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111.
中国不同气候带植被挥发性有机化合物通量与生态系统演替的相关性 总被引:2,自引:0,他引:2
从群落水平和生态系统演替的角度对中国热带,亚热带和温带生态系统植物挥发性有机化合物(VOC)通量的研究表明,异戊二烯通量呈现出在生态系统演替的早期到中期阶段随着演替的的进行而升高,在先锋性灌木和乔木阶段达到高峰,然后又随着演替的发展而逐渐下降的演替格局,而其他VOC通量则有随着演替的进行而上升的趋势。生态系统不同演替阶段异戊二烯通量的变化可能与植物获取养分氮有关,根据植物VOC释放通量的生态演替格局,可以建立全球陆地生态系统的VOC模型,对大气化学过程中的VOC时空动态进行很好的模拟。 相似文献
112.
David P. Watts 《American journal of primatology》1985,8(1):1-10
This report describes observations on the ontogeny of food choice in mountain gorillas (Gorilla gorilla beringei), made during a 17-month field study of mountain gorilla feeding ecology in the Parc National des Volcans, Rwanda. Data are presented on the feeding behavior of two infants observed from birth to the age of 8 months and on older infants and juveniles. This information is compared with data on the composition and diversity of the diets of young adults and adults in the same social group. Initial feeding by infants is usually synchronized with the mother's behavior: infants ingest the same food, or a different part of the same plant species, currently being eaten by the mother or just eaten by her. This suggests that observational learning is largely responsible for the transmission of food preferences. Most feeding by young infants, whether or not synchronized with the mother's, is on those foods eaten most frequently by adults. Infants also independently sample potential foods, some of which are apparently not consumed by adults. The frequency of sampling declines with age, although even adults occasionally ingest foods not observed to be eaten by other adults. By the age of 3 years, young mountain gorillas have developed the basic dietary patterns of adults, in terms of the number of foods eaten, the proportions in which specific foods are consumed, and diet diversity and equitability. There is a strong possibility that chemical cues influence food choice, but their role remains unclear. 相似文献
113.
114.
Latitudinal comparison of altitudinal changes in forest structure,leaf-type,and species richness in humid monsoon Asia 总被引:10,自引:0,他引:10
M. Ohsawa 《Plant Ecology》1995,121(1-2):3-10
A new template for mountain vegetation zonation along latitudinal gradients is proposed for examining geographical pattern of various forest attributes in humid monsoon Asia. The contrasting temperature regime in tropical and temperate mountains, i.e., the former is a non-seasonal, temperature-sum controlled environment, and the latter is a seasonal, low temperature limiting environment, leads to different altitudinal patterns of tree height distribution and species richness. In the tropical mountains, both tree height and species richness decrease steeply, and the tree height often stepwise. The decline of tree height and species diversity in the temperate mountains is far less pronounced except near the forest limit. Both trends are explained by their temperature regime. 相似文献
115.
116.
Fernández Escudero Ignacio Alberto Tinaut Francisca Ruano 《International journal of biometeorology》1993,37(2):83-88
Proformica longiseta, an ant species endemic to certain high mountains, has been studied with regard to its tendency to nest underneath rocks. This behaviour led us to investigate whether a particular type of rock is selected, and, if so, the advantages to this species of the selection. This study was located at 2400 m above sea-level in the Sierra Nevada mountains (Granada, Spain). To determine the range of rock sizes available, in eight control plots the thicknesses were recorded and also the maximum and minimum diameters of all rocks with surface area of more than 6 cm2. A total of 1724 rocks were recorded, noting among the rock types available those that were used for nesting. Also as a preliminary estimate of the thermal characteristics of the rocks, we recorded the temperatures of the air, soil surface, soil under a rock covering an ant nest, and soil at 30 cm depth. The results indicate thatP. longiseta selects flat rocks with a surface area/thickness ratio of 2–5, the thickness being not less than 1.5 cm, the surface area being 50–250 cm2 and volume less than 1000 cm3. This type of rock offers the nests two beneficial but apparently contradictory effects: (1) protection against high temperatures on hot days, and (2) warmth on colder days by absorbing the diffusing solar heat more effectively than the air or soil around the nest. 相似文献
117.
118.
West European Rock lizards, Lacerta (Iberolacerta) have small widely separated ranges in highland areas. Mitochondrial and nuclear DNA sequences corroborate the monophyly of the group and show it is not closely related to any of the other Rock lizards with which it was formerly placed in Archaeolacerta, an assemblage for which there is no evidence of clade status. L. (Iberolacerta) consists of four main units: L. (I.) horvathi of NW Croatia and neighbouring regions; the Pyrenees species, L. (I.) bonnali, L. (I.) aranica and L. (I.) aurelioi; L. (I.) cyreni of the Iberian Sistema Central, with distinctive populations in the Sierras de Bejar, Gredos and Guadarrama; and L. (I.) monticola of the Serra da Estrela of Central Portugal and NW Spain, this unit also contains L. (I.) cyrenimartinezricai of La Peña de Francia, W. Spain and a distinctive population in the Montañas de Sanabria. L. (Iberolacerta) has persisted in some mountain ranges for at least 4.2 ± 1.4 Ma and may have been restricted to mountains by competition from Wall lizards (Podarcis). Its clade status shows it has lost range extensively and has produced few external branches since its initial fragmentation. In contrast, Podarcis diversified about the time L. (Iberolacerta) fragmented, producing a series of widespread lineages that have persisted until the present time. The mainly European subfamily Lacertinae, to which both L. (Iberolacerta) and Podarcis belong, diversified rapidly 13–9 Ma ago, probably largely replacing other lacertid lizards of earlier origin. As another round of replacement started at approximately 9 Ma ago with the spread of Podarcis, this may be a recurrent phenomenon in the evolution of some lizard communities. 相似文献
119.
Sustained aerobic exercise not only affects the rate of force development but also decreases peak power development. The aim of this study was to investigate whether anaerobic power of amateur mountain bikers changes during the first half of the competition season. Eight trained cyclists (mean ± SE: age: 22.0 ±0.5 years; height: 174.6 ± 0.9 cm; weight: 70.7 ± 2.6 kg) were subjected to an ergocycle incremental exercise test and to the Wingate test on two occasions: before, and in the middle of the season. After the incremental exercise test the excess post-exercise oxygen consumption was measured during 5-min recovery. Blood lactate concentration was measured in the 4th min after the Wingate test. Maximum oxygen uptake increased from 60.0 ± 1.5 ml min-1 kg-1 at the beginning of the season to 65.2 ± 1.4 ml min-1 kg-1 (P < 0.05) in the season. Neither of the mechanical variables of the Wingate test nor excess post-exercise oxygen consumption values were significantly different in these two measurements. However, blood lactate concentration was significantly higher (P < 0.001) in season (11.0 ± 0.5 mM) than before the season (8.6 ± 0.4 mM). It is concluded that: 1) despite the increase of cyclists’ maximum oxygen uptake during the competition season their anaerobic power did not change; 2) blood lactate concentration measured at the 4th min after the Wingate test does not properly reflect training-induced changes in energy metabolism. 相似文献