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61.
Takuo Yamakura Akio Hagihara Sukristijono Sukardjo Husato Ogawa 《Ecological Research》1987,2(3):215-227
The form of tropical trees was studied with reference to the production structure of the component individuals of a tropical
rain forest stand in Sebulu, East Kalimantan in Indonesian Borneo, since the production structure as a physical or bio-economical
basis of tree form still remains obscure in tropical rain forests. The pipe model theory successfully explained the crown
shapes of different trees, and its parameter, designated as specific pipe length, suggested an increase in the cost of leaf
mass growth with an increase in crown size. A mathematical model consisting of exponential functions of aboveground height
was applied for describing stem form, and its properties were examined through changes in its coefficients and by adopting
an assumption of the geometrical similarity of individual stem form as a criterion for comparing differences in stem form
among individual trees. Furthermore, the cost of buttersses was discussed using the relation between bole- and buttress weight
calculated from the mathematical model. 相似文献
62.
Takakazu Yumoto 《Ecological Research》1987,2(2):133-145
Animal pollination in a warm temperate evergreen broad-leaved forest was observed on Yaku-shima Island, south of Kyushu, Japan.
Three groups of plants were categorized: canopy-flowering tree species, understory-flowering tree species, and climber and
epiphyte species. Each of these formed different pollination systems. The canopy-flowering tree species had shallow, dish-shaped
flowers and utilized various types of opportunistic pollinators. Most of the climber and epiphyte species had deep, tube-shaped
flowers and specialized pollinators, although some climber species which bloomed in the canopy especially in winter, had opportunistic
pollinators. The understory-flowering tree species had large dish- or funnel-shaped flowers and endothermic pollinators able
to tolerate the dark and cold conditions under the canopy. The individual trees of canopy-flowering tree species produced
large numbers of flowers simultaneously (mass-flowering) and had a well synchronized flowering period. Each canopy-flowering
tree species segregated its flowering time from those of the anothers. Climber and epiphyte species and most of the understory-flowering
tree species produced small numbers of flowers sequentially (extended flowering) and showed a long flowering period. 相似文献
63.
64.
The influence of crabs on litter processing in high intertidal mangrove forests in tropical Australia 总被引:10,自引:0,他引:10
Summary Measurements of litter fall and litter removal by crabs, in conjunction with estimates of litter decay by microbes and tidal export of litter from three high-intertidal mangrove forests were made during a year-long study in tropical northeastern Australia. In forests dominated by Ceriops tagal and Bruguiera exaristata, litter standing stocks remained low on the forest floor (mean 6 g·m-2), although litter fall was high; 822 and 1022 g·m-2·y-1, respectively. Sesarmid crabs removed 580 (Ceriops) and 803 (Bruguiera) g·m-2·y-1, or 71 and 79%, of the total annual litter fall from the forest floor. Relative to the rate of litter removal by crabs, microbial turnover of whole, unshredded litter was insignificant, accounting for <1% of annual litter fall. Export of litter by tides was estimated to remove 194 (Ceriops) and 252 (Bruguiera) g·m-2·y-1 or 24 and 25% of annual litter fall. In a forest dominated by Avicenniamarina, in which an ocypodid crab was more abundant than sesarmids, litter standing stocks were higher (mean 84 g·m-2) and crabs removed less litter; 173 g·m-2·y-1 or 33% of the annual litter fall of 519 g·m-2·y-1. Microbial turnover of intact litter was more important in the Avicennia forest (168 g·m-2·y-1 or 32% of annual litter fall), and tides exported 107 g·m-2·y-1 or 21% of litter production. In areas where sesarmid crabs were absent or rare in Ceriops forests, there were significantly higher standing stocks of litter and slower rates of leaf removal. Taking into account the probable assimilation efficiencies of sesarmid crabs feeding on mangrove leaves, we estimate that in Ceriops and Bruguiera forests leaf processing by crabs turns litter over at >75 times the rate of microbial decay alone, thus facilitating the high sediment bacterial productivity in these forests. The importance of litter processing by crabs increases with height in the intertidal in tropical Australia, in contrast to New World mangrove forests, where the reverse is true.Contribution No. 445 from the Australian Institute of Marine Science 相似文献
65.
Seasonal changes in the pigments, carbohydrates and growth of red spruce as affected by ozone 总被引:9,自引:7,他引:2
R. G. ALSCHER R. G. AMUNDSON J. R. CUMMNG S. FELLOWS J. FINCHER G. RUBIN P. VAN LEUKEN L. H. WEINSTEIN 《The New phytologist》1989,113(2):211-223
Two-year-old red spruce seedlings were exposed to various levels ot ozone, from 0.4 to 3 times ambient levels, in open-top chambers in Ithaca, NY, USA. Exposures, which varied with changes in day length, commenced on May 30, 1987 and continued until December 14, 1987. Seedling biomass, carbohydrate contents, pigment contents, and rate of electron transport were assessed twice monthly during the fumigation period. Orthogonal quadratic or cubic polynomials were used to model the response through time each variable measured. A one-way analysis of variance model was fitted to every regression coefficient in each polynomial model to test for ozone effects on seasonal physiological patterns. Ozone did not influence growth, foliar pigment content, foliar starch content, root carbohydrate content, or rate of electron transport. The seasonal change of needle raffinose content differed between exposed to low (0.4 ×, 1×) and high (2×, 3×) ozone levels. There was also a trend towards reduced total soluble sugar content foliage during late autumn in higher ozone treatments. 相似文献
66.
Near a hen house (50–600 m), vitality ofPinus sylvestris, N-, P-, K-, Ca-, Mg-contents of the needles, N-, Mg-, K-, Ca- and Al-contents in soil extracts and NH3/NH
4
+
-contents of the air were determined. Damage symptoms occurred when N-immissions hit the canopy directly. In contrast no visible decline of the above ground plant could be observed if N was mainly deposited on the soil. 相似文献
67.
The pH of weak-acid solutions is controlled by acid concentration (HA + A–), the degree of acid dissociation (A–/HA), and the strength of the acids present (pKa). We developed an empirical approach that allows the relative importance of each of these factors to be estimated for soils. This empirical model was applied to soils collected from an old-field plantation of loblolly pine (Pinus taeda L.) at 5 and 25 years of age. During this period, soil pH dropped by 0.3 to 0.8 units, and extractable calcium, magnesium and potassium declined by 20 to 80%. The empirical model indicates that the decline in pH resulted largely from the reduction in base saturation of the exchange complex. However, the average acid strength of the exchange complex decreased during the 20 years, preventing a greater decline of perhaps 0.1 to 0.2 units in the observed pH. The rate of decrease in the acid neutralizing capacity to pH 3.5 was about 1.3 kmolc/ha annually, while the increase in base neutralizing capacity was about 2.7 and 1.6 kmolc/ha annually to pH 5.5 and 8.2, respectively. Extractable alkali and alkaline earth cations declined by about 2.2 kmolc/ha annually, matched by the rate of increase in aluminium. These changes demonstrated the dynamic nature of poorly buffered soils, and indicated that changes in soil acidity may be expected over a period of decades (especially following changes in land-use). 相似文献
68.
Classification and ordination of macroinvertebrate assemblages to predict stream acidity in upland Wales 总被引:2,自引:2,他引:0
Macroinvertebrates were collected from riffles at 104 sites in upland Wales during April and July 1984. Species assemblages were ordinated by DECORANA, classified by TWINSPAN and related to stream chemistry and other environmental factors using correlation and multiple discriminant analysis. DECORANA axis 1 was most strongly correlated with pH and aluminium concentration whilst axis 2 correlated with stream gradient and flow. Four TWINSPAN site groups established in each season were also principally related to pH and aluminium concentration, and reflected overall taxon-richness; differences between groups were most apparent during spring, when catchment forest cover and taxon-richness were also related. A dichotomous key based on indicator species was established for each season with the coleopteran Hydraena gracilis Germar and the Ephemeroptera, including Baetis rhodani Pictet, important indicators at Level 1. We propose that these indicator systems may be used for the rapid detection and assessment of acid waters throughout Wales, and that the methodology is applicable generally. 相似文献
69.
Vegetation dynamics in the coastal area of the Seto Inland Sea region in Japan, where wild fires occur frequently, were described
using a stationary Markov model. In this region, vegetation types ofMiscanthus-Pleioblastus grassland,Lespedeza-Mallotus scrub,Pinus-Rhododendron forest andCrassocephalum-Erechtites community have been identified, and these show cyclic succession under the influence of fires.
The model uses parameters determining fire frequency and rate of successional change to analyze the effect of variation in
these parameters on the areal ratio of each vegetation type at equilibrium and on the time taken for one vegetation type to
succeed another (elapsed successional time). The effect of fire frequency differs between hypothetical habitats with high
and low productivity. A policy for vegetation management in areas of high and low productivity is proposed. The advantages
and limitations of applying Markov models to studies of vegetation succession are also discussed. 相似文献
70.
Eizi Suzuki 《Journal of plant research》1990,103(3):297-312
In two forest stands, one domonated byAbies spectabilis, and the other byPinus wallichiana-Picea smithiana, 198 cores were taken from 105 conifers in May 1983 and the annual ring widths were measured. The annual ring widths usually
had significant similarities between cores taken from the same tree and with cores taken from different trees. these similarities
increased with tree size. The climatic change affected the large trees more strongly than it did the small trees. Micro environmental
changes, such as canopy gap affected the small trees more strongly. Annual ring widths were also correlated with the annual
precipitations at Jumla 30 km south of the plots for a recent 20 year period. A multiple regression analysis between ring
width and seasonal precipitation showed that the growth ofA. spectabilis was correlated primarily with the rain from May to August and secondarily with that from September to December in the previous
year. 相似文献