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Experimental Investigations on the Environmental Determination of {delta}13C at Different Altitudes 总被引:1,自引:0,他引:1
The influence of environmental variables which are known tochange with altitude on the 13C of leaves of Nardus stricta,have been investigated in controlled environment experiments.Low temperature and an increased incidence of freezing temperaturescaused 13C to increase. In contrast, lowered atmospheric pressurereduced 13C. Increased leaf surface wetness and soil water contentalso caused a decrease. Plants from different altitudes didnot differ consistently or significantly in their responses. Key words: Carbon isotope discrimination, altitude, temperature, atmospheric pressure, freezing 相似文献
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1. Specific leaf area (SLA), carbon isotope ratio (δ13 C) and leaf nitrogen content (N) were measured in litter in 1993 and in the litter layer and canopy in 1996 in a pedunculate Oak ( Quercus robur ) wood at Wytham, Oxford.
2. The frequency distribution of SLA of leaves falling through the late summer and autumn of 1993 changed with a greater contribution of leaves of high SLA earlier in the period. For the same SLA leaves falling earlier in the season had less negative δ13 C and higher N content than leaves falling later.
3. The frequency distribution of SLA of litter leaves was similar in both years but litter leaves had lower N and less negative δ13 C in 1996.
4. In the canopy, there was a highly significant negative relationship between height in the canopy and SLA in green and senescent leaves. The relationship between SLA and both δ13 C ratio and leaf N was different between green, senescent and litter leaves.
5. The frequency distribution of foliage in the canopy estimated from the frequency of SLA in the litter and the vertical pattern of SLA in the canopy was similar to the distribution measured by the 'drop-line' method. 相似文献
2. The frequency distribution of SLA of leaves falling through the late summer and autumn of 1993 changed with a greater contribution of leaves of high SLA earlier in the period. For the same SLA leaves falling earlier in the season had less negative δ
3. The frequency distribution of SLA of litter leaves was similar in both years but litter leaves had lower N and less negative δ
4. In the canopy, there was a highly significant negative relationship between height in the canopy and SLA in green and senescent leaves. The relationship between SLA and both δ
5. The frequency distribution of foliage in the canopy estimated from the frequency of SLA in the litter and the vertical pattern of SLA in the canopy was similar to the distribution measured by the 'drop-line' method. 相似文献
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Drought stress differentially affects leaf-mining species 总被引:2,自引:0,他引:2
JOANNA T. STALEY SIMON R. MORTIMER GREGORY J. MASTERS MICHAEL D. MORECROFT VALERIE K. BROWN MICHELE E. TAYLOR 《Ecological Entomology》2006,31(5):460-469
Abstract. 1. The impact of climate change on phytophages is difficult to predict, due in part to variation between species in their responses to factors such as drought stress. Here, the hypothesis that several species within the leaf-mining feeding guild will respond in a consistent way to changes in rainfall patterns is tested, using a manipulative field experiment.
2. Summer drought, enhanced summer rainfall, and control treatments were imposed on a calcareous grassland community, and the responses of five leaf-mining species were assessed.
3. One leaf-mining species was more abundant under enhanced rainfall, one was more abundant under drought, and the other three species showed no consistent response to the rainfall treatments. Higher parasitism levels under drought may partly explain the response of one species ( Stephensia brunnichella ) to the treatments.
4. These results show that generalisations relating to drought stress impacts cannot be drawn at the feeding guild level for leaf-mining insects. 相似文献
2. Summer drought, enhanced summer rainfall, and control treatments were imposed on a calcareous grassland community, and the responses of five leaf-mining species were assessed.
3. One leaf-mining species was more abundant under enhanced rainfall, one was more abundant under drought, and the other three species showed no consistent response to the rainfall treatments. Higher parasitism levels under drought may partly explain the response of one species ( Stephensia brunnichella ) to the treatments.
4. These results show that generalisations relating to drought stress impacts cannot be drawn at the feeding guild level for leaf-mining insects. 相似文献
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