|Alternative Title||Ecological Effects and Influencing Factors of Terraced Fields|
|Place of Conferral||北京|
|Keyword||梯田，土地利用，生态 效应 ，可持续 性， 国家尺度 Terraces, Land Use, Ecological Effects, Sustainability, National Scale|
梯田作为山地丘陵区传统 的 整地方式 ，有利于农业集约化 其 建设的目的是保持水土，改善立地环境，便于农业生产。 本研究 以梯田为对象，通过采样 实验分析了云贵高原、太行山区和黄土高原三个 典型 区域梯田修建对土壤理化性质的影响 及其分异规律 ，并重点探讨了以甘肃定西为代表的黄土 高原 梯田土壤 养分 随土地利用、坡向和海拔变化的响应 规律 通过问卷 访谈 调查 了 梯田区社会 经济、人口 结构 、土地利用 和 生态可持续性等 以及 梯田区可持续农业 存在 的 主要问题通过整合分析探讨了 中国范围内 不同地理区域、不同的梯田结构、土地利用、修建年限、气候和地形等影响下，梯田效应（包括 调控径流、 蓄水保土 、改良土质、粮食增产等 ）的变化规律 。 基于 以上研究， 以期为梯田的 合理 修建 与 可持续 管理提供 科学 支撑 。 主要研究结果如下:
（1） 云南旱作坡地 在开垦为水稻 梯田 的过程中促进了土壤养分的积累，对
（2）国家尺度上梯田平均减流效益为 53.6%，减沙效益为 68.2%，蓄水效益
（3 ）梯田结构显著影响其蓄水效益和粮食增产效益，土地利用方式显著影响梯田的减流减沙效益和固碳效益 。 水平沟的 蓄水效益 最 高 ，特别是修建于陡坡的水平沟，其次是反坡梯田和隔坡梯田；水平沟和鱼鳞坑由于其特有的凹形结构有利于接收来自上坡位的肥沃表土，固碳效益较高；在坡度较平缓的山坡地区，梯田修建应以水平梯田、隔坡梯田和坡式梯田为主，而在 25°以上的陡坡，则应修建水平沟、鱼鳞坑；农业梯田适宜修建于平缓坡地上，陡坡梯田上则应以生态林和经济林为主 。
（4 ）蓄水效益随着土层深度的增加而 下 降 0–100 cm深度土壤蓄水效益主要受梯田结构改变地表蒸散发和水流路径的影响 而 100–200 cm深度土壤蓄水效益主要受土地利用改变植物根系吸收的影响。与温度相比，降水量对梯田土壤蓄水 效益和固碳效益 的影响更显著。不同修建年限的梯田，修建初期固碳效益和粮食增产效益低 此后效益增加 6–10年能发挥有效的碳汇作用 。 梯田的固碳效益随坡度增加而增加，粮食增产效益随坡度增加而下降，蓄水效益在 15°以上随坡度增加而增加，减流减沙效益表现为随坡度先增加后减小再增加的 变化趋势 。
As an ancient agro-ecosystem in mountainous hilly areas, terraces are conducive to agricultural intensification. Generally, the purpose of terrace construction is to conserve water and soil, improve the site environment and facilitate agricultural production. Through field sampling and experimental analysis, the soil physical and chemical properties (including soil mechanical composition, pH, organic carbon, total nitrogen, ammonium nitrogen, nitrate nitrogen, total phosphorus, effective phosphorus, total potassium, and effective potassium) of terraces and slopes in Yunnan, Hebei and Gansu were compared. And we also discussed the responses of soil fertility of terraces across different land use, slope aspect and elevation in hilly and gully regions of the loess plateau. Through questionnaire survey, this study analyzes the social and economic condition, population, land use, and ecological sustainability, and explores effective ways of sustainable agriculture in terraced areas, in order to provide reference for the sustainable use and management of terraces. Through meta-analysis, this study explored different terracing structure, land use, construction years, climate and topography on the changing regulation of terracing efficiency (including the benefits of runoff and sediment reduction, soil water storage benefit, carbon sequestration benefit, and soil quality improvement and grain production increase). The following important progress and results have been achieved:
(1) The dryland sloping land in Yunnan of southern China promoted the accumulation of soil nutrients in the process of reclamation for rice terraces, and had significant effects on soil pH, total nitrogen, organic carbon and carbon-nitrogen ratio. The terraced fields in Gansu and Hebei had weaker effect on soil quality. The effect of terracing on soil organic carbon content is consistent with the effect on total nitrogen content. The soil nutrient of the terraced fields in the loess plateau is at a low level, but the potassium content is high. Soil pH, organic carbon, total nitrogen, available phosphorus, total potassium and available potassium in the sunny slope were higher than those in the shady slope. Soil pH, organic carbon, carbon nitrogen ratio and total potassium content decreased significantly with increasing altitude. Ammonium, nitrate, total phosphorus, available phosphorus and available potassium increase with altitude. The soil organic carbon and total nitrogen have strong spatial autocorrelation.
(2) The average runoff and sediment reduction benefits of terracing are 53.6% and 68.2% in China, respectively, the water storage benefit is 23.2%, and the grain yield increase benefit is 64%. Terracing increased the soil organic carbon, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium on different degrees, and their contents increased by 25.3%, 26.6%, 17%, 16.8%, 22.1%, 41.2% and 13.7%, respectively. The water storage benefit and runoff reduction benefit of terraces are significantly higher in the southern China than those in the northern China, while the benefit of sediment reduction, yield increase and carbon sequestration in the northern China are higher than in the southern China.
(3) Terracing structures significantly affect the benefits of soil water storage and grain yield increase benefit, land use patterns significantly affect the benefits of runoff and sediment reduction and soil carbon storage benefit. Level ditch has the highest water storage benefit among the different terracing structures, especially the level ditches built on the steep slopes. The level ditches and fish scale pits show the highest carbon storage benefit, because the unique concave structures are favorable for receiving fertile topsoil from the uphill position. Stepped terraces are suitable for construction on gentler slopes, and level ditches and fish-scale pits are suitable for steep slopes above 25°. The cropland terraces are suitable for the gentle slopes, while the steep terraces should be dominated by forest and tree cropland.
(4) The water storage benefit of terracing decreases with the increase of the soil depth. The 0–100cm depth's soil water storage benefit is mainly affected by the surface evapotranspiration and water flow path caused by the terrace structure, while the 100–200cm depth's soil water storage benefit is mainly affected by plant root absorption. Compared with temperature, the effect of precipitation on the soil water storage in terraced fields is stronger. The terraced fields with different construction years have low carbon storage benefit at the beginning years of construction, and the benefits will increase afterwards, and effective carbon sinks can be exerted after 6–10 years’ terracing. The carbon storage benefit of terraces increases with the increasing slope gradient. The crop yield increase benefit decreases with the increasing slope. The storage efficiency increases with the increase of slope gradient above 15°. The benefit of runoff and sediment reduction is increased first, then decreased and then increased with slope gradient increase.
|陈蝶. 梯田生态效应及其影响因素研究[D]. 北京. 中国科学院生态环境研究中心,2019.|
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