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排序方式: 共有91条查询结果,搜索用时 15 毫秒
1.
关于平原区的水土保持问题 总被引:3,自引:0,他引:3
水土流失是指在水力、重力、风力等外营力的作用下,水土资源和土地生产力的破坏和损失,包括土地表层损失和水的损失。我国是世界上水土流失最为严重的国家之一,尤其在山区和丘陵区。随着经济社会的发展,人口、资源、环境矛盾问题日益突出,笔者发现平原区也存在水土流失问题,且由于平原面积大,地貌类型多,加上人为因素的影响,致使平原区水土流失带来的危害日益严重,从贯彻落实新《水土保持法》的角度出发,本文重点介绍平原区水土流失的类型和特点,并提出了治理各种类型水土流失的措施。对于保护平原区的生态环境和促进经济的可持续发展有很重要的意义。 相似文献
2.
For species whose decline preceded the modern era and whose distribution is in the developing world, it is difficult to map suitable habitat across its former range. Eld’s deer (Cervus eldi) is an endangered cervid whose range across Southeast Asia was reduced during the last century to disjoint populations in Myanmar and Cambodia. We used ecological data from the present populations to determine landscape and habitat parameters that would help us predict the occurrence of the species in forests not yet surveyed. The suitable-forest GIS model was created using four readily available datasets for elevation, forest type, canopy closure, and human density. Comparison of the GIS model with 24 verified sightings of Eld’s deer during recent large mammal surveys in Cambodia, found 22 sightings (92%) within predicted suitable forest. Use the suitable-forest GIS model to survey a province in southern Lao People’s Democratic Republic, located a single, previously unreported population from 9 patches surveyed. In a separate analysis, a logistic regression model to predict Eld’s deer habitat in Northern Cambodia found percent tree cover, presence of wetlands, and distance to villages as the best predictors of deer, similar to variables used in the GIS model, with the exception of the importance of wetlands. Using mean annual rainfall to rank suitable-forest patches identified in the GIS model indicated dry dipterocarp forests in Northeastern Cambodia and Northern Myanmar have the highest potential to conserve eld’s deer. Examination of the suitable-forest GIS map and current protected areas indicated only Cambodia, with 11% suitable forest protected, has placed sufficient dry dipterocarp forest under protected status. Other Southeast Asia countries have not recognized dry dipterocarp forest as a significant ecotype worthy of conservation status. 相似文献
3.
Tithipong PLANGSANGMAS Hathaipat RATTANATHANYA Wanlaya TIPKANTHA Saowaphang SANANNU Umaporn MAIKAEW Jessada THAEONOEN Bencharong SANGKHARAK Pornpiroon CHINSON Watcharin HIN-ON Nathavut KANATIYANONT Boripat SIRIAROONRAT Nantarika CHANSUE Parntep RATANAKORN 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2022,84(1):181
The plains zebra (Equus quagga) is a zebra species commonly kept in zoos around the world. However, they are not tame like their domestic relatives and are difficult to immobilize. We immobilized 30 captive plains zebra with a combination of etorphine hydrochloride (2–4 mg), acepromazine (8 mg), and xylazine hydrochloride (30 or 50 mg) to perform physical examination and blood sample collection for disease diagnostics. Physiological parameters including heart rate, respiratory rate, body temperature, and hemoglobin oxygen saturation were recorded. All zebras exhibited satisfactory anesthesia and fully recovered without re-narcotization. The results suggest that etorphine hydrochloride-acepromazine-xylazine hydrochloride combination for plains zebra immobilization is a safe and sufficient regimen for short procedures such as wellness examinations and sample collection. 相似文献
4.
从中原农耕文化的角度将中原文化与企业文化结合在一起,对塑造河南企业文化的影响思想进行了分析。 相似文献
5.
中原地区丹红杨插干造林技术研究 总被引:1,自引:0,他引:1
丹红杨是中国林业科学研究院2003年培育成功的新一代超速生抗虫杨,雌株。耐桑天牛、易生根、速生(年胸径生长量达5.8 cm,年平均高生长量4.9 m)。为了提高丹红杨的造林成活率,进行了杨树插干深栽造林试验。试验结果表明,丹红杨采用插干深栽造林方法与传统的带根植苗造林相比,具有成本低、成活率高、生长量大等特点,是一种比... 相似文献
6.
Regional mapping of soils helped to identify and map 24 soil-geomorphic units on the Deoha/Ganga–Ghaghara Interfluve in the Upper Gangetic Plains (Himalayan Foreland Basin). On the basis of luminescence ages soil-geomorphic units can be grouped into five members of a Morphostratigraphic Sequence with ages of ≤ 1.7 ka, 1.8–3.6 ka, 4.6–6.4 ka, 6.8–10 ka and > 10 ka. Except for two units with sandy parent material, all the members with loamy parent materials show systematic increase in the degree of soil development from Member QGMS-I to V. Major pedogenic processes are salinization, alkalinization, illuviation, calcrete development and gleying, and degradation of some micromorphological features is observed in the oldest soils.Regional mapping and dating of soils show that the Interfluve between the Deoha/Ganga–Ghaghara rivers is bounded by longitudinal faults, along the bounding rivers. The major longitudinal faults trend N–S or NNE–SSW in the northern region; turn N–S in the central region and take easterly to SEE direction in the south, giving the Interfluve a curvilinear shape. Strike of a set of six transverse extensional normal faults changes from approximately E–W to NEE–SWW in the southernmost region of the Interfluve. Downthrown sides are to the south and to the east in northern region and western region, respectively.Due to the activity of different segments of various transverse faults during a probably dry sub-humid to semi-arid climatic period of 10–5 ka, terminal fans were deposited on the downthrown blocks. Thus, role of extensional tectonics in an overall compressional regime is significant. Also, tilting of smaller blocks leading to the shifting away of large rivers seems to be an additional control on the distribution of soils and sedimentation on the Interfluve. 相似文献
7.
Olaf Erenstein 《Agricultural Systems》2011,104(1):54-62
Conservation agriculture practices are being advocated to help sustain crop productivity gains and secure environmental sustainability in the Trans-Gangetic Plains, India’s Green Revolution heartland. The paper illustrates the use of village surveys as a quasi-quantitative system analysis tool to derive implications for agricultural research and development. Drawing from village surveys in 170 communities, the paper assesses current crop residue management practices in Punjab and Haryana’s rice-wheat, basmati-wheat and non-rice-wheat cropping systems. The prevalence of wheat as the winter crop implies an intensive collection, trading and use of wheat straw as basal feed for dairy livestock; which contrasts with the diverse crop residue management of the monsoon crops. The increased use of combine harvesters has spurred the rapid advent of mechanical wheat straw reapers whereas the bulk of combine harvested rice straw is burned in situ. Present crop residue management practices are largely incompatible with year-round mulch retention despite significant biomass production. The research and development community faces the challenge of evening out straw use and management over seasons to ensure at least partial residue retention if its calls for conservation agriculture in this important sub-region are to succeed. The paper also reiterates the worrying decline of groundwater tables associated with the rice-wheat system. 相似文献
8.
嘉兴平原桑园土壤分类及肥力的调查 总被引:1,自引:0,他引:1
选择浙北嘉兴平原桑园代表性土壤,进行调查,研究其成因、分类及特性,并对高低产桑园土壤的理化性状进行化验分析,明确了嘉兴平原桑园土壤是历史上由人工堆迭而成,在分类系统上归属于潮湿土纲、正常潮湿土亚纲、潮土土类、暗潮土亚类、堆迭土土属,又分为粘质堆迭土、壤质堆迭土、粉质堆迭土3个土种。在统计众多土壤理化性状数据的基础上,暂拟本区高产桑园土壤16项理化性状,作为本地区桑园地力建设的参考。 相似文献
9.
《Journal of Crop Improvement》2013,27(1-2):119-144
SUMMARY More than twenty cropping systems are practiced in India. Rice-wheat and rice-rice are the major cropping systems practiced in an estimated 120 districts and 50 districts of the country, respectively. The rice-wheat cropping system (RWCS) of the Indo-Gangetic Plains (IGP) region of South Asia (Bangladesh, India, Nepal, and Pakistan) is the creation of the agricultural green revolution. Higher production of rice and wheat was necessary to meet the calorie needs of an increasing population in this region; as a result, the percent of malnutrition amongst children and adults decreased during the green revolution era. However, in recent years, there has been a reduction in both the rate of malnutrition decline and of the partial and total factor productivity of the RWCS in India. One of the many reasons for the decreased rate of malnutrition decline is micronutrient deficiency. Malnutrition amongst children and adults is a silent emergency in South Asia, including India. This review compares the food consumption habits, nutritional status, and cropping system practiced for different states of India to provide reasons for shifting the rice-wheat cropping system through crop diversification. Diversification of the RWCS will increase the supply of legumes and vegetables, help to diversify the diets consumed, and increase micronutrient intake. This approach is important for a largely vegetarian population of India, and is therefore, considered to be one of several important Food Systems strategy to address the silent emergency of malnutrition in the region. 相似文献
10.
从狭义中原的地理范畴,解读各类历史典籍中所记录的秦汉前中原及与中原相关的地理内容,从中把握秦汉以前中原古代地理发展的历史脉络、地理成就、发展特点及蕴含的历史地理价值。研究认为,在中国区域性地理发展历史中,尤其是秦汉前中原古代地理发展史不仅可以独立成章,而且形成极具理性的中原古代地理体系,并深刻地影响了中国古代地理科学的历史发展过程。 相似文献