The value of vegetation cover for ecosystem services in the suburban context     

《Urban Forestry & Urban Greening》2016

Latin-American cities can be characterized by dynamic processes of urbanization that encroach upon the natural and semi-natural surrounding landscapes. Our study presents the effects of landscape development, transformed from semi-natural conditions into a mostly disperse suburban settlement. We explore the impact that this transformation has had on this context by three ecosystem services that regulate rainwater runoff, enhance microclimate conditions and help to improve air quality by monitoring vegetation cover. We have designed a spatio-temporal hierarchical analysis which employs remote sensing techniques to capture the structural changes of this landscape over long, medium and short term scales on two spatial levels. This methodological approach was tested in the Metropolitan Area of Santiago (MAS) as case study area. Despite of the increase in impervious surfaces due to urban processes, there has also been an increase in vegetation cover, which has led to an improvement in the provision of the above-mentioned ecosystem services. Hence, if diverse urbanization processes continue and they are coupled with an increase in vegetation cover, the provision of ecosystem services could also expand. This phenomenon can be observed in some areas, where public and private green spaces are created and maintained. Our data analyses give evidence that certain types of suburban areas which increase the share of vegetation cover can provide daily ecological benefits for urban neighborhoods, and beyond, for adjacent areas. Moreover, suburban development can successfully provide ecological benefits to citizens. Such processes can only be ecologically sustainable if the composition of vegetation is well-adapted to the regional climatic conditions.  相似文献   

Yield Performance of Wheat Isolines with Different Dosages of the Short Arm of Rye Chromosome 1          下载免费PDF全文

D. C. Maheepala  B. Ehdaie  J. G. Waines 《Journal of Agronomy and Crop Science》2015,201(2):152-160

Translocations of the short arm of rye (Secale cereale L.) chromosome 1 (1RS) in wheat (Triticum aestivum L. cv. Pavon 76) are known to increase root biomass. Such an increase enhances water and nutrient uptake and may improve grain yield. Two greenhouse experiments and a field experiment were carried out at the University of California, Riverside, in 2012 and 2013 under well‐watered and terminal drought treatments to evaluate phenotypic characters associated with varying dosages of 1RS, including grain yield. The genotypes used were cultivar Pavon 76 (R₀), Pavon 76/Pavon1RS.1AL (F₁ hybrid) with a single dosage of 1RS (R₁A), Pavon 1RS.1AL with two dosages of 1RS (R₂A), Pavon 1RS.1DL (R₂D) also with two dosages of 1RS and Pavon 1RS.1AL‐1RS.1DL (R₄AD) with four dosages of 1RS. There was a significant positive correlation between number of dosages of 1RS and root biomass. However, no correlation was found between root biomass and grain yield per plant. Drought in the field experiment reduced grain yield significantly. Under well‐watered field conditions, grain yield of R₂A (215.9 g plant^?1) was significantly greater than those of R₂D (191.8 g plant^?1) and R₄AD (161.7 g plant^?1). Also, grain yield of R₄AD was significantly less than those of F₁, Pavon 76 and R₂D under well‐watered conditions. Under drought field conditions, no significant differences were found among the genotypes for grain yield was found between F₁ (14.7 g plant^?1) and R₄AD (12.4 g plant^?1). Harvest index was significantly greater in well‐watered (44.2 %) than in drought (34.6 %) field conditions. On average, genotypes F₁ (42.3 %) and R₂A (40.6 %) had higher harvest index than R₂D (38.3 %) and R₄AD (35.5 %) in the field. Also, Pavon 76 (40.2) and R₂D (38.3) had higher harvest index than R₄AD. Drought tolerance was lowest for R₄AD due to its relatively lower grain yield potential. In general, Pavon 1RS.1AL carrying two dosages of 1RS showed higher grain yield under wet treatments. Pavon 1RS.1AL‐1RS.1DL carrying four dosages of 1RS produced the largest shoot and root biomasses, but the least grain yield.  相似文献   

Determination and Analysis of Heavy Metal Content in the Soil from Beef Cattle Farms in Three Regions of Xinjiang     

ZHANG Chao  LIU Ying-yu  ZHANG Xiao-hong  Wumaierjiang  YAO Gang 《中国畜牧兽医》2016,43(5):1244-1249

In order to study and evaluate the feeding environment of the beef cattle farms in Xinjiang, the contents of heavy mentals in the soil from 8 beef cattle farms in Xinjiang Aksu, Yili and Tacheng regions were tested according to the Field of Livestock and Poultry Environment Quality Standard (NY/T 388—1999).The atomic absorption spectroscopic method was used to determine the contents of As, Hg, Pb, Cd, and Cr.The mean contents of As, Hg, Pb, Cd, and Cr in 8 beef cattle farms soil were 0.389, 0.568, 22.708, 0.573 and 149.449 mg/kg, respectively, and they were all below the upper limit of NY/T 388—1999.The comprehensive heavy metal pollution index of 8 beef cattle farms were 0.577 to 0.994, and the index were 0.7 to 1 of two observation points in Yili and one observation point in Tacheng.The soil environment quality of these 3 farms were at the level of slight cleaning.The comprehensive heavy metal pollution index of other five observation points were ≤0.7, the soil environment was in a clean level.The soil environment of beef cattle farms in these three regions conformed to the standards of livestock for environment quality and safe products.  相似文献   

穗期玉米昼夜生理状态规律的遥感综合探测研究     

元楠楠  邢立新  张艳红  潘响亮 《江西农业学报》2015,(5)

针对QY、PRI、NDVI、水势分别从不同的方面反映玉米的生理状况,以甜糯二号玉米作为材料,通过田间试验测量玉米昼夜4个参数值,研究了QY、PRI、NDVI、水势4个参数的昼夜变化,并且分析它们之间的相关性。结果表明,QY、水势、PRI三者具有很强的相关性,并且能建立回归模型表示它们之间的联系。  相似文献   

Response of labile organic C and N pools to plastic film removal from semiarid farmland soil          下载免费PDF全文

S. S. Luo  L. Zhu  J. L. Liu  L. D. Bu  S. C. Yue  Y. F. Shen  S. Q. Li 《Soil Use and Management》2016,32(4):535-542

To examine the effects of plastic film removal on grain yield and soil organic matter (SOM), a spring maize (Zea may L.) field experiment was conducted for 5 yr at Changwu Agricultural and Ecological Experimental Station of Northwest China. Compared with traditional plastic film mulching during entire growing stages (FM), plastic film removal at the silking stage (RM) resulted in a 6.3% higher average maize yield. Under the RM treatment, soil organic carbon and total nitrogen significantly increased after the 5‐yr cultivation in the 0‐ to 20‐cm layer. Significant increases in extractable organic C (EOC), KMnO₄‐oxidizable C (KMnO₄‐C) and C management index (CMI) in the 0‐ to 20‐cm layer, and light fraction organic C and EOC in the 20‐ to 40‐cm layer were observed in response to plastic film removal after the 1‐yr treatment; the responses were more significant after 5 yr. Under the RM treatment, significant increases in microbial biomass C, light fraction organic N, extractable organic N, KMnO₄‐C and CMI were also observed after five years in the 20‐ to 40‐cm layer. Moreover, KMnO₄‐C and EOC were much more sensitive than other labile SOM fractions to the application of RM, even after only 1 yr of cultivation. Therefore, compared with mulching for the whole growing season, plastic film removal at the maize silking stage is an effective option for increasing yields and enhancing SOM concentration and soil sustainability in the regions with semiarid monsoon climates that have sufficient rainfall during maize reproductive stages.  相似文献   

茶叶杜瓜高效立体栽培技术研究初报     

王碧林  俞燎远  钟海东 《茶叶》2016,(3):159-161

茶树在进化过程中形成了喜阴喜湿和喜漫射光、怕强光直射的特性,适度遮阴的条件下,可改变茶园田间小气候,从而提高茶叶产量和品质。本研究茶叶和杜瓜立体栽培,充分利用了土地资源,提高复种指数,增加单位面积产出率。作者认为,一般茶树品种皆可套种,然白化类黄化类茶树品种尤为适应。杜瓜密度以每667m~220~30株为宜,杜瓜藤蔓在棚顶30%~40%左右的遮阴率为佳,将有利于茶树生长提高产量并改善茶叶品质。过密藤蔓造成茶园过度遮阴,茶树冠面阳光不足将影响茶树生长降低茶叶产质量。杜瓜套种使春茶开采期提早2~3天;每667 m~2茶园增收茶叶450元,杜瓜籽增收2700元,净产值增加2100元,比普通茶园增收20%~30%。  相似文献   

东北地区春玉米临界氮浓度稀释曲线的建立和验证   总被引：3，自引：0，他引：3  

卢宪菊  郭新宇  温维亮  于泽涛 《中国农业科技导报》2019,21(11):77-83

过量施氮是目前玉米栽培中存在的普遍现象,基于临界氮浓度稀释曲线计算得出的氮营养指数是诊断氮营养丰缺的重要手段。基于东北地区4个生态点的试验数据,构建了东北地区春玉米临界氮稀释曲线,并在此基础上建立了氮营养指数模型和需氮量模型,结果表明,东北地区春玉米地上部临界氮浓度与生物量符合幂函数关系。利用独立试验资料对建立的临界氮浓度稀释曲线进行检验,发现基于临界氮浓度稀释模型计算的氮营养指数可以准确诊断玉米植株的氮营养状况,并计算出实时的氮素需求量。该研究建立的东北地区春玉米临界氮稀释模型可以为该地区春玉米的氮营养诊断和动态调控提供较好的理论和技术指导。  相似文献   

Effect Of Replacing Fish Meal With Blood Meal On Chemical Composition Of Supplement For Nile Tilapia (Oreochromis Niloticus)     

J. G. Kirimi  J. M. Munguti 《East African Agricultural and Forestry Journal》2017,82(1):1-9

The objective of the work was to evaluate the effect on the nutrient content of replacing fish meal (FM) with blood meal (BM) in fish supplement. Three isonitrogenous diets (35% crude protein) were formulated using FM as the main source of animal protein (BM0); 50% replacement of FM with blood meal (BM50); or 100% replacement of FM with BM (BM100). The chemical composition (ash, crude protein, crude fat and crude fibre) and amino acid composition were determined. Replacement of FM with BM did not affect the proximate composition of the diet apart from ash content which decreased with the level of substitution. Substituting fish meal with blood meal reduced the levels of methionine, lysine, isoleucine, leucine, proline, valine and increased the levels of arginine, phenylanine and alanine in the diet. Amino acid indices revealed that BM0 had more amino acids with the highest chemical scores followed by BM50 and BM100. In all the diets, methionine was the most limiting amino acid. The essential amino acid index of the diets reduced with the level of replacement of FM (0.94, 0.88 and 0.77). The study showed substitution of up to 50% FM with BM gave a useful protein diet and 100% gave almost a poor protein diet.  相似文献   

低海拔异地育肥牦牛与本地杂交肉牛(秦川×西门塔尔)在不同非蛋白氮水平饲粮条件下血液生理生化指标及生长性能的差异   总被引：1，自引：0，他引：1  

张娇娇  闫琦  刘培培  李珊珊  王惟惟  白彦福  丁路明 《动物营养学报》2017,29(11)

为探究异地育肥牦牛模式,本试验对比了低海拔异地育肥耗牛与本地杂交肉牛(秦川×西门塔尔)在同等条件下血液生理生化指标和生长性能的差异。将体重相近的8头1岁本地杂交肉牛(秦川×西门塔尔)和8头4岁青海牦牛各分为2组,每组4头,同一品种的2组试验牛分别饲喂低非蛋白氮饲粮[LNPN,饲粮中缓释尿素添加量为1.0%(干物质基础)]和高非蛋白氮饲粮[HNPN,饲粮中缓释尿素添加量为1.5%(干物质基础)]。预试期10 d,正试期50 d。结果发现:牦牛与肉牛均在LNPN条件下表现出最高的平均日采食量和最小的料重比。饲粮非蛋白氮水平未对牦牛与肉牛的血常规指标造成显著影响(P0.05),但是牦牛在各饲粮条件下中性粒细胞数目(Gran#)、平均红细胞体积(MCV)、平均红细胞血红蛋白含量(MCH)、红细胞分布宽度标准差(RDW-SD)、平均血小板体积(MPV)和血小板分布宽度(PDW)显著高于肉牛(P0.05),而平均红细胞血红蛋白浓度(M CHC)和血小板数目(PLT)显著低于肉牛(P0.05)。饲粮非蛋白氮水平未对肉牛和牦牛各项血清生化指标产生显著影响(P0.05)。牦牛在各饲粮条件下血清总蛋白(TP)、尿素氮(UN)、肌酐(GREA)、免疫球蛋白A(Ig A)、免疫球蛋白M(Ig M)和免疫球蛋白G(Ig G)水平均显著高于肉牛(P0.05)。牦牛在HNPN条件下的血清白蛋白(ALB)水平显著低于LNPN条件下(P0.05)。本试验结果表明,在肉牛和牦牛育肥饲粮中添加1.0%的缓释尿素替代饲粮蛋白质是可行的;低海拔异地育肥牦牛不会对牦牛健康产生不利影响。  相似文献   

非线性、分形与期锌市场价格     

文先明  周贤军  张蜜 《湖南农业大学学报(自然科学版)》2011,(3):31-35

从非线性角度研究期锌市场，运用R/S分析法对期锌市场进行分析，发现期锌市场的Hurst指数为0.6183,其价格收益率序列是分维时间序列，具有分形结构，维数为1.6174。期锌市场的平均周期长度为176天，具有强持续性和相关性。关联系数为19.47%，远远大于国外相关市场。在风险方面，期锌市场的风险比期铜市场的要小，而比股票市场的风险要大。  相似文献