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首页> 外文学位 >Modeling mixed plant species pasture growth and tree effect on forage growth in a silvopastoral system.
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Modeling mixed plant species pasture growth and tree effect on forage growth in a silvopastoral system.

机译：模拟牧草系统中混合植物物种的牧草生长和树木对牧草生长的影响。

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摘要

The main objectives of this research were to: (1) Estimate plant growth parameters for GRASIM using numerical optimization procedures while enforcing plant physiological constraints; (2) Simulate the competition between coexisting forage species for light, water and nutrients and their utilization for dry matter production; and (3) Simulate tree effects on understorey crop/forage growth in terms of light and rainfall interception, soil water and nutrient uptake.; A numerical optimization procedure was designed to systematically search for the best combination of the growth parameters used by GRASIM. Physiologically-based ranges for these parameters derived from literature were used as upper and lower limits for the parameters during optimization. The procedure was utilized to estimate these growth parameters for a barley crop. The optimized parameter set allowed GRASIM to simulate closely its growth from a two-year experiment conducted at the American University of Beirut research center in the Bekaa Valley, Lebanon.; In the second part of the research, competition among coexisting forage species on a naturalized pasture was modeled on the basis of leaf area distribution in the mixture for the partitioning of light interception and soil water evapotranspiration demand and on the basis of dry mass distribution for the soil nitrogen uptake. Two-year grazing experiments on a mixed naturalized pasture at the Pennsylvania State University Beef Research Farm, State College, PA provided forage biomass data for model evaluation. The multispecies GRASIM reasonably simulated the growth dynamics of the mixed pasture across two growing seasons.; In the last part of the research, the tree effects on understorey pasture growth in a silvopastoral system were evaluated by explicit simulation of tree canopy light and rainfall interception, water and nutrient uptake. The algorithms for modeling these effects were incorporated into the multispecies GRASIM to form a simple agroforestry model. The new model was evaluated using forage biomass and soil moisture data collected from a silvopasture field experiment that was conducted on naturalized grassland in a forest plantation, West Lafayette, Indiana. The model closely simulated the growth of multiple forage species under a walnut tree canopy.
机译：这项研究的主要目的是：（1）使用数值优化程序估算GRASIM的植物生长参数，同时加强植物的生理限制; （2）模拟共存的牧草种类对光，水和养分的竞争及其对干物质生产的利用; （3）从采光和降雨拦截，土壤水和养分吸收方面模拟树木对下层作物/草料生长的影响；设计了数值优化程序来系统搜索GRASIM使用的生长参数的最佳组合。这些参数的基于生理的范围是从文献中得出的，用作优化过程中参数的上限和下限。该程序用于估算大麦作物的这些生长参数。优化的参数集使GRASIM可以在黎巴嫩贝卡谷地的贝鲁特美国大学研究中心进行的为期两年的实验中紧密模拟其生长；在研究的第二部分中，基于混合物中叶面积的分布来划分光捕获和土壤水分的蒸腾需求，并基于干物质的分布，对天然牧场中共存的牧草物种之间的竞争进行了建模。土壤氮素吸收。在宾夕法尼亚州立大学宾夕法尼亚州立大学牛肉研究农场的混合自然牧场上进行的两年放牧实验为模型评估提供了饲料生物量数据。 GRASIM多物种合理地模拟了两个生长季节混合牧场的生长动态。在研究的最后一部分，通过对树冠光和降雨截留，水分和养分吸收的显式模拟，评估了树木对牧草系统中下层牧草生长的影响。对这些效应进行建模的算法已整合到多物种GRASIM中，以形成一个简单的农林业模型。该新模型是使用从牧草场田间试验收集的牧草生物量和土壤水分数据进行评估的，该试验是在印第安纳州西拉法叶的人工林的天然草地上进行的。该模型密切模拟核桃树冠下多种草料的生长。

著录项

  • 作者

    Zhai, Tong.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Agricultural.; Agriculture General.; Environmental Sciences.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 p.5064
  • 总页数 193
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农业工程;
  • 关键词

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