有效营造城市特色景观研究

在经济全球化和信息高度发达的今天,城市文化出现多元化的现象,导致全球范围内的文化"趋同",各种设计形式和手法简单的如同潮流般被模仿.现从城市景观的基础理论入手,分析建设有城市特色景观的重要性和意义.在借鉴国外的理论研究和实践经验的基础上,探索营造城市特色景观的有效方法和途径.     

堤滩刺槐林改建栽培油桃

1998年从山东省果树引进超五月火油桃，利用砍伐刺槐后的堤滩地栽培，经3年管理，平均666.7m^2产油桃1602.4kg，经济效益显著。     

Computation of the Boltzmann entropy of a landscape: a review and a generalization

Landscape Ecology - A key goal of landscape ecology is to understand landscape ecological processes across space and through time, with reference to the central organizing principles of nature....     

Light studies in a spacing trial with apple on a dwarfing and a semi-dwarfing rootstock

Light interception by the orchard canopies in a spacing trial with Golden Delicious and Jonathan on M IX and on M II was measured in 1968, 1969 and 1970. In 1969 and 1970 light distribution over the Golden Delicious hedges in the high-density plots was also measured and related to fruit and foliage distribution and to fruit quality. Simultaneously, integrated light readings at 100–200 locations were taken over 24-hour periods, using a photochemical method.Although all plots attained their ceiling yield level in 1967, the 6th year after planting, light interception continued to increase from 1968 to 1970. In the low-density plots — 1100 trees per ha on M IX and 660 trees per ha on M II — the canopies intercepted roughly half of the incident light and yields levelled off at 40 tons per ha. The high-density M IX plot (3300 trees per ha) intercepted two-thirds, the high-density M II plot (2260 trees per ha) more than three-quarters of incident light. Both plots yielded more than 70 tons per ha in 1967 and 1968, but thereafter the yield level dropped, especially for trees on M II, presumably because of mounting inter-tree competition for light.Light levels in the hedges in the high-density plots at equal distances from the hedge perimeter were very much the same for both varieties, for both rootstocks and in the two years. Light levels fell sharply towards the interior and bottom parts of the hedges. The main advantage of the M IX hedge was its smaller cross section, leaving little room for a poorly illuminated centre. At lower light levels weight per fruit and especially fruit colour declined, but the relation between light level and fruit quality was not consistent for both rootstocks and in both years. These inconsistencies could be explained on the basis of differences in pruning system, affecting the type of wood on which the fruit is borne.Fruit was concentrated in the interior part of the hedges, so that a high proportion of the crop suffered from the poor light conditions in this part. Fruit distribution was generally correlated with foliage distribution. In the M IX hedge by far the highest leaf density was found in the centre of the hedge. This is an advantage in comparison with the large leaf area — relatively unproductive and casting much shade — in the top of the M II hedge. Light measurements before and after fruit removal suggested that the shade cast by the fruit is negligible as compared to shading by the foliage.It is concluded that canopy architecture in the high-density M IX plot, with a leaf area index of 2.15, is close to the optimum for single row planting systems in Northwest Europe. Gains in percentage light interception, as in the high-density M II plot, are associated with a greatly inferior light distribution over the canopy, leading to lower yields per unit growth and deterioration of fruit quality. In addition to light, pruning strongly influences fruit quality.     

The distribution of a threatened migratory bird species in a patchy landscape: a multi-scale analysis

Understanding the driving forces behind the distribution of threatened species is critical to set priorities for conservation measures and spatial planning. We examined the distribution of a globally threatened bird, the corncrake (Crex crex), in the lowland floodplains of the Rhine River, which provide an important breeding habitat for the species. We related corncrake distribution to landscape characteristics (area, shape, texture, diversity) at three spatial scales: distinct floodplain units (“floodplain scale”), circular zones around individual observations (“home range scale”), and individual patches (“patch scale”) using logistic regression. Potential intrinsic spatial patterns in the corncrake data were accounted for by including geographic coordinates and an autocovariate as predictors in the regression analysis. The autocovariate was the most important predictor of corncrake occurrence, probably reflecting the strong conspecific attraction that is characteristic of the species. Significant landscape predictors mainly pertained to area characteristics at the patch scale and the home range scale; the probability of corncrake occurrence increased with potential habitat area, patch area, and nature reserve area. The median potential habitat patch size associated with corncrake occurrence was 11.3 ha; 90% of the corncrake records were associated with patches at least 2.2 ha in size. These results indicate that the corncrake is an area-sensitive species, possibly governed by the males’ tendency to reside near other males while maintaining distinct territories. Our results imply that corncrake habitat conservation schemes should focus on the preservation of sufficient potential habitat area and that existing management measures, like delayed mowing, should be implemented in relatively large, preferably contiguous areas.     

Estimating density of a territorial species in a dynamic landscape

Context

Conservation planning for at-risk species requires understanding of where species are likely to occur, how many individuals are likely to be supported on a given landscape, and the ability to monitor those changes through time.

Objectives

We developed a distribution model for northern spotted owls that incorporates both habitat suitability and probability of territory occupancy while accounting for interspecies competition.

Methods

We developed range-wide habitat suitability maps for two time periods (1993 and 2012) for northern spotted owls that accounted for regional differences in habitat use and home range size. We used these maps for a long-term demographic monitoring study area to assess habitat change and estimate the number of potential territories based on available habitat for both time periods. We adjusted the number of potential territories using known occupancy rates to estimate owl densities for both time periods. We evaluated our range-wide habitat suitability model using independent survey data.

Results

Our range-wide habitat maps predicted areas suitable for territorial spotted owl presence well. On the demographic study area, the amount of habitat declined 19.7% between 1993 and 2012, while our estimate of the habitat-based carrying capacity declined from 150 to 146 territories. Estimated number of occupied territories declined from 94 to 57.

Conclusions

Conservation and recovery of at-risk species depends on understanding how habitat changes over time in response to factors such as wildfire, climate change, biological invasions, and interspecies competition, and how these changes influence species distribution. We demonstrate a model-based approach that provides an effective planning tool.

     

果实乃日中储水库:一个长期争议的问题(英文)

20世纪初创立的所谓"果实乃日中储水库"的理论,在70—80年代受到了挑战。反对者认为原来理论创立者所采用的是切枝试材而非完整植株,属于试验方法上的错误。他们怀疑切枝试材会迫使形成一种非自然的水势梯度,导致蒸腾的叶片能够从果实获取水分。本文报道氚水示踪法在完整植株上的试验结果,证明果实的水分完全可以被叶片抽走,此外,"去果实"和"留果实"的对比试验证明果实的存在有利于降低叶片在昼间的缺水程度,即叶水势相对较高。作者指出果实在夜间对水分的竞争力往往超过叶片,所以结果多的果树植株反而容易受旱而死。因此,单纯把果实比喻为"储水库",作为科学用语似不恰当。     

Behavior as a tool for assessing a managed landscape: a case study of the Karner blue butterfly

In an increasingly human-dominated landscape, effective management of disturbance-maintained ecosystems, such as grasslands and savannas, is critical to the conservation of biodiversity. Yet, the response of individual organisms to landscapes created by disturbances and management is rarely studied. In this study, we examined the endangered Karner blue butterfly, Lycaeides melissa samuelis, in a heterogeneous oak savanna. Our objective was to quantify the butterfly’s habitat use and behavior to assess the effects of prescribed burning. The oak savanna management in Ohio, USA divides each Karner blue site (n = 4) into three units. Each one-third unit is then burned, mowed, or unmanaged in an annual rotation within each site, and the result is a fire return interval of ~3 years. Our surveys measured habitat use, while behavior observations quantified reproduction and foraging for the two annual broods. Our habitat use results showed burned treatments were recolonized quickly, but there was not a clear selection for burned treatments. Foraging rates were similar in all treatments; however, females oviposited significantly less in unmanaged treatments (only 5 of 127 ovipositions). This oviposition preference was likely due to habitat degradation and the availability of recently burned, early successional habitat. Since Karner blues avoided reproduction in units unburned for ≥4 years, these units could be burned to create high quality early successional habitat. These results demonstrate how behavioral decisions can be pivotal forces driving spatial population dynamics. Our case study demonstrates how a fine-scale landscape perspective combined with measurements of behavioral processes can assist with management decision-making.     

Experimental study of a new hypertension-related gene Slc7a8

AIM: To investigate the disease related genes in SHR.METHODS: The total RNA samples were obtained from second-order mesenteric arteries and kidney of SHR and WKY.Microarray containing over 10 000 genes was used to determine the level of mRNA expression in two groups.The genes were identified using real time quantitative RT- PCR.RESULTS: 19 down-regulated genes were determined by microarray,which were classified as chaperones,transport,growth factors,signal transduction,nuclear factor and lipoprotein.The result was confirmed by the method of real time quantitative RT- PCR.It was found that the Slc7a8 gene was up-regulated 9.3 fold in SHR.CONCLUSION: Slc7a8 gene may relate to hypertension.Further study on the Slc7a8 gene and its function would help us wholly understand the mechanism of hypertension and provide new clue to hypertension causes.     

A Method to Efficiently Apply a Biogeochemical Model to a Landscape

Biogeochemical models offer an important means of understanding carbon dynamics, but the computational complexity of many models means that modeling all grid cells on a large landscape is computationally burdensome. Because most biogeochemical models ignore adjacency effects between cells, however, a more efficient approach is possible. Recognizing that spatial variation in model outputs is solely a function of spatial variation in input driver variables such as climate, we developed a method to sample the model outputs in input variable space rather than geographic space, and to then use simple interpolation in input variable space to estimate values for the remainder of the landscape. We tested the method in a 100 km×260 km area of western Oregon, U.S.A. , comparing interpolated maps of net primary production (NPP) and net ecosystem production (NEP) with maps from an exhaustive, wall-to-wall run of the model. The interpolation method can match spatial patterns of model behavior well (correlations>0.8) using samples of only 5 t o 15% of the landscape. Compression of temporal variation in input drivers is a key step in the process, with choice of input variables for compression largely determining the upper bounds on the degree of match between interpolated and original maps. The method is applicable to any model that does not consider adjacency effects, and could free up computational expense for a variety of other computational burdens, including spatial sensitivity analyses, alternative scenario testing, or finer grain-size mapping.     

Landscape drivers of connectivity for a forest rodent in a coffee agroecosystem

Landscape Ecology - The majority of remaining tropical forests exist as fragments embedded in a matrix of agricultural production. Understanding the effects of these agricultural landscapes on...     

Behaviour of some pesticides in a nutrient-film and in a rock-wool system

Adsorption of ethoprophos, tetrachlorvinphos and etridiazole onto rock-wool was found to be much weaker than adsorption onto soils. The rates of transformation in water and in water plus rock-wool at 20°C were low. The concentration of etridiazole was measured in a nutrient-film system with recirculating nutrient solution. The decrease was rapid in the first few hours but was more gradual afterwards, to low values at 8 days after application. Etridiazole penetrated poorly into the lower part of a rock-wool system when the solution was trickled near the stem-base of the tomato plants.     

Utilization of a habitat mosaic by cotton rats during a population decline

This study describes the demographic features of a population of Sigmodon hispidus utilizing the habitat mosaic provided by a Carolina Bay on the Atlantic coastal plain of South Carolina. A total of 71 cotton rats were captured 160 times on a 4 ha grid during a winter decline from 25/ha to less that 1/ha. Body weights of adults declined until early February and then increased; those of subadults grew very slowly until February followed by a spurt in growth. Weight gain did not differ between survivors and non-survivors for males, but female survivors gained 1.5 g per week more than non-survivors. Female subadults exhibited higher mortality early in the decline and males later.Adult females were randomly distributed across 8 microhabitats, whereas adult males were almost exclusively confined to heavy Rubus cover. Subadult males used wet sites more than any other cohort; subadult females were widely distributed using drier sites most frequently. By the end of the decline, all survivors were localized in Rubus-dominated patches. No statistically significant changes in electromorph genotypes or allele frequencies were detected, but survivors had a higher frequency of the F-allele at the adenylate kinase locus than did non-survivors (42.3% vs. 16.7%).Our findings affirm the importance of a landscape perspective in understanding the population dynamics of cotton rats, and show how a habitat mosaic influences survival differentially among sex-age cohorts.     

酸甜风味西瓜新品种‘SW’选育

<正>目的与意义:随着生活水平的提高,生产者和消费者对西瓜品质提出了更高的要求,因此选育高品质的西瓜品种就显得尤为重要。西瓜果实品质包括商品品种、感官品质和营养品质。有机酸的成分与含量在感官品质、营养品质和果实代谢中起重要作用。合适的糖酸比是形成优质风味果实的必要条件,当果实的含糖量都较高时,高酸含量的果实更受喜爱。目前新疆农业科学院哈密瓜研究中心已成功选育出一系列风味甜瓜品种,具有广阔的市场前景。西瓜果     

以公司名义越权订立担保合同的效力问题

农村稳则国家稳,农村和则天下和。我国是一个农业大国,解决好农村社会纠纷对治国安邦意义重大。那么,如何培养农民的自我保护意识,让他们“敢于维权、善于维权”?本栏目以近年来“三农”领域内发生的具体维权事件为着眼点,结合相关法律法规,对事件发生的原因和处理结果进行全面梳理审视,一方面为合法权益受到侵害的人们指点迷津;另一方面,为法律体系的进一步完善抛砖引玉。     

香蕉trihelix转录因子MaGTL1a的分离及特性

【目的】研究香蕉MaGTL1a转录因子的特性及其基因表达规律,探讨MaGTL1a转录因子在香蕉果实成熟过程中的作用。【方法】以香蕉果肉c DNA为模板,采用RT-PCR获得MaGTL1a序列;利用烟草瞬时表达法和酵母系统分析MaGTL1a亚细胞定位和转录调控活性;通过实时荧光定量PCR分析MaGTL1a在香蕉果实成熟过程中的表达;运用烟草BY2悬浮细胞瞬时表达法研究MaGTL1a启动子活性。【结果】MaGTL1a c DNA序列含有1个2 283 bp的开放阅读框,编码761个氨基酸,属于trihelix转录因子的GT-2亚家族;亚细胞定位和转录活性分析显示,MaGTL1a定位于细胞核,并在酵母和植物体内具有转录激活活性;实时荧光定量PCR和启动子活性试验表明,MaGTL1a转录水平和启动子活性均受乙烯诱导,并且MaGTL1a转录水平随着香蕉果实的成熟进程而明显增强。【结论】MaGTL1a是一个受乙烯诱导和核定位的转录激活子,可能参与了香蕉果实成熟的调控。