Ecological safe management of terraced rice paddy landscapes
Ecological safe management of terraced rice paddy landscapes
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DOI：
10.1016/j.still.2008.07.010
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发表时间：
2009-03
影响因子：
6.5
通讯作者：
B. Lennartz;R. Horn;R. Duttmann;H. Gerke;R. Tippkötter;T. Eickhorst;I. Janssen;M. Janssen;B. Ruth;T. Sander;Xuezheng Shi;K. Sumfleth;H. Taubner;Bin Zhang
中科院分区：
文献类型：
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作者：
B. Lennartz;R. Horn;R. Duttmann;H. Gerke;R. Tippkötter;T. Eickhorst;I. Janssen;M. Janssen;B. Ruth;T. Sander;Xuezheng Shi;K. Sumfleth;H. Taubner;Bin Zhang
稻田景观的生态安全管理是一个由五个德国工作组和中国合作伙伴组成的联合研究项目的重点。该项目旨在表征中国东南部梯田农业景观的尺度依赖结构和过程。具体目标是启发遥感敏感信息和土壤特征的空间分布之间的联系，以及土壤结构过程及其与垂直和横向水分流失和溶质淋溶的关系。实验流域位于中国东南部。无论是从第四纪粘土或红砂岩发育的土壤表现出（人造）层状结构，具有三个水力功能层：水坑层，犁盘和（水不饱和）底土。土壤质地和选定的化学参数的悬链线和集水区规模的分析证实，即使在旧的梯田和彻底修改的景观，原来的结构（不受人为影响）的悬链线土壤属性分布持续存在。因此，将地形属性作为解释变量的共同区域化技术的应用被认为是适合于描述土壤性质分布的悬链线和流域尺度。现场田间规模调查表明，水稻土表现出动态的土壤-水系统，这是由机械种子床准备（puddling）一方面和干燥和湿润循环，包括积水/淹水期的另一方面。结果发现，水力特性主要取决于作为水稻田的耕作时间。与早期的研究相比，我们发现，犁盘的饱和导水率的进一步下降可能仍然发生在20年后。然而，即使是在较老的稻田里，水的损失也可能很大，主要是因为周围堤坝的功能无效。Pedon和骨料调查表明，水稻土具有明显的双重孔隙性质，大孔隙网络由裂缝和生物孔隙组成，穿透犁盘和堤岸。老稻田的积水层收缩潜力大于新稻田，而犁盘土壤的积水层收缩潜力则相反。膨胀和收缩也影响了土壤微生物的生存条件，特别是排水后，可居住的孔隙空间显着减少。孔隙尺度和微生物学调查表明，排水诱导的压力减少微生物多样性和减少土壤微生物栖息的丰度。除了新提出的管理策略与经常性的湿润和干燥周期，我们建议保持（饱和）平衡条件在较长的时间内，以减少土壤结构动态和水的损失和化学浸出的风险与优先流。
Ecological safe management of rice paddy landscapes is in focus of a joint research project comprising five German working groups and Chinese partners. The project is aiming at characterizing the scale-depending structures and processes of agricultural landscape of terraced paddy fields in southeast China. The specific objectives were the enlightenment of the linkage between remote sensible information and the spatial distribution of soil features, as well as soil structural processes and their relation to vertical and lateral water losses and solute leaching. The experimental watershed is located in southeast China. The soils which either developed from quaternary clay or red sandstone exhibit a (man-made) layered structure with three hydraulic-functional horizons: puddled layer, plough pan and the (water unsaturated) subsoil. The analysis of soil texture and selected chemical parameters on the catenary and catchment scale confirmed that even in old terraced and thoroughly modified landscapes, the original structures (unaffected by man) of catenary soil property distributions persist. Thus, the application of co-regionalization techniques incorporating topographical attributes as explaining variables was found to be suitable to characterize soil property distributions on both the catenary and the catchment scale. On-site field scale investigations revealed that paddy soils exhibit a dynamic soil–water system which is driven by the mechanical seed bed preparation (puddling) on the one hand and drying and wetting cycles including ponded/flooded periods on the other. It was found that the hydraulic properties depend mainly on the duration of cultivation as a rice paddy. In contrast to earlier studies, we found that a further decrease in the saturated hydraulic conductivity of the plough pan may still occur after 20 years. Even in older rice paddies, however, water losses may be significant mainly because of ineffective functioning of the surrounding bunds. Pedon and aggregate investigations demonstrated the pronounced dual porosity nature of the paddy soils with a macropore network consisting of cracks and biopores penetrating both the plough pan and the bunds. The shrinkage potential of the puddle layer was higher in older paddy fields than in younger ones while it was vice versa for soil from the plough pan. Swelling and shrinkage affected also the living conditions for soil microorganisms especially after drainage when the habitable pore space was significantly reduced. Pore scale and micro-biological investigations revealed that drainage induced stress reduced micro-biodiversity and decreased abundances of soil inhabiting microorganisms. In addition to newly proposed management strategies with recurrent wetting and drying cycles, we suggest maintaining (saturated) equilibrium conditions over longer periods to reduce soil structural dynamics and the risks of water losses and chemical leaching involved with preferential flow.