刺五加生长过程及其允收量方程的初步研究

本文对刺五加生长过程和年允收量进行了初步研究。刺五加种群绝大多数由12龄以下的植株组成。单株高生长和地径生长的数量模型为:Hi=0.210A+1.1656logAi(r_1=0.9895)和Di=0.1833+0.9832logAi(r_2=0.9660);刺五加年允收量方程为W年=K_1·K_2·K_3·W总,其中,年允收系数K_1=0.083;采收系数K_2=0.800;经济量系数K_3=0.550;即W年=0.037W总。     

Comparison of modeling approaches to quantify residue architecture effects on soil temperature and water

RZ-SHAW is a hybrid model, comprised of modules from the Simultaneous Heat and Water (SHAW) model integrated into the Root Zone Water Quality Model (RZWQM) that allows more detailed simulation of different residue types and architectures that affect heat and water transfer at the soil surface. RZ-SHAW allows different methods of surface energy flux evaluation to be used: (1) the SHAW module, where evapotranspiration (ET) and soil heat flux are computed in concert with a detailed surface energy balance; (2) the Shuttleworth–Wallace (S–W) module for ET in which soil surface temperature is assumed equal air temperature; and (3) the PENFLUX module, which uses a Penman transformation for a soil slab under incomplete residue cover. The objective of this study was to compare the predictive accuracy of the three RZ-SHAW modules to simulate effects of residue architecture on net radiation, soil temperature, and water dynamics near the soil surface. The model was tested in Akron, Colorado in a wheat residue-covered (both standing and flat) no-till (NT) plot, and a reduced till (RT) plot where wheat residue was incorporated into the soil. Temperature difference between the soil surface and ambient air frequently exceeded 17 °C under RT and NT conditions, invalidating the isothermal assumption employed in the S–W module. The S–W module overestimated net radiation (R_n) by an average of 69 Wm⁻² and underestimated the 3-cm soil temperature (T_s3) by 2.7 °C for the RT plot, attributed to consequences of the isothermal assumption. Both SHAW and PENFLUX modules overestimated midday T_s3 for RT conditions but underestimated T_s3 for NT conditions. Better performances of the SHAW and PENFLUX surface energy evaluations are to be expected as both approaches are more detailed and consider a more discretized domain than the S–W module. PENFLUX simulated net radiation slightly better than the SHAW module for both plots, while T_s3 was simulated the best by SHAW, with a mean bias error of +0.1 °C for NT and +2.7 °C for RT. Simulation results for soil water content in the surface 30 cm (θ_v30) were mixed. The NT conditions were simulated best by SHAW, with mean bias error for θ_v30 within 0.006 m³ m⁻³; RT conditions were simulated best by the PENFLUX module, which was within 0.010 m³ m⁻³.     

基于模式搜索算法的Van Genuchten方程参数优化

针对目前Van Genuchten方程参数优化方法的不足,本文通过理论分析得出Van Genuchten方程参数的单调函数,即为单极值函数。因此,可使用局部搜索能力较强的模式搜索算法识别Van Genuchten方程参数。算例及误差分析表明:模式搜索算法求解Van Genuchten方程参数算法实现简单、运算速度快、适用性强、计算精度高,为Van Genu-chten方程参数的求解提供了一条新途径。     

基于GIS和USLE的龙墩水库小流域土壤侵蚀评估研究

本研究以南京市高淳区龙墩水库流域为研究对象,利用通用土壤流失方程(USLE)模型与地理信息系统(GIS)技术结合的方法对流域土壤侵蚀进行模拟预测。结果表明:整个流域年均土壤侵蚀模数为4 343.46 t/km~2,属中度侵蚀。整个流域微度和轻度侵蚀所占面积比例相对较大,两者所占面积比例之和超过了63%,极强度和剧烈侵蚀虽然所占面积较小,但却产生了超过了70%的侵蚀量。不同土地利用类型中土壤侵蚀强度差异较大,年均侵蚀模数旱田草地水田林地,侵蚀量旱田水田草地林地。通过GIS将整个流域划分为13个子流域,子流域4、5、10由于区域内大部分是旱田,土壤侵蚀模数较大,为流域内土壤侵蚀的关键源区,子流域10侵蚀模数和侵蚀量都比较大,应该重点关注;而子流域1、9和12由于侵蚀总量较大,也应该保持一定的关注。所有子流域土壤侵蚀量都主要来自高强度侵蚀等级,其中以剧烈侵蚀为主。因此,控制土壤侵蚀应该优先考虑高强度侵蚀等级区域。     

A Computer Program for Automatic Watering Based on Potential Evapotranspiration by Penman Method and Predicted Leaf Area in Miniature Pot Rose Production

In this study, we developed a computer program for automatic prediction of watering time point by considering the environmental factors such as solar radiation, air temperature and relative humidity based on the multiple linear regression equation of leaf area and Penman Method. The experiments were carried out for a year in two watering experimental plots, one of which was controlled by pF value, and the other by the computer program. After comparing the results of the two plots, the following findings were obtained. In the computer program plot, the observed and predicted values of both leaf area and evapotranspiration indicated significant correlation at the 1% level, which suggested that the computer program had high prediction accuracy. In addition, no significant difference was observed between the two experimental plots with respects to the plant height, plant diameter, leaf area, leaf number, fresh weight, and dry weight, which demonstrated that the plants in the computer program plot had normal growth. On the other hand, although the number of flower buds and flowering shoots showed higher values at the end of certain cultivations in the computer program plot than those in pF value plot, we proposed that it was due to the effect of cumulative daily solar radiation in the greenhouse, rather than the watering. Thus, we have reached the conclusion that the computer program for automatic prediction of watering time point developed by this study has high applicability in miniature pot rose production.     

用Penman-Monteith方法与Penman修正算法计算参照作物腾发量的比较

利用阿克苏地区1975-2004年的逐日气象资料,分别采用Penman—Monteith公式与Penman修正公式计算了新疆农一师灌区的参照作物腾发量及其辐射项和空气动力项的逐日均值和旬日均值,比较了2种计算方法的绝对偏差和相对偏差,并对引起偏差的原因进行了分析。     

新生代农民工择业行为及影响因素实证分析——基于结构方程模型

基于对新生代农民工的问卷调查数据,运用结构方程模型探讨影响新生代农民工择业行为的各种因素以及因素之间的关系和强度。结果表明:新生代农民工择业行为体现出明显的主观意识,外界影响因素对个人因素产生不同程度的影响,并通过个人因素对最终职业选择产生影响。     

Applying the USLE Family of Models at the Sparacia (South Italy) Experimental Site

Soil erosion is a key process to understand the land degradation, and modelling of soil erosion will help to understand the process and to foresee its impacts. The applicability of the Universal Soil Loss Equation (USLE) at event scale is affected by the fact that USLE rainfall erosivity factor does not take into account runoff explicitly. USLE‐M and USLE‐MM, including the effect of runoff in the event rainfall–runoff erosivity factor, are characterized by a better capacity to predict event soil loss. The specific objectives of this paper were (i) to determine the suitable parameterization of USLE, USLE‐M and USLE‐MM by using the dataseries of Sparacia experimental site and (ii) to evaluate their performances at both event and annual scale. The measurements allowed to establish the relationships for calculating the factors of USLE, USLE‐M and USLE‐MM usable at the Sparacia experimental area. At first, for slope‐length values greater than 33 m, the calibration of USLE model at event scale pointed out that sediment delivery processes, that is processes involving deposition of the transported eroded soil particles, occur. The analysis showed that USLE and USLE‐M tend to overestimate low event soil losses, while for USLE‐MM, this tendency is less pronounced. However, the USLE‐MM performed better than USLE and USLE‐M and was able to reproduce better than other two models the highest soil loss values that are the most interesting from a practical point of view. The results obtained at annual scale were generally consistent with those obtained at event scale. Copyright © 2016 John Wiley & Sons, Ltd.     

南方红壤区植被覆盖因子估算模型构建与验证

研究红壤区植被覆盖因子变化规律、构建植被覆盖因子计算模型可为该区域水土流失防治及动态监测提供科学依据。该研究基于广东省五华县水土保持试验推广站200余场降雨试验观测数据,分析了影响水土流失的各关键因子与次降雨土壤侵蚀模数(Individual Rainfall Event Soil Erosion Modulus,ISEM)间定量关系,基于中国土壤流失方程计算了系列次降雨事件不同植被覆盖度对应植被覆盖因子值,构建了植被覆盖因子值与植被覆盖度间数学模型,从点、面2个尺度对模型计算精度进行了验证。结果表明:1)ISEM随植被覆盖度增加而降低;ISEM与雨前土壤表层含水率间存在显著正相关对数关系;ISEM随坡度增加呈先增后减的变化规律;ISEM随次降雨量、次降雨侵蚀力和次降雨径流深呈显著正相关线性变化关系。2)构建了植被覆盖因子值与植被覆盖度间二阶指数衰减模型,该模型决定系数和纳什系数分别达0.947和0.876。点尺度验证结果表明90%样本模型计算值与观测值相对误差均小于0.30;面尺度验证结果表明,70%～80%的植被覆盖因子计算值相对误差不超过0.1。总体而言,该模型计算精度较为理想,但由于研究对象典型的时空尺度特征,仍需要更多观测数据对该模型进行完善和验证。研究成果可为深入理解红壤区土壤侵蚀规律、水土流失动态监测提供有益参考。     

作物单株产量与株行距的关系

建立了作物单株产量与株行距之间的关系式，给出了根据目标产量确定种植密度的计算方法。