首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3篇
  免费   0篇
林业   2篇
  1篇
  2021年   1篇
  2011年   2篇
排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
For any country, the forest policy is an important guideline to maintain forest resources and their interaction with other land uses. India devised its first National Forest Policy (NFP) back in 1894. There has been a paradigm shift from timber production to forest conservation followed by community-based agroforestry and social forestry bringing a change in perspective towards forest resources. This change has been socio-economic, cultural and ecological. Since the 1952 NFP, there has been an advocacy for 33% forest cover with a 60% forest cover in mountainous and hilly regions. This objective was reiterated in the NFP 1988 and also confirmed in the National Forestry Commission report in 2006. This paper reviews the probable reasons for these targets. This paper also analyzes forest cover trends at state level and assesses the likelihood of meeting the prescribed policy targets under present perspective of land use practices. Only three Indian states meet the prescribed policy, while three more have the potential to do so, if their state wasteland area is afforested. Among the rest, a few states may achieve the 33% goal provided land conversion to tree cover is not hindered, and adequate resources are available at state level. The Planning Commission (XI Five-year Plan, 2007–12) has emphasized inclusion of other natural ecosystems (including treeless areas and trees outside forests) to forest cover. The paper also examines the above prescribed targets in light of the Planning Commission recommendations. It is argued that that the NFP should be re-visited and revised to meet the targets, along with setting a more realistic and attainable target for Indian forest and tree cover.  相似文献   
2.

Soybean is a temperate photosensitive crop but has adapted to sub-tropical and tropical countries of lower latitudes also. Photoperiodic and maturity genes confer latitudinal adaptation in this crop. Genotyping of accessions of higher latitudes have shown the role of photoinsensitivity, conferred by recessive photoperiodic alleles (e1/e2/e3/e4), in adaptation of the crop to high latitudes but information is not available for lower latitudinal countries like India. We genotyped and calculated the photosensitivity of 101 cultivated Indian soybean varieties and found that majority of the varieties (86) were photosensitive and had the dominant alleles at these loci. Four genotypic classes (e1-as/E2/E3/E4, E1/e2/e3/E4, E1/e2/E3/E4 and E1/E2/e3/E4) were observed for varieties with recessive alleles. Photoinsensitive alleles at E1 and E2 loci significantly reduced the days to flower, maturity and photosensitivity percentage. Adaptive role of photoperiodic alleles was inferred from breeder seed requirement of these varieties for 35 years. Although the photosensitive class contributed 81% to the total seed requirement the weighted mean contribution of this class (380 Q/year) was far less than that of photoinsensitive class (648 Q/year). Photoinsensitivity is essential for perpetuation of crop in higher latitudes. Present report highlights the novel role of photoinsensitive alleles in adaptation of soybean to rainfed, short growing and sub-tropical conditions of lower latitudes by conferring earliness.

  相似文献   
3.
The changes in species composition, abundance and forest stand structure were analyzed across altitudinal regimes in tropical for- ests of Eastern Ghats of northern Andhra Pradesh, India. Three 1-ha plots were established with one each in low, medium and high altitudes. A total of 153 species, 2129 stems (709 stems ·ha -1 ) of ≥10 cm girth were enumerated. Species richness and diversity pattern varied along altitud- inal gradient and increased with the altitude. Species richness varied from 52 to 110 species·ha -1 and stand density from 639 to 836 stems·ha -1 with average basal area of 34.39 m 2 ·ha -1 . Shannon-Wiener index (H’) ranged from 4.55 to 5.17. Low altitude (i.e., Site 1) is dominated by Xylia xylocarpa (59.22) and Lagerstroemia parviflora (23.90), medium altitude (i.e., Site 2) by Xylia xylocarpa (45.50) Bursera serrata (17.29), and high altitude (i.e., Site 3) has Schleichera oleosa (28.25) Pterocarpus marsu- pium (26.55) as predominant species. Taxonomically, Rubiaceae (12 species), Fabaceae (12), Euphorbiaceae (11), Rutaceae (7) and Lauraceae (7) were dominant families. Density-wise, Fabaceae, Combretaceae, Euphorbiaceae, Anacardiaceae and Myrtaceae were abundant. Thus, conservation assessment based on altitudinal regimes and the information on species structure and function can provide baseline information for monitoring and sustaining the biodiversity.  相似文献   
1
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