The storage and utilization of carbohydrates in response to elevation mediated by tree organs in subtropical evergreen broad-leaved forests

Global climate change can affect tree growth and carbon sink function by influencing plant carbohydrate synthesis and utilization,while elevation can be used as an ideal setting under natural conditions to simulate climate change effects.The effect of elevation on tree growth may depend on organ type.However,the allocation patterns of nonstructural and structural carbohydrates(NSCs and SCs,respectively)in different tree organs and their response to elevation remain unclear.We selected four dominant tree species,Schima superba,Castanopsis eyrei,Castanopsis fargesii and Michelia maudiae,along an elevation gradient from 609 to 1,207 m in subtropical evergreen broad-leaved forests and analyzed leaf,trunk,and fine root NSCs,carbon(C),nitrogen(N)and phosphorus(P)concentrations and the relative abundance of SCs.Leaf NSCs increased initially and then decreased,and trunk NSCs increased with increasing elevation.However,root NSCs decreased with increasing elevation.The relative abundance of SCs in leaves and trunks decreased,while the relative abundance of root SCs increased with increasing elevation.No significant correlations between SCs and NSCs in leaves were detected,while there were negative correlations between SCs and NSCs in trunks,roots,and all organs.Hierarchical partitioning analysis indicated that plant C/N and C/P were the main predictors of changes in SCs and NSCs.Our results suggest that tree organs have divergent responses to elevation and that increasing elevation will inhibit the aboveground part growth and enhance the root growth of trees.A tradeoff between the C distribution used for growth and storage was confirmed along the elevation gradient,which is mainly manifested in the"sink"organs of NSCs.Our results provide insight into tree growth in the context of global climate change scenarios in subtropical forest ecosystems.

Combined community ecology and floristics,a synthetic study on the upper montane evergreen broad-leaved forests in Yunnan,southwestern China

The upper montane evergreen broad-leaved forest in Yunnan occurs mainly in the zone of persistent cloud and has a discontinuous,island-like,distribution.It is diverse,rich in endemic species,and likely to be sensitive to climate change.Six 1-ha sampling plots were established across the main distribution area of the upper montane evergreen broad-leaved forest in Yunnan.All trees with d.b.h.>1 cm in each plot were identified.Patterns of seed plant distributions were quantified at the specific,generic and family levels.The forests are dominated by the families Fagaceae,Lauraceae,Theaceae and Magnoliaceae,but are very diverse with only a few species shared between sites.Floristic similarities at the family and generic level were high,but they were low at the specific level,with species complementarity between plots.Diversity varied greatly among sites,with greater species richness and more rare species in western Yunnan than central Yunnan.The flora is dominated by tropical biogeographical elements,mainly the pantropic and the tropical Asian distributions at the family and genus levels.In contrast,at the species level,the flora is dominated by the southwest or the southeast China distributions,including Yunnan endemics.This suggests that the flora of the upper montane forest in Yunnan could have a tropical floristic origin,and has adapted to cooler temperatures with the uplift of the Himalayas.Due to great sensitivity to climate,high endemism and species complementarity,as well as the discontinuous,island-like,distribution patterns of the upper montane forest in Yunnan,the regional conservation of the forest is especially needed.

Role of urban remnant evergreen broad-leaved forests on natural restoration of artificial forests in Chongqing metropolis

The effects of urban remnant natural evergreen broad-leaved forest (EBLF) on the restoration of artificial pine forests surrounding it were studied with reference to species composition,biodiversity,dominant species and stand structure on Mt. Tieshanping in Chongqing metropolis,Southwest China. The seeds from the remnant EBLF naturally facilitate the restoration process of artificial Pinus massoniana forests near it. The similarity of species composition between the artificial Pinus massoniana forests and the remnant EBLF and biodiversity index of the artificial Pinus massoniana forests decrease as the distance from the remnant EBLF increases. Castanopsis carlesii var. spinusa is the dominant species in the ground vegetation,shrub layer and sub-tree layer of the Pinus massoniana forests near the remnant EBLF. However,the natural restoration processes of those farther away from the remnant EBLF are restricted for the absence of seed source of the inherent components of the remnant EBLF,and the anthropogenic measures should be taken to facilitate the restoration process.

Community ecology and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracts, Bangladesh

We investigated the floristic composition, woody species diversity and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracks, Bangladesh. We recorded 25 families, 37 genera, 40 species and 1771 woody individuals in a 0.09 ha plot. Euphorbiaceae and Moraceae were the most species- rich families, and Castanopsis, Ficus and Terminaliawere the most species-rich genera. Bursera serrata Wall. ex Colebr. was the dominant species in terms of highest importance value （13%）. Trema orientalis （L.） B1 was typically a light demanding species as it appeared in the top can- opy with only one individual having the seventh highest IV, but had no regeneration. The expected maximum number of species （Smax） was 140, indicating that many species may invade the forest as the Sm~ is greater than the recorded total number of species. The nature of the disappear- ance and appearance of species in the present forest reflects instability of floristic composition. The values of Shannon＇s index H＇ and Pielou＇s index J＇ （evenness） were 3.36 bit and 0.63, respectively. These values show moderately high species diversity as compared to other subtropical forests in the tropics. In addition, a sample area of 200 m2 in this forest would be sufficient for measuring the diversity indices H＂ and ,/＇, whereas the trend of J＇may indicate the rate of equality of individuals among the different species decreased with increasing area. The distribu- tion pattern for the total stand was completely random. However, the dominant species showed aggregate distribution for small areas, but random distribution for large areas. The spatial association between species showed that the strongest positive interspecific association occurred between Streblus asper Lour. and Castanea indica Roxh. （09 = 0.51）. As a whole, most species were weakly associated with each other, of which 58% species associations were completely negative. The result of cluster analysis showed that species pairs were spatially independent at all or most small clusters; stands of species from all clusters are mosa- ics of complete habitat and pioneer habitat. All patches in this forest community have similar habitat and regeneration niches, which could be a phenomenon for a young growth forest. Thus, the existence of habitat and regeneration niches may be an important factor in the maintenance of diversity in this forest.

Long-term changes in radial growth of seven tree species in the mixed broadleaf-Korean pine forest in Northeast China:Are deciduous trees favored by climate change?

The role of the temperate mixed broadleaf-Korean pine forest(BKF)in global biogeochemical cycles will depend on how the tree species community responds to climate;however,species-specific responses and vulner-abilities of common trees in BKF to extreme climates are poorly understood.Here we used dendrochronological meth-ods to assess radial growth of seven main tree species(Pinus koraiensis,Picea jezoensis,Abies nephrolepis,Fraxinus mandshurica,Phellodendron amurense,Quercus mongolica,and Ulmus davidiana)in an old-growth BKF in response to climate changes in the Xiaoxing’an Mountains and to improve predictions of changes in the tree species compo-sition.Temperature in most months and winter precipita-tion significantly negatively affected growth of P.jezoensis and A.nephrolepis,but positively impacted growth of P.koraiensis and the broadleaf species,especially F.mandshu-rica and U.davidiana.Precipitation and relative humidity in June significantly positively impacted the growth of most tree species.The positive effect of the temperature during the previous non-growing season(PNG)on growth of F.mandshurica and Q.mongolica strengthened significantly with rapid warming around 1981,while the impact of PNG temperature on the growth of P.jezoensis and A.nephrolepis changed from significantly negative to weakly negative or positive at this time.The negative response of radial growth of P.jezoensis and A.nephrolepis to precipitation during the growing season gradually weakened,and the negative response to PNG precipitation was enhanced.Among the studied species,P.koraiensis was the most resistant to drought,and U.davidiana recovered the best after extreme drought.Ulmus davidiana,P.jezoensis and A.nephrolepis were more resistant to extreme cold than the other species.Climate warming generally exacerbated the opposite growth patterns of conifer(decline)and broadleaf(increase)spe-cies.Deciduous broadleaf tree species in the old-growth BKF probably will gradually become dominant as warming continues.Species-specific growth-climate relationships should be considered in future models of biogeochemical cycles and in forestry management practices.

Comparative Study of Carbon Storage and Allocation Characteristics of Mature Evergreen Broad-leaved Forest

Evergreen broad-leaved forest is an important forest type in China.This paper analyzes the allocation characteristics of vegetation and soil carbon pool of evergreen broad-leaved forest,to understand the current status of research on the carbon storage of evergreen broadleaved forest as well as shortcomings.In the context of global climate change,it is necessary to carry out the long-term research of evergreen broad-leaved forest,in order to grasp the formation mechanism of evergreen broad-leaved forest productivity,and the impact of climate change on the carbon sequestration function of evergreen broad-leaved forest ecosystem.

The rapid climate change-caused dichotomy on subtropical evergreen broad-leaved forest in Yunnan： Reduction in habitat diversity and increase in species diversity

Yunnan's biodiversity is under considerable pressure and subtropical evergreen broad-leaved forests in this area have become increasingly fragmented through agriculture,logging,planting of economic plants,mining activities and changing environment.The aims of the study are to investigate climate changeinduced changes of subtropical evergreen broad-leaved forests in Yunnan and identify areas of current species richness centers for conservation preparation.Stacked species distribution models were created to generate ensemble forecasting of species distributions,alpha diversity and beta diversity for Yunnan's subtropical evergreen broad-leaved forests in both current and future climate scenarios.Under stacked species distribution models in rapid climate changes scenarios,changes of water-energy dynamics may possibly reduce beta diversity and increase alpha diversity.This point provides insight for future conservation of evergreen broad-leaved forest in Yunnan,highlighting the need to fully consider the problem of vegetation homogenization caused by transformation of water-energy dynamics.

The Comparison of Cold tolerance of Three Species of Evergreen Broad-leaved Woody Plants

[Objectives]This study aimed to select evergreen broad-leaved woody plants with higher ornamental value and stronger cold tolerance for introduction from the south to the north,and to apply them to urban greening,so as to enrich the plant community structure of the landscape in the northern region.[Methods]Three species of evergreen broad-leaved woody plants,i.e.,Ligustrum lucidum,Ilex cornuta and Eriobotrya japonica,were selected as the experimental materials.The morphological performances and the changes of the physiological indexes were observed and measured during the overwintering period in the open field in Beijing.The relationship between the indexes and the low temperature was also analyzed.The strength of cold tolerance of the three species was compared.[Results]The electrical conductivity,the contents of MDA and proline were negatively correlated with the corresponding low temperature.The contents of soluble sugar and soluble protein increased with the dropping temperature,but they had little response to the short-term temperature rise.[Conclusions]Combined with morphological and physiological indexes,it was found that the changes of the contents of proline and soluble sugar among the physiological indexes were closely related to the cold tolerances of the three tree species of broad-leaved woody plants.The cold tolerance of I.cornuta was the strongest,E.japonica was the second,and that of L.lucidum was the worst.

Change in Species Diversity during Recovering Process of Evergreen Broad-leaved Forest

Evergreen broad-leaved forestis one of the most important vegetation types in China.Because of the human activities,evergreen broad-leaved forest has been destroyed extensively,leading to degraded ecosystem.It is urgent to conserve and restore these natural forests in China. In this paper,the tendency and rate of species diversity restoration of the evergreen broad-leaved forest in Daming Mountain has been studied.The main resultsare as follows:(a)In subtropical mid-mountain area,species diversity in degraded evergreen broad-leaved forestcan be restored. Through analyzing b diversity index of communities in different time and space,it was found that the species composition of communities tend to be the same as that in the zonal evergreen broad-leaved forest.(b)The restoration rate of evergreen broad-leaved forest was very fast.Planting Chinese fir after clear-cutting and controlled burning of the forest,178 species appeared in a 600m^2 sample area after 20 years’natural recovering.Among the sespecies,58 were tree layer and the height of community reached 18m.The survey suggested that it would take only 20 years for the degraded forest to develop into community composed of lightdemanding broad-leaved pioneer trees and min-tolerance broad-leaved trees,and it need another 40~80 years to reach the stage consisting of min-tolerance evergreen broad-leaved trees.(c)Species number increased quickly at the early stage(2-20years)during vegetation recovering process toward the climax,and decreased at the min-stage (50-60 years),then maintained a relatively stable level at the late-stage (over 150 years).

Studies on Material Cycling in Evergreen Broad-Leaved Forest Ecosystem in Hangzhou: Ⅰ. Precipitation Distribution

Through the long-term plot studies on the precipitation distribution in the evergreen broad-leaved forest ecosystem in Hangzhou for two years, it was indicated that the pattern of precipitation distribution included larger amounts of penetration water and stemflow and a lower amount of interception water. The results revealed that the main factors to infulence the percentages of penetration and stemflow were the air temperature and the leaf area of the forest. The quantity of seepage through the litter layer was much larger than that through the soil layers which decreased sharply with soil depth. The output of water from the ecosystem by surface runoff and deep infiltration through the soil was much lower, only being 5.20 percent of the rainfall, while the water evapotranspiration loss was as large as more than 90 percent of it. The losses by the soil evaporation and plant evapotranspiration were the largest part of output in this forest ecosystem.

Studies on Material Cycling in Evergreen Broad-LeavedForest Ecosystem in Hangzhou: Ⅳ. Uptake, Storageand Return of S by Vegetation

The work was carried out to study the uptake, storage and return of S in the evergreen broad-leaved forestecosystem of Hangzhou in Zhejiang Province, China, based on the annual increments of plants and S contentsper unit weight plant organs as well as the measured data about the biological return and decomposition.Results showed that the vegetation layer had an annual S uptake of 55.02kg ha￣(-1) , which accounted for 15.8% of the total S storage in the vegetation layer. The S uptake was the highest in the arbor layer but thelowest in the shrub layer. The biological return of S was 50% higher than the biological uptake, indicatingthe relatively high cycling efficiency of S. Nevertheless, S had a relatively low rate of biological release, so thatS trended to accumulate in the litter layer. S taken up by plants each year came mostly from precipitationand the reserve of soil.

Studies on Material Cycling in Evergreen Broad-Leaved Forest Ecosystem in Hangzhou: Ⅱ . Dynamics and Decomposition Characteristics of Litter

Through the long-term plot study on the litter and its decomposition in the evergreen broad-leaved forest ecosystem in Hangzhou for more than two years,it was resulted that the annual litter production was 5.85 t ha^-1,most of which was the fallen leave (79.5 percent) and the withered branches and fruits were far less (7.1 and 13.4 percents respectively).The dynamics of the fallen litter was shown as a curve of two-peak pattern which appeared in April and September each year.The half-life of the litter was 1.59 years.The decay rate of the litter attenuted as an exponential function.The annual amount of the nutrient returned to the ground through the litter was as large as 223.69kg ha^-1.The total current amount of the litter on the ground was 7.47t ha^-1.The decay rate in the first half of a year was 45.18 percent.This ecosystem remained in the stage of litter increasing with time.

Studies on Material Cycling in Evergreen Broad-LeavedForest Ecosystem in Hangzhon: Ⅲ. S Concentrationand Its Storage in Vegetation

This paper reveals the variations of S concentration among the leaf surface and other organs of variousplant species, and presents the distribution natures of S storage in the evergreen broad-leaved forest vege-tation in Hangzhou on the basis of the tested data concerning plant S contents. The result was that theS concentrations on the tree leaf surfaces varied with the testing time and plant species. The range of Scontents in various organs of a plant was 2.086- 4.245 S g kg￣(-1), varying with plant species in this forest.The S content in the leaves was the highest, followed by that in the branches, trunks and roots, which showedthat there was an apical dominance of S distribution. The total amount of S storage in the vegetation wasas large as 349.97 S kg ha￣(-1). The S distribution in this vegetation had two characteristics as follows: 1)for the vegetation layers, arbor layer > renewal layer > herb layer > shrub layer; and 2) for the verticaldistribution per unit height (m), root stratum (0 - 0.20 m of soil depth)> stratum nearby the ground surface(0 - 0.5m) > canopy (4.0- 9.5m) > trunk stratum (2.0- 4.0m).

Carbon Reserve Characteristics of Arbor Layer in Mid-subtropical Evergreen Broad-leaved Forest

In this paper, secondary forest of Pinus massoniana , coniferous-broad-leaved mixed forest and broad-leaved evergreen forest were taken as research objects, to explore carbon reserve of arbor layer and its spatial distribution characteristics. At different succession stages, the sequence of organic carbon content in each organ was secondary forest of P. massoniana > coniferous-broad-leaved mixed forest> broad-leaved evergreen forest. Carbon reserve of arbor layer was the highest in broad-leaved evergreen forest, which was 129.34 t/hm 2, followed by coniferous-broad-leaved mixed forest (95.83 t/hm 2), and the minimum was 85.27 t/hm 2 in secondary forest of P. massoniana . In each stand type, the sequence of carbon reserve of each organ in arbor layer was trunk>root>branch>leaf>bark. Carbon reserve of arbor layer mainly concentrated in trunk, and the proportion to carbon reserve of arbor layer declined from secondary forest of P. massoniana to broad-leaved evergreen forest, while it had increasing relationship in root. In secondary forest of P. massoniana , coniferous-broad-leaved mixed forest and broad-leaved evergreen forest, individual with the diameter more than 20 cm accounted for the majority of carbon reserve in the arbor layer.

Biomass Characteristics of the Arbor Layer in Different Stands of the Evergreen Broad-Leaved Forest

In this paper, the Pinus massoniana forest in the early stage of succession, the coniferous broad-leaved mixed forest in the middle stage of succession, and the evergreen broad-leaved forest in the late stage of succession were studied, and the biomass and its spatial distribution characteristics of the tree layer in different succession stages of the ecosystem were discussed. The results showed that the biomass of the arbor layer was the highest in the evergreen broad-leaved forest, which was 292.51 t/ hm2, followed by the coniferous and broad-leaved mixed forest, which was 206.87 t/hm2, and the Pinus massoniana forest, which was 171.76 t/hm2. The biomass of trunks accounted for the largest proportion in the total biomass of the arbor layer, which reduced from the Pinus massoniana forest to the evergreen broad-leaved forest. The proportion of the biomass of roots in the total biomass of the arbor layer increased from the Pinus massoniana forest to the evergreen broad-leaved forest. The biomass of the diameter class above 20 cm in the Pinus massoniana forest, the coniferous and broad-leaved mixed forest and the evergreen broad-leaved forest accounted for a large proportion of total biomass.

Optimization models of stand structure and selective cutting cycle for large diameter trees of broadleaved forest in Changbai Mountain

The optimum models of harvesting yield and net profits of large diameter trees for broadleaved forest were developed, of which include matrix growth sub-model, harvesting cost and wood price sub-models, based on the data from Hongshi Forestry Bureau, in Changbai Mountain region, Jilin Province, China. The data were measured in 232 permanent sample plots. With the data of permanent sample plots, the parameters of transition probability and ingrowth models were estimated, and some models were compared and partly modified. During the simulation of stand structure, four factors such as largest diameter residual tree （LDT）, the ratio of the number of trees in a given diameter class to those in the next larger diameter class （q）, residual basal area （RBA） and selective cutting cycle （C） were considered. The simulation results showed that the optimum stand structure parameters for large diameter trees are as follows： q is 1.2, LDT is 46cm, RBA is larger than 26 m^2 and selective cutting cycle time （C） is between 10 and 20 years.

Forest structure,productivity and soil properties in a subtropical ever-green broad-leaved forest in Okinawa,Japan

Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 5400 stems-ha^-1 （ -〉 3.0 cm DBH）; 64% of those stems were smaller than 10 cm DBH. The total basal area was 54.4 m^2-ha^-1, of which Castanopsis sieboldii contributed 48%. The forest showed high species diversity of trees. 80 tree species （≥ 3.0 cm DBH） from 31 families was identified in the thirty sampling plots. C. sieboldii and Schima wallichii were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were, 3.36 for Diversity index （H＇）, 0.71 for Equitability index （J＇） and 4.72 for Species richness index （S＇）, all of which strongly declined with the increase of importance value of the dominant, C. sieboldii. Measures of soil nutrients indicated low fertility, extreme heterogeneity and possible A1 toxicity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil exchangeable K^＋, Ca^2＋, and Ca^2＋/Al^3- ratio （all p values 〈0.001） and a negative relationship with N, C and P. The results suggest that soil property is a major factor influencing forest composition and structure within the subtropical forest in Okinawa.

Structure and floristic composition of old-growth wet evergreen forests of Nelliampathy Hills, Southern Western Ghats

We analyze the structure and composition of old-growth wet evergreen forest of Nelliampathy hills, the chain of hills lying immediately south of Palghat Gap, in the southern Western Ghats of India. We sampled 30 plots of 0.1 ha each （50 m × 20 m） at six locations enumerating all plants ？ 10 cm girth at breast height. We pooled the data and computed various structural parameters. There were 152 species of 120 genera and 51 families of the study area. Of these, 118 （77%） were trees, 24 were climbers （16%） and 10 were shrubs （7%）. Species richness varied from 58–99 per 0.5 ha sample and Shannon indices of diversity ranged from 4.4 to 5.2. Fifty-nine per cent （89 species） of the species were Indian Sub-continent elements and 34% （51 species） are endemic to the Western Ghats. Fifteen species are listed in various threat categories. Aglaia and Litsea were the most species-rich genera. Numbers of families ranged from 27–43 per 0.5 ha sample. Euphorbiaceae and Lauraceae were the most species-rich families. Stand density varied from 1714 to 2244 stems·ha？1 and basal area from 53.6 to 102.1 m2·ha？1. The vegetation was dominated by 3–6 species and six dominance patterns characterized the species composition within the hill complex. The old-growth evergreen forests of Nelliampathy exist as small fragments rich in biodiversity and can be used as benchmarks for comparison with disturbed forests.

Low net primary productivity of dominant tree species in a karst forest, southwestern China： first evidences from tree ring width and girth increment

Aboveground net primary productivity(ANPP)of two dominant species, one deciduous tree(Platycarya strobilacea) and one evergreen tree(Machilus cavaleriei),was estimated based on the tree-ring width and the girth increment as well as allometric functions in a karst evergreen and deciduous broadleaved mixed forest in central Guizhou Province, southwestern China. Results showed that the ANPP increased from 1961 to 2015, especially during the last 20–30 years, but with strong variations. The deciduous tree had higher ANPP than the evergreen tree according to two kinds of estimates by the tree ring and girth increment. The averaged ANPP for these two mature trees was 2.27 kg/individual/year, ca. 8 t/ha/year considering the normal stand density. Such karst forest productivity was lower than the natural subtropical forests in China and in the world.

Tree species diversity and utilities in a contracting lowland hillside rainforest fragment in Central Vietnam

Background： Within the highly bio-diverse ‘Northern Vietnam Lowland Rain Forests Ecoregion＇ only small, and mostly highly modified forestlands persist within vast exotic-species plantations. The aim of this study was to elucidate vegetation patterns of a secondary hillside rainforest remnant（elevation 120–330 m, 76 ha） as an outcome of natural processes, and anthropogenic processes linked to changing forest values.Methods： In the rainforest remnant tree species and various bio-physical parameters（relating to soils and terrain）were surveyed on forty 20 m × 20 m sized plots. The forest＇s vegetation patterns and tree diversity were analysed using dendrograms, canonical correspondence analysis, and other statistical tools.Results： Forest tree species richness was high（172 in the survey, 94 per hectare）, including many endemic species（〉16%; some recently described）. Vegetation patterns and diversity were largely explained by topography, with colline/sub-montane species present mainly along hillside ridges, and lowland/humid-tropical species predominant on lower slopes. Scarcity of high-value timber species reflected past logging, whereas abundance of light-demanding species, and species valued for fruits, provided evidence of human-aided forest restoration and ‘enrichment＇ in terms of useful trees. Exhaustion of sought-after forest products, and decreasing appreciation of non-wood products concurred with further encroachment of exotic plantations in between 2010 and 2015. Regeneration of rare tree species was reduced probably due to forest isolation.Conclusions： Despite long-term anthropogenic influences, remnant forests in the lowlands of Vietnam can harbor high plant biodiversity, including many endangered species. Various successive future changes（vanishing species, generalist dominance, and associated forest structural-qualitative changes） are, however, expected to occur in smal forest fragments.Lowland forest biodiversity can only be maintained if forest fragments maintain a certain size and/or are connected via corridors to larger forest networks. Preservation of the forests may be fostered using new economic incentive schemes.