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1.
Takuya Kajimoto 《Ecological Research》1989,4(1):55-69
Aboveground biomass and litterfall ofPinus pumila scrubs, growing on the Kiso mountain range in central Japan, were investigated from 1984 to 1985. The biomass of two research
plots (P1 and P2) with different scrub heights was estimated by two methods, the stratified clip technique and the allometric
method. Aboveground total biomass estimated by the latter method reached 181 ton d.w. ha−1 in P1 and 132 ton d.w. ha−1 in P2. Creeping stems contributed to about half of the total biomass. Although estimates of woody organs differed between
the two plots, leaf biomass estimates were almost the same at 15.5 ton d.w. ha−1. The canopies of the twoP. pumila scrubs were characterized by a large mean leaf area density of 5.0 m2 m−3. Despite this large area density, relatively moderate attenuation of light intensity was observed. Specific leaf area generally
increased with reduced leaf height. Annual total litterfall was estimated to be 3.60 ton d.w. ha−1 yr−1 in P1 and 2.39 ton d.w. ha−1 yr−1 in P2. Annual leaf fall in both plots was approximately 2.0 ton d.w. ha−1 yr−1. Leaves fell mainly in early autumn. Annual loss rates of branches, estimated as the sum of annual branch litterfall and
the amount of newly formed attached dead branches, were 0.29 ton d.w. ha−1 yr−1 in P1 and 0.37 ton d.w. ha−1 yr−1 in P2. 相似文献
2.
Biomass, litterfall, litter standing crop, and decomposition was studied in a native subtropical alluvial forest locally known as Selva Marginal (SM) and an exotic Ligustrum lucidum forest (LF) at the Reserva Integral de Punta Lara, Buenos Aires Province, 34°47S and 58°1W. The alluvial forest site was at the southern limit of distribution of subtropical forests in South America. The Ligustrum forest was invading disturbed areas. Total biomass was 147.7 Mg/ha (86% aboveground and 14% belowground) in the SM, and 71.4 Mg/ha (93% and 7%, respectively) in the LF. Litterfall was 10.3 Mg/ha·yr and 13.8 Mg/ha·yr respectively. Annual leaf decomposition rate was greater for Ligustrum (k=4.07) than for SM species (k=1.48). The mean residence time of aboveground biomass was 12 yr for the SM and 5 yr for the LF. The k1 values (litterfall/standing crop) were 1.9 and 2.0 for SM and LF respectively. The influence of coastal road and wall in the hydroperiod, native forested wetland ecosystem survival and exotic forest invasion is discussed. 相似文献
3.
At altitudes between 1300 m to 2100 m in the Etna massif (Sicily), an endemic species of theBetula genus,Betula aetnensis Rafin, grows in a well-defined microclimatical context. Aboveground biomass and nutrient content studies within one stand revealed no significant differences from the otherBetula species, normally found in colder more temperate climate regions.Throughout the studied sites, biomass production, nutrient cycling and various structural or physiological characteristics (leaf area index) varied very little.Other researches indicate that the originality ofBetula aetnensis lies more in the histological or anatomical characteristics of its water conducting system which enables the species to adapt to Mediterranean-climate summer droughts in the Etna massif.
Riassunto Sull'Etna, tra 1300 e 2100 m d'altitudine, in una zona microclimaticamente ben definita del versante nordorientale, si rinviene laBetula aetnensis Rafin.Dallo studio della fitomassa e della mineralomassa aerea del bosco di Monte Baracca, è emerso che non vi sono differenze notevoli con le altre specie indagate del genereBetula, più caratteristiche dei climi temperati e freddi.La produzione di biomassa, cosi come la gestione degli elementi nutritivi, è molto simile ai diversi popolamenti già indagati, cosi come certe caratteistiche strutturali e fisiologiche (leaf area index).L'originalità dellaBetula aetnensis è da ricercarsi nel vantaggio che ne ricava, a livello endogeno, sfruttando le caratteristiche istologiche ed anatomiche del suo apparato conduttore, che le consentono un efficace ed eccellente adattamento alle condizioni di siccità estive particolari del clima mediterraneo del vulcano.相似文献
4.
J. Zavitkovski 《Plant and Soil》1981,60(3):409-422
Litterfall was sampled in 3- to 7-year-old irrigated and fertilized plantings of Populus Tristis#1 in northern Wisconsin. Leaves accounted for more than 90 per cent of the total litter and reached an asymptotic value of about 4,000 to 4,200 kg/ha. Leaf litterfall culminated in late September or first half of October. Inadequate light appeared to be responsible for an early (June) leaf fall in dense plantings. The maximum cumulative leaf area index ranged from 8.4 to 8.7. The pattern of foliation and defoliation was similar: it started with small leaves in the lower canopy and ended with large leaves of the upper canopy. Longevity of the small leaves was shorter than that of the large leaves. Leaf size was positively affected by fertilization but was not affected by a discontinuation of irrigation by mid-July during the droughty 1976. The specific leaf weight ranged from 2.6 mg/cm2 in the lower canopy to 10.2 mg/cm2 in the upper canopy. The specific leaf weight of litter leaves was 4 to 38 per cent lower than that of green leaves of the same size. 相似文献
6.
Jeffrey M. Klopatek 《Plant and Soil》2007,294(1-2):157-167
Litterfall and fine root production were measured for three years as part of a carbon balance study of three forest stands
in the Pacific Northwest of the United States. A young second-growth Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stand, a second-growth Douglas-fir with red alder (Alnus rubra Bong.) stand, and an old-growth (∼550 years) Douglas-fir stand were monitored for inputs of carbon and nitrogen into the
soil from litterfall and fine root production, as well as changes in soil C and N. Fine root production and soil nutrient
changes were measured through the use of soil ingrowth bags containing homogenized soil from the respective stands. Litterfall
biomass was greatest in the Douglas-fir-alder stand (527 g m−2 yr−1) that annually returned nearly three times the amount of N as the other stands. Mean residence time for forest floor material
was also shortest at this site averaging 4.6 years and 5.5 years for C an N, respectively. Fine root production in the upper
20 cm ranged from 584 g m−2 in the N rich Douglas-fir-alder stand to 836 g m−2 in the old-growth stand. Fine root production (down to one meter) was always greater than litterfall with a below:above ratio
ranging from 3.73 for the young Douglas-fir stand to 1.62 for the Douglas-fir-alder stand. The below:above N ratios for all
three stands closely approximate those for biomass. Soil changes in both C and N differed by site, but the soil C changes
in the old-growth stand mirrored those obtained in an ongoing CO2 flux study. Results from the soil ingrowth bags strongly suggest that this method provides a simple, but sufficient device
for measuring potential fine root biomass production as well as soil chemical changes. 相似文献
7.
地统计学方法在长白落叶松人工林凋落物现存量估测中的应用 总被引:2,自引:0,他引:2
采用地统计学的变异函数分析方法定量研究了15年生落叶松(Larix olgensis)人工纯林凋落物层重量的空间异质性特征,利用地统计学的克里格内插法结合定积分,对凋落物层的重量进行了估测.结果表明1)不同分解层次的凋落物重量的变异函数曲线理论模型均为球状模型,空间变异主要是由结构性因素引起,且空间自相关程度均属中等以上(空间结构比>25%).2)非参数统计的成对样本符号检验结果表明,变异函数分析结果基础上的克里格内插法适用于凋落物重量的估计.利用此估计值,拟合其与位置坐标值之间的多元回归关系均为二元十次余弦级数多项式.利用此多项式,通过定积分的方法(积分区间为整块样地的大小),估计出15年生落叶松人工纯林中凋落物层的未分解、半分解、完全分解和腐殖质层的重量分别为4.7753、5.4129、8.0742、10.9269t hm-2.3)采用地统计学的克里格空间插值,结合多元回归和定积分的方法,可以实现落叶松人工林凋落物层重量的准确估计. 相似文献
8.
Effect of typhoon disturbance on fine litterfall and related nutrient input in a subtropical forest on Okinawa Island, Japan 总被引:1,自引:0,他引:1
Typhoons are frequent on Okinawa Island, southwestern Japan. The effects of typhoon disturbance on the patterns of fine litterfall and related nutrient inputs in a subtropical evergreen broad-leaved forest were studied over 5 years from May 1996 to April 2001. Annual fine litterfall averaged 7558 kg ha−1 (range from 6188 to 9439 kg ha−1) for six sampling plots over 5 years, which differed significantly among years (p<0.001) but not among plots (p=0.122). A seasonal maximum was most evident for leaf litter component. Woody litter fell more irregularly through the year, and peak fall varied with typhoon and windstorm. The mean ratio of annual litterfall mass of sexual organs to leaves was 0.06, much lower than that in other tropical and subtropical rain forests. Nutrient concentrations varied in litterfall components, but were not significantly different among plots. The lowest concentrations of N and P in leaf litter were observed in March, which is also the month with the greatest leaf fall. However, the highest concentrations were recorded in typhoon season. Nitrogen and P concentrations were 34% and 106% greater in the green leaves that fell during typhoons than in senescent leaves. Mean nutrient inputs by litterfall were: N 83, P 3.2, K 25, Ca 71, Mg 19, Al 12, Na 10, Fe 0.86 and Mn 3.9 kg ha−1 yr−1, and differed significantly among years for all elements (p<0.0005) and among plots only for K (p<0.05) and Mn (p<0.0001). Typhoon disturbance strongly affected annual fine litterfall and related nutrient inputs, which contributed an average of 30% of the annual litterfall mass, and from 30% to 39% (for different nutrient elements) of annual total nutrient inputs. The results from this study suggest that typhoon-driven maintenance of rapid cycling of P and N and their high availability in soil appears to be an important mechanism to maintain productivity in the subtropical forest on Okinawa Island. 相似文献
9.
Ecosystem-level experiments on the effects of atmospheric CO2 enrichment and N deposition on forest trees are urgently needed. Here we present data for nine model ecosystems of spruce
(Picea abies) on natural nutrient-poor montane forest soil (0.7 m2 of ground and 350 kg weight). Each system was composed of six 7-year-old (at harvest) trees each representing a different
genotype, and a herbaceous understory layer (three species). The model ecosystems were exposed to three different CO2 concentrations (280, 420, 560 μl l−1) and three different rates of wet N deposition (0, 30, 90 kg ha−1 year−1) in a simulated annual course of Swiss montane climate for 3 years. The total ecosystem biomass was not affected by CO2 concentration, but increased with increasing N deposition. However, biomass allocation to roots increased with increasing
CO2 leading to significantly lower leaf mass ratios (LMRs) and leaf area ratios (LARs) in trees grown at elevated CO2. In contrast to CO2 enrichment, N deposition increased biomass allocation to the aboveground plant parts, and thus LMR and LAR were higher with
increasing N deposition. We observed no CO2 × N interactions on growth, biomass production, or allocation, and there were also no genotype × treatment interactions.
The final leaf area index (LAI) of the spruce canopies was 19% smaller at 420 and 27% smaller at 560 than that measured at
280 μl CO2 l−1, but was not significantly altered by increasing N deposition. Lower LAIs at elevated CO2 largely resulted from shorter branches (less needles per individual tree) and partially from increased needle litterfall.
Independently of N deposition, total aboveground N content in the spruce communities declined with increasing CO2 (−18% at 420 and −31% at 560 compared to 280 μl CO2 l−1). N deposition had the opposite effect on total above ground N content (+18% at 30 and +52% at 90 compared to 0 kg N ha−1 year−1). Our results suggest that under competitive conditions on natural forest soil, atmospheric CO2 enrichment may not lead to higher ecosystem biomass production, but N deposition is likely to do so. The reduction in LAI
under elevated CO2 suggests allometric down-regulation of photosynthetic carbon uptake at the canopy level. The strong decline in the tree nitrogen
mass per unit ground area in response to elevated CO2 may indicate CO2-induced reductions of soil N availability.
Received: 11 May 1997 / Accepted: 4 August 1997 相似文献
10.
Soil phosphorus fractionation and phosphorus-use efficiencies of tropical rainforests along altitudinal gradients of Mount Kinabalu, Borneo 总被引:4,自引:0,他引:4
We studied soil phosphorus (P) fractionation and P-use efficiencies (PUEs) of rainforests along altitudinal gradients (700–3100
m) on two types of parental rocks (sedimentary versus ultrabasic) on Mount Kinabalu, Borneo. Sedimentary rocks were known
to contain more quartz (which does not adsorb P) than ultrabasic rocks. The pool (top 30 cm) of total P was always greater
on sedimentary (ranging from 34.9 to 72.6 g m–2) than on ultrabasic (9.0–29.2 g m–2) rocks at comparable altitudes. Accordingly, the pools of organic P and labile inorganic P were always greater on sedimentary
than on ultrabasic rocks. The pool of primary mineral, calcium P increased upslope from 1.7 to 4.3 g m–2 on sedimentary rock, suggesting that the altitudinal sequence of the sites reflected a decreasing magnitude of soil weathering
upslope. The pool of calcium P on ultrabasic rock did not vary consistently with altitude (1.2–2.8 g m–2), probably reflecting the greater between-site variability of primary mineral P in parent rocks. When all sites were compared,
the pool of most labile, bicarbonate-extracted inorganic P increased (ranging from 0.02 to 1.85 g m–2) with increasing calcium P. Calcium P was therefore considered to be an important P source to the biota on Kinabalu. Gross
patterns in the variation of PUE (indexed as the reciprocal of the P concentration in litter) were best explained by the pool
size of actively cycling P (total P minus occluded inorganic P). PUE, however, demonstrated distinct altitudinal patterns
to generate an intricate conrol of P use pattern by soil P pools and altitude.
Received: 2 August 1998 / Accepted: 28 November 1999 相似文献