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植物光合生产力与冠层蒸散模拟研究进展   总被引:36,自引:0,他引:36  
植物的光合与蒸腾的模拟已经从经验模型发展到过程模型的时代。概括地论述叶片和冠层尺度上,植物生理生态的基本过程,分析近年来几个有代表性的模型在模拟光合作用,蒸腾作用时,对这些听参数化处理的方法,即在叶片水平上,以Farquhar的叶片光合作用的生化模型,Ball-Berry的气孔导度模型等为基础。  相似文献   
2.
黄河流域内蒙古段植被时空变化特征及条带状分布成因   总被引:1,自引:0,他引:1  
张皓月  占车生  夏军  胡实  宁理科  邓晓娟 《生态学报》2022,42(21):8818-8829
监测干旱、半干旱地区植被覆盖度的动态变化,评估大尺度区域地质背景,尤其是活动构造在植被变化过程中发挥的作用对植被时空格局的认识具有重要意义。黄河流域内蒙古段地处干旱半干旱区,植被多依赖于地下水;且该地区活动构造较发育,是认识植被非地带性特征的理想区域。基于中分辨率成像光谱仪(MODIS)、归一化植被指数(NDVI)、气象与土地利用数据,对2000-2018年黄河流域内蒙古段植被覆盖度(FVC)的时空变化及稳定性进行分析,在此基础上针对河套段植被条带状特征及其成因进行讨论。结果表明,近20年研究区的FVC总体表现为增加趋势。降雨增加是大黑河流域、浑河流域及十大孔兑区域FVC增加的主要原因,沙漠地区FVC的增加得益于三北防护林工程建设。大黑河与浑河流域水分条件较好,物种多样性丰富,植被覆盖度高,能较好的抵御气候变化;而十大孔兑区域和沙漠地区FVC较低,生态系统脆弱,对气候波动的响应较大。河套灌区受人类活动主导,对气候变化的敏感性较低。河套段山前植被赋存环境为条带状地下水溢出带,在地下水储量增多条件下呈条带状增加趋势;而在山前过渡带,新构造运动及其造成的较大地表高差使得土壤层薄且储水能力较差,表现为FVC的高波动。现今黄河干流沿岸植被受土地利用转变影响整体减少;且在河流摆动、河道变迁扰动下,稳定性较差。河套盆地与鄂尔多斯台地边界处,受隐伏断裂和地震活动影响,地下水易沿带状透水断裂下渗,难以维持浅表水分和稳定的补给条件,使得FVC呈线状显著降低,且稳定性较差。研究从宏观水文地质条件和地表过程的角度,更加深入认识了植被空间分布的非地带性特征,为相似地区的研究提供了较好的科学依据。  相似文献   
3.
田超 《应用生态学报》2023,(8):2194-2204
为揭示黄河三角洲盐碱地地区的降水来源、形成及影响机制,利用降水稳定同位素,特别是δ17O、17O-excess,以及气团轨迹模型HYSPLIT,研究黄河三角洲东营地区5—10月不同时间尺度及降水强度[(<5、5~10、10~25、25~50、>50 mm·d-1)]的降水同位素变化特征及水汽来源。结果表明:5—10月降水同位素的变化范围较大,旱季降水的同位素变化范围小于雨季,且比雨季富集。降水强度<5 mm·d-1的降水,δ′18O[δ′18O=ln(δ18O+1)]与δ′17O[δ′17O=ln(δ17O+1)]的降水线斜率最小,为0.5211,降水易受水汽源地蒸发作用的影响;10 mm·d-1≤降水强度<25 mm·d-1时,斜率最大,为0.5268。对于0~50 mm·d-1...  相似文献   
4.
《植物生态学报》2014,38(12):1356
Aims The objective of this study was to compare the values of respiration under light derived by fitting a photosynthetic CO2 response model and measurements, in order to provide information for model optimization. Methods Using combined gas exchange measurements and a low O2 (2% O2) method, the responses of photosynthetic rate (Pn) to CO2 at different light intensities (2 000, 1 500, 1 000 and 500 μmol·m–2·s–1) in the flag leaves of wheat were measured. The measured data were fitted by a biochemical model, a rectangular hyperbola model and a modified rectangular hyperbola model of the photosynthetic response to intercellular CO2 concentration (A/Ci) and air CO2 concentration (A/Ca), aiming to approach the reasonability of the fitted results obtained from the models. Important finding The sequence of fitting effect of the three CO2 response models in descending order was as follows: modified rectangular hyperbola model > rectangular hyperbola model > biochemical model. Fitted values of A/Ca curve was more reasonable than A/Ci curve, because the photorespiration and mitochondrial respiration under light (Rd) estimated by the former better matched the measured values. However, there were significant differences in the whole between the fitted and measured values. The reason could be that the effect of CO2 concentrations on Rd and apparent photorespiration (Rpa) is neglected in all the current CO2 response models. Our results showed that CO2 concentration had a marked effect on Rpa and Rd. With increasing CO2 concentration, Rpa and Rd increased first, and then decreased sharply. Take 2 000 μmol·m–2·s–1 for example, Rpa varied between 5.035 and 11.670 μmol CO2·m–2·s–1, and Rd varied between 0.491 and 2.987 μmol CO2·m–2·s–1. Regression analysesindicated that Rpa and Rd were well related to CO2 concentrations at different light intensities.  相似文献   
5.
《植物生态学报》2014,38(10):1110
Aims Despite the increasing attention given to the rate of mitochondrial respiration under light (Rd), considerable confusion persists over whether mitochondrial respiration in the dark (Rn) is inhibited by light and whether Rd is affected by light intensity. The objective of this study is to test the hypotheses: 1) Rn is not inhibited by light; 2) the rate of Rd changes with light intensity; and 3) the photosynthetic refixation of CO2 produced by Rn accounts for the apparent disparity between Rd and Rn.
Methods In the present study, 0.02 mol·mol–1 O2 (i.e. 2% O2) was used to saturate Rn and to inhibit photorespiration (Rp). By using combined gas exchange measurements and a low O2 (2% O2) method, the post-illumination CO2 release rate of Rn, photosynthetic rate (Pn) in response to photosynthetically active radiation (PAR) in 2% O2 at either 380 or 0 μmol·mol–1 CO2, of C3 (Triticum aestivum and Glycine max) and C4 (Zea mays and Amaranthus hypochondriacus) plants, were measured.
Important finding Rn was not inhibited by light. At 2% O2 and 0 μmol·mol–1 CO2, the measured parameters could be used to accurately estimate Rd when CO2 concentration was set for 0 μmol·mol–1. Rd decreased with increasing light intensity. Although Rd was lower in the dark, this could be accounted for by photosynthetic re-fixing of respiratory CO2. For all plants tested, CO2 recovery rates increased with increasing light intensity (from 50 and 2 000 μmol·m–2·s–1).  相似文献   
6.
耕作措施和施肥方式对麦田杂草密度和生物量的影响   总被引:8,自引:0,他引:8  
为明确我国华北地区麦玉轮作系统小麦免耕的推广和施肥方式的改变对麦季杂草生长的影响,在免耕实施5年后,调查了麦田杂草密度、单株质量和生物量。结果表明:华北地区小麦生长早期,免耕有降低麦田杂草总密度和优势种播娘蒿密度趋势,但差异并不显著;相对于传统耕作,免耕秸秆覆盖和不覆盖处理总杂草生物量显著降低,其中播娘蒿生物量分别降低了57%和73%;免耕也使播娘蒿单株质量降低了27%~53%;免耕秸秆覆盖和不覆盖处理播娘蒿的株高分别比传统耕作降低了25%和19%;但一般情况耕作方式并没有显著影响离子草和麦家公生长;相对于分次施肥,集中施肥杂草生物量降低了21%~68%,播娘蒿生物量降低了58%~65%,麦家公降低91%;免耕在一定程度上抑制了某些杂草的生长,但追肥促进了杂草的快速生长。  相似文献   
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