Needle Collection Time for Nutrient Evaluation in Christmas Tree Production     

《Communications in Soil Science and Plant Analysis》2012,43(1-2):471-477

Christmas tree needle sampling to evaluate nutrient need is an established practice. Data to support the recommended fall sampling time in Oregon and Washington were not found. In addition, the recommendation for needle sampling of Fraser fir in North Carolina was made without data from winter months. The goal for this article is to affirm or modify recommended needle sampling time. Needles of Douglas fir, Turkish fir, Nordmann fir, Noble fir, Grand fir, and Fraser fir Christmas trees were collected monthly for a year, dried, and analyzed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and boron (B). No single period was found for any species when needle nutrient concentration was stable for all elements determined. Needle collection time was chosen by integrating cultural practices, likelihood of nutrient deficiency, and needle nutrient concentration changes for species grown in an area. Needle collection is recommended during February in western Oregon and Washington. The current sampling time, fall, is logical for Fraser fir Christmas tree production in North Carolina.  相似文献   

荔枝龟背天牛幼虫空间分布型研究   总被引：3，自引：0，他引：3  

韩日畴  徐洁莲 《昆虫天敌》1994,16(4):175-182

对荔龟背天牛幼虫于荔枝园中的空间分状况调查和分析，表明该虫的空间分布为负二项分布；空间图式是聚集型；分布的基本成分为疏松的个体群。聚集行为受环境因素（主要是荔枝品种）的影响，此外，利用分布型参数确定了龟背天牛的理论抽样数并建立了序贯抽样检定表。  相似文献   

Potential of weed seedbanks for managing weeds: a review of recent New Zealand research     

Anis Rahman  Trevor K. James  Nik Grbavac 《Weed Biology and Management》2001,1(2):89-95

Weed seedbanks are the primary source of weeds in cultivated soils. Some knowledge of the weed seedbank may therefore be appropriate for integrated weed management programs. It would also be very useful in planning herbicide programs and reducing the total herbicide use. However, a number of problems are inherent in the estimation of the seedbank size for arable weeds that usually have annual life cycles. In a long-term research project we have investigated the dynamics of weed seedbanks in corn fields for the past 8 years. Specific studies have included (i) developing cheap and efficient methods for estimating the weed seedbank; (ii) developing guidelines for efficient soil sampling (including the number and size of samples); (iii) influence of cultivation methods on weed seed distribution; (iv) mapping the spatial variability of the seedbank; (v) estimating the rate of seedbank decline for certain weed species; and (vi) assessing the potential of using the weed seed content in the soil to predict future weed problems. This paper reviews and summarizes the results of our research on the above aspects. The strong correlation between seedlings emerged in the greenhouse and seeds extracted in the laboratory for the most abundant weed species has demonstrated the potential for using the weed seed content of the soil to predict future weed infestations. The next step is to establish correlations with field emergence under commercial conditions using the sampling guidelines developed in our studies. Subsequently, we aim to offer the weed seedbank estimation as a commercial service to farmers for planning the most appropriate weed management options.  相似文献   

甘薯地土壤线虫群体分布规律及取样方法研究   总被引：2，自引：0，他引：2  

海棠  武保悦  金凤柱  胡跃高 《中国植保导刊》2006,26(10):7-10

在5年连作甘薯地,于甘薯移栽前和移栽后的不同时间,调查甘薯穴中和穴间、株间和行间以及各样点不同土层线虫的群体数量。分析明确了植物寄生线虫和非植物寄生线虫群体的水平分布和垂直分布规律,提出了研究和了解甘薯地土壤线虫发生动态的调查取样方法。  相似文献   

Identification of Landscape Elements Related to Local Declines of a Boreal Grey-sided Vole Population     

Frauke Ecke  Pernilla Christensen  Per Sandström  Birger Hörnfeldt 《Landscape Ecology》2006,21(4):485-497

Several studies indicate a long-term decline in numbers of different species of voles in northern Fennoscandia. In boreal Sweden, the long-term decline is most pronounced in the grey-sided vole (Clethrionomys rufocanus). Altered forest landscape structure has been suggested as a possible cause of the decline. However, habitat responses of grey-sided voles at the landscape scale have never been studied. We analyzed such responses of this species in lowland forests in Västerbotten, northern Sweden. Cumulated spring densities representing 22 local time series from 1980–1999 were obtained by a landscape sampling design and were related to the surrounding landscape structure of 2.5×2.5 km plots centred on each of the 22 1-ha trapping plots. In accordance with general knowledge on local habitat preferences of grey-sided voles, our study supported the importance of habitat variables such as boulder fields and old-growth pine forest at the landscape scale. Densities were negatively related to clear cuts. Habitat associations were primarily those of landscape structure related to habitat fragmentation, distance between habitat patches and patch interspersion rather than habitat patch type quantity. Local densities of the grey-sided vole were positively and exponentially correlated with spatial contiguity (measured with the fragmentation index) of old-growth pine forest, indicating critical forest fragmentation thresholds. Our results indicate that altered land use might be involved in the long-term decline of the grey-sided vole in managed forest areas of Fennoscandia. We propose two further approaches to reveal and test responses of this species to changes in landscape structure.  相似文献   

微孔草的分布及植物群落特征研究   总被引：5，自引：0，他引：5  

王钦  尚可政 《草业科学》1998,15(1):18-26

采用定量样地法,对孔微草这一特种油料植物的群落结构、群落变异以及群落特征进行了研究。结果表明,微孔草干物质生产量占总量的比率,休闲地为９．１６％、撩荒地为１６．９０％、油草地为１５．３２％、燕麦地为１０．６６％、青稞地为５．９７％;群落系数相应为８７．０９％、８７．９１％、９１．８２％、９５．６５％、９３．６０％;优势度相应为９．６０％、１３．４５％、１１．９９％、１６．６１％、７．１３％。经主分  相似文献   

成套小样园作为典型众数抽样调查单元的方法     

甄学宁  邓扬柱 《福建林学院学报》1999,19(1):44-46

本文介绍了用成套小样园作为典型众数抽样调查单元的方法测定两个不同林分小班的蓄积，并与用点抽样和不同形状样地的系统抽样结果相比较，表明用成套小样园作为典型众数抽样调查单元的方法能满足９０％以上的精度，而且工效很高；作者也探讨了使用此法的条件．  相似文献   

次黄筒天牛生物学特性及卵的空间分布研究   总被引：2，自引：0，他引：2  

陶静霞  堵鹤鸣 《蚕业科学》1997,23(4):197-201

次黄筒天牛在江苏太仓1～2年发生一代，幼虫在枝干内越冬，成虫6月上旬～7月中旬羽化，取食桑树的嫩叶、叶脉，产卵于桑树新梢端部。卵期13d，幼虫蛀入枝条，先向上蛀食到梢端再调头向下蛀食，枝条短的幼虫可入拳越冬，第2年5月中旬化蛹，蛹期约16d。被害株有效条数降低，影响产叶量。该虫卵的空间分布为聚集型。个体间相互吸引但聚集强度不高，并在此基础上提出了序贯抽样模型。  相似文献   

3种提取基因组DNA方法的比较分析     

刘燕  刘孟洲  徐彦祥 《中国畜牧兽医》2008,35(4):45-47

分别采用3种不同的方法提取基因组DNA，比较所提取的DNA的质量以及提取所需时间、费用，以期选择一种高效、简洁快速、价格合理的提取方法。结果发现这3种方法提取的质量都能达到相关分子生物学试验的要求，但在操作步骤、时间、价格等方面存在差异，具体比较结果可为分子生物学试验选择提取方法提供依据。  相似文献   

Comparison of sampling and isolation procedures for recovery of Yersinia enterocolitica serotype O:3 from the oral cavity of slaughter pigs   总被引：2，自引：0，他引：2  

T Nesbakken 《Acta veterinaria Scandinavica》1985,26(1):127-135

Yersinia enterocolitica serotype 0:3/biotype 4 was isolated from the oral cavity of altogether 32 (68.1 %) of 47 freshly eviscerated slaughter pigs. Most efficient recovery was achieved by cultivation of tissue samples from both tongue and tonsils of the same individual. The isolation rate so obtained was significantly higher than that obtained by separate examination of either tonsil swabs or tongue swabs. However, the isolation frequency achieved by combined swabbing of the 2 sites was not significantly different. In general, tonsils were more productive for the recovery of 0:3 strains than were tongues, and tissue samples yielded higher isolation rates than did swabs. Three-week cold enrichment in a low selective medium proved essential for optimal recovery. However, the highest number of isolates was obtained using a combination of methods, including direct plating and selective enrichment in a modified Rappaport broth in addition to cold enrichment.  相似文献