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1.
Knowledge on the structure and composition of the plant communities has enormous significance in conservation and management
of forests. The present study aimed to assess the community attributes, viz., structure, composition and diversity in the
moist and dry sal (Shorea robusta) forests in the West Bengal province of India and compare them with the other sal forests of India. The phytosociological
data from these forests were quantitatively analysed to work out the species richness, diversity, evenness, dominance, importance
value, stand density and the basal area. The analysis showed that plant richness and diversity in moist sal forests of northern
West Bengal are higher than the dry sal forests of south-west Bengal; a total of 134 tree (cbh ≥30 cm), 113 shrub and 230
herb species were recorded in the moist sal forest compared to 35 tree, 41 shrub and 96 herb species in dry sal forest. Papilionaceae
was observed to be the dominant family. Dry sal forests had higher tree dominance (0.81) and stand density (1,006 stems ha−1) but lower basal area (19.62 m2ha−1) while moist sal forest had lower tree dominance (0.18) and stand density (438 stems ha−1) but higher basal area (56.52 m2ha−1). Tree species richness and stem density across girth classes in both the types decreased from the smallest to largest trees,
while the occurrence rate of species increased with increase in girth class. A t-test showed significant differences in species richness, basal area and the stand density at 95% confidence level (p = <0.05) in the two forest types. The CCA indicated very low overall match (canonical correlation value = 0.40) between the
two sets of variables from moist and dry sal types. The differences in these forests could be attributed to the distinct variations
in climatic conditions- mainly the rainfall, disturbance regimes and the management practices. 相似文献
2.
Species richness and density of understory plants were investigated in eight 1 ha plots, distributed one each in undisturbed
and disturbed tropical evergreen, semi-evergreen, deciduous and littoral forests of Little Andaman island, India, which falls
under one of the eight hottest hotspots of Biodiversity in the world viz. the Indo-Burma. One hundred 1 m−2 quadrats were established in each 1 ha plot, in which all the understory plants (that include herbs, undershrubs, shrubs
and herbaceous climbers) were enumerated. The total density of understory plants was 6,812 individuals (851 ha−1) and species richness was 108 species, representing 104 genera and 50 families. Across the four forest types and eight study
plots, the species richness ranged from 10 to 39 species ha−1. All the disturbed sites harbored greater number of species than their undisturbed counterparts. Herbs dominated by species
(63%) and density (4,259 individuals). The grass Eragrostis tenella (1,860 individuals; IVI 40), the invasive climber Mikania cordata (803; IVI 20) and the shrub Anaxagorea luzonensis (481; IVI 17.5) were the most abundant species. Poaceae, Asteraceae, Acanthaceae, Orchidaceae and Euphorbiaceae constituted
the species-rich families represented by 6 species each. The species-area curves attained an asymptote at 0.8 ha level except
in sites DD and DL, indicating 1 ha plot is not sufficient to capture all the understory species in disturbed forests. The
alien weeds formed about one-fourth of the species richness (31 species; 28%) and density (1,926 individuals; 28.3%) in the
study sites, indicating the extent of weed invasion and the attention required for effective conservation of the native biodiversity
of the fragile island forest ecosystem. 相似文献
3.
Forests play a major role in global carbon (C) cycle, and the carbon density (CD) could reflect its ecological function of
C sequestration. Study on the CD of different forest types on a community scale is crucial to characterize in depth the capacity
of forest C sequestration. In this study, based on the forest inventory data of 168 field plots in the study area (E 111°30′–113°50′,
N 37°30′–39°40′), the forest vegetation was classified by using quantitative method (TWINSPAN); the living biomass of trees
was estimated using the volume-derived method; the CD of different forest types was estimated from the biomass of their tree
species; and the effects of biotic and abiotic factors on CD were studied using a multiple linear regression analysis. The
results show that the forest vegetation in this region could be classified into 9 forest formations. The average CD of the
9 forest formations was 32.09 Mg ha−1 in 2000 and 33.86 Mg ha−1 in 2005. Form. Picea
meyeri had the highest CD (56.48 Mg ha−1), and Form. Quercus liaotungensis + Acer mono had the lowest CD (16.14 Mg ha−1). Pre-mature forests and mature forests were very important stages in C sequestration among four age classes in these formations.
Forest densities, average age of forest stand, and elevation had positive relationships with forest CD, while slope location
had negative correlation with forest CD. 相似文献
4.
Biomass and net production were measured in aPhyllostachys bambusoides stand in Kyoto Prefecture, central Japan, which had carried out gregarious flowering in 1969 and has been recovering vegetatively.
The culm density fluctuated around an average value of 12 040 ha−1 during the research period (1985–91). Annual recruirment and mortality rates of culms were 1340 and 1133 ha−1, respectively. The mean diameter at breast height increased from 7.28 cm in 1985 to 8.68 cm in 1991, and the biomass of culms
increased from 71.3 to 111.6t ha−1 over the same time period. Branch and leaf biomasses were almost constant, 10.0 and 9.4t ha−1 on average, respectively. The leaf area index of the stand was 11.6 ha ha−1, which is one of the largest values found in Japanese forests. The belowground biomass of 32.6t ha−1 for rhizomes and 14.8t ha−1 for fine roots resulted in the smaller ratio of aboveground parts to the root system (2.38) than those determined for forest
stands. The amount of litterfall, excluding culms and large branches, was large (9.13t ha−1 year−1), corresponding to those measured in equatorial stands. The aboveground net production was 24.6t ha−1 year−1, larger than the average value reported for forest stands under similar weather conditions. 相似文献
5.
Altitudinal changes in carbon storage of temperate forests on Mt Changbai, Northeast China 总被引:8,自引:0,他引:8
Biao Zhu Xiangping Wang Jingyun Fang Shilong Piao Haihua Shen Shuqing Zhao Changhui Peng 《Journal of plant research》2010,123(4):439-452
A number of studies have investigated regional and continental scale patterns of carbon (C) stocks in forest ecosystems; however,
the altitudinal changes in C storage in different components (vegetation, detritus, and soil) of forest ecosystems remain
poorly understood. In this study, we measured C stocks of vegetation, detritus, and soil of 22 forest plots along an altitudinal
gradient of 700–2,000 m to quantify altitudinal changes in carbon storage of major forest ecosystems (Pinus koraiensis and broadleaf mixed forest, 700–1,100 m; Picea and Abies forest, 1,100–1,800 m; and Betula ermanii forest, 1,800–2,000 m) on Mt Changbai, Northeast China. Total ecosystem C density (carbon stock per hectare) averaged 237 t C ha−1 (ranging from 112 to 338 t C ha−1) across all the forest stands, of which 153 t C ha−1 (52–245 t C ha−1) was stored in vegetation biomass, 14 t C ha−1 (2.2–48 t C ha−1) in forest detritus (including standing dead trees, fallen trees, and floor material), and 70 t C ha−1 (35–113 t C ha−1) in soil organic matter (1-m depth). Among all the forest types, the lowest vegetation and total C density but the highest
soil organic carbon (SOC) density occurred in Betula ermanii forest, whereas the highest detritus C density was observed in Picea and Abies forest. The C density of the three ecosystem components showed distinct altitudinal patterns: with increasing altitude, vegetation
C density decreased significantly, detritus C density first increased and then decreased, and SOC density exhibited increasing
but insignificant trends. The allocation of total ecosystem C to each component exhibited similar but more significant trends
along the altitudinal gradient. Our results suggest that carbon storage and partitioning among different components in temperate
forests on Mt Changbai vary greatly with forest type and altitude. 相似文献
6.
Changes in species composition and density of trees >10 cm gbh in a tropical dry evergreen forest in Puthupet, south India are interpreted for the period between 1992 and 2002. A 1-ha plot was inventoried in 1992 and was recensused in 2002. During the 10-year interval tree taxa diversity as well as stand density increased, but the basal area value decreased. Tree species richness increased by 21% (from 24 to 29 species) by an addition of eight species and local extinction of three species. The tree density increased just by eight individuals (from 1330 stems ha−1 in 1992 to 1338 ha−1 in 2002), but the basal area decreased by 8% (from 37.5 to 34.5 m2 ha−1). Many species (11 numbers) have increased in abundance rather than decreased. Many surviving species seem to have considerable stability in abundance at the local scale. The density of smaller stems (10 29 cm gbh) increased by 15.3%, while that of the larger trees decreased drastically (81.6%). Ninety percent of the missing stems were from the middlestorey of the forest. Tree density changes among the three ecological guilds revealed a decrease in stem density and an increase in basal area in the lowerstorey; while the middlestorey exhibited a reverse trend. Family-wise, tree density changes revealed that the majority of families (67%) showed an increase in stem density. Long-term studies on tree population changes are essential to estimate tree mortality and recruitment rates, which will provide a greater insight in tropical forest dynamics. 相似文献
7.
A field experiment was conducted at the Bangladesh Rice Research Institute, Joydebpur, Dhaka during the late wet season. Basal
application of P at both 5 and 10 kg ha−1 significantly increased total biomass production and nitrogen fixation byAzolla pinnata R. Brown (local strain). Addition of both 5 and 10 kg P ha−1 in equal splits at inoculation and at six day intervals thereafter during growth periods of 12, 24 and 36 days increased
biomass production and nitrogen fixation by Azolla over that attained with the basal application. Biomass and nitrogen fixation
using a split application of 5 kg P ha−1 exceeded that attained with basal application of 10 kg P ha−1 and split application of 10 kg P ha−1 resulted in 0.58, 11.2, and 18.3 t ha−1 more biomass, and 0.47, 18.9, and 18.3 more kg fixed N ha−1 at 12, 24 and 36 days, respectively, than the same amount applied as a basal application. Analyses indicated that the critical
level of dry weight P in Azolla for sustained growth was in the range of 0.15–0.17%. Compared with the control, where no P
was added, and additional 30 and 36 kg N ha−1 were fixed after 24 and 36 days, respectively, when P was provided at 10 kg ha−1 using a split application. A separate field study showed that flooded rice plants received P from incorporated Azolla with
about 28% of the P present in the supplied Azolla being incorporated into the rice plants. 相似文献
8.
Problems of estimating population parameters and production of fish in a tropical rain forest stream,North Venezuela 总被引:1,自引:1,他引:0
The River Todasana is a small rain tropical forest stream emptying to the Caribbean Sea (Venezuela). Fish were sampled by
electrofishing at three contiguous sites (pool, riffle, raceway). Nine species were recorded. Their mean biomass and production
were: 43.72 kg ha−1 and 36.94 kg ha−1 yr−1, maximum: 55.47 kg ha−1 and 42.33 kg ha−1 yr−1, respectively. 相似文献
9.
Invasion by a Perennial Herb Increases Decomposition Rate and Alters Nutrient Availability in Warm Temperate Lowland Forest Remnants 总被引:3,自引:0,他引:3
Rachel J. Standish Peter A. Williams Alastair W. Robertson Neal A. Scott Duncan I. Hedderley 《Biological invasions》2004,6(1):71-81
We determined the impact of the invasive herb, Tradescantia fluminensis Vell., on litter decomposition and nutrient availability in a remnant of New Zealand lowland podocarp–broadleaf forest. Using
litter bags, we found that litter beneath mats of Tradescantia decomposed at almost twice the rate of litter placed outside the mat. Values of k (decomposition quotient) were 9.44±0.42 yrs for litter placed beneath Tradescantia and 5.42±0.42 yrs for litter placed in native, non-Tradescantia plots. The impact of Tradescantia on decomposition was evident through the smaller forest floor mass in Tradescantia plots (2.65±1.05 t ha−1) compared with non-Tradescantia plots (5.05±1.05 t ha−1), despite similar quantities of annual leaf litterfall into Tradescantia plots (6.85±0.85 t ha−1 yr−1) and non-Tradescantia plots (7.45±1.05 t ha−1 yr−1). Moreover, there was increased plant nitrate available, as captured on resin bags, in Tradescantia plots (25.77 ± 8.32 cmol(−)/kg resin) compared with non-Tradescantia plots (9.55±3.72 cmol(−)/kg resin). Finally, the annual nutrient uptake by Tradescantia represented a large proportion of nutrients in litterfall (41% N, 61% P, 23% Ca, 46% Mg and 83% K), exceeded the nutrient
content of the forest floor (except Ca), but was a small proportion of the topsoil nutrient pools. Taken together, our results
show that Tradescantia increases litter decomposition and alters nutrient availability, effects that could influence the long-term viability of
the majority of podocarp–broadleaf forest remnants affected with Tradescantia in New Zealand. These impacts are likely mostly due to Tradescantia's vegetation structure (i.e., tall, dense mats) and associated microclimate, compared with native ground covers.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
The present study was undertaken in seven major forest types of temperate zone (1500 m a.s.l. to 3100 m a.s.l.) of Garhwal
Himalaya to understand the effect of slope aspects on carbon (C) density and make recommendations for forest management based
on priorities for C conservation/sequestration. We assessed soil organic carbon (SOC) density, tree density, biomass and soil
organic carbon (SOC) on four aspects, viz. north-east (NE), north-west (NW), south-east (SE) and south-west (SW), in forest
stands dominated by Abies pindrow, Cedrus deodara, Pinus roxburghii, Cupressus torulosa, Quercus floribunda, Quercus semecarpifolia and Quercus leucotrichophora. TCD ranged between 77.3 CMg ha−1 on SE aspect (Quercus leucotrichophora forest) and 291.6 CMg ha−1 on NE aspect (moist Cedrus deodara forest). SOC varied between 40.3 CMg ha−1 on SW aspect (Himalayan Pinus roxburghii forest) and 177.5 CMg ha−1 on NE aspect (moist Cedrus deodara forest). Total C density (SOC + TCD) ranged between 118.1 CMg ha−1 on SW aspect (Himalayan Pinus roxburghii forest) and 469.1 CMg ha−1 on NE aspect (moist Cedrus deodara forest). SOC and TCD were significantly higher on northern aspects as compared with southern aspects. It is recommended that
for C sequestration, the plantation silviculture be exercised on northern aspects, and for C conservation purposes, mature
forest stands growing on northern aspects be given priority. 相似文献
11.
The dynamics of aboveground big woody organs over 10 cm diameter was studied at a mature foothill dipterocarp forest in West
Sumatra. The biomass of big woody organs was estimated to be 519 m3 ha−1 or 408 metric ton ha−1 by means of a pipe model theory. The diameter distribution showed a convex curve and the mode was found at a diameter of
about 20 cm. The standing mass of big dead woody litter on the forest floor was 116 m3 ha−1, which accounted for 22% by voume or 9.5% by weight of the biomass of living organs respectively. Thedbh observation with two 1-ha plots for 4 yr and 5 yr respectively revealed that the average net production rate was 9.5 ton
ha−1 yr−1. The death rate (7.9 ton ha−1 yr−1) accounted for 83% of the net production rate and was nearly equivalent to the decay rate (7.5 ha−1 yr−1) of dead wood on the forest floor. The balance between the death and decay rates was confirmed for each diameter class. Average
turnover periods for big woody organs and dead woody litter were estimated to be 43 and 8.1 yr, respectively. Standing masses
of live anddead woody materials accumulated in the study forest were approximately equal to those obtained in a mature tropical
lowland rainforest, whereas the flow rates were lower, being only 70% of the corresponding values. 相似文献
12.
We document spatial changes in species diversity, composition, community structure, and mortality of trees across a gradient
of water availability in a tropical dry forest in western Mexico. This gradient occurs along the main stream of a small watershed
of less than 1 km in length. Four 30 × 80 m plots were established systematically to include the driest (ridge top of the
watershed) to the wettest sites (watershed bottom) within this watershed. All stems larger than 5 cm were identified, and
measured for diameter and height. Dead stems larger than 5 cm were measured and classified as: a) found on live or dead trees,
and b) standing (“snags”) or lying (“downlogs”) on the ground. The number of recorded species per plot declined from 73 to
44 species as water availability decreased. A decline in estimated total richness, and in Shannon-Wiener and Simpson diversity
indices was also observed in the drier plots. Species composition strongly changed along the gradient, with the two ends of
the gradient sharing only 11% of the species. Stem density and percentage of dead stems and trees increased in abundance and
basal area from the wetter to the drier sites. Tree and stem size (basal area, height and stem diameter) showed the opposite
trend. Nonetheless, total basal area of live trees was largest at the two end gradient locations and oscillated between 12.22
m2 ha−1 and 7.93 m2 ha−1. Proportion of snags increased towards the driest site (from 46 to 72%), while that of down logs decreased. Overall, our
results suggest that small-scale gradients of water availability play a paramount role in the spatial organization of tree
communities in seasonal tropical environments.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
D. Morales M. Soledad Jiménez Agueda M. González-Rodríguez Jan Čermák 《Trees - Structure and Function》1996,11(1):34-40
Stand structure and leaf area distribution of a laurel forest in the Agua García mountains of Tenerife are described. The
site is situated at 820 m a.s.l., faces NNE, and has a humid mediterranean climate. Summer droughts are mitigated by relatively
high air humidity and clouds. The natural mixed hardwood forest is composed of six major tree species: Laurus azorica (Seub.) Franco, Persea indica (L.) Spreng, Myrica faya Ait., Erica arborea L. and two species of Ilex (I. platyphylla Webb & Berth. and I. canariensis Poivet.). The experimental stand had a density of 1693 trees ha – 1, a basal area of 33.7 m2ha – 1, and a cumulated volume of above-ground parts of trees of 231 m3 ha – 1 with a corresponding dry mass of 204 ton ha – 1. Diameters at breast height ranged from 6 to 46 cm. Mean concentration of plant dry mass per volume was 1.17 kg m – 3. The vertical pattern of leaf area distribution in individual trees for all tree species was characterized by a Gaussian-like
curve. Stand leaf area index was 7.8. These evergreen, broad-leaved (laurisilva or lucidophyllous) forests represent a relic
forest that was widespread in the Mediterranean region some 20 million years ago. Our data illustrate some of the structural
characteristics of this historically widespread forest type.
Received: 2 December 1994 / Accepted: 6 November 1995 相似文献
14.
A field experiment conducted at Central Rice Research Institute, Cuttack, during three successive seasons showed that with
the 120-day-duration variety Ratna two dual crops ofAzolla pinnata R. Brown (Bangkok isolate) could be achieved 25 and 50 days after transplanting (DAT) by inoculating 2.0 t ha−1 of fresh Azolla 10 and 30 DAT respectively. One basal crop of Azolla could also be grown using the same inoculum 20 days
before transplanting (DBT) in fallow rice fields. The three crops of Azolla grown—once before transplanting and twice after
transplanting—gave an average total biomass of 38–63 and 43–64 t ha−1 fresh Azolla containing 64–90 and 76–94 kg N ha−1 respectively in the square and rectangular spacings. Two crops of Azolla grown only as a dual crop, on the other hand, gave
26–39 and 29–41 t ha−1 fresh Azolla which contained 44–61 and 43–59 kg N ha−1 respectively.
Growth and yield of rice were significantly higher in Azolla basal plus Azolla dual twice incorporated treatments than in
the Azolla dual twice incorporation, Azolla basal plus 30 kg N ha−1 urea and 60 kg N ha−1 urea treatments. Azolla basal plus 30 kg N ha−1 urea and 60 kg N ha−1 urea showed similar yields but Azolla dual twice incorporation was significantly lower than those. The different spacing
with same plant populations did not affect growth and yield significantly, whereas Azolla growth during dual cropping was
8.3 and 64% more in the rectangular spacing than in the square spacing in Azolla basal plus Azolla dual twice incorporation
and Azolla dual twice incorporation treatments. 相似文献
15.
Soil nutrients affect spatial patterns of aboveground biomass and emergent tree density in southwestern Borneo 总被引:2,自引:0,他引:2
Studies on the relationship between soil fertility and aboveground biomass in lowland tropical forests have yielded conflicting
results, reporting positive, negative and no effect of soil nutrients on aboveground biomass. Here, we quantify the impact
of soil variation on the stand structure of mature Bornean forest throughout a lowland watershed (8–196 m a.s.l.) with uniform
climate and heterogeneous soils. Categorical and bivariate methods were used to quantify the effects of (1) parent material
differing in nutrient content (alluvium > sedimentary > granite) and (2) 27 soil parameters on tree density, size distribution,
basal area and aboveground biomass. Trees ≥10 cm (diameter at breast height, dbh) were enumerated in 30 (0.16 ha) plots (sample
area = 4.8 ha). Six soil samples (0–20 cm) per plot were analyzed for physiochemical properties. Aboveground biomass was estimated
using allometric equations. Across all plots, stem density averaged 521 ± 13 stems ha−1, basal area 39.6 ± 1.4 m2 ha−1 and aboveground biomass 518 ± 28 Mg ha−1 (mean ± SE). Adjusted forest-wide aboveground biomass to account for apparent overestimation of large tree density (based
on 69 0.3-ha transects; sample area = 20.7 ha) was 430 ± 25 Mg ha−1. Stand structure did not vary significantly among substrates, but it did show a clear trend toward larger stature on nutrient-rich
alluvium, with a higher density and larger maximum size of emergent trees. Across all plots, surface soil phosphorus (P),
potassium, magnesium and percentage sand content were significantly related to stem density and/or aboveground biomass (R
Pearson = 0.368–0.416). In multiple linear regression, extractable P and percentage sand combined explained 31% of the aboveground
biomass variance. Regression analyses on size classes showed that the abundance of emergent trees >120 cm dbh was positively
related to soil P and exchangeable bases, whereas trees 60–90 cm dbh were negatively related to these factors. Soil fertility
thus had a significant effect on both total aboveground biomass and its distribution among size classes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
Development of ground vegetation biomass and nutrient pools in a clear-cut disc-plowed boreal forest
Marjo Palviainen Leena Finér Ari Laurén Hannu Mannerkoski Sirpa Piirainen Michael Starr 《Plant and Soil》2007,297(1-2):43-52
Nutrient leaching from forest substrate after clear-cutting and subsequent soil preparation is strongly influenced by the
capacity of ground vegetation to sequester the released nutrients. We studied the rates and patterns of biomass and nutrient
accumulation in ground vegetation growing on ridges, in furrows and on undisturbed surfaces for 2–5 years after disc-plowing
in eastern Finland. The biomass of mosses on ridges remained significantly lower than that in furrows and on undisturbed surfaces.
Field layer biomass on ridges and in furrows was significantly lower than on undisturbed surfaces throughout the study period.
Field layer biomass increased more on ridges than in furrows. Root biomass on ridges and undisturbed surfaces was considerably
higher than in furrows. Five years after disc-plowing, total biomass and nutrient pools for ridges (biomass 4,975 kg ha−1, N 40 kg ha−1, P 5 kg ha−1, K 20 kg ha−1 and Ca 18 kg ha−1) and undisturbed surfaces (biomass 5,613 kg ha−1, N 43 kg ha−1, P 5 kg ha−1, K 22 kg ha−1 and Ca 18 kg ha−1) were similar, but considerably lower for furrows (biomass 1,807 kg ha−1, N 16 kg ha−1, P 2 kg ha−1, K 10 kg ha−1 and Ca 6 kg ha−1). Ridges covered 25% of the area, furrows 30 and 45% was undisturbed surfaces. Taking into account the proportion of each
type of surface, values for the whole prepared clear-cut area were 4,312, 34, 4, 18 and 14 kg ha−1 for biomass, N, P, K and Ca, respectively. Biomass and nutrient pools had not returned to uncut forest levels at the end
of the 5-year study period. The results indicate that mosses and field layer vegetation respond differently to soil preparation,
that the development of biomass on ridges, in furrows and on undisturbed surfaces proceeds at different rates, and that the
biomass and nutrient uptake of ground vegetation remains below pre-site preparation levels for several years. However, ridges,
which are known to be the most susceptible to leaching, revegetate rapidly.
Responsible Editor: Tibor Kalapos. 相似文献
17.
Felipe Zamborlini Saiter Frederico Augusto Guimarães Guilherme Luciana Dias Thomaz Tânia Wendt 《Biodiversity and Conservation》2011,20(9):1921-1949
The tree changes of 1.02 ha of montane forest at the Santa Lúcia Biological Station, southeastern Brazil, were analyzed using
two surveys separated by an interval of 11 years with the aim of confirming the patterns of stability of structure and diversity
over time. In the original survey all trees with diameter at breast height ≥6.4 cm were sampled. In second survey (this study),
dead trees, survivors and recruits in the same forest were reported. The data suggest a dynamic balance of the forest structure
because mortality (−1.06% year−1 for number of trees and −0.85% year−1 for basal area) was very close to recruitment (0.89% year−1) and ingrowth (1.05% year−1). The high diversity of the original survey (H′ > 5.2) was maintained by the turnover species. The main tree populations also showed stability of number of trees and basal
area. This pattern was shared by most of the 28 local endemic species, ensuring the maintenance of their populations in the
plot. 相似文献
18.
DeXiang Chen YiDe Li HePing Liu Han Xu WenFa Xiao TuShou Luo Zhang Zhou MingXian Lin 《中国科学:生命科学英文版》2010,53(7):798-810
Biometric inventories for 25 years, from 1983 to 2005, indicated that the Jianfengling tropical mountain rain forest in Hainan,
China, was either a source or a modest sink of carbon. Overall, this forest was a small carbon sink with an accumulation rate
of (0.56±0.22) Mg C ha−1yr−1, integrated from the long-term measurement data of two plots (P9201 and P8302). These findings were similar to those for
African and American rain forests ((0.62±0.23) Mg C ha−1yr−1). The carbon density varied between (201.43±29.38) Mg C ha−1 and (229.16±39.2) Mg C ha−1, and averaged (214.17±32.42) Mg C ha−1 for plot P9201. Plot P8302, however, varied between (223.95±45.92) Mg C ha−1 and (254.85±48.86) Mg C ha−1, and averaged (243.35±47.64) Mg C ha−1. Quadratic relationships were found between the strength of carbon sequestration and heavy rainstorms and dry months. Precipitation
and evapotranspiration are two major factors controlling carbon sequestration in the tropical mountain rain forest. 相似文献
19.
A hinoki stand was divided into the following two layers: one was a leafed upper layer consisting of leaves and woody elements,
such as stems, living branches and dead branches; the other was a leafless layer consisted of woody elements, such as stems
and dead branches. Photosynthetic photon flux density (PPFD) penetrating through the stand was measured in relation to the
silhouette area of leaves and woody elements. The silhouette area, on a ground area basis, was 11.2 ha ha−1 for leaves (leaf area index), 0.26 ha ha−1 for stems, 0.40 ha ha−1 for living branches and 0.69 ha ha−1 for dead branches, yielding a total wood silhouette area of 1.35 ha ha−1. The apparent extinction coefficient,K, was computed to be 0.420 ha−1 ha for the leafed layer, while the extinction coefficient of woody elements,K
c, was computed to be 1.01 ha−1 ha for the leafless layer. The cumulative wood silhouette area density from the top of the canopy down to a given depth increased
with an increase in the corresponding leaf area density within the leafed layer. The extinction coefficient of leaves,K
F, was estimated to be 0.367 ha−1 ha. Of the PPFD extinguished within the canopy, the fraction (K
F/K) due to leaves alone was evaluated to be 87.4%. 相似文献
20.
Koichi Takahashi 《Plant Ecology》2010,211(1):159-169
Stand dynamics was studied over 13 years in a cool-temperate conifer-hardwood forest, northern Japan. A total 30 hardwood
species and one conifer, Abies sachalinensis, larger than 1.5 cm DBH were recorded. The total stand density was 1677 trees ha−1 at the beginning, decreasing to 1184 trees ha−1 (30% reduction) over the study period, but the total stand basal area was almost unchanged (about 49 m2 ha−1). This large reduction in total density was mainly due to the death of saplings and infrequent recruitment. Number of recruits
gradually decreased with time, while that of dead trees was constant. Cause of death of small trees was mainly due to suppression
by tall trees. Skewness of the DBH frequency distribution varied among the species. A less skewed frequency distribution (i.e.,
few number of saplings) was shown by shade-intolerant species such as Populus maximowiczii and Betula maximowicziana, and a more skewed frequency distribution (i.e., large number of saplings) by shade-tolerant species such as Acer mono and Tilia japonica. DBH frequency distribution changed to less skewed patterns with reduction of density in most species during the census period.
Rank of shade tolerance positively correlated with tree density and skewness, and negatively correlated with mean DBH. Skewness
also positively correlated with recruitment rates. Furthermore, rank of shade tolerance positively correlated with seed size.
These results suggest that shade-intolerant species regenerated immediately after disturbances by wide dispersal of small
seeds, but their recruitment was interrupted after that. By contrast, shade-tolerant species were able to recruit even after
the ceasation of recruitment of shade-intolerant species, but suffered severe mortality due to the increasing shading with
the progress of stand development. This study suggests that the stand is still developing, with changes in species composition
and size structure, and that species differences in shade tolerance and seed size are important for the stand structural changes. 相似文献