Simulation of soil types in Teramo province (Central Italy) with terrain parameters and remote sensing data

Soil surveys are an essential source of information for land management although a limited budget often reduces the amount of data available. Even if the dataset is limited, geostatistics can provide a valid estimation tool through a weighted moving average interpolation (kriging). Often, however, the spatial variability of soil properties appears smoothed and short range variability is underestimated by this kind of interpolation technique. A more realistic distribution of a given variable on the territory can be obtained through models based on stochastic simulation.     

Prediction of multinomial probability of land use change using a bisection decomposition and logistic regression

Land use change is an important research area in landscape ecology and urban development. Prediction of land use change (urban development) provides critical information for making the right policies and management plans in order to maintain and improve ecosystem and city functions. Logistic regression is a widely used method to predict binomial probabilities of land use change when just two responses (change and no-change) are considered. However, in practice, more than two types of change are encountered and multinomial probabilities are therefore needed. The existing methods for predicting multinomial probabilities have limits in building multinomial probability models and are often based on improper assumptions. This is due to the lack of proper methodology and inadequate software. In this study, a procedure has been developed for building models to predict the multinomial probabilities of land use change and urban development. The foundation of this procedure consists of a special bisection decomposition system for the decomposition of multiple-class systems to bi-class systems, conditional probability inference, and logistic regression for binomial probability models. A case study of urban development has been conducted to evaluate this procedure. The evaluation results demonstrated that different samples and bisection decomposition systems led to very similar quality and performance in the developed multinomial probability models, which indicates the high stability of the proposed procedure for this case study.     

浙江象山杨梅产量分析

根据浙江省象山1986~2006年杨梅产量、种植面积资料和同期气象资料,分别用多项式和滑动平均方法对杨梅产量进行了分析,得出杨梅的气象产量主要与其花芽分化期、成熟期的一些气象因子有关,并在分析基础上建立了杨梅单产模拟预测模型。     

Performance and fitness traits versus phenotypic appearance in the African Ankole Longhorn cattle: A novel approach to identify selection criteria for indigenous breeds

Ankole cattle are well known for their massive white horns and red coat colour. These characteristics are attributed to centuries of cultural breeding practices. Two experiments with traditional cattle keepers were carried out at a governmental Ankole nucleus farm in south-western Uganda to identify phenotypic characteristics as well as production and fitness traits which are important indigenous selection criteria. Forty one body measurements each were taken from 15 bulls and 35 cows and phenotypic characteristics were described in detail. In the first experiment 12 groups of 6 to 8 cattle keepers were invited to rank several groups of 4–5 animals according to their preference for a breeding bull or cow based on phenotype alone. In the second experiment the ranking was based on phenotype and a hypothetical life history that was randomly assigned to each animal on each day of experiment. The history included milk yield (on own performance for cows and that of the dam for bulls), fertility of the animal and its sire as well as events of East Coast Fever. For analysis, Generalized Multinomial Logit Models were fitted. To compare different models the likelihood-based pseudo R square measure was used. The results indicate that, in the selection of cows, performance and fitness traits are emphasized by the cattle keepers while in the selection of bulls, the phenotypic appearance of the animal plays an important role. Individual fertility followed by milk performance are the main criteria for selecting cows, resistance to East Coast Fever was of highest importance in bulls. In both sexes a dark red coat colour was highly rated. The study indicates that the methodology of preference ranking combining phenotype and a hypothetical life history may provide insight into indigenous selection criteria of stock owners elsewhere.     

Temporal development of crown condition of beech and oak as a response variable for integrated evaluations

The evaluation uses the longest available time series for beech and oak defoliation in Germany. The data from Hesse, starting from 1984, show a typical pattern: for the first 12 years, a continuous increase in defoliation was observed ranging from an average value of 14% in 1984 to a peak value of 30%. This was followed by a subsequent decrease in the loss of foliage accompanied by a high variability, until the last monitoring in 2003, where an average value of 25% defoliation was observed. For both tree species, the years of trend reversal were identical. The same pattern was observed in the German federal states: Rhineland-Palatinate, North Rhine-Westphalia, and Bavaria. The year of trend reversal was identical in Hesse and Rhineland-Palatinate. In North Rhine-Westphalia, it occurred 1 year earlier and in Bavaria 3 years earlier. Whereas defoliation trends were clearly demonstrated, tree mortality did not appear on a large scale. The sample trees were grouped into four discrete clusters according to their annual defoliation values from 1984 to 2003. In 1996, the clusters represent 15, 25, 35, and 50% defoliation values. Regarding beech in Hesse, there was no overlap in the defoliation curves observed among the different clusters. These four clusters having different degrees of defoliation over the whole time span of 20 years were used for a further detailed statistical analysis. For discrete variables like crown spacing and—in the case of beech—fruit bearing, mosaic plots were applied in order to visualize relations of low dimensional contingency tables, with defoliation trends being used as the response variable. The data show for beech a very clear relation between defoliation and age, relative crown spacing, stand composition, and fruit bearing. Regarding oak, besides age and relative crown spacing, the years with significant appearance of biotic stress factors—leaf eating insects—show a clear relation to trends of defoliation. The statistical model used in this study—logistic regression—allows applying a multinomial response variable and a number of continuous or categorical explanatory variables. With this approach, an iterative optimized selection of effect variables was used to test the relevance of different variables on the defoliation pattern of the same four clusters mentioned above. For this, the variables were grouped in an iterative process with five steps, starting with a few basic variables of tree and site information, and ending with a total of more than 20 variables in the fifth step. The process selects first the variables which are of significance on the defoliation, and calculates the possible errors in the grouping of the different trees to the four clusters. In this analysis of beech, the basic tree and stand variables: age, relative crown spacing, stand composition and fruit bearing proved to be the most relevant group of parameters, with the other variables explaining the variation of defoliation only to a minor extent. More complex model levels do not change any basic selected variables; however, Cation Exchange Capacity (CEC), C/N-ratio, Al- and Ca-proportion of CEC are additionally selected and give a hint of the relevance of soil conditions. Regarding beech, the errors of the statistical model are lower compared to oak.     

农户采用不同稻作方式的影响因素分析 ——基于江苏省淮安市淮安区的农户调研数据

【目的】探讨农户对不同稻作方式的采用行为及影响因素,为稻作方式的发展及推广工作提供科学依据。【方法】基于实地调研数据,运用Multinomial Logistic模型对农户采用直播稻、机插稻和手栽稻的行为结果及影响因素进行实证分析。【结果】稻作方式的省工特性对农户采用直播稻和机插稻均有显著影响;稻作方式信息可获得性对农户采用机插稻有显著影响;稻作方式的生产性投入与农户采用直播稻呈负相关;水稻种植面积与农户采用直播稻呈负相关,与农户采用机插稻呈正相关;农户兼业性与其采用直播稻和机插稻呈正相关。【结论】稻作方式的劳动投入量是影响农户采用行为的关键因素;农户的兼业性促进了其对轻简稻作方式的采用;生产性投入低是农户采用直播稻的重要原因。推进水稻规模经营、为农户提供方便有效的技术信息可促进机插稻的发展。     

农户对节水灌溉系统中智能IC卡应用的满意度研究——以山东省兰陵县为例

水利信息化的首要任务是在全国水利业务中广泛应用现代信息技术,建设水利信息基础设施,解决水利信息资源不足和有限资源共享困难等突出问题。本研究对农村水利设施中智能IC卡的应用进行了实地调研,考察农户对于智能IC卡应用的满意度,再运用多元Logistic模型研究影响农户满意度的因素,分析现有系统在推广、使用过程中出现的问题和需要改进的地方,以期对政府的推广提出政策建议,对相关系统研发部门提出改进建议。     

新型农村金融机构引入区农户借贷行为影响因素实证研究

通过对西部两省6个新型农村金融机构引入县域517家农户的问卷调查,运用多分类Logistic回归模型对农户借贷行为的影响因素进行实证分析。结果显示,劳均负担人口等5个变量对只获得新型农村金融机构贷款影响显著;农户年收入等7个变量对只获得非新型金融机构贷款影响显著;农户耕地面积等5个变量对同时获得两类贷款影响显著。农户年收入、负债水平在以上3种情况下均显著地影响了农户的借贷行为。针对影响农户不同借贷行为的决定性因素及其作用方向,提出了相应的政策建议。     

基于地域分异与农户兼业视角下农户参与农地流转行为的研究

深入研究农户农地流转参与行为的影响因素,对促进农地流转具有现实意义。基于地域分异与农户兼业视角,通过构建多元Logistic模型,实证检验地域分异与农户兼业对农户参与农地转出和转入行为的影响。结果表明：（1）区域经济发展水平对农户农地转出行为和转入行为均有显著正向影响,它能显著促进农户参与农地转出和农地转入;（2）区位性质对农户农地转出行为有显著影响,但对农户农地转入行为却无显著影响;（3）农户兼业程度对农户农地转出行为有显著正向影响,但对农户农地转入行为有显著负向影响;（4）家庭劳动力数、家庭承包地面积和承包地块数对农户农地转出行为,分别有显著的负向、正向和正向影响,但对农户农地转入行为却无显著性影响。农地流转政策制定应从政策差别化、兼业深度化、经营规模化3个方面着手。     

基于multinomial logit模型的产品线中消费者选择购买行为研究

在multinomial logit模型基础上建立了一个消费者选择模型,模型假设产品线中的每种产品对每个消费者的效用都服从一定的概率分布,消费者总是按照效用最大化来作出购买决策。在考虑消费者的保留价格服从Gumbel分布的情况下,得出消费者购买产品线中某种产品的概率,最后联系实际情况进一步分析了消费者在现实生活中做出购买决策的依据。