杉檫混交根系效应的研究

In this paper,the root system and their associated effect of mixed forest of Cunninghamia lanceolata and Sassafras tsumu at eight-year-old were investigated and analyzed.The results showed that Sassafras tsumu might play a important role in improving the root system of Cunninghamia lanceolata growth due to the single root weight of Cunninghamia lanceolata in mixed forest of Cunninghamia lanceolata and Sassafras tsumu was evidently more than that of Cunninghamia lanceolata in pure forest,and that there were different mixed effects in mixed forest of Cunninghamia lanceolata and Sassafra tsumu in different slope situation,which meant that the associated effect was better in higher slope situation than in lower slope situation,and which reflected in the effect of Sassafra tsumu to the height and D.B.H.growth of Cunninghamia lanceolata.This Study indicated that the associated effect was positively related to the effect of roots system.     

Root stoichiometric dynamics and homeostasis of invasive species Phyllostachys edulis and native species Cunninghamia lanceolata in a subtropical forest in China

The community species abundance and diversity declined with bamboo invasion had been widely reported worldwide.However,the physiological strategies used during root competition between native species and invasive bamboo are poorly understood.To clarify the mechanisms underlying such strategies,the stoichiometric dynamics and homeostasis of nitrogen,phosphorus,organic carbon in root orders of Phyllostachys edulis(I du [=Ⅰ-Pe,years 1 and 2];Ⅱ du [=Ⅱ-Pe,years 3 and 4]),Cunninghamia lanceolata in transition and pure forests were analyzed.With increasing intensity of bamboo invasion,N,P,and C content of C.lanceolata root orders declined,N and P content in P.edulis rhizome orders declined,while C increased,the stoichiometric ratios in mixed forest interface mainly increased,and the stoichiometric differences within native and invasive species root orders narrowed.Meanwhile,the stoichiometric homeostasis index(H) of elements in the same root order and even the same elements in different root orders were not consistent.H of most root orders(except some H_P) was greater than 4,the H ranked order was Ⅰ-Pe Cl Ⅱ-Pe in mixed interfaces,and the N:P ratio of most species root orders was greater than 16,despite being affected by invasion.Our research concluded that the bamboo invasion narrows stoichiometric differences within root orders,and the juvenile bamboo rhizome has a stronger capacity for homeostatic regulation than in adult bamboo and C.lanceolata,which is a key determinant of bamboo invasion success.     

Community structure and biodiversity in plantations and natural forests of seabuckthorn in southern Ningxia, China

Two types of sampling plots of seabuckthorn (Hippophae rhamnoides) communities were investigated in Pengyang County of Ningxia region by a typical sampling method to study the characteristics of community structure and biodiversity. Composition and dominant species of each community were analyzed by the importance value of species as an index. The number of individuals and the importance value, as well as Sorensen’s similarity coefficient, Shannon-Wiener diversity index, Pielou’s evenness index and Simpson’s dominance index, were used as indices to compare characteristics of community structure, similarity and biodiversity between plantations and natural forests of seabuckthorn. The results indicate that the importance values of species of natural seabuckthorn communities were dispersed and the difference between dominant species was not statistically significant. Diversity indices of natural seabuckthorn communities reflected by species richness and evenness were higher than that of plantations. Com-munity structure of natural seabuckthorn forests is more complex. We propose that natural forest can be used as sample to guide se-lection of plant species in silviculture in order to improve biodiversity of plantation.     

Composition and mineralization of soil organic carbon pools in four single-tree species forest soils

Forest soil carbon(C) is an important component of the global C cycle. However, the mechanism by which tree species influence soil organic C(SOC) pool composition and mineralization is poorly understood. To understand the effect of tree species on soil C cycling, we assessed total, labile, and recalcitrant SOC pools, SOC chemical composition by ~(13) C nuclear magnetic resonance spectroscopy, and SOC mineralization in four monoculture plantations. Labile and recalcitrant SOC pools in surface(0–10 cm) and deep(40–60 cm) soils in the four forests contained similar content. In contrast, these SOC pools exhibited differences in the subsurface soil(from 10 to20 cm and from 20 to 40 cm). The alkyl C and O-alkyl C intensities of SOC were higher in Schima superba and Michelia macclurei forests than in Cunninghamia lanceolata and Pinus massoniana forests. In surface soil, S.superba and M. macclurei forests exhibited higher SOC mineralization rates than did P. massoniana and C.lanceolata forests. The slope of the straight line between C_(60) and labile SOC was steeper than that between C_(60) and total SOC. Our results suggest that roots affected the composition of SOC pools. Labile SOC pools also affected SOC mineralization to a greater extent than total SOC pools.     

Fine-scale habitat differentiation shapes the composition,structure and aboveground biomass but not species richness of a tropical Atlantic forest

Evaluating the influences of fine-scale habitat heterogeneity on the composition, diversity, structure and functioning of forests is critical to understand how tropical forests will respond to climate change and devise forest management strategies that will enhance biodiversity conservation and aboveground biomass stock. Here, we hypothesized that topographic and soil factors determine fine-scale habitat differentiation, which in turn shape community composition, species richness, structure and aboveground biomass at the local scale in tropical forests.To test this hypothesis, we selected two areas(each100 × 100 m) with contrasting fine-scale topographic conditions where all trees, palms and lianas with a diameter at breast height ≥ 10 cm were tagged and identified to species. In each selected area, 100 subplots of 10 × 10 m were established. We mainly found that higher topographic variability caused higher habitat differentiation with changes in species composition and community structure,but did not change species richness. Our habitat-scale analyses indicated that, in the less heterogeneous area, the distribution of species was more uniform along a fine-scale topographical gradient with no variation in convexity,which induced changes in structure and aboveground biomass, but not in species richness. The nonsignificant relationship between species richness and aboveground biomass may be attributable to species redundancy or functional dominance. This study suggests that environmental filtering is a fundamental process for shaping community assembly and forest functioning along a local topographical gradient in tropical forests.     

Tree species diversity and stand structure along major community types in lowland primary and secondary moist deciduous forests in Tripura, Northeast India

Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura.Overall 10,957 individual trees belonging to 46 family,103 genera and 144 species were counted at ≥30 cm DBH(diameter at breast height) using 28 permanent belt transects with a size of 1 ha(10 m × 1000 m).Four different tree communities were identified.The primary forests was dominated by Shorea robusta(mean density 464.77 trees ha-1,105 species) and Schima wallichii(336.25 trees ha-1,82 species),while the secondary forests was dominated by Tectona grandis(333.88 trees ha-1,105 species) and Hevea brasiliensis(299.67 trees ha-1,82 species).Overall mean basal area in this study was 18.01m 2 ·ha-1 ;the maximum value was recorded in primary Shorea forest(26.21 m 2 ·ha-1).Mean density and diversity indices were differed significantly within four different communities.No significant differences were observed in number of species,genera,family and tree basal cover area.Significant relationships were found between the species richness and different tree population groups across the communities.Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumulation of native oligarchic small tree species.Seventeen species were recorded with <2 individuals of which Saraca asoka(Roxb.) de Wilde and Entada phaseoloides(L.) Merr.etc.extensively used in local ethno-medicinal formulations.The present S.robusta Gaertn dominated forest was recorded richer(105 species) than other reported studies.Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests.Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur.The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species in secondary T.grandis L.dominated community.     

Logging and topographic effects on tree community structure and habitat associations in a tropical upland evergreen forest,Ghana

We determined the response of tree community structure to logging disturbance and topography,and the patterns of tree-habitat associations in Tano Offin Forest Reserve,Ghana.We sampled trees in 27 20 m× 20 m plots randomly and equally distributed in three topographic habitats(slope,valley,and hilltop) in each of two forests:logged and unlogged.Two topographic features,altitude and degree of slope,were measured and related with species composition.Overall,there were significant effects of logging and topographic habitat and their interaction on species diversity and composition,with the unlogged forest and valley habitat supporting higher diversity.Tree diversity varied among the topographic habitats in the logged but not in the unlogged forest.There were topographic effects on abundance of individual species but not on tree community abundance and basal area.Logging and its interaction with topographic habitat showed significant effects on tree abundance and basal area.Some species were associated with specific topographic habitats or a combination in the logged and unlogged forests.However,the patterns of habitat associations of the species differed between the logged and unlogged forests.     

Effects of gap size on diversity of soil fauna in a Cunninghamia lanceolata stand damaged by an ice storm in southern China

Cunninghamia lanceolata(Lamb.) Hook. is economically the most important tree species in southern China and has been cultivated in plantations on a large scale. This species is widely used in construction, furniture, utensils and shipbuilding. Soil fertility of C. lanceolata stands affects soil structure, porosity and nutrient availability, which causes changes in fauna activity. During January to February 2008,an ice storm caused extensive damage to C. lanceolata stands.Despite the environmental importance of soil fauna, basic information on the distribution and diversity of soil fauna in C.lanceolata stands after ice storm damage is lacking. To assess the response of soil fauna diversity and distribution to forest gaps following the ice storm, five small gaps(each 30–40 m~2),five large gaps(each 80–100 m~2) and five canopy cover plots were selected within a 2-ha C. lanceolata stand. Soil samples were collected from 0 to 10 cm depth in March 2011 to measure soil fauna diversity and abundance. The abundance and community composition of the soil fauna varied with gap size. In canopy cover sites, the number of individuals was 2.0 and 5.2 times greater than in the small gaps and large gaps.Three taxa(Nematoda, Oribatida and Insecta) of soil invertebrates occurred commonly, and Nematoda dominated the communities in all three habitat types. The Shannon–Wiener diversity index, Margalef diversity index, and Pielou evenness index were high in the small gaps, indicating that they harbored the most species, with the most even distribution, and the highest diversity. Our results indicated that gap size apparently affected abundance and community composition of the soil fauna.     

An impacts of logging operations on understory plants for the broadleaved／Korean pine mixed forest on Changbai Mountain, China

Natural regeneration of tree species is important to the sustainability of native forest ecosystems in the temperate zone of northeast China. This study compared the densities and heights of seedlings and the diversities of shrubs and herbs on three sites of logging operations: log-skidding trails (LST), logging gaps (LG) and log landing sites (LLS). Sites undisturbed by logging gaps operations were sampied as control. The species, counts and height of tree seedlings and the species, counts, height and percentage coverage of shrubs and herbs were recorded in the field. The highest density and greatest height of regeneration trees were observed at LG and LST. The effects of LST on the densities of broadleaved trees were greater than those of coniferous trees. The difference in seedling density between LLS and control was significant (p=0.05). There was no significant difference in average seedling height for all the tree species between the disturbed sites and control. There were more shrub and herb species at the disturbed sites than at control. The diversity of understory plants at LG was the highest among all the sites. LST and LLS were different in shrub diversity, so were LLS and control. Both LG and LLS were different from control in herb diversity. Active measures need to be taken on the operation sites to protect the coniferous trees and the diversities of understory plants for sustaining the structure and composition of the broadleaved-Korean pine mixed forest on Changbai Mountain of China.Since different operation sites have different effects on different tree species, site-dependent actions must be taken to assure the regeneration of ecologically important tree species.     

Dendroclimatological study of Sabina saltuaria and Abies faxoniana in the mixed forests of the Qionglai Mountains,eastern Tibetan Plateau

Tree-ring chronologies were developed for Sabina saltuaria and Abies faxoniana in mixed forests in the Qionglai Mountains of the eastern Tibetan Plateau. Climategrowth relationship analysis indicated that the two co-existing species reponded similarly to climate factors, although S.saltuaria was more sensitive than A. faxoniana. The strongest correlation was between S. saltuaria chronology and regional mean temperatures from June to November. Based on this relationship, a regional mean temperatu...     

闽北山地杉木纯林和杉阔混交林林下植物多样性研究

对福建省建瓯市的杉木(Cunninghamia lanceolata)纯林及3种杉阔混交林的林下植物多样性进行了调查和分析。结果表明:混交林林下灌木层的丰富度指数和Shannon-wienner多样性指数值均大于草本层,除杉木×鹅掌楸混交林外,其他2种混交林草本层的优势度指数值大于灌木层,均匀度指数则是灌木层大于草本层;混交林林下植物种类较少,优势种明显,且分布不均;4种多样性测度指标在不同混交林中差异不大,混交林与杉木纯林差异亦不明显。研究结果可为改进闽北山地杉木纯林及其混交林的培育和经营管理、实现杉木林可持续经营提供参考。     

杉木蓝果树混交林林分生产力及生态效应研究

从林分结构、生物量、群落特征、生产力、培肥土壤、涵养水源及林内小气候等方面对不同混交模式的杉木蓝果树混交林及其纯林进行的研究结果表明:杉木蓝果树是具有较高生产力和协调种间关系能力的针阔混交树种。7年生3︰1杉木蓝果树带状混交林蓄积量和生物量分别比杉木纯林提高7.24%和18.22%,同时混交林还表现出比杉木纯林更好的培肥土壤、涵养水源、改善林内小气候等生态功能。结果表明:3︰1杉木蓝果树带状模式是值得南方林区大力推广的杉阔混交模式。     

杉木与七种阔叶树混交造林效果的初步研究

通过对7种优良乡土阔叶树种与杉木混交林的调查研究,结果表明:杉阔混交林提高了林分蓄积量,促进杉木和阔叶树种成林、成材。混交林中的杉木普遍比杉木纯林生长好,只有杉檫混交林例外。杉木和木兰科观光木、乳源木莲、壳斗科红锥、格氏栲以及樟科的檫树、樟树混交造林,有利于发展珍贵阔叶树种种群规模,具有推广应用前景。处理好种间关系是营造混交林成败的关键。     

毛竹杉木混交造林对土壤养分及林木生长的影响

对福建省宁化县方田乡泗坑村营造的7年生杉木毛竹混交林和杉木、毛竹纯林的林下土壤养分及林木生长量进行调查分析,结果表明:毛竹杉木混交林的土壤有机质、全氮、全磷、全钾、水解氮、速效磷、速效钾的含量均比毛竹纯林和杉木纯林高,毛竹杉木混交林中毛竹、杉木的平均胸径、平均高、枝下高、冠幅、单株材积生长量均比毛竹、杉木纯林高。表明,毛竹、杉木混交造林改善了土壤养分,促进林分的生长。     

福建柏与萌芽杉木混交林经营效果的调查研究

安溪半林林场在杉木迹地上营造福建柏,并选留杉木萌芽条形成福建柏杉木混交林,不论混交林经营密度大小,福建柏生长均比纯林好。大、中密度组的福建柏生长比萌芽杉木快,但在小密度组则相反。萌芽杉木在大、中密度条件下,生长不如同龄纯林,在小密度条件下的平均树高、胸径是纯林的140.2%和148.2%。说明福建柏与萌芽杉木混交培育方式是成功的,但到15年生以后,经营密度以1 500株.hm-2左右,混交比例6∶4为宜。     

栽杉留阔模式群落区系特征研究

通过标准地调查 ,研究 2 9年生栽杉留阔模式及杉木纯林 (对照 )群落区系特征 ,结果表明 :栽杉留阔模式群落植物属和种组成数量 (10 2属、138种 )均大大超过杉木纯林群落 (87属、10 8种 ) ,具有生物多样性和更强的水土保持功能。其区系特征与杉木纯林相比有较大不同 ,群落间的相似性较小。栽杉留阔模式群落乔木层中落叶阔叶树种具有较大的重要值。栽杉留阔模式群落草本层以阳性种类为主 ,未发现观音座莲 ,而观音座莲是杉木纯林的指示植物。 2个群落种子植物属的分布区类型都是以热带成分为主 ,栽杉留阔模式群落属的热带分布比例小于杉木纯林     

酸枣杉木混交林林分生长研究

为解决目前南方林区人工林针叶化引起的系列生态问题,挖掘本地乡土树种,发展阔叶树种造林,通过营造不同混交模式的酸枣杉木混交林,进行不同混交模式酸枣杉木混交林林分生长效应的比较研究,结果表明:不同混交比例的酸枣杉木混交林群落特征和林分生长存在较大差异,不同林分蓄积量大小排序为:酸枣纯林>酸枣×杉木(1∶3)混交林>酸枣×杉木(1∶2)混交林>酸枣×杉木(1∶1)混交林>杉木纯林,其中杉木×酸枣(3∶1)混交林是种间关系较为协调并具较高生产力的混交模式,值得南方林区大力推广。     

细柄阿丁枫杉木混交林的水源涵养功能研究

杉木萌芽林改造成的细柄阿丁枫杉木混交林的水源涵养功能研究结果表明 :混交林的水源涵养能力有较大程度提高 ,其林冠层和枯枝落叶层的持水量分别比杉木纯林高 17 0 %和 5 0 32 % ,且土壤入渗速度加快 ,蓄水能力提高 ,0～ 40cm土壤层的蓄水量约为杉木纯林的 1 7倍 ,这对于今后改造杉木低产林与规划经营水源涵养林有一定的参考价值     

杉木与楠木、鹅掌楸混交林及其纯林的生长差异

以杉木纯林为对照,对同林龄楠木＋杉木、鹅掌楸＋杉木混交林的生长量和经济效益进行了比较,结果表明：造林9年后,鹅掌楸的胸径、树高和材积均高于楠木,混交林中杉木的生长差异不大,但胸径和材积显著小于纯林;2种混交林的经济产出均高于纯林,但差异不大。