基于工作空间的果园作业平台结构参数优化与试验

为提高果园作业平台的适用性和操作灵活性,根据乔砧密植的纺锤形苹果种植模式确定其目标工作空间,以工作空间尺寸偏差、工作空间体积和平均可操作度描述其可达工作空间性能,分析了平台主要结构参数杆长和关节变量（关节角、连杆偏移）对工作空间性能的影响。建立了以可达工作空间性能和结构紧凑为指标的优化模型,利用遗传算法求解得出最优参数为：杆2和杆4的长度分别为988、879mm,关节1、3的关节角范围分别为[107°,256°]、[-118°,-76°],关节5、6的连杆偏移最大值分别为720、340mm。优化后其可达工作空间尺寸偏差分别减小96.09%、95.60%,体积减小4.69%,平均可操作度增加1.43%。对优化后的果园作业平台进行了实地果园工作空间试验,结果表明：承载质量为65kg、横坡坡度为15°、纵坡坡度为15°时,工作空间尺寸偏差最大,分别为16.2、16.7mm,比原型分别减小93.89%、93.76%。     

弥雾灌对枣园冠层环境和光合特性及产量品质的影响

针对高温低湿的极端干旱气候易造成南疆枣树盛花期出现焦花及坐果率低、光合速率下降等问题,在枣园冠层布设弥雾系统,在枣树盛花期以弥雾时间和弥雾次数为变量设置3个处理(M1为每天弥雾3次,每次20 min;M2为每天弥雾2次,每次20 min;M3为每天弥雾2次,每次40 min),CK为对照,不弥雾,通过田间试验研究不...     

马尾松高产脂种子园家系选择

以马尾松（Pinus rnassoniana）高产脂种子园自由授粉家系子代测定林为对象,分析了4年生家系生长性状（树高、胸径、材积和活轮枝数）及抗虫性的遗传变异规律,估算了各性状的遗传力,并进行了相关性分析。结果表明,除抗虫性存在显著差异外,材积、胸径、树高、活轮枝数生长性状在家系问均存在极显著的遗传差异;生长性状受较强遗传力控制,而抗虫性受中强度遗传力控制;家系各生长性状问具有高度相关性,而产脂力、抗虫性和各生长性状间没有相关性。利用最佳线性预测的单性状（材积）及多性状联合（抗虫性和家系产脂力）估算家系育种值,选出了2个马尾松优良家系作为桂东南育种和推广材料。     

Effectiveness of sloping agricultural land technology on soil fertility status of mid-hills in Nepal

Hedgerows with intercropping systems were established at the ICIMOD test and demonstration site at Godawari to assess the effective-ness of Sloping Agricultural Land Technology (SALT) in reducing run-o...     

陕北黄龙山森林植物群落的初步研究

水文对森林植物群落的类型、结构、生活型谱、排序和动态做了初步研究。结果表明:森林植物群落分2个植被型,4个群系,19个群丛组;群落垂直结构分乔术、灌木、草本3层,植物组成分属于34科、76属108种;群落生活型谱反映了气候条件;群落排序结果满意;顶极植物群落为松栎林,山杨、白桦林将为辽东栎林演替,油松林与山杨林、白桦林之间的动态演替关系值得进一步研究。     

山地苗圃幼苗管护措施探析[

山地苗圃的管理有别于一般苗圃,管理方式较粗放,因此,在山地苗圃培育优质苗木产品,对从业者的技术要求更高,必须幼苗管理开始做起。文章根据实践,对山地苗圃幼苗早期养护技术进行了总结,并从控草管理、水肥管理、苗木塑形3个方面进行了阐述。     

马尾松高产脂种子园嫁接技术

以广西藤县马尾松高产脂种子园为研究对象,对嫁接成活率及生长量的影响因子进行研究。结果表明:①嫁接人员的技术熟练程度和采穗母树的年龄是决定嫁接成活率和生长量的关键。②嫁接宜采用穗条全包保湿的方法,坡向对嫁接成活率影响不大。③无性系嫁接成活率及生长量与采穗母树的年龄呈极显著负相关,而与产脂力呈正相关,但与无性系母树来源地、母树年龄和大小没有相关性。④无性系生长量和其内部变异系数皆较大,且与无性系相关。     

Regional Conservation in the Virunga-Bwindi Region

SUMMARY

Bwindi Impenetrable National Park and the Virunga Volcano region are the last remaining habitats of the highly endangered mountain gorilla (Gorilla beringei beringei). This conservation area, shared by Uganda, Rwanda and the Democratic Republic of Congo, also acts as a refuge for biodiversity and high endemism in the Albertine Rift of Central East Africa. This particular region has suffered from a number of years of civil strife, which have severely affected the management of these forests. This paper will explore the experiences of the International Gorilla Conservation Programme (IGCP) obtained throughout the development of regional processes that are working towards establishing a transboundary-protected area. The establishment of a regional framework and tools utilized are described. The costs and constraints incurred by the IGCP and the resulting positive impacts on conservation are also highlighted.     

Effect of human disturbance on the structure and regeneration of forests in the Nevado de Toluca National Park, Mexico

Sample plots were established in the principal forest types in the the Nevado de Toluca National Park, Mexico including those dominated by Pinus hartwegii, Abies religiosa, Quercus laurina and Alnus jorullensis. The vertical structure was defined by three strata in the coniferous forests and two strata in the broadleaved forests. Timber harvesting in Abies religiosa and Quercus laurina forests and fires generated by humans in Pinus hartwegii forests impeded the recruitment of saplings. Mature trees were also heavily impacted by logging in Pinus hartwegii forests. On the contrary, Alnus jorullensis forests were increasing due to the disturbance of Pinus and Quercus forests, as well abandoned crop lands within the park. A combination of logging, uncontrolled fire, and grazing appears to be compromising the recruitment of important tree species in this national park. These factors, together with human settlements, have also increased the proportion of early successional species. Changes in forest structure from human disturbance indicate a need to control these activities if conservation goals are not to be compromised.