Monitoring forage production for farmers’ decision making

Objective management of grazing livestock production systems needs monitoring of forage production at the managerial unit level. Our objectives were to develop a system that routinely estimates forage above-ground net primary production (ANPP) at the spatial and temporal resolution required by farmers in the Pampas of Argentina, and to facilitate adoption of the system by end users as a managerial support tool. Our approach was based on the radiation use efficiency (RUE) logic, which proposes that ANPP is determined by the amount of photosynthetically active radiation absorbed by the canopy (APAR), and the efficiency with which that energy is transformed in above-ground dry matter (radiation use efficiency, RUE). APAR is the product of incoming photosynthetically active radiation (PAR) and the fraction absorbed by the canopy (fPAR). We estimated fPAR as a non-linear function of MODIS normalized difference vegetation index (NDVI). RUE was empirically estimated for the two principal forage resources of the region, yielding the following relations: ANPP = 0.6 × APAR + 12, (R² = 0.86; p < 0.001; n = 18) for the upland sown pastures, and ANPP = 0.27 × APAR + 26, (R² = 0.74; p < 0.001; n = 18) for the lowland naturalized pastures, with ANPP in g/m²/60 days and APAR in MJ/m²/60 days. The models were able to predict independent ANPP values with acceptable accuracy. Computational procedures were automated and run in a Relational Data Base Manager System that stored and managed all the information. The system is currently monitoring 212,794 ha in 83 farms and provides monthly ANPP values for the previous month and a history of the last 6 years. The data so generated show ANPP differences between the two major forage resources, considerable variability of a given month’s ANPP among years and paddocks, and contrasting among-farm differences in the efficiency of conversion of ANPP and forage supplements into beef production. The system was well accepted by end users who utilize it mainly for making near real time decisions according to last month ANPP, and explaining results of previous production cycles by incorporating ANPP as an explicative variable. However, there were differences among farmers in the degree of utilization, apparently related to the advisor’s attitude toward this new technology. Our results indicate that (1) forage production of large extensions can be monthly monitored at the paddock level by a small laboratory with capabilities in geographic information systems, and (2) advisors and farmers apply this information to their managerial decisions.     

油菜基质块苗移栽机对辊式取苗装置设计与试验

纸质链钵育苗移栽是一种起源于日本的轻简高效作物育苗移栽技术。针对国产链钵育苗册制册技术及设备缺乏、育苗册长期依赖进口的问题,该研究提出一种集涂胶、压痕、走纸、折叠等环节的链钵育苗册制册方案,在阐述六边形截面钵体链钵育苗册制册原理的基础上,运用电机与气动元件驱动各工作部件协调动作的方式,设计了一套能自动实现链式育苗钵成型及集合成册的小型链钵育苗册制册机样机。通过涂胶装置、压痕装置、走纸装置和折叠收纸装置等关键部件的设计分析,确定了相关结构参数,并进一步设计了自动化运行的控制系统。基于样机的完整制册试验结果表明,当制册效率为60册/h、链钵长度在12.16～21.28 m时,平均合格率为91.55% ;使用所制链钵育苗册育苗发芽率为96.21%,幼苗长势良好,可被轻松拖拽并展开成链,满足育苗与轻简化自动移栽的要求。

     

Population impacts of endangered short-tailed albatross bycatch in the Alaskan trawl fishery

We conduct a decision analysis that explores the effects of trawl-related fishery mortality on achieving the population recovery goals for the US federally-endangered short-tailed albatross (Phoebastria albatrus), proposed by the US Fish and Wildlife Service. A population model is constructed and its parameters estimated using data on counts of the numbers of albatross chicks and eggs at Torishima Island, Japan, where 83% of the world’s population of this species is found. Bayesian inference is used to assign probabilities to alternative plausible rates of fishing mortality and as the basis for population projections with different levels of trawl mortality to determine their effects on achieving the population recovery goals. The analyses of the impact of trawl mortality on the Torishima short-tailed albatross population suggests that exceeding the current expected incidental take in the Alaskan groundfish trawl fishery, two in any 5-year period, by as much as a factor of 10 would have little impact on when the proposed recovery goals for the species are achieved. A quantitative approach that addresses uncertainty, such as that outlined in this study, could aid the process to evaluate allowable limits in light of species recovery goals by addressing both take limits and recovery goals within the same framework.     

FORESTAR：A decision—support system for multi—objective forest management in Northeast China

Past monoculture forestry in China has contributed to countrywide ecological disasters and economic difficulties in forestry regions. China‘s new forestry programs, Natural Forest Conservation Program and Returning Farmlands to Forests Program, provide opportunities for ecosystem management of mountain forests in China. A decision support system, FORE-STAR, has been developed for better managing and protecting natural forests in Changbai Mountain area. It uses GIS-based forest inventory data at a scale of forestry bureau. The first version contains two sub-modules: forest operation and forest res-toration. Under each sub-module, users can compare several decision options and make optimal choices. It can help field for-esters, forest managers, and policy makers make multi-objective and consistent decisions in planning forest management at hierarchical administrative scales.     

青贮灌装平台的研制

青贮灌装平台的研制主要对设备的结构和传动进行了设计和计算。利用中型马力拖拉机提供牵引和动力输出,实现平台在移动中连续、均匀地卸料,满足青贮灌装机的生产效率,保证与青贮灌装机的对接,保证青饲运输拖车卸料灵活。     

同龄林收获调整的最优控制问题探讨

从最优控制理论的观点看,森林收获调整可认为是对森林资源系统实施最优控制(造林、采伐)的过程。作者用状态空间分析法导出了系统的状态方程,表明它是系统状态的一种反馈控制。作者提出了森林资原系统的期望稳定状态,将前人称为法正森林状态的理想森林以其特例的形式包含在其中。以期望稳定状态作为终端条件,结合控制约束,建立了线性离散收获调整最优控制模型。在讨论了极大值原理对模型的求解以后,将模型进行等价转换,化成了一个数学规划模型。用一个实例验证了模型的实用性。     

城乡结合部农地城市流转决策框架及管控系统设计

分析了农地流转决策的影响因素,并提出除了应考虑流转前后土地边际收益变化,从＂农村-城市＂土地生态系统以及农村、城市土地供给需求平衡全面考虑土地开发/保护决策,随后进一步提出了以政府为主导的流转管控系统组成及内容,包括：①城市土地的供给和需求调控;②农地城市流转的收益分配调控;③农地城市流转管控微观决策系统;④农地城市流转管控信息系统。