我国园林机械行业发展及市场容量预测

通过对园林机械行业发展的回顾,结合我国经济及对生态环境建设投入资金的持续增长等形势,论述了园林机械需求及其未来5年我国园林机械市场的容量。预计我国对园林机械的需求将持续增长。     

Self‐thinning models for even‐aged stands of Pinus sylvestris,Picea abies and Betula pendula

Self‐thinning models were developed to describe the relationship between the stem number and mean diameter of even‐aged and monospecific tree stands undergoing self‐thinning. The models were developed separately for Pinus sylvestris L., Picea abies (L.) Karst. and Betula pendula Roth. stands. Data from 41 unthinned permanent sample plots were used. According to Reineke's equation and the —3/2 power rule of self‐thinning, a log‐log plot of average tree size and stem density will give a straight, self‐thinning line of constant slope. According to this study, the slope of the line consistent with Reineke's equation varies for different tree species. Within tree species, the intercept of the self‐thinning line varies according to site index.     

中国林业产业结构演变趋势及弹性模型分析

为研究中国林业产业结构演变的趋势和特点,采用灰色预测方法对2012—2030年的林业产值数据进行预测,根据林业3大产业产值在林业总产值中所占的比重将林业产业演变过程分为3个阶段,运用弹性模型分别对这3个阶段的林业产业结构特点进行分析。结果表明,中国林业产业结构由“一、二、三”的结构模式逐渐向“二、一、三”的结构模式演变,到第3阶段演变为“二、三、一”的结构模式;在林业产业结构演变过程中,林业第一、二产业对林业总产值的影响不断增强,并且林业第一产业比第二和第三产业的影响更大,林业第三产业在第2阶段时相对于第1和第3阶段对林业总产值的影响较小。     

基于“3S”技术的辽宁省某尾矿库扩容工程生态影响预测与评价

以辽宁省某尾矿库为例,基于GIS技术,利用2010年的TM遥感影像及地形图,预测该尾矿库扩容后的生态影响。分析结果显示:尾矿库扩容工程对生态的影响主要体现在土地利用、植被、生态景观和地形地貌的变化4个方面。     

内蒙古柠条生物量建模

以内蒙古自治区的常见灌木种柠条(Caragana microphylla)为研究对象,基于大样本的生物量实测数据,利用非线性误差变量联立方程组方法,建立了单株水平的地上生物量模型及其相容的地下生物量模型和根茎比模型,并建立了基于平均植冠面积和密度或覆盖度的群落水平的总生物量模型。结果表明:植冠面积是影响单株生物量的首要因子,其次才是丛生枝个数;基于植冠面积和丛生枝个数的单株地上生物量模型,其确定系数能接近0.7,但地下生物量模型的确定系数要低些,还不到0.5;单株地上生物量和地下生物量模型的平均预估精度均能达到90%左右,总生物量的平均预估精度能达到92%以上,完全可用于内蒙古自治区范围内柠条灌木林的生物量估计。以单株总生物量模型为基础,直接推导出不同密度或覆盖度的群落总生物量模型,可为建立群落水平的灌木生物量模型提供借鉴。     

Genetic variation of the rate of leaf appearance in maize: Possible yield prediction at the early stage

Summary Evidence of genetic variation for early vigour is presented using maize line × tester crosses. The leaf appearance rate and associated variance components are affected by a physiological stress attributable to the transition to autotrophic nutrition by the plant. At this stage, specific combining ability plays an important role in the total genetic variation. It is concluded that differing genetic controls exist in early and late material, and that this difference is also manifested in leaf initiation and elongation rates. The ground coverage rate, as a component of plant development, is genetically correlated to total dry matter yield. The genetic correlations vary according to the growth stage.     

Stability Analysis of Yield in Maize,Wheat and Sorghum and its Implications in Breeding Programs*

Six stability statistics: (b_i, s²_di, , , and ) were estimated for maize, wheat and sorghum in different environments by using three statistical models. The significant linear portion of genotype × environment interaction for maize indicates different hybrids responded differently to environments, whereas the non-significant genotype × environment interaction (linear) were found for wheat and sorghum suggest that all genotypes responded similarly as the environments change. However, the highly significant pooled deviations (deviation from regression) for all three crops make yield predictions from the model less reliable. When regression coefficients (b_i) were non-significant, s²_di, became an important statistic in estimating stability. It appears that the regression coefficient, b_i, was best used to estimate genotypic adaptability, whereas s²_di, for stability. Maize and sorghum had negative correlations between the mean yield and stability statistics, s²_di, , and , suggesting that high yield and stability are not mutually exclusive in the range of environments used in this study; however, such correlations did not occur in wheat. Thus, maize and sorghum hybrids with high yield potential and high stability could be identified and selected. Correlations between mean yield and b_i, or , were positive and significant for maize and sorghum but were non-significant for wheat, indicating that such relationships may be species specific. Under a given set of testing environments, the stability ranking associated with each maize hybrid is correlated to and depends on other hybrids included in the analysis.     

A plant ideotype for Bromus inermis Leyss. in Western Canada

Summary This study relates the yield of two harvests of Bromus inermis Leyss. to tiller type and morphology. Tillers were classified as being nonelongated, elongated and headed. At four times during the growing season, observations were made of tiller density; individual tiller weight; leaf number, area and weight; stem length, area and weight; leaf to stem ratio; specific leaf weight; head area and weight.Results showed that there was a pattern of tiller control over yield which was different for each of the two harvests. Stem characters contribute more to yield than leaves. Growth, early in the season, had a prominent effect on yield of the first harvest and also influenced the second harvest. Height at the time of each harvest was highly predictive of yield of the respective harvests. A morphological ideotype for bromegrass harvested twice in a season was described.     

全国粮食总产海温预测预报模式研究

本文使用太平洋286点海水温度资料,对我国粮食总产及其地理分布进行多时效的动态监测.为了能一次预报出整个的产量场,首先对初始场作自然正交展开,提取前P个主成分进行海温网格点的复相关计算,用以筛选因子组建预报方程.预报模式采用时效可任意指定的动态链接式,它可以通过海温这个“窗口”,实现对全国粮食总产前景的连续监测.     

基于游程检测法重构集合经验模态的养殖水质溶解氧预测

为了提高水产养殖中溶解氧的预测精度,该文提出了基于集合经验模态(ensemble empirical mode decomposition,EEMD)分解、游程检测法重构、适宜的单项预测算法建模和BP神经网络非线性叠加的组合预测模型。该模型首先将溶解氧原始序列用EEMD分解法进行分解,得到了多个分量;其次,用游程检测法将这些分量重构成高频分量、中频分量和低频分量等3个分量;接着,针对高频分量波动性大且复杂、中频分量呈现周期性、低频分量几乎呈线性的特点,采用粒子群(particle swarm optimization,PSO)优化的最小二乘支持向量机(least square support vector machine,LSSVM)对高频项进行预测,采用极限学习机(extreme learning machine,ELM)对中频项预测,采用非线性回归(nonlinear regression method,NRM)对低频项预测;最后,将3个分量预测的结果用BP神经网络进行重构得到最终的预测结果。将该模型应用于江苏省溧阳市埭头黄家荡特种水产养殖场的溶解氧预测中,试验表明,该种以游程检测法重构EEMD为基础的混合预测模型的预测精度高于PSO-LSSVM和单一的ELM预测模型。在预测未来48 h的溶解氧值时,该模型的预测值与实测值的均方根误差RMSE为0.099 2、平均相对误差均值MAPE为0.078、平均绝对误差MAE为0.015 5,R~2为0.995 5。表明该模型有较好的预测精度和泛化能力,能够满足现代化水产养殖业对溶解氧精细化管理的高要求。