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1.
We studied leaf litter fall, decomposition and nutrient release patterns of Shorea robusta and Tectona grandis by using a litter bag technique to better understand the release pattern of nutrients to soil from leaf litter. Annual litterfall varied from 13.40 ± 2.56 t ha?1 a?1 for S. robusta to 11.03 ± 3.72 t ha?1 a?1 for T. grandis and the decay constant (k) of decomposed leaf litter was distinctly higher for T. grandis (2.70 ± 0.50 a?1) compared to S. robusta (2.41 ± 0.30 a?1). Biomass loss was positively correlated with the initial litter C, WSC, C/N and ash content in S. robusta and N, P and K concentration for T. grandis. Biomass was negatively correlated with lignin and L/N ratio for S. robusta and L, WSC, L/N and C/N ratio for T. grandis (P < 0.01). Nutrient use efficiency (NUE) and nutrient accumulation index (NAI) of S. robusta was higher than for T. grandis. The retranslocation of bioelements from senescent leaves ranked as P > N > K. Annual N, P and K input to soil through litterfall differed significantly between the two species in the following order: N>K>P. S. robusta was superior in terms of K and P return and T. grandis was superior in terms of N return. The two tree species showed a similar patterns of nutrient release (K > P > N) during decomposition of their leaf litter. Nutrients of N, K and P were the primary limiting nutrients returned to soil through litterfall with important roles in soil fertility and forest productivity.  相似文献   

2.
为了评价印度东部曼尼普尔亚热带橡树混交林中的土壤养分收支平衡情况,研究了全年不同月份的3个主要树种,枹栎(Quercus serrata)、木荷(Schima wallichi)和滇石栎(Lithocarpus dealbata)的枯落物分解和营养回归情况。印度东部橡树林是生产柞蚕丝的重要经济树种。林下2-7月月枯落物为25.6 g·m-2(7月)和198.0 g·m-2(2月),年枯落物为1093 8g·m-2。在初始月(11月3),滇石栎森林壤土的氮和碳浓度最高,其次是在枹栎林。最低的是木荷林。但就木质素和纤维素含而言,木荷林中的最高,其次是袍栎林和滇石栎林。滇石栎林(k=0.54)具有较高的枯落物分解率,这与月初枯落物中含有较高的氮和碳浓度以及低含量的纤维素相符合。然而,在木荷森林中枯落物分解率低,是与月初时森林土中具有低浓度氮和碳及高浓度木质素和纤维素相符合。在不同月份,剩余的生物量与木质素、碳、碳氮比和纤维素含量呈正相关,但与氮含量呈负相关。由于环境条件的影响,在寒冷和冬季枯落物分解率最低,而在雨季枯落物分解率最高。图3表5参52。  相似文献   

3.
In northeastern India, subtropical forests are over-exploited for timber, fuel wood and common agricultural practice like shifting cultivation, which are responsible for the degradation of natural forest. In degraded areas, large-scale plantations of different species of Quercus have been raised since 1980 for the production of economic Tasar silk. Conversion of natural forest into plantation affects the process of nutrient cycling due to management practices. Thus, it would be of importance to study the litterfall, litter decomposition process and the factors regulating the rate of litter decay in these ecosystems to improve recommendations for their management and conservation. We recorded litterfall by using litter traps and decomposition of leaf litter by nylon net bag technique to understand the amount of organic matter and nutrient return and their release in soils of forest and plantation in Manipur, northeast India. Total litterfall was 419.9 g m−2 year−1 in plantation and 547.7 g m−2 year−1 in forest. Litter decomposition rate was faster at plantation site than the forest in the early stage of litter decomposition whereas the reverse was observed at later stages of decomposition. Stepwise regression analysis showed the significant role of relative humidity and mean temperature on mass loss rates in the forest. Relative humidity, maximum temperature, population of fungi and actinomycetes were the best predictor variables for mass loss rates in plantation. Nutrient retranslocation efficiency and the immobilization of N and P in forest litter were higher than plantation. This suggests that Q. serrata growing in natural ecosystem in oligotrophic condition adapted strong nutrient conservation mechanisms to compete with the other plant species for the meager soil nutrients. The same species in plantation loses these adaptive capabilities because of exogenous supply of nutrients and in the absence of intense competition with other plant species. Thus, the optimization of organic and chemical fertilizer input in plantation is recommended for maintaining the soil fertility level to produce quality leaf for silkworm by conserving essential nutrients in the system.  相似文献   

4.
评估了印度米佐拉姆3种柚木林分(Tuirial:500m asl,Sairang:200m asl和Phunchawng:550m asl)在2006年生长蓄积量。为了掌握柚木体积特性和种群结构,随机建立5个直径等级,即a(10-20cm),b(20-30cm),c(30-40cm),d(40-50cm),和e(50-60cm)。研究表明,研究地内个体密度在280-620stems·hm-2之间,平均直径在27.48—35.43cm之间,平均高度为17.87-22.24m,总的基础面积为24.28-45.80m2·hm-2,最大和最小总生长蓄积量分别为669.01m3·hm-2和284.7m3·hm-2。该物种现有种群结构确保其可以长期存在。  相似文献   

5.
The growing stock assessment of three different teak forest stands (Tuirial: 500 m asl, Sairang: 200 m asl and Phunchawng: 550 m asl) was done in 2006 in Mizoram, India. Five diameter classes were arbitrarily established for knowing the volume attribute data and population structure, viz. a (10-20 cm), b (20-30 cm), c (30-40 cm), d (40-50 cm), and e (50-60 cm). Results revealed that the density of the individuals among the studied stands varied from 280 stems/ha to 620 stems/ha. The average diameter of all the individuals ranged between 27.48 cm and 35.43 cm. Similarly, the average height was oscillated between 17.87 m and 22.24 m. The total basal area was recorded between 24.28 m2.ha-1 and 45.80 m2.ha"l. The maximum and minimum values of total growing stock under all the diameter classes were 669.01 m3.ha-1 and 284.7 m3.ha-1, respectively. The representation of population structure of different stands explained that the perpetuation of this species was ensured for a quite long time.  相似文献   

6.
Spatial variation in tree-regeneration density is attributed to the specialization of tree species to light availability for germination and growth. Light availability,in turn, varies across the gap-understorey mosaic. Canopy gaps provide an important habitat for the regeneration of tree species that would otherwise be suppressed in the understory. In subtropical forests, there is still a knowledge-gap relating to how canopy disturbances influence tree-regeneration patterns at local scale, and if they disproportionately favor regeneration of certain species. We aim to analyze whether canopy gaps promote tree regeneration, and tree species are specialized to gaps or understory for germination and growth. We sampled vegetation in 128 plots(0.01 ha), equally distributed in gaps and below canopy, in two subtropical Shorea robusta Gaertn.(Sal) forests in Nepal, recording the number of tree seedlings and saplings in each plot. We compared the regeneration density of seedlings and saplings separately between gaps and the understorey. The mean densities of seedlings and saplings were higher in the gaps at both sites;although there was no difference in the seedling density of the majority of the species between the habitats. No species were confined to either gap or understorey at the seedling stage. We conclude that gaps are not critical for the germination of tree species in Sal forests but these are an important habitat for enabling seedlings to survive into saplings. The classification of trees into regeneration guilds mainly based on germination does not apply to the majority of tree species in subtropical Sal forests. Our results reaffirm that gap creation promotes tree regeneration by favouring seedling survival and growth and can influence forest management for conservation, as well as for plantations.  相似文献   

7.
Biomass and nutrient transfer (N, P, K, Ca, Mg) of bilberry (Vaccinium myrtillus L.) leaf litter fall, as well as decomposition and nutrient release, were studied in four mature forest stands situated in Central and South Sweden. Bilberry leaf litter fall amounted to between 33 and 55 kg ha‐1 yr‐1 in the four stands. Only minor differences between sites were noted for litter concentrations of N, P and Ca, whereas K and Mg showed somewhat larger variability. Relative amounts of the five nutrient elements in the litter fall were generally in the order N > Ca > K > Mg > P. The amounts of nutrients returned to the forest floor by the annual leaf litter fall in the stands ranged from 0.4 to 0.8 kg ha‐1 for N, 0.4 to 0.6 kg ha‐1 for Ca, 0.2 to 0.7 kg ha‐1 for K, 0.1 to 0.2 kg ha‐1 for Mg and 0.04 to 0.08 kg ha‐1 for P.

The decomposition of the local bilberry leaf litter was followed by means of litterbags during three years. At all sites there was an extremely rapid mass loss from the litter (between 45% and 54%) during the first four to five months of decomposition. After this initial phase, the decomposition rates decreased markedly and after three years the accumulated mass losses of the litters varied between 64% and 78% at the studied sites. After two and three years of decomposition, three of the sites exhibited almost similar litter mass losses whereas at the fourth site the litter was decomposed to a significantly lower degree. The pattern of nutrient release from the decomposing bilberry leaf litter differed somewhat from site to site. Minor differences were, however, noted for P, Ca and Mg while N and K were more strongly retained in the litter at one of the sites.  相似文献   

8.
9.
The present study describes the floristic composition and dominance pattern of sal forests in Ranchi,Jharkhand,eastern India.Vegetation was studied in 47 belt transects(509100 m)that had 137 plant species(110 identified and 27 unidentified)belonging to 51 families.The family Fabaceae with 17 species(8 spp.belonging to subfamily Faboideae,6 spp.to Caesalpinioideae and 3 spp.to Mimosoidieae)contributed the most to diversity,followed by Rubiaceae(8 spp.)and Euphorbiaceae(6 spp.).Tree density in sal was inversely related to species richness.Total tree density(C 10 cm GBH)in the studied forests was 397 individuals ha-1,with a basal cover of 262.50 m2 ha-1.Important plants of conservation concern are Pterocarpus marsupium Roxb,Andrographis paniculata(Burm.f.)Wall,Sterculiaurens Roxb.,Tinospora cordifolia(Willd.)Miers,and Asparagus densiflorus(Kunth)Jessop.Phanerophytes had the highest percentage(71%,with percentage deviation from normal life form of?25)followed by therophyte(15%,with percentage deviation?2).Observed percentage deviation from normal life form was much lower(with?2 percentage deviation)in both chamaephytes(8%)and therophytes(15%),suggesting that the studied sal forests are favorable for supporting various plants species.The forest management strategies should focus on the increasing demands for different timber and non-timber forest products to conserve the plant diversity of these natural forests.  相似文献   

10.
(竹思)(竹劳)竹属是优先竹种,仅分布在印度东北部到孟加拉、尼泊尔、不丹和缅甸一带,其在森林生态系统的生态作用不为人知。由于凋落物质量、凋落物分解及营养释放形态的分析是了解任何系统中土壤肥力管理的基础,因此在卡查、阿萨姆和印度东北部的湿热带林中开展研究,目的是了解凋落物分解形态,研究目的如下:(1)凋落物的初期化学成分;(2)凋落物的失重和近似碳功能;(3)叶、箨凋落物的营养释放形态。用叶代技术测量思劳竹属叶和箨凋落物的分解损失。叶凋落物中含有较高浓度的氮、磷和钾,而箨凋落物中含有很高的碳、灰分和纤维素。失重以原干重来表示,并以时间呈指数下降。叶和箨指数的方程式如下:Y=175.38 e-0.3048x.,r=0.9689和Y=139.55 e-0.2674x.,箨凋落物的损失率比叶低,但它的C/N,L/N和L/P值较高。氮释放形式是两相同的,磷浓度的初期上升,而后呈下降趋势,而钾的释放则在整个分解过程发生。叶和箨凋落物中有机复合物的浓度在分解过程中下降。本文也对凋落物分解过程中保存土壤肥力的意义进行了讨论。  相似文献   

11.
Tectona grandis (teak) is one of the most important timber species worldwide and India is one of the major teak growing countries. Though some volume equations were developed in the past in India, merchantable volume equations (any top diameter or bole length) are not available. Moreover, the models developed were neither quantitatively and qualitatively evaluated nor validated with independent data sets. Hence, the objective of this study was to develop appropriate volume equations to predict total tree volume and merchantable volume for teak in Karnataka.

Linear and non-linear equations were used to model the relationship of the volume with respect to diameter at breast height (dbh) and total height. Merchantable volume equations for estimating merchantable volume to any minimum top diameter or bole length have also been constructed. The equations tested mostly fitted well to the data. Other models developed elsewhere tended to underestimate the volume, especially at dbh ≥ 23 cm. The geometric cylinder volume equation, in combination with a stem form factor of .40, is widely used for teak in Karnataka but they were found to be less precise compared to regression equations when applied to the present data set. Model validation indicated that models should be calibrated with local data for greater accuracy in the prediction.  相似文献   

12.
Sal (Shorea robusta Gaertn. f.) forests cover over 11 millionha in India, Nepal and Bangladesh, and these forests are conventionallymanaged for timber. Recently, interest in producing multipleproducts from sal forests has increased; accordingly, a silviculturalregime for managing sal forest for multiple products is a centralconcern. Forest managers need a comprehensive scientific understandingof natural stand development processes and anthropogenic factorsaffecting sal forest when designing silvicultural regimes formultiple-product management. We review ecology and productivityplus anthropogenic niches of sal forests. Information on edaphicfactors, phenology and stand development processes (regeneration,growth characteristics, soil nutrient requirement, growth allocation,nutrient cycling, stand structure and successional stages) isimportant for designing scientific forest management of salforest; likewise, knowledge of anthropogenic factors associatedwith use of sal forest is also required for effective implementationof the recently paradigmed management efforts. Sal forest silviculturehas been evolving since the beginning of the twentieth centurymainly concentrating on timber production, though the sal forestshave always been used also for grazing and collection of fodder,fuelwood, litter and many other products. Instead of integratingthese products in sal forest management, governments have attemptedto control these additional uses through enforcing forest legislation.These attempts resulted in the persistent conflicts betweenthe interests of local people and the government, and the deterioratingcondition of sal forests. Community-based forestry in this regionemerged in response to the severe degradation of forest resources,and local people initiated protection practices and demonstratedthe success of sal forest from coppice. The coppice systemsallow managing forests with intermittent products (non-timberforest products, including fodder and litter) while producingtimber in the long term. Accordingly, a policy has been developedto manage coppice sal forest for multiple products. Managingthe sal forest for multiple products is, however, a relativelyrecent development and scientific investigations on variousaspects of multiple-product forest management need to be initiated.Ecological processes indicate good prospects of managing salforest for multiple products. The review indicates that theecological processes and anthropogenic factors form sound basisfor developing multiple-product management.  相似文献   

13.
Stem straightness, axis persistence, presence/absence of protuberant buds and epicormics, diameter and height have profound influence on timber quality and volume of teak (Tectona grandis). Provenance trials of teak were established in the 1970s in Ghana, as part of the Food and Agriculture Organization (FAO) International Series of Provenance Trials, with the view of selecting teak germplasm for sites with specific environmental conditions. Two field trials were located in dry semi-deciduous (dry) and moist semi-deciduous (moist) ecological zones of Ghana. They consisted of 13 provenances, including four landraces each from Ghana and Indonesia, and two and three provenances from India and Laos, respectively. Trees were assessed at 9, 17 and 28 years to (1) quantify the potential variation in quality and timber volume production, (2) examine possibilities for determining early selection of parameters of superior provenances and (3) select provenances for sites with particular environmental conditions. Production traits were higher on the moist site than the dry site. Mean height was 23.2 and 20.2 m tree?1, stem cross-sectional area at breast height was 0.0896 and 0.0474 m2 tree?1, and stem volume was 0.75 and 0.34 m3 tree?1 for the moist and dry sites, respectively. Nilambur provenance from moist India had the highest mean stem straightness score of 19% above average, whereas Savannakhet from Laos had the best protuberant bud score with 18% of the trees above average. Indonesian landraces performed better in the dry zone, whereas provenances from India and Laos performed better in the moist zone. Phenotypic correlations between age 9 and 28 years were moderate (r 0.54–0.90) to high (r > 0.90) for production and qualitative characteristics, indicating feasibility of early assessment for identification of superior provenances. Nilambur and Savannakhet II provenances proved to be favourable choices for the moist zone, whereas the Temandsang provenance from Indonesia was found to be the best choice for the dry site.  相似文献   

14.
We studied the regeneration of tree species in the sub-tropical forest of Alaknanda Valley in Garhwal Himalaya, India. The overall regeneration status was fairly good in the study area. Seedling density ranged between 520 and 1,240 seedlings per ha while the density of saplings varied between 400 and 800 saplings per ha. Out of eight sites studied, five sites, viz., A1 , A2 , B1 , B2and C2contained the highest number of seedlings (280-480 per ha) and saplings (200-440 per ha) for Pinus roxburghii and remaining three sites viz., C1, D1and D2represented the highest number of seedlings (240-400 per ha) and saplings (200-240 per ha) for Anogeissus latifolius. The DBH class distribution of the tree species revealed that the highest number of individuals was concentrated in the lower diameter classes while smallest numbers were found in the higher diameter classes. Species such as Acacia catechu, Anogeissus latifolius, Dalbergia sissoo, Engelhardtia spicata, Lannea coromandelica, Mallotus philippensis and Pinus roxburghii have the largest number of saplings and seedlings in the lower DBH classes, suggesting that they have good regeneration potential. Other species such as Aegle marmelos, Bauhinia variegata, Bombax ceiba, Cassia fistula, Erythrina variegata, Haldinia cordifolia, Mangifera indica, Ougeinia oojeinensis, Phyllanthus emblica, Syzygium cumini, Terminalia alata and Toona hexandra have either no or very small number of saplings in the lower DBH classes, which indicates that the status of these species implies poor regeneration.  相似文献   

15.
Teak(Tectona grandis L.f.) is widely planted in the world due to its high market demand, economic, ecological and social value. Its plantations have mostly been established and expanded into sites that are acidic to severely acidic in southern China. But, there are no available and specific evidence-based nutrient management techniques. To better recognize and understand the relationship between teak tree growth and nutrient content in the foliage and soil and establish nutrient norms are critical to optimally manage these young plantations. We studied the foliar nutrient and soil chemistry in 19 representative teak plantations aged 5–8 years. Regression analysis indicated that the mean annual increment of teak volume was linearly and positively correlated with foliar N, Ca, Fe and B concentrations, with soil base saturation percentage,available P and Zn concentrations, and negatively correlated with soil Al concentration. Only if the Ca and Mg contents in soil were enhanced, could the increase in soil base saturation percentage benefit teak growth. A revised classification of low-and high-yielding stands was established by using a sorting method of principal components over 6 foliar macro and 8 micro elements in a Diagnosis and Recommendation Integrated System(DRIS). Specific DRIS norms for teak plantations in acid soils were derived.The nutrient balance of N, P, K Ca, Mg, Zn, B with Fe or Al, Ca with Mg, and Fe with Al provided a key to promote the growth of teak in acid soils. Meanwhile, soil Zn was also found as a primary trace element that affected teak growth in this study.  相似文献   

16.
17.
《林业研究》2021,32(3)
Tropical forest cover change along with increasing fragmentation has detrimental effects on the global biodiversity. In the current study change in both forest cover and fragmentation of Koraput district have been assessed in the past three decades(1987-2017) and future decade(2017-2027), which has been modelled using logistic regression showing a gradual decrease in the forest cover and increase in fragmentation. The long term deforestation rates from 1987 to 2017(current period) and from 1987 to 2027(predicted period) were found to be-0.018 and-0.012, respectively. Out of the total geographical area, 2027 number of grids(1 km2) out of 8856 grids were found to have shown extinction of forest in the study period. The conversion of forested lands into other land uses has been one of the major causes of deforestation in Koraput, especially because of the increasing mining activities and establishment of three major industries namely National Aluminium Company(NALCO), Damanjodi, Hindustan Aeronautics Limited(HAL), Sunabeda and Ballarpur Industries Limited(BILT). The forest fragmentation reveals a negative trend, recording highest conversion from large core fragments to edge(191.33 km2) and the predicted period has also shown the same trend of negative change, which poses serious danger to the structure of the forests. Out of all the landscape matrices calculated, number of patches will increase to 214 in 2027 from 93 in 1987. In the test between geographically weighted regression(GWR) and ordinary least square regression(OLS), GWR was the better fit model for drawing a spatial relationship between forest cover and fragmentation changes. The study confirmed that the forest cover change has impacted the forest fragmentation in the study area. The programmes like REDD + should be implemented along with the experiences of Community Forest Management and the joint forest management should be intensified at community level in order to develop better management practices to conserve habitats in biodiversity rich areas.  相似文献   

18.
Teak(Tectona grandis L.f.) is a popular hardwood species native to South and South-East Asia. The possible association of amplified fragment length polymorphism(AFLP) marker with morphological variables of eleven important characters viz. girth at breast height(GBH), height of tree, bole height, branch knots, presence of fluting, spiral stem, leaf hair, leaf length/breadth ratio, branching pattern, bark colour and petiole shape for nine natural populations comprising 180 genotypes of teak(9 populations × 20 trees). The phenogram constructed using Euclidean distances for the eleven morphological characters showed that the populations were not grouped according to their geographical origin. The Mantel's test for pairwise correlation between Euclidean distances of different morphological variables and genetic distances from AFLP data revealed that only petiole character(r =0.269; p =0.046) and height of tree(r =0.200; p =0.001) were significantly correlated with that of AFLP data matrix. The nine populations in this study covered a geographic area of about 1000 km stretch along the Western Ghat of South India. A test of correlation between genetic and geographic distance matrices revealed a significant positive correlation(r =0.475; p =0.009). The lack of perfect congruence between morphological and molecular data except for geographic distance, tree height and petiole character suggested that the morphological system might be useful for the morphotypes management but not appropriate to study the genetic structure of the teak populations.  相似文献   

19.
After years of unsustainable logging, dry deciduous dipterocarp forest (DDDF) has become poor in timber stocks and has been converted to industrial crops such as rubber. The objectives of this study were to assess teak (Tectona grandis L.f.) tree establishment under degraded DDDF conditions and to determine factors that influence the suitability of teak as a forest enrichment tree species. A set of 64 experimental plots of 4 900 m2 each was set up and observed for 4–5 years for testing enrichment planting with teak under various combinations of two groups of factors: ecological conditions and forest status. Weighted, non-linear, multivariate regression models were used to detect key factors that influenced the suitability of teak. The results showed that at the age of 4 years the average dominant tree height (defined as 20% of the tallest trees in the experimental plot) reached 11.2, 7.8, 5.3 and 3.8 m for very good, good, average and poor suitability levels, respectively. Survival rates of planted teak from average to very good suitability levels were over 90%. Six key factors that affected the suitability of teak were waterlogging during the rainy season, altitude, stand volume of the degraded DDDF, soil type, percentage of sand and concentration of P2O5 in the soil. Under the extreme ecological and environmental conditions of the DDDF, enrichment planting with teak gave promising results.  相似文献   

20.
The influence of experimental acidification (diluted H2SO4) on mass-loss rates of needle and root litters was investigated in forests of Scots pine, lodgepole pine, Norway spruce and white birch located in a climatic transect through Sweden. Of the two dosages given (32 and 96 kg S ha−1), significant effects on mass-loss rates were observed mainly with the higher dose. When comparing the effect of acid on mass-loss rate of needle litter on all sites together for the whole 3-year period, no effect was seen. By distinguishing the different types of forest and understorey we found a significant general decrease in rate for needle litter of about 8% for the pine forest sites (n = 10). For the spruce sites (n = 8) and the birch sites (n = 2) no significant effects were seen. When considering single sites after 1 year of decomposition, significant effects (rate decrease) were also found for the birch forests. At some spruce sites significant differences in mass-loss rate were seen (both rate increase and rate decrease). When a significant effect was seen its magnitude was found to be dependent on the decomposition rate (soil biological activity) of that site.For root litter the results were less clear. No significance was seen when comparing all sites together or sites of one type of forest. Significant decreases in mass-loss rate after acid treatment were, however, noted for some of the sites after different incubation periods. The patterns of dynamics of the nutrients N, P, S, K and Ca were not affected whereas those of Mg and Mn were and significantly higher release rates were found for these nutrients after acid treatment. The release rates of the nutrients N, P, S, K and Ca from litter were proportional to litter mass-loss and for the Scots pine stands this meant a decreased release rate for these nutrients.  相似文献   

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