磺胺二甲嘧啶与地克珠利治疗塞北兔球虫病的效果比较研究

为探讨磺胺二甲嘧啶与地克珠利对塞北兔自然感染球虫病的治疗效果.试验选取日龄、营养状况、发病程度一致、体重差异性不显著的30只塞北兔为试验动物,将其随机分成3组,A组(磺胺二甲嘧啶组)、B组(地克珠利组)、C组(空白对照组),每组10只.向A组饮水中添加500 mg/kg磺胺二甲嘧啶,向B组饲料中添加2 mg/kg地克珠...     

干旱、半干旱区造林密度及其影响因素研究综述

通过对近年来有关造林密度的研究分析,详细阐述了造林密度与水分平衡的关系;造林密度与近自然造林的关系;造林密度与林种的关系。通过对上述影响因素的研究分析,结合干旱、半干旱地区的实际情况,给出该区域小叶锦鸡儿、胡枝子、油松、樟子松、沙地柏、油蒿等几种常见乔灌木树种造林的合理密度范围,为干旱地区造林绿化提供了理论依据。     

Implications of crude oil pollution on natural regeneration of plant species in an oil-producing community in the Niger Delta Region of Nigeria

The study evaluated the impact of crude oil pollution on natural regeneration of plant species in a major oil-producing community in the Niger Delta region of Nigeria. Three sites—unpolluted site(US), polluted and untreated site(PUS), and polluted and treated site(PTS)—were purposively chosen for the study. The seedling emergence method was used to evaluate soil seed banks in the various sites at two depths, 0 to 10 cm and 10 to 20 cm. Woody-plant species richness, abundance, and diversity were higher in the US seed bank than in the PUS and PTS seed banks. The highest number of non-woody plants was observed in the US, followed by the PTS, and then the PUS. Both species richness and diversity of non-woody plants were highest at the US, followed by the PUS, and lowest in the PTS. Woody species in the US seed bank were 87.5% and 80% dissimilar with those of the PUS and PTS at 0–10 cm and 10–20 cm respectively. No variation was observed between woody species in the PUS and PTS seed banks. Non-woody species at 0-10 cm US seed bank were 73.08% dissimilar with those of PUS at the two soil depths and 81.48/88.46% dissimilar with those of the 0–10/10–20 cm of the PTS respectively. At 10–20 cm, non-woody species of the US were 69.66% dissimilar with those from each of the two soil depths in PUS; and 73.91/81.82% dissimilar with those of 0–10/10–20 cm of the PTS respectively. Non-woody species variation between the PUS and PTS was higher at 10–20 cm than 0–10 cm. The poor seed bank attributes at the polluted sites demonstrates that crude oil pollution negatively affected the natural regeneration potential of the native flora because soil seed banks serve as the building blocks for plant succession. Thorough remediation and enrichment planting are recommended to support the recovery process of vegetation in the polluted areas.     

Optimizing any-aged management of mixed boreal forest under residual basal area constraints

The current trend of forest management in many countries is reduced use of clear-felling and planting, and increased use of continuous cover management. In Finland, the new forest act of 2014 made all types of cuttings equally allowable on the condition that if the post-cutting residual stand basal area is too low, the stand must be regenerated within certain time frame. Forest landowner can freely choose between evenand uneven-aged management. This study developed a method for optimizing the timing and type of cuttings without the need to categorize the management system as either even-aged or uneven-aged. A management system that does not set any requirements on the sequence of post-cutting diameter distributions is called any-aged management. Planting or sowing was used when stand basal area fell below the required minimum basal area and the amount of advance regeneration was less than required in the regulations. When the cuttings of 200 stands managed earlier with even-aged silviculture were optimized with the developed system, final felling followed by artificial regeneration was selected for almost 50% of stands. Reduction of the minimum basal area limit greatly decreased the use of artificial regeneration but improved profitability, suggesting that the truly optimal management would be to use natural regeneration in financially mature stands. The optimal type of thinning was high thinning in 97–99 % of cases. It was calculated that the minimum basal area requirement reduced the mean net present value of the stands by 12–16 % when discount rate was 3–5 %.     

土元的病害防治

一、膨胀病土元膨胀病又称大肚子病,是消化不良而引起的腹部膨大的疾病.病因 早春晚秋自然温度低,而天气变化无常.气温突然降低,新陈代谢水平降低,食物在消化道内发酵产生气体.症状 腹部肿大,爬行不便,食欲下降或停食,腹泻,粪便变为绿色或酱色,虫体表面的光泽消失,如治疗不及时,3天左右可导致死亡.     

蓝莓庄园，为种子建一个银行

Daniel的蓝莓有机庄园建在浙江省宁海县一个青山绿水的山村里。 每个都市人都有一个回归田园、亲近自然的梦想。如果不是Daniel他自己介绍,很难想象照片上这个戴着草帽、晒得黝黑的“农夫”在三年前却是一位外企的高管。     

现代化与自然共存：推进生态文明建设和构建美丽中国的基本目标

指出了从科学的角度来看,现代化与自然共存、经济建设与生物多样性和文化多样性保护共存是当今生态发展文明时代的奋斗目标,推进生态文明建设和构建美丽中国,就要围绕这些方面的要求来进行。简要地探讨了这方面的一些问题,并提出了相应的建议,供有关部门参考。     

烟雨武夷山

在一个烟雨迷蒙的日子来到武夷山。雨是雾状的,雨雾中的武夷山,像蒙着一层神秘面纱,这给予了我更多的想象。石头上长树,这是武夷山的奇观,也是武夷山的常态。巨大的石,上有树,下有水,山与水缠绕,水与树遥相呼应,于是这巨石不再单调呆板,平添了若干灵性。     

取法自然：纳西东巴文美学风格分析

东巴文承载了纳西族古老的美学传统,其文化精神契合于中国传统美学的意境体悟和生命意识.纳西先民以“林泉之心”直接观照自然,继而创造出具有和造化自然一样性质的审美意象,亦即所谓的“同自然之妙有”;同时把任自然的生活形态与精神境界都铸化在这种文字之中,体现了纳西东巴文与自然的亲密关系,而取法自然正是东巴文以主体之心体悟自然生命的结果,也是其最重要的美学风格.     

地带性植物在营建地域特色景观中的应用

在自然界中,植物与气候、地貌、土壤等环境要素共同形成一个自然综合体,因而地带内的植物可反映当地的综合环境特征,乃至风土人情。通过对地带性植物的概念和理论发展进行梳理,针对地带性植物资源分布调查的结果探讨城市园林绿地的营建方法,总结时下的关注热点及地带性植物在城市园林绿化中的应用特性和潜在价值。总结表明,以植物群落为主体的地域特色景观营建的理论和实践处于上升阶段。应以营建专类地带性植物景观为起点,模拟自然群落,建立人工生态系统,结合生态和气候、土壤等的地带性特征,展现人文历史风情。