Responses of Tree Transpiration and Growth to Seasonal Rainfall Redistribution in a Subtropical Evergreen Broad-Leaved Forest

Precipitation changes such as more frequent drought and altered precipitation seasonality may impose substantial impacts on the structure and functioning of forest ecosystems. A better understanding of tree responses to precipitation changes can provide fundamental information for the conservation and management of forests under future climate regimes. We conducted a 2-year seasonal rainfall redistribution experiment to assess the responses of tree transpiration and growth to manipulated precipitation changes in a subtropical evergreen broad-leaved forest. Three precipitation treatments were administered including a drier dry season and wetter wet season treatment (DD), an extended dry season and wetter wet season treatment (ED), and an ambient control treatment, with the total amount of annual rainfall being kept the same among the three treatments. Our results showed that the DD and ED treatments reduced daily transpiration of Schima superba by 8–16 and 13–25%, respectively. The ED treatment also reduced the DBH increment of larger S. superba individuals. In contrast, neither treatment showed obvious effects on the transpiration and DBH increment of another dominant species Michelia macclurei. However, the transpiration of both species showed clear inter-annual differences between the 2 years with contrasting annual rainfall (2094 vs 1582 mm). S. superba had a lower transpiration-to-precipitation ratio (T/P) compared to M. macclurei and showed decreased sensitivities to total solar radiation and vapor pressure deficit under the DD and ED treatments. These results indicate the deep-rooted S. superba may be suppressed with a lower ability to obtain water and assimilate carbon compared to the shallow-rooted M. macclurei under the precipitation seasonality changes, which could potentially cause shifts in species dominance within the forest community.     

关于上海境内中亚热带常绿阔叶林地带北界的一点意见

在1980年出版的“中国植被”一书中,我国亚热带东部地区中亚热带常绿阔叶林地带北界的东端,在上海境内是沿着长江中的崇明和横沙两岛之间通过的。即是说,除崇明岛外,上海是划入了中亚热带的植被地带之内。这条界线与1960年出版的“中国植被区划(初稿)”中所示的东端界线差距较大。1982年刘昉勋等对江苏境内中亚热带常绿阔叶林地带的北界问题,提出了新的商榷意见,认为“中国植被”中所划的这条界线在江苏境内位置偏北,不应包括整个太湖以及无锡和苏州两地,而应是跨过太湖,经过光福镇,包括吴县南部和吴江县地区,把中亚热带常绿阔叶林地带的北界向南推移了。这一划分对上海境内的问题颇有启发。上海位于长江三角洲的前缘,是由长江挟带的泥沙在江海相互作用下冲淤而成的冲     

南亚热带常绿阔叶林林下层植物的生物量及其测定方法的探讨

应用全收割法测定广东省鼎湖山南亚热带常绿阔叶林林下层植物生物量 ,林下植物总生物量为 12 9 58g/m2 ,其中茎、枝、叶、根的生物量占总生物量的比例约为 4 0 % ,9 0 % ,2 2 % ,2 9% .由部分实测数据建立林下植物个体生物量估算模型为W =0 0 0 4 2 ·H1 932 3.应用该模型得到的估算值 ,与收获实测值的相对误差仅为 1 8% ,具有良好的精度 .此外 ,还通过改变取样面积对该模型的适用性进行了探讨 .     

MODIS Based Estimation of Forest Aboveground Biomass in China

Accurate estimation of forest biomass C stock is essential to understand carbon cycles. However, current estimates of Chinese forest biomass are mostly based on inventory-based timber volumes and empirical conversion factors at the provincial scale, which could introduce large uncertainties in forest biomass estimation. Here we provide a data-driven estimate of Chinese forest aboveground biomass from 2001 to 2013 at a spatial resolution of 1 km by integrating a recently reviewed plot-level ground-measured forest aboveground biomass database with geospatial information from 1-km Moderate-Resolution Imaging Spectroradiometer (MODIS) dataset in a machine learning algorithm (the model tree ensemble, MTE). We show that Chinese forest aboveground biomass is 8.56 Pg C, which is mainly contributed by evergreen needle-leaf forests and deciduous broadleaf forests. The mean forest aboveground biomass density is 56.1 Mg C ha⁻¹, with high values observed in temperate humid regions. The responses of forest aboveground biomass density to mean annual temperature are closely tied to water conditions; that is, negative responses dominate regions with mean annual precipitation less than 1300 mm y⁻¹ and positive responses prevail in regions with mean annual precipitation higher than 2800 mm y⁻¹. During the 2000s, the forests in China sequestered C by 61.9 Tg C y⁻¹, and this C sink is mainly distributed in north China and may be attributed to warming climate, rising CO₂ concentration, N deposition, and growth of young forests.     

Phylogenetic Structure of Tree Species across Different Life Stages from Seedlings to Canopy Trees in a Subtropical Evergreen Broad-Leaved Forest

Investigating patterns of phylogenetic structure across different life stages of tree species in forests is crucial to understanding forest community assembly, and investigating forest gap influence on the phylogenetic structure of forest regeneration is necessary for understanding forest community assembly. Here, we examine the phylogenetic structure of tree species across life stages from seedlings to canopy trees, as well as forest gap influence on the phylogenetic structure of forest regeneration in a forest of the subtropical region in China. We investigate changes in phylogenetic relatedness (measured as NRI) of tree species from seedlings, saplings, treelets to canopy trees; we compare the phylogenetic turnover (measured as β_NRI) between canopy trees and seedlings in forest understory with that between canopy trees and seedlings in forest gaps. We found that phylogenetic relatedness generally increases from seedlings through saplings and treelets up to canopy trees, and that phylogenetic relatedness does not differ between seedlings in forest understory and those in forest gaps, but phylogenetic turnover between canopy trees and seedlings in forest understory is lower than that between canopy trees and seedlings in forest gaps. We conclude that tree species tend to be more closely related from seedling to canopy layers, and that forest gaps alter the seedling phylogenetic turnover of the studied forest. It is likely that the increasing trend of phylogenetic clustering as tree stem size increases observed in this subtropical forest is primarily driven by abiotic filtering processes, which select a set of closely related evergreen broad-leaved tree species whose regeneration has adapted to the closed canopy environments of the subtropical forest developed under the regional monsoon climate.     

模拟降水分配季节变化对南亚热带常绿阔叶林凋落物的影响

为探讨降水季节分配的变化对南亚热带常绿阔叶林凋落物的影响,在广东省鹤山国家野外生态观测站模拟干季更干(DD)和延长干季(ED)的野外降水控制实验,对森林生态系统中凋落物变化进行了分析研究。结果表明,该试验林年凋落物总量为9.24 t hm–2,在不同时期均以叶凋落物为主,约占50.7%~69.3%。DD处理显著减少了干季(10–3月)叶凋落物量(P0.01)。虽然DD处理下全年总凋落物量比对照降低了10.3%,但差异不显著。ED处理也减少了春季(4–5月)的叶和花果及总凋落物量,全年总凋落物量则比对照增加了11.3%,但ED处理对春季和全年凋落物量的影响均差异不显著。两种干旱处理对凋落物叶质量总体上影响不明显,但DD处理显著减小了火力楠(Michelia macclurei)凋落叶的木质素含量。因此,降水格局的变化可能会影响南亚热带森林土壤的碳汇能力。     

再论江苏境内中亚热带常绿阔叶林地带的北界问题

植被带是自然历史长期发展的产物,它在地球上的分布主要是受着大气候因素的制约与影响,有规律地逐渐演变的。恩格斯曾说过“绝对分明的界线是和进化论不两立的”,又说“一切对立的东西都经过中间各项互相过渡”。可见植被带之间并无截然的分界线,实际上是以一定幅度的过渡性带相连接的。为了便于揭示其分布     

Relationship Between Aboveground Biomass and Multiple Measures of Biodiversity in Subtropical Forest of Puerto Rico

Anthropogenic activities have accelerated the rate of global loss of biodiversity, making it more important than ever to understand the structure of biodiversity hotspots. One current focus is the relationship between species richness and aboveground biomass (AGB) in a variety of ecosystems. Nonetheless, species diversity, evenness, rarity, or dominance represent other critical attributes of biodiversity and may have associations with AGB that are markedly different than that of species richness. Using data from large trees in four environmentally similar sites in the Luquillo Experimental Forest of Puerto Rico, we determined the shape and strength of relationships between each of five measures of biodiversity (i.e., species richness, Simpson's diversity, Simpson's evenness, rarity, and dominance) and AGB. We quantified these measures of biodiversity using either proportional biomass or proportional abundance as weighting factors. Three of the four sites had a unimodal relationship between species richness and AGB, with only the most mature site evincing a positive, linear relationship. The differences between the mature site and the other sites, as well as the differences between our richness–AGB relationships and those found at other forest sites, highlight the crucial role that prior land use and severe storms have on this forest community. Although the shape and strength of relationships differed greatly among measures of biodiversity and among sites, the strongest relationships within each site were always those involving richness or evenness.     

九连山亚热带常绿阔叶林群落特征研究

于2008年在九连山保护区建立4 hm2固定监测样地,调查样地内胸径(DBH)≥1 cm的个体,以了解该区域的群落学特征.结果表明,群落的区系组成热带成分比较多,总体上呈现亚热带向热带过渡的区系特征.样地内共有植物58科、107属、221种,物种数和个体数较多的科为山茶科、樟科和壳斗科.群落稀有种较多,所占比例为40.72%.群落以红钩栲(Castanopsis lamontii)、米槠栲(C.carlesii)、罗浮柿(Diospyros morrisiana)、细枝柃(Eurya loquaiana)、罗浮栲(C.fabri)和丝栗栲(C.fargesii)为主要优势种.垂直结构由乔木上层(≥18 m)、乔木中层(10～18 m)、乔木下层(5～10 m)、灌木层(＜5 m)、草本层组成.样地内所有个体的径级分布呈现倒"J"型,表现群落的稳定与正常生长状态.红钩栲、米槠、罗浮柿、罗浮栲、木荷(Schima superba)、鸭公树(Neolitsea chuii)、红楠(Machilus thunbergii)和黄丹木姜子(Litsea elongata)呈现倒"J"型,种群稳定且处于正常增长状态.样地内未发现DBH≤15 cm的马尾松(Pinus massoniana)个体,该种群属于衰退型.九连山常绿阔叶林样地优势种在不同尺度和不同径级范围内以聚集分布为主.随着研究尺度的增加,不同物种聚集程度表现出不同的变化趋势.     

南亚热带常绿阔叶林优势种群的生物量与生物量增量

粘木种群的生物量为７０．１４ｔ／ｈｍ２,生物量增量为２．３２ｔｈｍ２ａ－１。其总生物量的９０％以上分布在ｄ≥２０ｃｍ的大树,仅有０．０４％～０．０５％分布在ｄ＜１０ｃｍ的小树。在各器官的分配是：树干为６５％,根为２５％,枝为１１％,而叶仅占有２％。粘木的平均径向增长为０．３５ｃｍ／ａ。应用树干解析法和形率法估算树干的生物量,两者的结果差别不大。但形率法则既省力省时,又较方便。粘木的形率为０．７１。     

Estimating the Aboveground Biomass of Bornean Forest

We apply a process‐based model, called 3‐PG (physiological principles for predicting growth), to estimate aboveground biomass for the primary forests of Borneo. Using publicly available soil and climate data, and parameterized with physiological traits of Bornean forest, the modeled aboveground biomass and basal area showed statistically significant relationships with field‐measured data from 85 sites across four major forest types. Our results highlight the possibility to expand the application of 3‐PG to forests of varying condition, which would facilitate inclusion of modeled forest biomass data for developing a Tier 3 carbon inventory system for Borneo.     

Distribution,Accumulation, and Cycling of Several Mineral Elements of the Lower Subtropical Evergreen Broad-Leaved Forest in Heishiding Nature Reserve

The distribution, accumulation, and cycling of N, P, K, Na, Ca, and Mg in terms of their concentration in the biomass was quite different from those in soil in Heishiding Nature Reserve (111°53′ E, 23°27′ N). The concentrations of N, Ca and P were higher in plant, and much lower in soil. The average content of the elements in different organs was in the order as: leaf>branch>bark>root>wood, although this was not true for all the elements. Trunk and leaf had the most and the least accumulation of the elements, respectively, and branch and root were comparable. In the forest, most of the elements (97 %) were concen- trated in the tree layer. The total amount of elements in the ecosystem was 3324.2 kg· ha-1 among which N amounted 1470.5, P 51.0, K 1097.7, Na 22.6, Ca 566.2, and Mg 116.2. Yearly absorption of the elements was 432.2 kg · ha-1 among which N amounted 207.1, P 6.5, K 144.9, Na 6.9, Ca 52.6, and Mg 14. 1; and element absorption among different organs accounted as 35.0 kg · ha-1 · a-1 in wood, 14.8, in bark, 66.1 in branch, 143.2 in leaf, 25.3 in root, and 147.7 in fine root (D<3 mm). Total return of the elements from litterfall, death and fallen trees was 311.8 kg · ha-1 · a-1, among which N accounted for 154.3, P 4.7, K 102.1, Na 6.2, Ca 34.5, and Mg 10.0. Return from different organs was: wood 10.2, bark 4.3, branch 17.0, leaf 123.0, root (not in- cluding fine root) 9.4, and fine root 147.7. Total retention was 120.4 kg · ha-1 · a-1 among which N accounted for 52.8, P 1.8, K 42.8, Na 0. 7, Ca 18. 1, and Mg 4.1; retention in different organs was: wood 24.8, bark 10.5, branch 49.1, leaf 20. 2, and root 15.9. Ca, Mg and P have higher cycling and utilization efficiencies.     

云南中山湿性常绿阔叶林起源的探讨

云南中山湿性常绿阔叶林广泛分布于海拔1800~3400 m的山地,这类常绿阔叶林在生态外貌上具有亚热带常绿阔叶林特征,但其分布生境却是暖温带-温带气候,且植物区系组成与热带植物区系有古老的渊源。该文以研究得比较深入的哀牢山中山湿性常绿阔叶林为例,对其植物区系与其气候条件的不协调进行剖析。哀牢山的中山湿性常绿阔叶林记录了种子植物110科386属821种。在植物区系科的地理成分上,无论是含种数多的科,还是所有科的分布区类型,都是以热带分布科为主,体现了它的远古热带起源背景。在该种子植物区系中,热带分布属占总属数的47.75%,热带分布种占总种数的33.45%,在近代演化上仍体现出明显的热带亲缘特征。按照哀牢山中山湿性常绿阔叶林分布地区的暖温带-温带气候条件,它相当于中国东部的暖温带落叶阔叶林地区。在中国东部地区类似气候条件的地带性植被的植物区系中,热带分布属通常只占总属数的25%~27%,云南中山湿性常绿阔叶林植物区系的地理成分与所在地的温带气候明显不协调。对这种现象的解释,笔者认为结合哀牢山地区曾经是低海拔夷平面,在第四纪以来才迅速抬升形成的地质历史,可能这里曾经在第四纪以前的热带-亚热带性质的植物区系和常绿阔叶林随着地形的迅速抬升,逐渐适应了因海拔上升而形成的温带气候,成为在云南高海拔山地存在的所谓中山湿性常绿阔叶林,其植物区系和植被的热带-亚热带性质及常绿阔叶生态外貌并未因气候改变而发生改变。     

云南松林与常绿阔叶林中枯落叶分解研究

采用分解袋的方法,研究了云南松、滇青冈和元江栲枯叶在针、阔叶林两种生境下的分解及养分动态变化规律。结果表明,滇青冈和元栲枯叶分解速率高于云南松针叶。在阔叶林下这些枯叶的分解系数（０．５５－０．６１ａ＾－１）要比在云南松林下的（０．５０－０．５３ａ＾－１）高。在分解过程中３种枯叶的Ｎ、Ａｌ、Ｆｅ、Ｚｎ元素含量表现出分解前期富积,后期释放的特征,Ｐ、Ｃａ元素在阔叶林地的分解中也有富积过程。而Ｍｇ、Ｋ元     

中国亚热带常绿阔叶林净第一性生产力的估算

中国亚热带常绿阔叶林净第一性生产力的估算倪健（中国科学院植物研究所生态室,北京１０００９３）ＥｓｔｉｍａｔｅｏｆｔｈｅＮｅｔＰｒｉｍａｒｙＰｒｏｄｕｃｔｉｖｉｔｙｆｏｒＳｕｂｔｒｏｐｉｃａｌＥｖｅｒｇｒｅｅｎＢｒｏａｄｌｅａｖｅｄＦｏｒｅｓｔｉｎＣｈ...     

Aboveground Forest Biomass and the Global Carbon Balance

The long‐term net flux of carbon between terrestrial ecosystems and the atmosphere has been dominated by two factors: changes in the area of forests and per hectare changes in forest biomass resulting from management and regrowth. While these factors are reasonably well documented in countries of the northern mid‐latitudes as a result of systematic forest inventories, they are uncertain in the tropics. Recent estimates of carbon emissions from tropical deforestation have focused on the uncertainty in rates of deforestation. By using the same data for biomass, however, these studies have underestimated the total uncertainty of tropical emissions and may have biased the estimates. In particular, regional and country‐specific estimates of forest biomass reported by three successive assessments of tropical forest resources by the FAO indicate systematic changes in biomass that have not been taken into account in recent estimates of tropical carbon emissions. The ‘changes’ more likely represent improved information than real on‐the‐ground changes in carbon storage. In either case, however, the data have a significant effect on current estimates of carbon emissions from the tropics and, hence, on understanding the global carbon balance.     

中国亚热带常绿阔叶林优势种常见种分布与气候的相关分析

 广泛收集植物的分布资料,包括杨梅科、胡桃科、壳斗科、木兰科、樟科、山茶科、金缕梅科、交让木科、杜英科、五加科、安息香科、冬青科、杜鹃花科、山矾科的优势种和常见种112个,利用目前在国际上被认为是较好的几种研究植被—气候相互关系的指标和方法,包括：Kira方法;Penman公式;Thornthwaite方法与分类;Holdridge生命地带分类系统指标与方法,分析中国亚热带常绿阔叶林优势种及常见种分布与气候的生态关系,找出它们的地理分布特征和气候指标特征,建立现代植被与气候的关系。(1)利用Kira的温暖指数(WI)和寒冷指数(CI)及徐文铎的湿润指数(HI),计算了中国亚热带常绿阔叶林112个优势种及常见种的水热指标值,分析了树种分布与气候的关系,并将优势种及常见种划分为5个Kira水热指标分布类群。(2)计算了112个优势种及常见种的Penman可能蒸散(PET)和干燥度(A)值,划分了5个优势种及常见种的Penman水热指标分布类群。(3)计算了树种的Thornthwaite潜在可能蒸散(APE)及湿润指数(IH)、干旱指数(IA)和水分指数(IM),划分了优势种及常见种的Thornthwaite水热指标分布类群。(4)计算了树种的Holdridge生物温度(BT)、可能蒸散(PE)、降水量(P)及可能蒸散率(PER),划分了优势种及常见种的Holdridge水热指标分布类群。     

广东石门台亚热带典型常绿阔叶林和亚热带山顶矮林群落特征

为了研究亚热带典型常绿阔叶林和亚热带山顶矮林的物种组成和群落结构,在广东石门台国家自然保护区内分别建立了1 hm2亚热带典型常绿阔叶林样地和1 hm2亚热带山顶矮林样地,以样地内所有胸径（DBH）≥1 cm的乔木、灌木和藤本为研究对象,分析两种森林类型的物种组成、密度、径级和株高结构。结果显示：（1）两种森林的Srensen物种相似性指数为0.41,优势种不同,但优势科却较相似;其中,茶科和杜鹃花科在两种森林中所占比例较高;（2）亚热带典型常绿阔叶林的幼苗（1 cm≤DBH〈2.5 cm）和幼树（2.5 cm≤DBH〈12.5 cm）密度都显著小于亚热带山顶矮林,但两种森林的小树（12.5 cm≤DBH〈25 cm）和大树（DBH≥25 cm）密度均无显著差异;亚热带典型常绿阔叶林幼苗和大树的平均胸径都显著大于亚热带山顶矮林,而幼树的平均胸径则显著小于亚热带山顶矮林,小树的平均胸径无显著差异;亚热带典型常绿阔叶林中小树和大树的平均高度都显著大于亚热带山顶矮林,而幼苗的平均高度显著小于亚热带山顶矮林,幼树的平均高度无显著差异。综合分析表明,亚热带典型常绿阔叶林和亚热带山顶矮林的物种组成、密度、胸径和高度结构差异较大,亚热带典型常绿阔叶林群落稳定性强于亚热带山顶矮林。     

Nutrient Dynamics in the Litter-Fall and Forest Floor of Evergreen Broad-Leaved Forest and Pinus yunnanensis Forest in Central Yunnan

The quantity of litter-fall and the standing crop of H sublayer in the forest floor of evergreen broad-leaved forest were higher than that of Pinus yunnanensis forest. The quantity of the forest floor changed with the quantity of litter-fall, and thera was a dynamic equilibrium between the litter-fall and forest floor. The content of nutrient elements of the forest floor was higher than that of litter-fall in both types. The order of nutrient element content in the forest floor differed from that in litter-fall. In the evergreen broad-leaved forest, the order was N > Ca > Si>K>Mg>Al>P>Fe>Mn>Zn>Cu,and in Pinus yunnanensis forest it was Ca>N>Si>K>Al>Mg >Fe>P>Mn>Zn>Cu. But the order of nutrient element content in the forest floor had changed: in evergreen broad-leaved forest it was Si > N > Al > Ca > Fe > K>Mg>P>Mn>Zn>Cu, the Pinus yunnanensis forest it was Si > AI>N>Ca>Fe>K>M>P>Mn>Zn>Cu. With increase in the intensity of litter decomposition Ash, Si and Al had obviously increased, N, Fe, P and K had also increased in varying degrees, but there was some reduction in Ca, Zn and Mg. The ratio of carbon and nitrogen in litter decreased' with increase in litter decomposition.     

中亚热带原生和次生湿性常绿阔叶林种子植物区系多样性比较

对瓦屋山的湿性常绿阔叶林破坏后自然恢复的次生群落及其与原生湿性常绿阔叶林的比较研究表明,中山湿性常绿阔叶林砍伐破坏后在封山条件下经过４２年的自然恢复形成的植被,已经形成常绿阔叶外貌,其物种多样性丰富,区系组成已经与破坏前相似;湿性常绿阔叶林的典型珍稀濒危和樗种已经随森林环境的恢复而迅速回归或就地保存;虽然自然恢复产次生林乔木层尚存在较多落叶伴生种,但优势种已与破坏前相似。有力地说明了中山湿性常绿阔