首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
农林复合措施保土保肥试验分析   总被引:2,自引:0,他引:2  
在安徽省开展了4组农林复合间作试验.结果表明,等高种植和棉花可明显降低径流中氮、磷的流失,其中等高种植山芋的径流中全氮、全磷分别为10.481mg/L和0.122mg/L,顺坡种植山芋的径流中全氮、全磷则分别为43.112mg/L和0.285mg/L;等高种植棉花的径流中全氮、全磷分别为3.779mg/L和0.109mg/L,顺坡种植棉花的径流中全氮全磷则分别为38.980mg/L和0.288mg/L.沟渠拦截了径流和泥沙,也拦截了水土携带的氮、磷,观察期间,沟渠拦截1号至4号地块径流中氮素总量分别为575.09,631.18,199.45,710.05 mg,磷素总量分别为54.54,21.42,23.24,30.13 mg;沟渠拦截1号至4号地块流失泥沙中氮素总量分别为3.00,2.95,1.07,3.35 g,磷素总量分别为0.80,0.67,0.21,0.69 g.山芋-杨树-棉花-杨树复合间作明显降低了农田水土和氮、磷流失量,观察期间,山芋-杨树-棉花-杨树复合间作的径流量和流失泥沙盆分别为2 623 cm3/m2和17.31 g/m2,而单一山芋种植下为3 138 cm3/m2和19.76 g/m2,单一棉花种植下为2 658 cm3 /m2和17.87 g/m;山芋和棉花单位面积产生径流中氮磷平均值分别为17.88 mg/m2和0.25 mg/m2,泥沙中氮磷平均值分别为21.30 mg/m2和5.24 mg/m2,而山芋-杨树-棉花-杨树复合间作的对应径流和泥沙中氮磷值分别为14.23,0.22,20.08,4.85 mg/m2.农林复合生产与沟渠拦截对保土保肥和防控农业面源污染,具有重要的作用.  相似文献   

2.
土壤-地下水中微塑料迁移的影响因素及机制研究进展   总被引:1,自引:1,他引:0  
微塑料在环境中广泛分布,世界范围内的农业土壤及地下水中都已发现微塑料污染,生态环境和人体健康受到严重威胁。研究土壤-地下水中微塑料迁移的影响因素及机制,对于准确评价其分布归趋及环境风险具有重要意义。该研究通过文献调研,对土壤-地下水环境中微塑料的来源、团聚及迁移研究进行梳理、归纳和总结,系统阐明了土壤-地下水中微塑料迁移的影响因素,剖析了影响微塑料迁移的机制,并对未来研究进行展望。土壤中微塑料的来源可分为原位型微塑料和外源输入型微塑料2种,地下水中的微塑料一般源自于土壤中微塑料的垂直迁移及地表-地下水微塑料交换。水体中微塑料的团聚受多种水环境因素的影响,其团聚程度与迁移能力密切相关,是迁移行为的基础和前提。土壤-地下水中影响微塑料迁移的因素可分为化学、物理、生物3类。水化学条件、介质成分、水流条件、介质物理条件、植物生长发育、小型动物及微生物的生命活动均会影响土壤-地下水中微塑料的迁移行为,且影响机制各不相同。目前,土壤-地下水中微塑料的迁移研究处于起步阶段,在进一步的研究中,野外尺度微塑料迁移、多元化微塑料迁移、微塑料特性对其迁移行为影响、微塑料迁移过程中的转化等研究值得重点关注。  相似文献   

3.
Soil compaction influences crop growth, movement of water and chemicals in numerous ways. Mathematical modelling contributes to better understanding of the complex and variable effects. This paper reviews models for simulating topsoil and subsoil compaction effects. The need for including both topsoil and subsoil compaction results from still increasing compactive effect of vehicular pressure which penetrates more and more into the subsoil and which is very persistent. The models vary widely in their conceptual approach, degree of complexity, input parameters and output presentation. Mechanistic and deterministic models were most frequently used. To characterise soil compactness, the models use bulk density and/or penetration resistance and water content data. In most models root growth is predicted as a function of mechanical impedance and water status of soil and crop yield—from interactions of soil water and plant transpiration and assimilation. Models for predicting movement of water and chemicals are based on the Darcy/Richards one-dimensional flow equation. The effect of soil compaction is considered by changing hydraulic conductivity, water retention and root growth. The models available allow assessment of the effects of topsoil and subsoil compaction on crop yield, vertical root distribution, chemical movement and soil erosion. The performance of some models was improved by considering macro-porosity and strength discontinuity (spatial and temporal variability of material parameters). Scarcity of experimental data on the heterogeneity is a constraint in modelling the effects of soil compaction. Suitability of most models was determined under given site conditions. Few of the models (i.e. SIBIL and SIMWASER) were found to be satisfactory in modelling the effect of soil compaction on soil water dynamics and crop growth under different climate and soil conditions.  相似文献   

4.
The fungicidal activities of Cassia tora extracts and their active principles were determined against Botrytis cineria, Erysiphe graminis, Phytophthora infestans, Puccinia recondita, Pyricularia grisea, and Rhizoctonia solani using a whole plant method in vivo and were compared with synthetic fungicides and three commercially available anthraquinones. The responses varied with the plant pathogen tested. At 1 g/L, the chloroform fraction of C. tora showed a strong fungicidal activity against B. cinerea, E. graminis, P. infestans, and R. solani. Emodin, physcion, and rhein were isolated from the chloroform fraction using chromatographic techniques and showed strong and moderate fungicidal activities against B. cinerea, E. graminis, P. infestans, and R. solani. Furthermore, aloe-emodin showed strong and moderate fungicidal activities against B. cinerea and R. solani, respectively, but did not inhibit the growth of E. graminis, P. infestans, P. recondita, and Py. grisea. Little or no activity was observed for anthraquinone and anthraquinone-2-carboxylic acid when tested at 1 g/L. Chlorothalonil and dichlofluanid as synthetic fungicides were active against P. infestans and B. cinerea at 0.05 g/L, respectively. Our results demonstrate the fungicidal actions of emodin, physcion, and rhein from C. tora.  相似文献   

5.
本实验选择具有优良肉质的本地金华猪与肉质较差的引进品种皮特兰猪杂交所产的金皮F2代为研究对象,检测金皮F2代猪CAST(calpastatin, CAST)基因、MyoG(Myogenin, MyoG)基因的PCR-MspI多态性,并结合肌球蛋白重链(MHC)免疫组织化学方法,研究猪背腰最长肌的肌肉组织学特性,并对其进行图像分析。结果发现,金皮F2代杂交猪背腰最长肌MHCs阳性(慢肌)纤维的比例为7.62%, 快肌纤维为92.38%。CAST基因的PCR扩增产物为1404bp的片段,酶切后分为A(628bp+499bp+277bp),B(499bp+371bp+277bp+257bp)两种等位基因;MyoG基因的PCR扩增产物长度为1050bp,酶切后分为A(462 bp +408 bp +180 bp)和B(408bp+290bp+180bp+162bp)两种等位基因。.AA、AB和BB基因型频率分别为 0.1795、0.5897和0.2308,A和B的基因型频率分别为 0.4743和0.5256。CC、CD和DD的基因型频率为0.3671,0.5696和0.0633, C和D的基因型频率分别为0.6519和0.3481。统计结果表明,AA、AB、AB、CC、CD、DD基因对眼肌面积,系水率、pH值、导电率等屠宰性状均无显著的影响。CAST基因的不同基因型对肌纤维的轴比有显著影响(P<0.05),AA单型有产生较多轴比大(近似椭圆形)肌纤维的倾向,而BB则控制形成更多的轴比小(近似于圆形)的肌纤维。具有AA单型的个体具有更多的肌间结缔组织,而具有BB单型的个体的肌间结缔组织较少(P<0.05),AB单型的个介于两者之间。MyoG基因MspI酶切后的各种基因型对肌肉的肌纤维大小和密度具有显著影响,具有DD基因型的个体的肌纤维面积较大,而具有CC基因型者肌纤维密度最大。  相似文献   

6.
卢旺达共和国山地丘陵区土壤侵蚀调查报告   总被引:1,自引:1,他引:0  
[目的]在卢旺达山地丘陵区开展土壤侵蚀调查,分析该区土壤侵蚀特征及成因,为尼罗河上游山地丘陵区土壤侵蚀预报和水土流失防治提供科学依据。[方法]在卢旺达布设4条调查路线并选择调查点,于2019年10月17—22日对调查点土壤侵蚀特征、成因及水土保持措施等进行了调查。[结果]卢旺达多山地且以农牧业为主,土壤侵蚀主要发生在坡耕地、损毁林地、建设用地等。坡耕地以片蚀和细沟侵蚀为主。损毁林地以片蚀和细沟侵蚀为主,部分出现沟蚀;当裸露地表形成草地或幼林后均较少发生土壤侵蚀。公路边坡、开挖边坡、土路路面及边坡等在降雨及径流的作用下产生沟蚀,部分路段偶有勤侵蚀发生。梯田是该国最主要的水土保持措施,具有较好的生态和经济效益。[结论]卢旺达土壤侵蚀主要以水力侵蚀为主,重力侵蚀次之。不合理的开垦坡地、毁林,加之多山的地形,导致侵蚀较为严重,威胁当地的生态安全及粮食安全。该区缺乏水土流失监测资料,需要重视水土保持基础理论研究,加强水土流失基础数据的监测和采集,同时需要加强其水土保持措施及土地管理工作,保障卢旺达农业的可持续绿色发展。  相似文献   

7.
氮硫互作提高大蒜氮、硫含量及其关键同化酶活性   总被引:1,自引:1,他引:0  
【目的】 从生理学角度研究氮、硫两种营养元素配施对大蒜氮硫关键同化酶的影响,揭示氮硫关键同化酶与植株氮、硫同化能力的关系,以期为大蒜合理施肥与提质增效提供理论参考。 【方法】 采用蛭石–珍珠岩盆栽方式,研究了不同浓度氮 (5、10、20 mmol/L)、硫 (2、4、8 mmol/L) 配施条件下,大蒜在幼苗期、花茎伸长期、鳞茎膨大初期和中期大蒜植株氮、硫含量,以及氮、硫关键同化酶活性的动态变化。 【结果】 大蒜植株氮含量总体呈上升趋势,在鳞茎膨大期达到最高水平,而硝酸还原酶 (NR)、谷氨酰胺合成酶 (GS) 活性变化呈先上升后下降趋势,在花茎伸长期至鳞茎膨大初期活性较高。硫含量总体呈先上升后平稳趋势,ATP-硫酸化酶 (ATPS) 活性在花茎伸长期达到最大值,而半胱氨酸合成酶 (OAS-TL) 活性则呈先下降后上升趋势,在花茎伸长期酶活性总体最低。鳞茎膨大期前,氮硫交互作用对氮、硫同化量有影响显著,而单因素影响不明显;鳞茎膨大期,单因素影响明显。硝酸还原酶、谷氨酰胺合成酶活性整体呈先升高后降低趋势。氮素对于 NR 活性影响显著,而对 GS 影响不显著;硫素仅在花茎伸长期和鳞茎膨大初期对NR活性有显著影响,而氮硫交互作用对 NR、GS 均有显著或极显著影响。氮素、硫素对 ATP-硫酸化酶、半胱氨酸合成酶活性无显著影响,而氮硫交互作用对其影响极显著。NR 活性在花茎伸长期、鳞茎膨大初期与植株氮呈显著正相关关系,ATPS 活性在花茎伸长期、鳞茎膨大初期与植株硫含量呈显著正相关关系,Pearson 系数分别为 0.690、0.847 和 0.662、0.816。鳞茎膨大初期和中期,GS 活性与氮含量呈显著负相关,相关系数分别为 –0.857、–0.693。OAS-TL 活性与硫含量整体呈负相关,而在鳞茎膨大初期为 0.646,呈显著正相关。 【结论】 大蒜生长过程中,氮、硫两元素间存在互作关系。NR、ATPS 等酶活性的提高增加了植株氮、硫同化能力,而 GS 则通过降低酶活性而促进氮的同化。在大蒜鳞茎膨大期前,氮、硫配施能够通过调控关键同化酶活性而影响氮、硫同化,进而影响植株生长;鳞茎膨大阶段,可以通过单一施肥达到调控大蒜植株氮或硫含量的目的。   相似文献   

8.
采用砂培试验方法,系统研究了不同水平氮锌配施对白三叶生长和生理生化特性的影响。结果表明,在缺锌条件下,随施氮水平增加,白三叶氮代谢和清除活性氧的能力、IAA、GAs含量下降,ABA、MDA含量增加,氮锌配施对生长和元素吸收表现为拮抗效应;在足量供锌条件下,与低量供氮相比,中量供氮时,白三叶氮代谢和清除活性氧的能力、IAA、GAs含量增加,ABA、MDA含量下降,氮锌配施对生长和元素吸收表现为协同效应。当高量氮时,氮锌配施则表现为拮抗效应。在判断氮锌复合作用类型时,应区分生长量变化引起的“浓缩效应”和“稀释效应”,应以生长量和吸收量变化来确定氮锌复合作用的类型。  相似文献   

9.
大蒜不同品种干物质生产与氮、磷、钾和硫的吸收特性   总被引:9,自引:0,他引:9  
以三个不同生产目的大蒜品种为试材,于出苗期、花茎伸长期、鳞茎膨大期末取样,测定不同(整个)生长发育阶段的每株干物质增重,每株总干物重和N、P、K、S吸收量,分析了大蒜干物质生产和N、P、K、S吸收特性,以期为合理施肥,制定大蒜优质高产栽培技术提供依据。结果表明:整个生育期早薹蒜2号N、P、K、S的吸收比率为8.96∶1∶5.03∶2.23,苍山蒜为6.01∶1∶2.90∶2.05,苏联2号为5.35∶1∶2.59∶1.83。三个品种大蒜对硫的吸收量大,分别占干重的0.64%、0.77%和0.90%。在花茎伸长期,N、P、K、S的吸收量、吸收比率和干物重比率均为最大。幼苗期干物重比率虽然比鳞茎膨大期小,但早薹蒜2号N、P、K和S的吸收量和吸收比率,苍山蒜N和S的吸收量和吸收比率,苏联2号N、K和S的吸收量和吸收比率高于鳞茎膨大期。而鳞茎膨大期苍山蒜P和K的吸收量和吸收比率,苏联2号P的吸收量和吸收比率高于幼苗期。在经济产量的形成过程中,3个品种对N和K的利用效率不显著;对P和S的利用效率存在显著差异,依次为早薹蒜2号苍山蒜苏联2号。  相似文献   

10.
Advances in pesticide environmental fate and exposure assessments   总被引:1,自引:0,他引:1  
Globalization of markets and the growing world population increase threats of invasive and exotic species and place greater demands on food and fiber production. Pest management in both agricultural and nonagricultural settings employs established practices and new biological, chemical, and management technologies. Pesticides are an essential tool in integrated pest management. Without pesticides a significant percentage of food and fiber crops would be lost, infectious diseases would increase, and valuable native habitats would be devastated. Therefore, it is important to understand the environmental fate of pesticides and assess their potential exposure and associated risks to human health and the environment. This paper summarizes the Advances in Pesticide Environmental Fate and Exposure Assessment symposium held at the 231st National Meeting of the American Chemical Society (Atlanta, GA, 2006). The focus of the symposium was to provide current information on advances in pesticide environmental fate and exposure assessments. Thirty papers were presented on advances ranging from subcellular processes to watershed-scale studies on topics including chemical degradation, sorption, and transport; improved methodologies; use of modeling and predictive tools; exposure assessment; and treatment and remediation. This information is necessary to develop more effective pesticide use and management practices, to better understand pesticide fate and associated exposures and risks, to develop mitigation and remediation strategies, and to establish sound science-based regulations.  相似文献   

11.
Three years of hourly sequential precipitation data from central Long Island, New York were analyzed to determine the concentrations of major anions and cations and their relationships to each other and to meteorological conditions. Findings with respect to sulfate, nitrogen in nitrate plus nitrite, nitrogen in ammonium, chloride and sodium ions and selected ratios are reported here. Concentrations of each of the first three species were highly correlated with concentrations of the others and with hydrogen ions. Little correlation was found between these species and either sodium or chloride ions but the latter two were highly correlated with each other. Concentrations of the first three species are highest in summer and lowest in winter. High concentrations were also found with cold front and squall line precipitation and with rain showers and thundershowers. Concentrations of these species are high with both low and high precipitation rates. Concentrations are highest with west and northwest winds due to the presence of major source regions in those directions. They are high with both low and high temperatures but lower in the moderate temperature range. Concentrations are high with low (3.0 to 3.9) and with high (6.0 to 6.9) pH but less at intermediate levels. Thus, concentrations of these species in precipitation are determined by complex chemical and meteorological interactions and relationships. Chloride and sodium were found to be largely of marine origin. Highest concentrations occur in the fall and with hurricanes, strong winds, and onshore wind directions. Concentrations decrease with increasing precipitation rate. At low concentrations, the chloride/sodium ratio is above the seawater ratio and excess chloride is present. At high concentrations the ratio is below the seawater ratio and a chloride deficit exists.  相似文献   

12.
苹果栽培区土壤参数的近红外及中红外测定   总被引:2,自引:0,他引:2  
Soil quality monitoring is important in precision agriculture.This study aimed to examine the possibility of assessing the soil parameters in apple-growing regions using spectroscopic methods.A total of 111 soil samples were collected from 11 typical sites of apple orchards,and the croplands surrounding them.Near-infrared(NIR) and mid-infrared(MIR) spectra,combined with partial least square regression,were used to predict the soil parameters,including organic matter(OM) content,pH,and the contents of As,Cu,Zn,Pb,and Cr.Organic matter and pH were closely correlated with As and the heavy metals.The NIR model showed a high prediction accuracy for the determination of OM,pH,and As,with correlation coefficients(r) of 0.89,0.89,and 0.90,respectively.The predictions of these three parameters by MIR showed reduced accuracy,with r values of 0.77,0.84,and 0.92,respectively.The heavy metals could also be measured by spectroscopy due to their correlation with organic matter.Both NIR and MIR had high correlation coefficients for the determination of Cu,Zn,and Cr,with standard errors of prediction of 2.95,10.48,and 9.49 mg kg-1 for NIR and 3.69,5.84,and 6.94 mg kg-1 for MIR,respectively.Pb content behaved differently from the other parameters.Both NIR and MIR underestimated Pb content,with r values of 0.67 and 0.56 and standard errors of prediction of 3.46 and 2.99,respectively.Cu and Zn had a higher correlation with OM and pH and were better predicted than Pb and Cr.Thus,NIR spectra could accurately predict several soil parameters,metallic and nonmetallic,simultaneously,and were more feasible than MIR in analyzing soil parameters in the study area.  相似文献   

13.
深圳水土保持科技示范园建设的理念与实践   总被引:4,自引:0,他引:4  
为促进当前水土保持科技示范园建设的良性发展,推广水土保持科技示范园建设的新理念和新模式,通过回顾深圳市水土保持科技示范园的建设过程,介绍深圳市水土保持科技示范园建设的理念与实践.深圳水土保持园区包括水土文化区、水土保持科普试验区2大部分,将文化性、景观性与水土保持各种技术展示相结合,建设以城市水土保持特色为主的专业示范园.突出在城市开发建设过程中对广大市民的水土保持宣传、对中小学生的科普教育,营造寓教于乐的户外课堂,同时分析园区建成后的运行管理.对今后水土保持示范园建设提出设想:准确定位,以科普宣传功能为主;规划设计创新,多专业领域参与,多方面、多层次宣传水土保持理论与实践内容;建立良好的园区运行管理机制,保障长期有效运营.  相似文献   

14.
针对渭北旱原地域辽阔,土地资源丰富,光热资源充足,但降水有限,且年季分布不均,旱灾发生频繁,生态环境脆弱,土壤瘠薄,资源利用率低,土地生产力低等客观条件,陕西省农科院在合阳甘井建立旱地农业研究试验站,长期进行了渭北旱原资源高效利用模式和旱地农业可持续发展攻关研究,先后构建了多种资源高效开发利用模式和与此相适应的技术体系。实践证明,该项目研究成果对消除这一地区贫困,保证粮食供给,减少和控制环境污染,提高土地生产力,优化农田生态,合理利用自然资源等有重要作用。  相似文献   

15.
煤田开采诱发环境地质问题及防治对策   总被引:1,自引:0,他引:1  
煤田开采沉陷引发了各种地质灾害和环境效应,包括地面塌陷、地裂缝、滑坡崩塌、泥石流等,对土地资源、水资源和大气环境、地表设施造成严重破坏和污染,也对人类生命财产安全造成重大损失。介绍了我国煤炭开采沉陷灾害的现状,论述了各种灾害和环境效应的形成机理,系统地总结了我国现阶段对各种灾害和环境效应的防治对策。主要的防治对策包括管理措施、控制沉陷的开采技术、沉陷预测、采空区的工程治理、地表建筑物防护、土地复垦等。实施综合防治措施和绿色开采是矿业发展的必由之路。  相似文献   

16.
黄淮南片粮仓现代农业发展战略   总被引:1,自引:0,他引:1  
皖北、苏北、鲁西南和豫东南的4省交界地区,有以淮北平原为主的砂姜黑土、黄泛区为主的风沙盐碱地等易旱易涝中低产田面积400万hm~2以上,虽然处于南北过渡带的黄淮南片,温热降水等自然资源条件较好,但因地理偏远、交通不便,科技文化和社会经济发展相对落后,农业高产潜力还未发挥。加快黄淮南片中低产田改造,建设黄淮南片第二粮仓,可以新增粮食50亿kg,在区域现代农业发展和保障我国粮食安全中具有重要作用。根据气候变暖和绿色提质增产增效的现代农业发展态势,提出以下黄淮南片粮仓现代农业发展战略:在种植业方面,第1是培育抗赤霉病的小麦品种,利用综合防治措施减轻小麦赤霉病的危害;第2是培育耐旱耐涝、脱水快适合机械化粒收的玉米新品种并快速示范推广;第3是扩大吨粮田建设,确保黄淮南片和国家粮食安全。在区域治理方面,重点改造淮北砂姜黑土、黄泛区的风沙盐碱地等易旱易涝区的中低产田,加强农田排灌系统基础投入,建设旱涝保收、林网路、渠井电配套的高标准农田。在现代科技装备方面,要加大农机补贴,增加大中型农机的数量,加强深翻深松农机的示范推广,普及农作全程机械化。在绿色提质增效方面,积极推行化肥农药减施,扩大环境友好型的绿色生物肥料制剂等应用,加强秸秆还田和生物资源等循环高效利用。在科技教育方面,要扩大职业教育规模,培养知识农民,专业服务工人,打造社会化服务的专业队伍。在区域经济发展方面,在皖北做强做大粮食品牌化生产,在苏北做大粮食规模化生产和培育现代新型产业,在鲁西南做好农林牧协同高效发展,在豫东南打造中国食品深加工的旗舰。在农业信息化建设方面,加大"互联网+"农业的普及,带动订单农业、外销农业、观光农业等的快速发展。建议国家及早启动黄淮南片第二粮仓重点科技专项,将黄淮南片粮食主产区和经济塌陷区建设成为国家主体粮仓和农业经济新兴区及环境优美的可持续发展区。  相似文献   

17.
周绪申  林超  罗阳 《农业环境保护》2010,(10):1884-1891
2009年对滦河水库系统潘家口-大黑汀水库的浮游植物时空变化特征进行研究,结果表明,潘家口-大黑汀水库共监测到浮游植物8门34科62属,其中本次研究共发现库区新记录藻类11属;种类最多的为绿藻门和硅藻门,分别有27属和14属,分别占32.4%和23.5%;其中优势种类为8属,常见种类为17属,次常见或稀有种类为37属。藻密度在春末和夏初较小,在秋季的8、9月生长量达到最大,在冬季又开始降低,以潘家口坝上样点为例,5月藻密度为160.9万个.L-1,9月藻密度1 721.27万个.L-1;春季主要的优势类群为硅甲藻,夏季为隐硅藻,秋季为蓝绿藻,夏秋季节的优势属为假鱼腥藻(蓝藻门)。藻类分布存在空间性差异,种类最多的样点(下池)共发现43属,种类最少的样点(大黑汀库区)仅发现20属。与20世纪80年代的调查结果相比,47属为共有浮游植物,相似性系数为64.8%,浮游植物群落结构由硅藻型向蓝-绿藻型转变,其中变化最大的样点为潘家口坝上,相似性系数仅为29.4%,藻类密度增加了近20倍,总磷和总氮浓度分别增加1.41倍和3.63倍,潘家口-大黑汀水库富营养化程度呈加剧趋势。  相似文献   

18.
在“四化”建设中人为水土流失的类型   总被引:1,自引:0,他引:1  
在“四化”建设中,人为水土流失的类型主要有山原区筑路造成的水土流失;开矿和采石造成的水土流失;兴修水利水电工程,乱弃沙石废土造成的水土流失;山原区建厂盖楼等基建工程和修建民房造成的水土流失;城乡工业企业排放大量粉尘、废渣、污染水源,加剧水土流失;毁林毁草开荒,陡坡开荒,造成人为水土流失;广种薄收、顺坡耕种、经济林垦复等旧的生产习惯,加速了水土流失;山原区居民发展木耳、天麻等副业生产,破坏了植被,加重了水土流失;城市垃圾、炉灰乱堆乱倒造成的水土流失。这9种类型,随着建设的蓬勃发展,有日益严重的趋势。  相似文献   

19.
基于GIS的农作物病虫害预警系统的初步建立   总被引:10,自引:1,他引:9  
该研究以建立农作物病虫害预警系统为目标,使用国产SuperMap IS.NET的GIS软件作为开发平台,以C 语言作为编程语言。该系统充分使用了GIS强大的空间分析功能和RS的快速、实时、大面积获取病虫害信息的功能,实现了GIS与RS在系统中的集成。系统最终将抽象的数据转化成清晰简明的电子地图,直观明了的显示了病虫害的发生程度和空间分布规律。该文重点介绍了此预警系统的数据库设计和系统的基本功能以及预警流程;最终,使用甘肃省庆阳地区西峰区2002年的小麦条锈病相关数据,来展示该预警系统中病害预测功能的实现过程,并获得了与实际报道相吻合的预警结果。研究表明,此预警系统能够对农作物病虫害进行分类预测,并根据预警结果对病虫害进行合理的预防和防治。  相似文献   

20.
Using the abundance and distribution of small mammals at 26 sites in an Atlantic forest landscape, we investigated how species abundance and alpha and beta diversity are affected by fragment size and the presence of corridors. To account for the variability in forest structure among fragments, we described and minimized the influence of foliage density and stratification on small mammal data. Sites were distributed among three categories of fragment size and in continuous forest. For small and medium-sized categories, we considered isolated fragments and fragments connected by corridors to larger remnants. Small mammal abundance and alpha and beta diversity were regressed against site scores from the first axis of a Principal Component Analysis on forest structure variables. Residuals were used in analyses of variance to compare fragment size and connectivity categories. Forest structure influenced total abundance and abundance of some species individually, but not the diversity of small mammal communities. Total abundance and alpha diversity were lower in small and medium-sized fragments than in large fragments and continuous forest, and in isolated compared to connected fragments. Three species were less common, but none was more abundant in smaller fragments. At least one species was more abundant in connected compared to isolated fragments. Beta diversity showed an opposite relationship to fragment size and corridors, increasing in small and isolated fragments. Results highlight the importance of secondary forest for the conservation of tropical fauna, the hyper-dynamism of small isolated fragments and the potential of corridors to buffer habitat fragmentation effects in tropical landscapes.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号