Landscape cohesion: an index for the conservation potential of landscapes for biodiversity

In urbanising landscapes, planning for sustainable biodiversity occurs in a context of multifunctional land use. Important conditions for species persistence are habitat quality, the amount and configuration of habitat and the permeability of the landscape matrix. For planning purposes, these determinants should be integrated into simple indicators for spatial conditions of persistence probability. We propose a framework of three related indices. The cohesion index is based on the ecology of metapopulations in a habitat network. We discuss how an indicator for species persistence in such a network could be developed. To translate this network index into an area index, we propose the concept of spatial cohesion. Habitat cohesion and spatial cohesion are defined and measured for single species or, at best, for species profiles. Since species differ in their perception of the same landscape, different species will rate different values of these indices for the same landscape. Because landscapes are rarely planned for single species, we further propose the index of landscape cohesion, which integrates the spatial cohesion indices of different species. Indices based on these concepts can be built into GIS tools for landscape assessment. We illustrate different applications of these indices, and emphasise the distinction between ecological and political decisions in developing and applying such tools. This revised version was published online in August 2006 with corrections to the Cover Date.     

陕北地区黄陵县与榆阳区蝴蝶多样性

通过对黄陵县及榆阳区蝴蝶多样性监测,旨在为陕北地区蝴蝶资源本底调查和环境监测提供基础数据。2016年5月至2018年8月在陕西省延安市黄陵县和榆林市榆阳区进行蝴蝶多样性监测,统计蝴蝶种类及群落多样性,并比较两样区各样线的蝴蝶资源相似性,共记录蝴蝶11 989号,隶属于5科54属78种。黄陵县共记录5科51属72种,蛱蝶科多样性指数和丰富度指数最高,而榆阳区共计5科34属43种,灰蝶科多样性指数和丰富度指数最高,两样区蝴蝶群落动态存在差异,黄陵县5月的蝴蝶物种丰富度最高,而榆阳区6月的丰富度最高。对不同样线蝴蝶多样性分析表明,黄陵县样区内各样线蝴蝶多样性指数、均匀度和丰富度均高于榆阳区。两样区蝴蝶物种组成相似度为0.47,为中等不相似,10条样线共有种10种。研究结果表明,蝴蝶多样性与生境关系密切,样区植物资源丰富,蝴蝶物种多样性和丰富度高。     

Advances in Phenazines over the Past Decade: Review of Their Pharmacological Activities,Mechanisms of Action,Biosynthetic Pathways and Synthetic Strategies

Phenazines are a large group of nitrogen-containing heterocycles, providing diverse chemical structures and various biological activities. Natural phenazines are mainly isolated from marine and terrestrial microorganisms. So far, more than 100 different natural compounds and over 6000 synthetic derivatives have been found and investigated. Many phenazines show great pharmacological activity in various fields, such as antimicrobial, antiparasitic, neuroprotective, insecticidal, anti-inflammatory and anticancer activity. Researchers continued to investigate these compounds and hope to develop them as medicines. Cimmino et al. published a significant review about anticancer activity of phenazines, containing articles from 2000 to 2011. Here, we mainly summarize articles from 2012 to 2021. According to sources of compounds, phenazines were categorized into natural phenazines and synthetic phenazine derivatives in this review. Their pharmacological activities, mechanisms of action, biosynthetic pathways and synthetic strategies were summarized. These may provide guidance for the investigation on phenazines in the future.     

A seasonal model of contracts between a monopsonistic processor and smallholder pepper producers in Costa Rica

We model the contractual arrangements between smallholder pepper (Piper nigrum L.) producers and a single processor in Costa Rica. Producers in the El Roble settlement sell their pepper to only one processing firm, which exerts its monopsonistic bargaining power by setting the purchase price of fresh pepper. It also sets quality norms that result in the rejection of considerable amounts of the pepper produced by individual farmers. Because the firm is not able to produce its own raw pepper and requires a sufficiently stable flow of the fresh product to be processed into high quality white pepper, it usually relies on contracts with individual smallholders. Nevertheless, the latter considered collective marketing and took the initiative to propose a group contract with the firm. Such a contract increases the producers’ bargaining power vis-à-vis the processing firm and reduces rejection rates as more care is taken when transporting the pepper to be processed. Although a group contract causes the firm to lose part of its monopsonistic rents, it also reduces transaction costs as only one contract must be negotiated instead of many. Both the firm and the producers benefit, yet from the very beginning of the association, the producers breached the group contract. We have used a mixed integer linear model which, given a set of constraints, maximises the weighted sum of the expected incomes of the firm and producers. We modelled the contract chosen by the firm and the producers according to the conditions included, such as minimum income requirements and risk considerations of both processor and farmers. We calibrated the model with data from pepper producers and the firm in El Roble. The results show that at different fresh pepper prices, the contract preferred changes with the bargaining power attributed to the firm and smallholders. However, in general, it can be concluded that fresh pepper prices high enough to cover the costs, for the farmers, of a group contract lead to lower rejection rates, and thus to more pepper of an acceptable quality, increasing the incomes of both the processor and the farmers. This is also of interest in agricultural policy-making.     

A participatory, farming systems approach to improving Bali cattle production in the smallholder crop-livestock systems of Eastern Indonesia

Bali cattle (Bos javanicus) account for about one quarter of the total cattle population in Indonesia and are particularly important in the smallholder farming enterprises of the eastern islands. The population of Bali cattle is declining in most areas of Eastern Indonesia because demand for beef cattle exceeds the local capacity to supply these animals. Indonesian agencies recognise that new strategies are required to improve the productivity of Bali cattle and to address major constraints relating to animal husbandry and nutrition. To date, the adoption of cattle improvement technologies has been historically slow in Indonesia, as is the case elsewhere.This paper reports on key findings from a long-term study conducted between 2001 and 2009 with smallholder households from six villages in South Sulawesi and Central Lombok, to develop and test an approach for evaluating and increasing the adoption of cattle and forage improvement technologies. The approach is based on the principles of farming systems and participatory research and involved four main steps; (1) benchmarking the current farming system; (2) identifying constraints to cattle production and strategies to address them; (3) desktop modelling of the production and economic impacts of selected strategies; and (4) on-farm testing of the most promising strategies with 30 participant smallholder households.The approach was found to be successful based on: (1) sustained adoption of a package of best-bet technologies by the 30 participating households; (2) evidence of positive production, social and economic impacts; and (3) significant diffusion of the cattle improvement technologies to other households in the project regions.     

Mode of action of famoxadone

Famoxadone is a preventative and curative fungicide recently developed for plant disease control. The molecule and its oxazolidinone analogs (OADs) are potent inhibitors of mitochondrial electron transport, specifically inhibiting the function of the enzyme ubiquinol:cytochrome c oxidoreductase (cytochrome bc₁). Visible absorbance spectral studies on the purified enzyme suggested that famoxadone bound close to the low potential heme of cytochrome b. This binding mode was confirmed in competitive binding experiments by studying the displacement of a radiolabelled OAD from submitochondria. EPR studies on the binding of famoxadone to submitochondria and purified bc₁ suggested its binding mode was more like that of myxothiazol than that of stigmatellin (ligands known to bind near the low potential heme). Zoospores of Phytophthora infestans, when given low concentrations of famoxadone and other OADs, were observed to cease oxygen consumption and motility within seconds and later the cells disintegrated, releasing the cellular contents. Famoxadone was a potent inhibitor of the growth of Saccharomyces cerevisiae when grown on non-fermentable carbon sources and it was an approximately 50-fold less potent inhibitor of growth when the yeast was grown on a fermentable carbon source, glucose. Such physiological observations are consistent with the loss of mitochondrial function imposed by famoxadone and OADs. Single amino acid changes in the apocytochrome b of baker's yeast cytochrome b located near the low potential heme altered the inhibition constants for the inhibitors famoxadone, myxothiazol, azoxystrobin and kresoxim-methyl differentially, thus strongly suggesting different binding interactions of the protein with the inhibitors. © 1999 Society of Chemical Industry     

乙虫脒对水稻螟虫的作用方式和应用研究

通过室内生物测定和田间试验 ,较系统地研究了乙虫脒对水稻螟虫的内吸、触杀和杀卵活性以及田间效果 ,同时评价了其对天敌的安全性。结果表明 :1)乙虫脒对二化螟和三化螟的内吸活性很好 ,且对二化螟的活性高于三化螟 ,2 5mg/ L乙虫脒对二化螟和三化螟的内吸杀虫效果分别为 90 .9%和 50 .0 % ,10 0mg/ L乙虫脒对三化螟的杀虫效果为 92 .3%。 2 )触杀活性高 ,对三化螟和二化螟的接触 L D50 值分别为 6 .4×10 -5μg/头和 2 .13× 10 -5μg/头 ,大大低于甲胺磷的 L D50 值 (1.331× 10 -3 和 1.781× 10 -3 μg/头 )。 3)综合活性好 ,对二化螟和三化螟分别只需 2 0和 2 5mg/ L即可达到 85%以上的防治效果。 4 )有一定的杀卵活性 ,2 0 0mg/ L对二化螟和三化螟的杀卵效果分别为 83.4 %和 0 .7% ,50 0 mg/ L对三化螟的杀卵效果为 93.4 %。 5)田间试验表明 ,112 .5g/ hm2 (a.i.,下同 )乙虫脒可有效控制三化螟枯心 ,在江苏省高淳地区 30 0 g/ hm2 可有效控制三化螟白穗 ,而在江苏省如东地区 6 7.5g/ hm2 即对三化螟和大螟白穗有较好的控制效果。此外 ,112 .5g/hm2 还对飞虱有较好的控制作用。 6 )对寄生蜂和蜘蛛较安全。     

我国西南岩溶地区发展畜牧业的战略设想

我国西南岩溶地区草地资源丰富 ,有适宜发展饲用植物的生物气候资源 ,有一定的家畜基础和技术储备 ,有社会发展的需求 ,因此有建成畜牧产业带的基础。现阶段虽然起点低 ,但潜力巨大 ,可以发展以林业为主的水土保持畜牧业、农耕地区的畜牧业、景观农业中的畜牧业、城郊畜牧业和山地畜牧业。畜牧业产业化应遵守 5项原则 ,并具备 8个方面的特色 ,可以考虑建立 1个产业中心群 ,2个产业带的设想。最后提出国家设立专项畜牧产业带的发展基金、组建省际协调组织、大力发展每个畜牧产业带的龙头企业和企业集团、建立完善的投资管理系统和技术支持系统等 5条具体建议     

大运公路绿色通道建设总体规划构想

通道绿化是山西省生态建设的一项重要内容。该文在实地调查、现场论证和深入细致研究的基础上,提出了大运路绿色通道建设指导思想、规划原则、建设目标和各区段的绿化模式。     

简评加州私有土地的木材管理

在加州,私人及私营公司拥有的生产性林地占４５％。为了收获木材,这些林地的业主需要持有执照的专业林业工作者准备一份详细的经营计划,该计划需经州政府广泛的审阅。这种经营计划往往耗资６０００～１２０００美元或更多的资金。计划的准备及州政府的审阅耗时６个月或更长的时间。林业工作者所作的决策受到法律、林地条件、经济状况和林地业主的目的等限制。林业实践法规对造林体系的选择及采伐后要达到 的更新量有详细的标准。