修剪高度对季节性温度变化下早熟禾生理生态特性的影响

修剪高度的差异会影响冷季型草坪草的生长,探究合理的修剪高度可为草坪草可持续利用提供理论基础。本研究通过测定两年生长季（2012年和2013年）草地早熟禾（8年生）草坪的外观质量（TQ）、地上部分生物量（AB）、光合作用（Pn）、总呼吸作用（R_total）和碳水化合物（TNC）等指标,探讨了修剪高度对冷季型草坪草生理生态特性的影响。试验结果表明,当大气温度高于23~24℃时,不同修剪高度7.6 cm （高修剪高度,HM）和3.8 cm （低修剪高度,LM）下的早熟禾TQ、AB和Pn均降低,与HM相比,在LM下下降更显著。在7—9月的高温条件下,早熟禾地上部分、根系和土壤R高于Pn;但在美国新泽西州较冷的季节（5—6月） Pn高于R。研究表明,较低的修剪高度尤其是在高温条件下降低了草坪草Pn,季节性温度变化下可以通过改变修剪高度影响成熟草坪草的生长,从而缓解高温对草坪生长带来的不利影响。     

山西天然草地主要有毒植物

山西省天然草地中有毒植物有３５科９１属１４８种，其中以亚高山草甸类草地中出现较多，占总产草量的１５％－１８．１％。文章就山西天然草地上出现数量较多，易引起家畜中毒的植物，从生态分布、有毒成分及对家畜的危害等方面进行了研究，并提出了防除的建议。     

黄花苜蓿的优良特性与开发利用

本文简要介绍了苜蓿属植物黄花苜蓿的分布、生境以及饲用价值高、抗寒、抗旱、耐盐碱等优良特性,并对其与紫花苜蓿相比所占的优势、对苜蓿育种的贡献及在草地改良中的生态价值进行了评述。在简述目前我国黄花苜蓿国研究现状的同时,提出要大力开发利用这一牧草资源,它必将对我国畜牧业生产、退化草地改良及水土保持等发挥重要作用。     

Understanding stakeholders’ opinions and preferences for non-native pet trade management in Florida

There is growing recognition of the link between the non-native pet trade and the introduction and establishment of invasive species due to the release and escape of non-native pets. However, it is unclear whether participants in the pet trade recognize the magnitude of this invasion risk. Successful mitigation of the pet trade invasion risk requires stakeholder support for, and participation in, regulations. We conducted 29 interviews in Florida to investigate key stakeholders’ opinions about the pet trade invasion risk and the effectiveness of potential regulations to mitigate this risk. Respondents framed the effectiveness of regulations in terms of their feasibility. Respondents also identified lack of trust and the existence of an adversarial relationship among stakeholder groups as major barriers to managing the pet trade invasion risk. Compliance with regulations may be improved if policy makers and managers utilize participatory decision-making to engage stakeholders in management of this risk.     

Genetic diversity of Bangladeshi native chickens based on complete sequence of mitochondrial DNA D-loop region

ABSTRACT

1. The aim of this study was to explore genetic diversity and possible origin of Bangladeshi (BD) native chickens. The complete mtDNA D-loop region was sequenced in 60 chickens representing five populations; naked neck, full feathered, Aseel, Hilly and autosomal dwarf. The 61 reference sequences representing different domestic chicken clades in China, India, Laos, Indonesia, Myanmar, and other Eurasian regions were included. The mtDNA D-loop sequence polymorphism and maternal origin of five BD populations were analysed.

2. A total of 35 polymorphic sites, and 21 haplotypes were detected in 60 mtDNA D-loop sequences. The haplotype and nucleotide diversity of the five populations were 0.921 ± 0.018 and 0.0061 ± 0.0019, respectively. Both mtDNA network and phylogenetic analysis indicated four clades (four haplogroups) in BD populations (21 haplotypes) along with 61 reference haplotypes. Clade E contained the most individuals (20) and haplotypes (11) of BD chickens, followed by clade D (17, 6), clade C (12, 2) and clade F (11, 2), respectively.

3. The higher number of unique haplotypes found in Yunnan, China, suggested that the origin of BD chickens was in this region. The haplotypes from different haplogroups were introduced in Bangladeshi chickens from India, China and Myanmar. The phylogenetic tree showed a close relationship of BD chickens with the clusters from India, China, Myanmar and Laos, and indicated the dispersion of BD chickens from these sources. The phylogenetic information revealed high genetic diversity of BD chickens because of their origin from different lineages with high genetic variation and distance, which was determined from four cluster and neighbour-joining trees.

4. In conclusion, BD populations had high genetic diversity. The mtDNA network profiles and phylogenetic trees showed multiple maternal origins of BD chickens from India, China, Myanmar and Laos.     

微机地理信息系统软件PC ARC／INFO功能简介

本文主要介绍了微机地理信息系统软件 PC ARC/INFO 的结构,主模块 ARC 及其主要子模块的功能,系统优化的方法及该系统当前的主要应用领域及前景展望。     

豌豆蚜生物生态学特性

豌豆蚜(Acyrthosiphon pisum)是许多豆科作物及牧草的重要害虫,不但直接取食寄主植物,造成严重的经济损失,而且还会传播多种植物病毒。豌豆蚜作为生态学研究的模式昆虫,具有复杂的生活周期、多样的生殖方式、表型可塑性以及与细菌复杂的共生关系等诸多特点,已成为众多科学家感兴趣的研究对象。本文全面总结了豌豆蚜生物生态学特性的研究成果,重点综述了豌豆蚜的多型现象和内共生菌研究的最新进展,提出研究豌豆蚜在全球气候和作物种植结构变化下生物生态学特性演变规律的必要性,加强其生态适应性及多型现象等遗传机制研究,以期为建立该虫的可持续防控技术体系提供依据。     

草坪与稀树草坪生态作用的比较分析

草坪和稀树草坪是城市绿地生态系统的重要组成部分。但是它们的生态作用又有较大差异 ,通过对降低噪音 ,吸附灰尘 ,降低温度与增加湿度等生态作用的测定和定量分析 ,证明草坪和稀树草坪对城市生态系统的有利影响都明显高于裸地 ,稀树草坪的作用又明显高于单一的草坪     

山东枣庄市沿运区域农业综合开发研究

以山东省枣庄市为例,通过对沿运区域资源条件的分析,以现代生态农业为理念,提出了山东省枣庄市沿运区域土地治理、农业现代化示范园建设、农业龙头企业培育、优质农产品生产基地等农业综合开发建设目标,为沿运区域现代农业综合开发提供了典型案例。