农业工程学报Issue(15)：101-107,7.DOI:10.11975/j.issn.1002-6819.2015.15.014
冻融期积雪覆盖下土壤水热交互效应
Soil moisture thermal interaction effects under snow cover during freezing and thawing period
摘要
Abstract
Seasonal frozen soils accounts for 54% of Chinese total acreage,mostly distributed in Northeast China where snowing is frequent. Soil moisture under snow cover may interact with temperature, both affecting many processes of biogeochemistry. However, few studies have focused on soil moisture and temperature interaction under snow covers. Therefore, this study investigated the soil moisture and temperature characteristics under seasonal frozen soils in field experiments. The experiment was set up in an experiment field of Northeast Agricultural University, Harbin, China. It was located in south Songnen Plain. During November 8 of 2013-April 28, 2014, four treatments were designed including bare land, natural snow cover land, snow compacted land, and snow thickened land. Each treatment was repeated three times. In bare land, snow was removed by hand. In snow compacted land, snow density was manually increased to 0.256 g/cm3. In the snow thickened land, snow depth was increased but snow density was similar with natural snow cover land. During the experiment, soil temperature was measured by thermometers at 5, 10, 15 and 20 cm soil depth, and soil moisture was measured by time domain reflectometery at same depth. Soil moisture data were divided into two parts: one for model establishment and the other for model validation. Relationship between soil moisture and temperature was described by exponential models. Fractal dimensions were used to evaluate complexity of soil moisture and temperature. The results showed that: 1) The whole experiment duration could be divided into rapid freezing stage, stable freezing stage, and melting stage; On March 1, the freezing depth reached the highest value of 118 cm; 2) Soil moisture and temperature could be well described by exponential models with determination coefficient about 0.9 and relative errors less than 5% for the model establishment and relative error less than 3% for the model validation; 3) The complexity of soil moisture and temperature interaction was simpler during freezing phase than the melting phase since the relative errors of the former were less than that of the latter; The relative errors decreased with increasing snow density and thickness during the freezing phase, but the contrast was observed during the melting phase, indicating the interaction of soil temperature and moisture is greatly affected by freezing-thawing process; 3) During melting stage, soil moisture was 14.31%, 15.9%, and 16.91% for natural snow, snow compacted, and snow thickened treatments, respectively, and soil temperature ranged -5.9-5.3, -3.6-6.9 and -3.1-3.8℃ for natural snow, snow compacted, and snow thickened treatments, respectively, and the interaction between soil moisture and temperature weakened; The complexity of soil temperature and moisture interaction increased with snow cover; and 4) The fractal dimension of soil temperature under different treatments lied between 1.4149-1.6019 during the freezing phase and 1.4621-1.5775 during the melting phase, revealing a downward trend with snow thickness and compactness during the freezing phase but an opposite trend during the melting phase; The fractal dimension of soil moisture ranged from 1.5047 to 1.5973 and from 1.547 to 1.6607 during the freezing and melting phases, respectively, with a similar trend with soil temperature changes among different snow cover treatments. The results are helpful in predicting soil temperature and moisture in sowing stage, and revealing soil moisture and temperature dynamics.关键词
分形/积雪/土壤/冻融期/复杂性/土壤水热互作效应Key words
fractals/snow/soils/freezing and thawing period/complexity/moisture thermal interaction effects分类
农业科技引用本文复制引用
付强,侯仁杰,王子龙,李天霄..冻融期积雪覆盖下土壤水热交互效应[J].农业工程学报,2015,(15):101-107,7.基金项目
国家自然科学基金（51279031，51209039）；黑龙江省自然科学基金（E201241）；黑龙江省杰出青年基金 （）
