Climate and fire drivers of forest composition and openness in the Changbai Mountains since the Late Glacial

Ongoing climate changes have a direct impact on forest growth;they also affect natural fire regimes,with further implications for forest composition.Understanding of how these will affect forests on decadal-to-centennial timescales is limited.Here we use reconstructions of past vegetation,fire regimes and climate during the Holocene to examine the relative importance of changes in climate and fire regimes for the abundance of key tree species in northeastern China.We reconstructed vegetation changes and fire regimes based on pollen and charcoal records from Gushantun peatland.We then used generalized linear modelling to investigate the impact of reconstructed changes in summer temperature,annual precipitation,background levels of fire,fire frequency and fire magnitude to identify the drivers of decadal-to-centennial changes in forest openness and composition.Changes in climate and fire regimes have independent impacts on the abundance of the key tree taxa.Climate variables are generally more important than fire variables in determining the abundance of individual taxa.Precipitation is the only determinant of forest openness,but summer temperature is more important than precipitation for individual tree taxa with warmer summers causing a decrease in cold-tolerant conifers and an increase in warmth-demanding broadleaved trees.Both background level and fire frequency have negative relationships with the abundance of most tree taxa;only Pinus increases as fire frequency increases.The magnitude of individual fires does not have a significant impact on species abundance on this timescale.Both climate and fire regime characteristics must be considered to understand changes in forest composition on the decadal-to-centennial timescale.There are differences,both in sign and magnitude,in the response of individual tree species to individual drivers.

Detecting forest landscape boundary between Mountain Birch and evergreen coniferous forest in the northern slope of Changbai Mountain

Boundaries between different forest types in Changbai Mountain Eastern China are results from complex interactions between forest ecosystems, topography, and geomorphology. Detecting and quantifying the transitional zones are highly important since high environmental heterogeneity and biodiversity are often found within these zones. In this study, we used GIS and multivariate statistics techniques(PCA and MSWA) to analyze data from Landsat TM satellite imageries and quantitatively determined the positions and widths of the landscape boundary between mountain birch and evergreen coniferous forests in the northern slope of Changbai Mountain. The results showed that the widths of the landscape boundary ranges from 30—50m while using the MSWA or/and PC method. Such detected widths are consistent with field transect data that suggests a 50m transitional zone width. The results further suggest that TM data can be used in combination with GIS and statistical techniques in determining forest landscape boundaries; MSWA is more reliable than PCA, while PCA can also be used to determine the landscape boundary when transects are properly located.

Structure and regeneration dynamics of three forest types at different succession stages of spruce – fir mixed forest in Changbai Mountain, northeastern China

Analyzing and understanding the structure and growth dynamics of forests at different stages is helpful to promote forest succession, restoration and management. Three spots representing three succession stages of spruce-fir mixed forest(SF: polar-birch secondary forest, MF: spruce-fir mixed forest and PF: spruce-fir near primary forest) were established. Structure, growth dynamics during two growth seasons for dominant tree species, regeneration were examined, and a univariate O-ring function statistic was used to analyze the spatial patterns of main regeneration tree species. Results showed that,(1) composition of tree species, periodic annual increment(PAI) of the diameter at breast height(DBH), basal area for overstory trees and of ground diameter(DGH) for saplings, were significantly different with the succession;(2) the current species composition and regeneration dynamics of SF suggested a development towards spruce-fir mixed forests. Pioneer species like Betula platyphyllaa will gradually disappear while climax species, such as Abies nephrolepis, Pinus koraiensis, Picea koraiensis and Tilia amurensis will dominate forest stands;(3) Despite the highest volume occurring in PF, and saplings in it grew better than in the others, this forest type is unstable because of its unsustainable structure of DBH class and insufficient regeneration; and(4) MF had the most reasonable distribution of DBH class for adult trees(DBH > 5.0 cm) and DGH class for saplings(H ≥30 cm and DBH ≤5 cm), as well as an optimal volume increment. Limiting canopy opening size can lessen the physiological stress and promote the growth and competitive status of regeneration. Management implications for increasing the gaps and thus creating better growth conditions for understory saplings and facilitating forest succession were discussed.

Dynamics of dominant tree species in a forest ecotone on the northern slop of Changbai Mountain

在在 broad-leaved/Korean 松( Pinus koraiensis )之间的森林交错群落的优势木种类的比赛和动力学在 Changbai 山的混交林和云杉冷杉木森林(也已知的同样黑暗的针叶树森林)，在东北中国的吉林省被使用 Lotka-Volterra 学习模型，基于从有为每一个的 20 m x90 m 的区域的 28 个样品阴谋的数据。结果证明在自然状况下面，社区的区别跟随了二条指令：一个人将是云杉(Picea jezoensis 和很少 P。koraiensis ) 并且冷杉木(Abiesnephrolepis )co 主导的针叶树森林，并且在平衡，冷杉木绝对是优势的(77.1% 相对优势(RD )) ；其它将是针叶树和阔叶的混交林，并且在平衡，阔叶的树种类是在 broad-leaved/Korean 松混交林的 50% RD 并且 66% RD 在阔叶并且云杉冷杉木混交林。学习证明两 broad-leaved/Korean 松混交林和黑暗针叶树森林是演替顶极群落，交错群落有过渡特征，并且森林社区的多样化建议继任的方向被本地产地影响。

Effects of Logging Intensity on Structure and Composition of a Broadleaf-Korean Pine Mixed Forest on Changbai Mountains,Northeast China

In order to identify a harvesting model which is beneficial for broadleaf-Korean pine mixed forest(BKF) sustainability, we investigated four types of harvested stands which have been logged with intensities of 0(T0, control), 15%(T1, low intensity), 35%(T2, moderate intensity), and 100%(T3, clear-cutting), and examined the impacts of logging intensity on composition and structure of these stands. Results showed that there were no significant differences between T0 and T1 for all structural characteristics, except for density of seeding and large trees. The mean diameter at breast height(DBH, 1.3 m above the ground), stem density and basal area of large trees in T2 were significantly lower than in T0, while the density of seedlings and saplings were significantly higher in T2 than in T0. Structural characteristics in T3 were entirely different from T0. Dominant tree species in primary BKF comprised 93%, 85%, 45% and 10% of the total basal area in T0, T1, T2 and T3, respectively. Three community similarity indices, the Jaccard′s similarity coefficient(CJ); the Morisita-Horn index(CMH); and the Bray-Curtis index(CN), were the highest for T0 and T1, followed by T0 and T2, and T0 and T3, in generally. These results suggest that effects of harvesting on forest composition and structure are related to logging intensities. Low intensity harvesting is conductive to preserving forest structure and composition, allowing it to recover in a short time period. The regime characterized by low logging intensity and short rotations appears to be a sustainable harvesting method for BKF on the Changbai Mountains.

Influencing Factors of Seed Long-distance Dispersal on a Fragmented Forest Landscape on Changbai Mountains,China

Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas.

Age structure of Tilia broad-leaved Korean pine forest on northern slope of Changbai Mountain

Based on a vast of field investigation on stamps in Tilia broad-leaved Korean pine forest on northem slope of Changbai Mountain, age structure of some major species were studied in this paper. The results showed that Korean pine population was composed of grouped patches with different ages. There were not strict intervals among the dominated generations,and the curve of age structure often had two or more peaks. The distribution of broad-leaved species in natural Korean pine forest was grouped or scattered, and age distribution was also uneven-aged. There existed close relation between quantity of broad-leaved species and Korean pine. So, it shaped multi-storied and uneven-aged mixed forest. The model of age structure and growth demonstrated their passive correlation, but growth became slow when woods had reached old age.

Species composition and minimum sampling area of a riparian mixed broadleaved-Korean pine forest in Changbai Mountain Nature Reserve

Riparian areas are unique although often small component of the overall watershed landscape. The structure of riparian forests along Erdaobai River on the north slope of Changbai Mountain were investigated by using field data collected from eight sampling transects perpendicular to the Erdaobai River channel. Two kinds of species-area saturation curves were used to examine the relationship between species number and minimum sampling area. The results showed that riparian gymnosperms accounted for a high proportion of all gymnosperms in the Changbai Mountain Nature Reserve while riparian ferns and angiosperms accounted for a relatively low proportion. The average minimum sampling areas of riparian forest that included 60%, 80%, and 90% of the community species pool were about 85, 185, and 328 m 2 , respectively; while those for nonriparian forest were about 275, 390, and 514 m 2 , correspondingly.

Carbon storage of a subtropical forest ecosystem: a case study of the Jinggang Mountain National Nature Reserve in south-eastern China

The carbon cycle of forest ecosystems plays a key role in regulating CO2 concentrations in the atmosphere. Research on carbon storage estimation of forest ecosystems has become a major research topic. However, carbon budgets of subtropical forest ecosystems have received little attention. Reports of soil carbon storage and topographic heterogeneity of carbon storage are limited. This study focused on the Jinggang Mountain National Nature Reserve as an example of a mid-subtropical forest and evaluated soil and vegetation carbon storage by field sampling combined with GIS, RS and GPS technology. We classified the forest into nine forest types using ALOS high-resolution remote sensing images. The evergreen broad-leaved forest has the largest area, occupying 26.5% of the total area, followed by coniferous and broad-leaved mixed forests and warm temperate coniferous forest, occupying 24.2 and 22.9%, respectively. The vegetation and soil carbon storage of the whole forest ecosystem were 1,692,344 and 5,514,707 t, with a carbon density of 7.4 and 24.2 kg/m^2, respectively, which suggests that the ecosystem has great carbon storage capacity. The topographic heterogeneity of the carbon storage was also analysed. The largest vegetation storage and soil storage is at 700–800 and 1000–1100 m, respectively. The vegetation carbon storage is highest in the southeast, south and southwest.

Species frequency of communities along northern slope of Changbai Mountain, Northeast China

The species distribution frequency of communities from 700 m to 1900 m along northern slope of Changbai Mountain was studied by using Raunkiaer’s frequency analysis methods in summer of 1999. The variation on composition and structure of communities with the increase of elevation was displayed from the point of view of frequency. The results showed that for all the species of community including tree, shrub and herb, the frequency presented a "L" shape even though there were difference among communities. The percentage of high frequency species increased with the increase of elevation. As one of important index in rejecting species spatial patterns, frequency not only show up the importance of species, but also the evenness of spatial distribution in community. Frequency figure could reveal the complexity and diversity of community at some extent.

Similarity between seed rain and neighbouring mature tree communities in an old-growth temperate forest

Seed distribution and deposition patterns around parent trees are strongly aff ected by functional traits and therefore infl uence the development of plant communities.To assess the limitations of seed dispersal and the extent to which diaspore and neighbouring parental traits explain seed rain,we used a 9-year seed data set based on 150 seed traps in a 25-ha area of a temperate forest in the Changbai Mountain.Among 480,598 seeds belonging to 12 families,17 genera,and 26 species were identifi ed,only 54%of the species with mature trees in the community were represented in seeds collected over the 9 years,indicating a limitation in seed dispersal.Understory species were most limited;overstory species were least limited.Species with wind-dispersed seed had the least limitation,while the lowest similarity in species richness was for animal-dispersed species followed by gravity-dispersed species;fl eshy-fruited species had stronger dispersal limitations than dry-fruited species.Generalized linear mixed models showed that relative basal area had a signifi cant positive eff ect on seed abundance in traps,while the contribution of diaspore traits was low for nearly all groups.These results suggest that tree traits had the strongest contribution to seed dispersal and deposition for all functional groups examined here.These fi ndings strengthen the knowledge that tree traits are key in explaining seed deposition patterns,at least at the primary dispersal stage.This improved knowledge of sources of seeds that are dispersed could facilitate greater understanding of seedling and community dynamics in temperate forests.

Landscape influences and management countermeasures of ginseng planting near Changbai mountain nature reserve

Ginseng planting in Northeast China brings economic benefits but affects forest landscape integrity and native ecological processes.In order to quantify the impacts of ginseng planting on the forest landscape,Fusong County in Jilin Province was selected as a study area.The number and distribution of ginseng fields over different time was quantified based on remote sensing and ground surveys.Grid analysis and multiple regression analysis were used to study the impacts of ginseng planting on the landscape.The results showed that altitudes and slopes of ginseng fields increased and became increasingly scattered and smaller closer to the Changbai Mountain Nature Reserve.Ginseng fields and abandoned fields increased total patches and total area of the local forested landscape,and shared edge lengths between ginseng fields and forests,resulting in continuous fragmentation of the landscape.Although the total area of existing and abandoned ginseng fields accounts for a small fraction of the total landscape,their negative impacts on ecosystem conservation is significant.The local government needs to rationally plan ginseng planting,scientifically implement the restoration of abandoned ginseng lands,and enhance awareness of ginseng farmers to environmental stewardship.Our study has important significance for maintaining the healthy and stable development of the local ginseng industry and for improving the quality of regional ecological environment.

Long-term protection effects of national reserve to forest vegetation in 4 decades: biodiversity change analysis of major forest types in Changbai Mountain Nature Reserve, China

The Changbai Mountain Nature Reserve (CNR) was established in 1960 to protect the virgin Korean pine mixed hardwood forest, a typical temperate forest of northeast China. We conducted systematic stud- ies of vascular diversity patterns on the north slope of the CNR mountainside forests (800-1700 m a.s.l.) in 1963 and 2006 respectively. The aim of this comparison is to assess the long-term effects of the protection on plant biodiversity of CNR during the interval 43 years. The research was carried out in three types of forests: mixed coniferous and broad-leaved forest (MCBF), mixed coniferous forest (MCF), and sub-alpine coniferous forest (SCF), characterized by different dominant species. The alpha diversity indicted by species richness and the Shannon-Wiener index were found different in the same elevations and forest types during the 43-year interval. The floral composition and the diversity of vascular species were generally similar along altitudinal gradients before and after the 43-year interval, but some substantial changes were evident with the altitude gradient. In the tree layers, the dominant species in 2006 were similar to those of 1963, though diversity declined with altitude. The indices in the three forest types did not differ significantly between 1963 and 2006, and these values even increased in the MCBF and MCF from 1963 to 2006. However, originally dominant species, P. koraiensis for ex- ample, tended to decline, while the proportion of broad-leaved trees increased, and the species turn- over in the succession layers trended to shift to higher altitudes. The diversity pattern of the under canopy fluctuated along the altitudinal gradient due to micro-environmental variations. Comparison of the alpha diversity in the three forests shows that the diversity of the shrub and herb layer decreased with time. During the process of survey, we also found some rare and medicinal species disappeared. Analysis indicates that the changes of the diversity pattern in this region are caused by both nature and human factors. Meteorological records revealed that climate has changed significantly in the past 43 years. We also found the most severe human disturbance to the CNR forests in the process of another field survey that is the exploitation of herb medicines and Korean pine nuts. We hope this research would give some guidance to the future reserve management in Changbai Mountain area.

Forest ecosystem services of Changbai Mountain in China

The forest ecosystem of the Changbai Mountain is the most typical upland temperate forest ecosystem in eastern Asia. It is also of the most primitive vegetation type that came into being through the natural succession of soil and vegetation following volcanic eruption. The forest ecosystem has great importance for maintaining the structures and functions of the watershed ecosystems of the Songhua River, the Yalu River and the Tumen River. We combined physical assessment method(PAM) with the value assessment method(VAM) to evaluate the forest ecosystem services of the northern slope of the Changbai Mountain, including eco-tourism, forest by-products, timber, soil and water conservation, air purification, and the recycling of nutritive elements. We also assessed the integrated forest ecosystem service and analyzed its dynamics. The service value provided by the Changbai Mountain forest ecosystem amounts up to RMB 3.38×1012 yuan, of which, water conservation is 66%, water conservation and air purification together make up 80%, while the timber value is only 7%. Therefore, developing the ecosystem services besides timber is the best way to exert the integrated value of the forest ecosystem services of Changbai Mountain.

Pollen flux and vertical dispersion in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains

The pollen flux in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains is presented in one year's experiments. The results indicate that arboreal pollen percentages are more than 65% and pollen flux is higher than 5000 grain·cm-2·a-1,while less than 2% and lower than 1000 grain·cm-2·a-1 for shrubby pollen,and less than 20% and lower than 3000 grain·cm-1·a-1 for herbaceous pollen for most samples at different heights. The pollen assemblages are similar to those in the samples under 8 m height where Pinus and Ouercus are dominant and followed by the few non-local pollen types,and Fraxinus percentages are high with a few non-local pollen types at 16 m to 32 m height as well as non-local pollen clearly increased at 40 m height. Comparisons between pollen assemblages and vegetation composition suggest that similarities are higher for pollen trap samples than for surface moss samples.

长白山原始阔叶红松(Pinus koraiensis)林及其次生林细根生物量与垂直分布特征

以我国东北长白山自然保护区内同一海拔梯度的原始阔叶红松林及其次生林——白桦山杨成熟林和白桦山杨幼林为对象,采用土钻取样法对不同演替阶段细根生物量的变化、细根垂直分布规律及其影响因子进行系统地研究。研究结果表明,在原始阔叶红松林的正向演替过程中,林地细根的总生物量逐渐增加,其中主要乔木细根的生物量逐渐增加,而灌木和草本细根的生物量则逐渐降低。在演替过程中,细根的垂直分布逐渐加深。在长白山地区,3块林地中细根生物量的组成分布受林分植被组成的影响;细根的垂直分布与土壤容重、水分含量以及不同土层中C、N含量存在一定的相关性,但与土壤温度则不存在相关关系。

长白山阔叶红松(Pinus koraiensis)林种子雨组成及其季节动态

为了解阔叶红松（Pinus koraiensis）林的种子雨组成及其在时间和空间上的动态变化，在长白山阔叶红松林25hm^2样地内，设置了150个种子收集器，收集掉落于种子收集器中的果实、种子等。所有收集到的样品分别鉴定其种类并分为成熟种实、未成熟种实、花序和果实或种子碎片及其附属物4类，计算各类别的数量，而后分别烘干秤重。从2005年6月到2006年11月，共收集到隶属11科12属20种的种实及其生殖器官残体。累计收集到121291粒种实，其中成熟种实23147粒，仅占所有种实总个体数的19．1％。种实数最多的树种是紫椴（Tilia amurensis）和水曲柳（Fraxinus mandshurica），两个树种种实的个体数占总个体数的90％。对2006年5月-11月种子雨季节动态的分析发现：种实在7月中旬至10月下旬数量极大，但主要由未成熟种实组成；在10月中旬出现成熟种实散落高峰，但未成熟种实仍占一定的比例。按每个收集器收集到的成熟种实数统计，成熟种实数量在100-200之间的收集器数量最多。按每个收集器收集到的树种数统计，收集器中最多收到的树种数为7，树种数为3和4的收集器个数最多。对6个主要树种成熟种实所在收集器的空间分布进行分析发现，紫椴和水曲柳的成熟种实在整个样地都有分布，春榆（Ulmusjaponica）、糠椴（T.mandshurica）、色木槭（Acermono）和假色槭（A．pseudo-sieboldianum）则只在样地的局部区域收集到成熟种实。成熟种实的空间分布与母树的空间分布大都表现出明显的相关性，表明这些树种的成熟种实并没有扩散到离母树较远的距离。

四川米仓山水青冈天然林下不同植物群落的土壤酶活性及化学计量特征

研究了四川米仓山自然保护区的水青冈(Fagus)天然林林下野扇花(Sarcococca ruscifolia)和箭竹(Fargesia spathacea)群落不同土壤(h)深度(0<h≤10 cm、10 cm<h≤20 cm)的酶活性、化学计量特征及其主要环境影响因子。研究结果表明:(1)在林下不同植物群落中,全氮(TN)含量表现为无植物群落高于有植物群落;在10 cm<h≤20 cm的土壤深度下,土壤全碳(TC)、碱解氮(SAN)含量表现为野扇花群落最高。(2)野扇花群落的土壤酶活性(酸性磷酸酶(AP)、1,4-β-N-乙酰葡糖胺糖苷酶(NAG))显著高于无植物群落和箭竹群落,β-葡萄糖苷酶(BG)、亮氨酸氨基肽酶(LAP)活性表现为箭竹群落最高,多酚氧化酶(PPO)、过氧化物酶(POD)活性表现为有植物群落显著高于无植物群落。(3)BG、LAP、PPO和POD这4种土壤酶活性与土壤pH呈显著正相关,土壤酶活性(除纤维二糖水解酶(CBH))均与土壤含水量呈显著正相关。冗余分析(RDA)结果显示,土壤含水量、SAN、TC含量分别解释了土壤酶活性及其化学计量特征变异的51.4%、40.5%、37.7%。(4)在3种不同植物群落下,向量角度(VA)均大于45°,表明3种不同植物群落下土壤微生物更易受到磷元素的限制。林下不同植物群落能影响土壤理化性质及土壤酶活性,土壤含水量、SAN和TC含量对土壤酶活性及其化学计量特征起主要调控作用。

基于视觉吸引的森林景观色彩要素识别及影响因素研究——以云南轿子山自然保护区为例

为探究影响森林景观视觉吸引力的色彩要素以及提升森林景观视觉质量的色彩营造途径,采用视觉行为实验对云南轿子山四季森林色彩景观视觉吸引力进行评估,从色彩组成与空间构成两方面进行森林色彩特征分析,基于色彩特征要素与公众视觉行为构建视觉吸引力评价模型,并分析影响景观视觉吸引力的色彩要素最佳阈值。结果表明:(1)轿子山森林四季色彩呈多样化特点,色相在红色、黄色、绿色、蓝色和蓝紫色中均有涉及。景观色谱集中在选择性色谱与点缀性色谱。(2)公众视觉注意力和焦点随着森林景观的色彩变化而改变。春、夏、秋三季森林景观更能引起公众视觉关注。(3)春季的红色、蓝紫色等彩色相是影响色彩景观视觉吸引力的主要因素;秋季的色彩要素组成与斑块空间构成共同影响色彩景观视觉吸引力;冬季的森林色彩景观,视觉吸引力与绿色相密切相关。研究结论可为森林景观高品质视景营造提供理论依据。

乌蒙山自然保护区十齿花林生态化学计量特征

以云南乌蒙山国家级自然保护区十齿花林为研究对象,利用单因素方差分析及多重比较等方法对其叶片、凋落物、土壤C、N、P含量及化学计量比进行分析,阐明十齿花林生态系统养分限制情况及养分循环特征。结果表明:十齿花林叶片、凋落物、土壤C平均含量分别为592.48、540.61、51.51 g·kg^(-1),N平均含量分别为19.41、15.45、1.66 g·kg^(-1),P平均含量分别为1.67、1.67、0.35 g·kg^(-1),各组分营养元素含量表现为叶片>凋落物>土壤;同一样地内植物叶片、凋落物和土壤C、N、P含量及化学计量比差异显著,不同样地土壤C、N、P含量及化学计量比、凋落物C含量差异显著,其余组分各指标差异不显著;叶片-凋落物N、C∶N显著相关,凋落物-土壤C显著相关;十齿花林生态系统主要受N素限制,凋落物的营养元素源于叶片,分解后归于土壤,为十齿花林生长发育提供养分支持,促进养分循环。