Seasonal metrics and environmental responses to forestry soil surface CO2 emission effluxes among three types of lower subtropical forests were consistently monitored over two years with static chamber-gas chromatograph techniques among three types of lower subtropical forests. Results showed that annual CO2 effluxes (S+L) reached 3942.20, 3422.36 and 2163.02 CO2 g·m−2·a−1, respectively in the monsoon evergreen broadleaf forest, mixed broadleaf-coniferous forest and coniferous forest. All the three types of forests revealed the same characteristics of seasonal changes with the CO2 effluxes peaking throughout June to August. During this peaking period, the effluxes were 35.9%, 38.1% and 40.2% of the total annual effluxes, respectively. The CO2 emission process responding to the environmental factors displayed significantly different patterns in forestry soils of the three types of forests. The coniferous forest (CF) was more sensitive to temperature than the other two types. The Q 10 values were higher, along with greater seasonal variations of the CO2 efflux, indicating that the structurally unique forestry ecosystem has disadvantage against interferences. All the three types of forestry CO2 effluxes showed significant correlation with the soil temperature (T s), soil water content (M s) and air pressure (P a). However, stepwise regression analysis indicated no significant correlation between air pressure and the soil CO2 efflux. With an empirical model to measure soil temperature and water content in 5 cm beneath the soil surface, the CO2 effluxes accounting for 75.7%, 77.8% and 86.5% of the efflux variability respectively in soils of BF, MF and PF were calculated. This model can be better used to evaluate the CO2 emission of soils under water stress and arid or semi-arid conditions.
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1.
Belowground carbon balance and carbon accumulation rate in the successional series of monsoon evergreen broad-leaved forest 总被引：4，自引：0，他引：4
ZHOU Guoyi ZHOU Cunyu LIU Shuguang TANG Xuli OUYANG Xuejun ZHANG Deqiang LIU Shizhong LIU Juxiu YAN Junhua ZHOU Chuanyan LUO Yan GUAN Lili LIU Yan 《中国科学D辑(英文版)》2006,49(3):311-321
The belowground part of terrestrial ecosystem is a huge carbon pool. It is believed that of the total 2500Gt carbon stored in global terrestrial ecosystem, soil carbon storage within the 1 m surface layer ac- counts for 2000Gt, which is 4-fold of vegetation car- bon storage[1,2]. Compared with the carbon in the vegetation, carbon in the deep soil layers is much more stable, and it will stay in soil profile permanentlyunless geological vicissitude occurs. Essentially, forest restoration is the… 相似文献
2.
通过对土壤、植被、林木生长量的野外调查，依据科学性、实用性原则，将河北坝上大滩示范区的造林立地类型划分为１２个立地类型：山地阴坡中下部厚土立地类型、山地阴坡上部薄土立地类型、山地阳坡中下部厚土立地类型、山地顶部岩石裸露立地类型、二阴滩地立地类型、下湿滩地立地类型、低缓小丘阴坡立地类型、低缓小丘阳坡立地类型、平缓砾质化或沙质耕地立地类型、平缓壤质耕地立地类型、缓起伏固定、半固定沙地立地类型 相似文献
3.
CO2 fluxes from soils and related environmental factors were measured in three forest ecosystems of Dinghu Mountain using static chamber-gas chromatograph technique for one year. The seasonal pattern of CO2 flux, contribution of litter on total CO2 flux and the correlations of CO2 flux with soil temperature and soil water content were examined for each type of forest. The results were given as followings: (1) The seasonal patterns of CO2 flux from soil of the three types of forest were similar, with a higher CO2 flux in rainy season than in dry season. The comparative relations of mean annual CO2 fluxes between the three sites were expressed as:monsoon forest ＞ mixed forest ＞ pine forest. (2) CO2 fluxes from litter decomposition in monsoon forest, mixed forest and pine forest accounted for 24.43%, 41.75% and 29.23% of the corresponding total CO2 fluxes from forest floor, respectively. (3) Significant relationships were found between CO2 fluxes and soil temperatures at 5 cm depth for the three types of forest, which could be best described by exponential equations. The calculated Q10 values based on soil temperature at 5 cm depth ranged from 1.86 to 3.24. More significant relationships were found between CO2 fluxes and soil water content when the annual variation coefficients of soil moisture were higher. 相似文献
4.
河北丰宁沙漠化土地综合整治试验示范区规划设计研究 总被引：1，自引：1，他引：1
分析了我国北方农牧交错带沙漠化强烈发展类型丰宁试验示范区的沙漠化土地综合整治制约因子、沙漠化土地的整治途径，并论述了试区沙漠化土地整治规划设计原则，总体布局和各类沙漠化土地整治的技术问题。 相似文献
5.
Pangupterus liui gen. et sp. nov. from the Jiufotang Formation of Sihedang, Lingyuan City, Liaoning Province is erected based on a nearly complete lower jaw. It is characterized by having a total of 36 slender curved teeth with sharp tips, forming a distinct fish-grabbing mechanism; the teeth are well-spaced and are circular in section; the length ratio of the mandibular symphysis to the whole jaw is 20%; and the ratio of the tooth root width to tooth length is 12%. Toothed pterosaurs make up about 56.3% of the pterosaur assemblage from the Jiufotang Formation, which indicates that toothed forms played a key role in the ecosystem. 相似文献
6.
鲁西北风沙化农田的风蚀机制、防治措施——以夏津风沙化土地为例 总被引：1，自引：0，他引：1
通过野外调查和室内风洞实验,分析了鲁西北风沙化土地农田风蚀的发生机制,并提出了防止农田风蚀的农林、水利措施。 相似文献
7.
Zhang Deqiang Sun Xiaomin Zhou Guoyi Yan Junhua Wang Yuesi Liu Shizhong Zhou Cunyu Liu Juxiu Tang Xuli Li Jiong Zhang Qianmei 《中国科学:地球科学(英文版)》2006,49(2):139-149
8.
河北坝上沙漠化土地褐沙蒿,冷蒿土壤生境特征研究 总被引：6，自引：0，他引：6
应用典范分析与聚类、回归分析相结合的方法，研究了河北坝上沙漠化土地褐沙蒿（Ａｒｔｅｍｉｓｉａｉｎｔｒａｍｏｎｇｏｌｉｃａ），冷蒿（Ａ．ｆｒｉｇｉｄａ）土壤生境的分类、排序及冷蒿、褐沙蒿生长分布与土壤条件的关系。结果表明：沿丘陵阴坡、平滩草地、丘陵顶部、丘陵阳坡、半阴坡砂质缓坡、固定沙地、半固定沙地依次沙漠化逐渐严重的土壤退化梯度，随着土壤中０．０５ｍｍ以下颗粒、土壤有机质、全氮、全钾含量的减少，褐沙蒿在群落中的重要值显著增加；冷蒿的生长分布不随土壤生境的变化而明显变化，而是与放牧强度有关。因此，褐沙蒿是本区土地沙漠化的指示植物，冷蒿是本区由于过牧引起的草场退化的指示植物。 相似文献
9.
一二年生植物引种成功的种源区域范围及科属范围都较多年生植物广，而对土壤基质、水分、人为活动等具体生境差异反应明显。最佳的引种植物有临夏燕麦、丹麦４４４燕麦、黑圆箭舌豌豆、３３３Ａ箭舌豌豆及Ｐｈａｌａｒｉｓ属的几个种等。 相似文献
10.
As one of the main load-carrying components of cable-stayed bridges,bridge towers are typically required to remain elastic even when subjected to severe ground motions with a 2%-3%probability of exceedance in 50 years.To fulfill this special requirement imposed by current seismic design codes,reinforcement ratios in the bridge towers have to be kept significantly higher than if limited ductility behavior of the tower is allowed.In addition,since the foundation capacity is closely related to the moment and shear capacities of the bridge tower,a large increase in bridge construction cost for elastically designed cable-stayed bridge is inevitable.To further investigate the possibility of limited ductility bridge tower design strategies,a new 1/20-scale cable-stayed bridge model with H-shaped bridge towers designed according to strong strut-weak tower column design was tested.The shake table experimental results are compared with a previous strong tower column-weak strut designed full bridge model.A comparison of the results show that ductility design with plastic hinges located on tower columns,i.e.,strong strut-weak tower column design,is another effective seismic design strategy that results in only small residual displacement at the top of the tower column,even under very severe earthquake excitations. 相似文献
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