity of woody plant species below evergreen forest at 1000 m. Ordination, using Nonmetric Multi...

Impacts of Celastrus-primed soil on common native and invasive woodland species

Invasive plant species have been shown to alter soil environments resulting in changes in soil chemistry, biota, and nutrient cycling. Few studies have focused on how soil changes affect co-occurring native species or plants of different growth forms. This study, located in Connecticut, USA, focused on the soil effects of the liana, Celastrus orbiculatus (oriental bittersweet), a prominent invader of eastern North America, using two different approaches. In a litter addition experiment, addition of C. orbiculatus leaf litter to uninvaded field soils showed an increase in soil nutrients, pH, and nitrogen mineralization over 2 years across a range of soil and forest community types. In a complimentary common garden-pot experiment, a suite of common, ecologically similar, native and invasive lianas and shrubs were grown in soils primed with C. orbiculatus. Invaded soil was compared to uninvaded field and control potting soils. The change in soil attributes was not significantly different when grown with native or invasive plants; however, soils grown with lianas had a greater decrease in nutrients than those grown with shrubs. Although soils from locations with C. orbiculatus were higher in nutrients than uninvaded soils, plant growth, as measured in root:shoot, root and stem biomass, relative growth rate of volume, and final biomass were not different in invaded and uninvaded soils for either lianas or shrubs. However, lianas had similar growth patterns in nutrient-sparse potting soil, while shrubs growing in potting soil had lower growth. Thus, negative impacts of invaded soils on plant growth are not universal, and the plant community may show a varied response to C. orbiculatus-primed soils depending on the level of resource competition.

长白山森林不同演替阶段比叶面积及其影响因子研究

Specific leaf area( SLA) is an important indicator of plant function trait,reflecting resources utilization strategy during the plant growth process. The typical forest communities under four different succession stages in Changbai Mountains were selected,the SLA and its influencing factors in different stages of successions were compared. The results showed that SLA was obviously different across forest successions,and significantly increased with forest succession stages. Correlation analysis showed that SLA had significant positive correlations with elevation、slope position、soil nitrogen( with P 0. 05).Further path analysis indicated that on early stage of succession,slope position was an important factor,while Path analysis model was with low path coefficient on middle stage of succession,and the negative effect of soil N was significant on later stage of succession.

Защитные лесные насаждения восточных районов Предволжья Республики Татарстан

The protective forest plantations of the eastern Volga region of the Republic of Tatarstan were investigated. The basic types of protective forest communities of the region were distignguished. The productivity of stands was difined, their condition was described. The authors characterized the biological diversity of forest stands on the level of plant species and ecosystem. The article also describes the types of soil, on which a learned protective forest plant communities of eastern Volga region were raised.

Colonization patterns of vascular plant species on decaying logs of Fagus sylviatica L. in a lower mountain forest belt: a case study of the Sudeten Mountains (Southern Poland)

Little is known about the vascular plant flora that grows on dead wood or about the ecological conditions of its development. We focused on montane beech forests in the Sudeten Mts. in southern Poland and chose Fagus sylvatica. The studies were conducted in the years 2003-2006 between 460 and 890 m a.s.l. Among others, the following parameters of dead logs were recorded: the type of forest community, the status of protection (protected vs. managed), altitude, shade, the humidity of the log, the area of the log (m 2 ) and the degree of the decomposition class. In total, 165 dead logs were analyzed. In total, 25 vascular plant species were encountered. Oxalis acetosella, Impatiens parviflora and Calamagrostis arundinacea were the most frequently found. The species composition of the colonized fallen logs differed significantly between the two forest communities in terms of DCA plot scores and also between the managed vs. protected forests. Canonical Constrained Analysis (CCA) revealed that decomposition degree, altitude and shade are significant factors among the five environmental variables that were studied. The study showed that the mean decomposition degree of beech logs as well as the cover of vascular plants overgrowing the logs was higher in the managed forests.

New localities of Protostropharia alcis (Basidiomycota, Agaricales) in Poland

The present paper provides new records of <em>Protostropharia alcis </em>in Poland. So far this species was known in the country only from several latest localities in the Biebrza National Park (Biebrza Basin) and the Kampinos National Park (Warsaw Basin). The new localities are situated in the Wigierski National Park (the East Sudetian Lake District) and in the north-western slope of Mt Wierzejska (the Holy Cross Mountains), where <em>P. alcis </em>was collected on dung of herbivores (eurasian elk and red dear) within several types of forest communities. All specimens of <em>P. alcis </em>were collected in recent years, from late September to early October, in the period 2012-2013. A full description and illustration of <em>P. alcis </em>based on gathered collections are given. Its delimitation, the knowledge of its ecology, general distribution, and threat is also briefly discussed. Based on the new and known distribution data for <em>P. alcis </em>in Poland, its red list category is proposed.

长白山不同演替阶段森林植物功能性状及其与地形因子间的关系

Plant functional trait has been a hot topic of ecological research in recent years. The difference of functional traits among different populations will decide competitive advantages and cause the changes of community structure,further leading to succession. The typical forest communities under four different succession stages in Changbai Mountains were selected,and the relationship between the functional traits of stems and leaves of dominant species in different layers were analyzed,also,the relationship of functional traits and terrain factors were studied,besides,functional traits in different stages of successions were compared. The results showed that leaf area( SLA) was positively correlated with leaf nitrogen content( LNC) and stem phosphorus content( SPC),and negatively correlated with leaf dry matter content( LDMC); leaf thickness( LT) was negatively correlated with LDMC; LNC was positively correlated with leaf phosphorus content( LPC) 、SNC、LDMC; SNC was positively correlated with SPC. Based on Grey correlation degree analysis,it indicated that the elevation was the most influential topographic factor on SLA,LNC,LPC,STD and SPC; LDMC and leaf thickness was most affected by slope aspect; and SNC was affected by slope position. There were differences in the functional traits of the plant species in tree layers of the forest communities,no obviously difference in shrub layers,as to the leaf functionaltraits,except of LDMC,LPC,SNC of the plant species in herbage layers had significant differences,other indicators no difference. LDMC and SLA are the main leaf functional traits that reflect the differences among communities succession.

Ground water as the main factor differentiating the natural vegetion in a landscape phytocomplex ("Grabowy" range in the Kampinos Forest Complex)

In the period 1973-1975 the depth of the ground water level and the moisture of the surface soil layer were investigated in various plant communities of the "Grabowy" range in the Kampinos Forest Complex (central Poland). The studies included a fragment of a landscape phytocomplex within which eight types of forest plant communities were distinguished. It was found that the plant communities change parallelly to the differences in the soil-water conditions (ground water level, physical properties and moisture of soils) in space.

小秦岭森林群落数量分类、排序及多样性垂直格局

PDF HTML阅读 XML下载 导出引用 引用提醒 小秦岭森林群落数量分类、排序及多样性垂直格局 DOI: 10.5846/stxb201308162093 作者: 作者单位: 河南农业大学 生命科学学院,河南小秦岭国家级自然保护区管理局,河南小秦岭国家级自然保护区管理局,河南农业大学 生命科学学院,郑州大学 离子束生物工程省重点实验室,河南农业大学 生命科学学院,河南农业大学 生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 河南省科技攻关（132102110133）；河南省教育厅科学技术研究重点项目（14A180013） Numerical classification, ordination and species diversity along elevation gradients of the forest community in Xiaoqinling Author: Affiliation: College of life sciences, Henan Agricultural University,Administration Bureau of Xiaoqinling National Nature Reserve of Henan,,,Henan Provincial Key Laboratory of Ion Beam Bio-engineering, Zhengzhou University,,college of life sciences, Henan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用分层取样的方法，沿小秦岭林区海拔梯度设立56块20 m×20 m样地，用多元回归树（MRT）方法对小秦岭森林群落进行分类，采用除趋势对应分析（DCA）进行排序，用广义可加模型（GAM）研究不同生活型物种多样性沿海拔梯度分布格局。结果表明：（1）56个样地进行MRT分类，经交叉验证并依据植物群落分类和命名原则，本区植物群落可分为5类；（2）样方DCA排序明确地揭示各群落类型生境分布范围，较好地反映小秦岭自然保护区森林群落与环境因子的关系；（3）不同生活型物种多样性指数随海拔梯度变化发生一定的波动，且呈现不同的多样性格局：丰富度指数中，乔木层呈显著的单峰分布格局，灌木层在中海拔段呈明显下降趋势，草本层随着海拔的升高总体呈下降趋势；Shannon-Wiener多样性指数中，不同生活型物种随海拔变化趋势与物种丰富度变化趋势大体相同；不同生活型物种的均匀度指数随海拔变化趋势较平缓。 Abstract:Forest community classification, ordination, and species diversity patterns along altitudinal gradients can reveal relationships between species distribution and environmental factors, providing an important basis for understanding the function of mountain ecosystems. Quantitative analysis is an important approach to research the community classification and sorting. And can reveal profoundly the ecological relationship between plant communities and environmental factors. Species diversity altitude gradient pattern study can further reflect the biological and ecological characteristics of species, distribution and its adaptability to the environment, to reveal the biological diversity environment gradient variation rule, and is important basis to know the mountain ecosystem function and carries on the reasonable operation. But different area and different life forms of species due to the restriction of various factors and present different gradient pattern. Therefore, for a specific mountain to carry out a case study of the species diversity altitude pattern is very necessary to. Xiaoqinling Nature Reserve is located at the intersection of northern, northeastern, central and southwestern plant community types resulting in rich plant resources. The unique geography, climate, and vegetation conditions make Xiaoqinling an ideal location to research forest communities. Few studies exist about the number of forest community types and species diversity along an altitudinal gradient in Xiaoqinling. However, in recent years, due to population pressures and large-scale economic development there have been declines in biodiversity in protected areas. We conducted a field investigation of 56 plots (20 m×20 m) in Xiaoqinling. The main site factors, forest communities were classified through ordination and species diversity patterns along the altitudinal gradient were analyzed using multivariate regression trees (MRT), detrended correspondence analysis (DCA), and generalized additive model (GAM). Results showed that, (1) forest communities were classified into 5 types by MRT. Ⅰ: Euptelea pleiospermum-Acer grosseri-Glechoma longituba + Poa acroleuca Association, Ⅱ: Pinus armandii + Betula utilis-Salix phylicifolia-Carex siderosticta Association, Ⅲ: Quercus mongolica-Rosa bella-Cayerus compressus Association, Ⅳ: Pinus armandii + Quercus baronii var. baronii + Cotinus coggygria-Forsythia suspensa-Cayerus compressus Association, Ⅴ: Pinus armandii + Pinus tabulaeformis-Acer grosseri-Oplismenus undulatifolius Association; (2) the results of DCA clearly reflected the distribution range of various community types and better reflect relationships between species distribution and environmental factors; (3) GAM simulation results show that along an altitudinal gradient woody have clearer distribution patterns than herbs. Richness index in the tree layer showed a significant unimodal distribution pattern, the shrub layer showed a downward trend in mid-elevation and herbceous layer showed a downward trend with increasing altitude. The Shannon-Wiener index showed the same trends as the richness index. The Pielou index of three-layer distribution showed little variation with increasing altitude. Forest community structure and vertical pattern of species diversity vary with altitude gradient have important significance to reveal biodiversity environment gradient variation rule. The results help to deeply understand the space distribution pattern of forest community and ecological characteristics of species and for the future provide the corresponding theoretical basis for management and protection, as well as to elucidate mountain flora distribution and diversity of vertical distribution pattern to accumulate basic data. 参考文献 相似文献 引证文献

湘中丘陵区南酸枣阔叶林群落特征及群落更新

Broad-leaved forest community dominated by Choerospondias axillaries is one of the main forest community types in the hilly area of central Hunan province,which plays a very important role in forest succession processes in subtropical region. In this study,a large permanent plot with an area of 1 hectares was established in the typical forest community of C.axillaries at the Dashanchong forest farm,Changsha county in the hilly region. The large plot was divided into 100 smaller sample plots of 100 square meters( 10m×10m). The characteristics of the C. axillaries community were investigated in detail to analyze biodiversity and regeneration dynamics of the community. In order to investigate the plant diversity of shrub and herb in the smaller plots,16 small samples were set up and distributed evenly in the sample plots,each small sample with area of 2m×2m. Plant diversity and succession dynamics were analyzed based on these field data. The results showed:( 1) in the arborous layer,there were 59 species in total which were more than 1 cm in diameter at breast height( DBH),belonging to 25 families and 42 genera in the community;( 2) the dominant species is C. axillaries with the largest important value( IV) of 23. 57 in the community. It was characterized with normal distribution in tree heights and DBH for the tree species of C. axillaries,with only 6 saplings of 1. 0cm to 1. 5 cm in DBH.( 3) The IV was 10. 46 for Symplocos setchuensis,7. 98 for Eurya muricata,5. 39 for Vernicia montana,and 4. 17 for Litsea coreana,respectively. The ratio of saplings,with less than 1. 5 cm in DBH,varied with different tree species,which was 22. 0% of saplings for the S.setchuensis population,16. 8% for E. muricata,11. 7% for A. montana,and 11. 0% L. coreana,respectively. The diameter structures of the 4 tree species showed an inverted J curve type.( 4) Considering the stratified structure of forest stands,the overstory were mainly occupied by C. axillaries,the understorey by S. setchuensis,E. muricata,V. montana and L. coreana.( 5) Forest seedlings were mainly dominated by evergreen broad-leaved tree species which regenerated well,with exception of C. axillaries saplings. These results indicated that the advantage of C. axillaries in the community was diminishing,whileas the importance of S. setchuensis,E. muricata,V. montana and L. coreana was increasing. Those evergreen broad-leaved tree species should be the dominate species in next succession stages,suggesting the C. axillaries broad-leaved community in hilly region of central Hunan province was developing toward the evergreen broad-leaved forest community succession.( 6) There were a total of 37 species in shrub and herb layer. The species with the largest five important values are Oropetalum chinensis,Rhododendron mariesii,Vaccinium bracteatum,Gardenia jasminoides and Rhododendron simsii,with an IV of 54. 59,21. 85,4. 98,4. 63 and 4. 53,respectively. The Loropetalum chinensis and Rhododendron mariesii were both dominant species in the shrub layer.

자연림 군집형 분류에 의한 교란의 정도와 임분 발달 사이의 관련성 검토

The correlation between disturbance intensity and stand development was evaluated on the basis of natural forest community type classification in areas of Baekhaksan (more disturbed area) and Hwangaksan (less disturbed area). The vegetation data were collected by point-centered quarter sampling method, and they were subjected to cluster analysis for classifying community types and to analysis of species composition and species diversity for reviewing ecological characteristics. By the method of cluster analysis, natural forests of Baekhaksan were classified into Quercus forest community, Pinus densiflora community, Q. variabilis community, and Q. mongolica community. Those of Hwangaksan were divided into P. densiflora community, Q. mongolica community, Q. forest community, and Mixed mesophytic community. It is presumed that more developed and less disturbed forest area shows multiple species community pattern and more diversified structure than less developed and more disturbed forest area. In Korean peninsula, the abundance of red pine may play an important indicator to estimate the developmental pattern of the forest after artificial disturbance. The overall evaluation indicated that less disturbed Hwangaksan area had more developed stand pattern with mixed mesophytic community, more complicated species composition, and higher species diversity than Baekhaksan area.

Assessing Naturalness in Northern Great Lakes Forests Based on Historical Land-Cover and Vegetation Changes

The concept of naturalness was developed to assess to what degree landscapes represent a natural state. Protected areas are often regarded as the remnants of untouched landscapes although many landscapes commonly perceived as pristine have a long history of human impact. Here, we introduced a historical perspective into the concept of naturalness and the analysis of the effectiveness of protected areas by analyzing historical trajectories in land-cover and forest communities for the Pictured Rocks National Lakeshore on Michigan's Upper Peninsula (USA). Distribution of land-cover and forest community types was reconstructed for pre-settlement time (around 1850), the height of agricultural expansion (1928), and modern conditions (2000). Naturalness of the landscape was assessed by analyzing similarity between pre-settlement and current conditions and by assessing landscape continuity (1850-1928-2000). We compared changes in the strictly protected park core zone with those in the inland buffer zone with ongoing sustainable logging, and a not protected area adjacent to the park. Forest was the dominant land-cover type over the entire study period. We detected a gradient in land-cover continuity from the core zone (81% continuity) to the inland buffer zone (74%) and the area outside the park (66%). Northern hardwood was the dominating forest type in all time points with high continuity (76%). In contrast, pine forests show a more dynamic pattern with more than 50% of the initial forests switching to non-forest or early succession forest types by 1928. More than half of the study area was considered as "natural virgin" (no changes in land-cover and forest community type) with a higher portion within the park than in the adjacent area. In contrast, areas with low naturalness are more abundant outside the park. Our study demonstrates the value of integrating historical information into naturalness assessments and the results provide useful information for future park management. More broadly speaking, our study advances research on the effectiveness of protected areas, by going beyond simple measures of averted deforestation, and introducing approaches to directly measure naturalness.

Plant Communities of Travertine Outcrops of the Saturnia Area in Southern Tuscany (Central Italy)

Abstract A phytosociological survey was carried out in a poorly known travertine area of southern Tuscany harbouring a rich vegetation mosaic with chamaephytic garrigues, species-rich xerophytic grasslands, chasmophytic coenoses, annual species-dominated communities, shrublands and thermophilous deciduous forests. Field sampling and data analysis allowed to identify and characterize several community types, some of which of significant interest due to their ecological specificity and rarity in peninsular Italy. In particular, our data confirm the associations Pistacio terebinthi-Paliuretum spinosae and Pistacio terebinthi-Quercetum pubescentis, respectively a shrub and forest community type previously unknown for Tuscany. In addition, a new therophytic association of travertine debris named Sedetum hispanico-caespitosi and placed in the Hypochoerion achyrophori alliance (Brachypodietalia distachyi order, Tuberarietea class) is also described. Finally, dynamic relationships between the vegetation types are highlighted and the presence of conservation priority habitats in the area are pointed out.

Quantification of repeated gap formation events and their spatial patterns in three types of old-growth forests: Analysis of long-term canopy dynamics using aerial photographs and digital surface models

Treefall gaps are important elements of forest dynamics, as they contribute substantially to regeneration and forest turnover rates. Repeated gap formation, i.e. the formation of new gaps in areas where gaps have previously occurred then closed within decadal timeframes, is also believed to occur frequently and to contribute significantly. However, most gap studies have focused on the relationships among gap size, associated light levels and regeneration processes. In contrast, little reliable, quantitative information on the frequency of repeated gap formation events and their spatial patterns is available. To quantify repeated gap formation events in old-growth forests, we re-analyzed our previously published data on long-term canopy dynamics in three forest types (warm-temperate, cool-temperate and subalpine coniferous forests) in Japan, using digital surface models developed from aerial photographs taken in different years. Estimated repeated gap formation rates were 2.6%/32years (0.081%/year), 3.8%/43years (0.088%/year) and 8.3%/43years (0.193%/year) in the warm-temperate, cool-temperate and subalpine forest, respectively. The size distributions of repeated gap areas were skewed towards small areas, did not differ among the three forest types and closely fitted a power-law function. The mean repeated gap area also did not differ among forest types. The repeated gap areas were generally distributed along the edges of old gaps in the warm-temperate and cool-temperate broadleaved forests, according to a torus-translation test. Within the old gaps, continuous and/or rapid height growth was detected in sites with repeated gap events, and dramatic changes in canopy height were observed in sites adjacent to the edges of old gaps, which could have been due to the lateral expansion of branches and their subsequent destruction. These analyses revealed that the temporal and spatial canopy dynamics of the studied forest communities were very diverse and more dynamic than previously reported. Hence, future analyses of data obtained from Large-scale and Long-term Monitoring sites (LLMs) established in various types of forest communities around the world should pay attention to repeated gap formation events and their spatial patterns.

Soil seed banks in a mature coniferous forest landscape: dominance of native perennials and low spatial variability

AbstractSoil seed banks are important to vegetation recruitment, ecosystem functioning and land management. We evaluated composition of 0–5 cm soil seed banks and relationships of seed banks with forest community types (ranging from low-elevation pinyon–juniper to high-elevation bristlecone pine), vegetation cover and environmental variables within a 40,000-ha relatively undisturbed coniferous forest landscape in Nevada, USA. We collected samples from 36 sites and used the emergence method to assay seed banks. Seed density averaged 479 seeds m− 2across sites and a total of 39 taxa were detected. Most (79%) of these taxa were perennials and 35 of 39 (90%) were native. Moreover, 62% of seed-bank taxa were in the vegetation of mature forests, an uncommon finding in studies of forest soil seed banks. Seed-bank density, species richness and composition did not display strong relationships with forest community types, vegetation cover or environmental variables. Weak relationships likely arose from the relatively uniform seed-bank density among sites, where 50% of sites had seed densities in the range of 106–282 m− 2. Results suggest that while seed banks on this landscape are not large, they provide recruitment potential for some native perennial species of mature, relatively undisturbed communities.

Geographical patterns of selected features of the soil and herb layer in central and north European scots pine forests

This paper defines the relationships between geographical location (which determines macroclimatic differentiation and reflects the history of the vegetation), soils (which determine hydrolytic acidity, degree of base saturation and organic carbon content), and selected characteristics of vegetation (species richness, herb layer biomass, moss layer biomass) in one type of forest community, namely, pine forests of the Vaccinio-Piceetea class. The study area covers the major part of the European domain of pine forests, from 70.15°N (Norway) to 50.35°N (Poland) and from 12.02°E (Sweden) to 33.6°E (Russia). The geographical pattern shows the following correlations: (a) a rise in the number of vascular plant species in the herb layer as one moves from west to east and from north to south; (b) no significant relationship between geographical location and the biomass of the herb layer, but it is possible to divide the study area into two parts: central Scandinavia, characterized by a high level of biomass, and the rest of the area, characterized by lower herb layer biomass; (c) a south-north increase in the standard deviation of herb layer biomass (serving also as a measure of spatial heterogeneity of the forest floor in terms of the synusial structure of the community); (d) greater biomass of the bryophyte (moss+lichen) layer in the north than in the south and in the east than in the west; (e) stability at lower latitudes of standard deviation for moss biomass (serving also as a measure of spatial heterogeneity of the forest floor in terms of the synusial structure of the community), albeit with a sharp increase north of latitude 55°N.

森林自然更新过程中地上氮贮量与生物量异速生长的关系

研究植物氮贮量与生物量(M)之间的异速生长关系对于开展生态系统碳收支和氮循环研究具有重要意义。目前大量对氮贮量与生物量关系的研究主要集中在个体水平,对于群落水平的氮贮量和生物量之间的异速生长关系,以及群落自然更新过程如何影响该关系仍有待深入研究。利用3种森林类型皆伐后20多年自然更新过程中氮贮量和生物量的数据,采用简化主轴回归方法(reduced major axis, RMA)对不同自然更新阶段的森林氮贮量和生物量之间的异速生长指数和常数进行比较。结果表明:在不同的更新阶段,3种森林类型的植物氮贮量和生物量之间的异速生长指数均接近于1.0 (即N∝M^{0.91 -1.07})。异速生长常数随更新时间的增加而逐渐降低,导致3种森林类型整体上氮贮量正比于生物量的0.85次幂。异速生长常数的降低可能是由于在更新过程中叶生物量占整体生物量的比例逐渐下降,导致其对N吸收的生态化学计量制约所造成。;Exploring the relationship between tissue nitrogen content (N) and its biomass (M) is crucial for understanding ecosystem carbon balance and N cycling because N is one of the limiting nutrients for the primary production in most terrestrial ecosystems. Although much has been learnt about N utilization and distribution within plant body, how N and M are coupled at the community level, especially for ecosystems after disturbance, remains inadequately understood. Prior work indicates that N and M often co-vary in a manner that can be expressed as a power law, mathematically taking the form N = β^Mα, where β is an allometric constant and α is the scaling exponent. Although it has been demonstrated that N scales as approximately the 3/4 power of M across a wide diversity of plant communities, considerable uncertainty exists as to whether this 3/4 scaling relationship is valid for all forested communities or whether it changes as a function of forest successional stage. To fill this gap, data on N and M were collected from different woody species of three different forest community-types (i.e. cove hardwoods, mesic, mixed-oak community, and the dry, mixed-oak community) over 20-years of succession following commercial clear-cutting in a watershed (WS7) located in the Coweeta Hydrologic Laboratory. Total stand nitrogen content scaled nearly isometrically with respect to total stand biomass (i.e. N∝M^≈1.0) for 16 out of the 18 successional stages of the three community types. The mean scaling exponents of N vs. M for the cove hardwood community, the mesic, mixed-oak community, and the dry, mixed-oak community were 0.96, 0.99 and 0.97, respectively. Our observations make it reasonable to suppose that the isometric scaling relationship of N vs. M should scale up from the level of individual trees to the level of an entire forest stand at each particular successional stage. Despite this homogeneity in N vs. M scaling exponents across the different successional stages and the three community-types, all three forest communities had allometric constants that decreased systemically with increasing stand age. The highest <em>Y</em>-intercept was observed immediately after clear-cutting, whereas the lowest <em>Y</em>-intercept was observed approximately 20 years after cutting. Specifically, N scales as the 0.85-power of M across entire data set as a consequence of the systemic decrease in the numerical value of the allometric constant as succession progresses. Thus, the 3/4 scaling relationship of N vs. M likely results from neglecting the effects of shifting allometric constant with increasing stand age. Our data provide an example of how a systemic change in allometric constants could result indirectly in a significant change in the scaling exponent controlling the relationship between total N content and biomass at the level of an entire forest. Furthermore, the decrease in the allometric constants over stand development may be due to the concurrent decrease in the ratio of leaf biomass to total aboveground biomass (LAR) as succession proceeded. Such results suggest ways to bridge the gap between plant physiological constraints and stand (community) allometry, and highlight the importance in understanding and modeling the nutrient allocation patterns at the level of stand.

Soil Seed Banks and Forest Succession Direction Reflect Soil Quality in Ziwuling Mountain, Loess Plateau, China

AbstractThe paper presents a study by taking the soil seed banks and vegetation successions of the forests in Ziwuling Mountain as indicators to analyze the effects of the ages, and the litter layers and soil depths at growing locations in seven types of forest communities on their seed bank formations and soil quality. The results showed that the seed banks at different growing locations in the communities increased in the order of upper slope, middle slope, and lower slope; the seed storages of the seed banks in the different layers of the communities varied, much more higher in the litter layers than in 0–15 cm, and the seed storages of the seed banks in the seven types of forest communities ranked in the increasing order of Pinus tabulaeformis forest, Pinus shenkaneusis forest, Quercus liaotungensis forest, Populus davidiana forest, Betula platyphylla forest, scrub communities, and grassland communities; in the meantime, the seed storage of seed banks peaked in 30–50 years old P. shenkaneusis forest, 30–40 years old P. tabulaeformis forest, 15–30 years old Q. liaotungensis, and P. davidiana and B. platyphylla forests, and 10–15 years old scrub and grassland communities, and the ages of the communities varied with the seed storages of the seed banks in a significantly correlative manner following a fitted exponential equation. In addition, the soil seed banks of the seven types of communities consisted of rich and diverse species with the herbaceous and shrub species greatly outnumbering the arbor species; in general, the coniferous forests were composed of 31 kinds of plants, the deciduous and broadleaf forests consisted of 20–29 plant species, the shrubs contained 27 plant species, and the herbaceous plants numbered 20 plant species; The various species compositions contained only 4–6 arbor species with most being foreign species. In each of the compositions, Bothriochloa ischemum was the grassland plant with the highest occurrence frequency, Sophora viciifolia and Hippophae reamnoides were the shrub plants with the highest occurrence frequencies, and Q. liaotungensis was the arbor plant with the highest occurrence frequency, and they followed by P. shenkaneusis and P. tabulaeformis. These results showed that soil seed banks and forest successions are better indicators for soil quality from natural successions.

Links between plant diversity, carbon stocks and environmental factors along a successional gradient in a subalpine coniferous forest in Southwest China

In all, 48 sites of subalpine coniferous forest that had undergone natural regeneration for 5–310 years were selected as study locations in the Southwest China. We compared species richness ( S), plant diversity (Shannon–Wiener index, H′; Margalef index, R), and above- and below-ground ecosystem carbon (C) pools of six plant communities along a chronosequence of vegetation restoration, and we also examined evidence for a functional relationship between plant diversity and C storage. Our results showed that above-ground C increased significantly (over 52-fold), mainly due to the increase of C in aboveground living plants and surface litter. Soil organic carbon (SOC) content increased from the herb community type (dominated by Deyeuxia scabrescens, P1) to mixed forest type (dominated by Betula spp. and Abies faxoniana, P4), which constituted the main C pool of the system (63–89%), but decreased thereafter (communities P5–P6). The mean C stock in the whole ecosystem – trees, litter layer and mineral soil – ranged from 105 to 730 Mg C ha −1 and was especially high in the spruce forest community type (dominated by Picea purpurea, P6). On the other hand, the relationships between C stocks (soil, aboveground) and mean annual temperature or altitude were generally weak ( P > 0.05). Moreover, we did not detect a relationship between S and aboveground C storage, while we found a significant negative relationship between H′, R and aboveground C storage. In addition, our experiment demonstrated that total root biomass and litter C/N ratio were significant functional traits influencing SOC, while S, R, and H′ had little effect. Path analysis also revealed that litter C/N ratio predominantly regulated SOC through changes in the quantity of microorganisms and soil invertase enzyme activity.