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 0 毫秒
1.
Northeast India is rich in Citrus genetic diversity representing several wild and cultivated species. Besides commercially cultivated species, several wild, semi-wild and domesticated species namely Citrus indica, C. macroptera, C. ichangensis, C. latipes, C. megaloxycarpa and C. assamensis are found to grow in Northeast India. These species have great potential in improvement of Indian Citrus industry being source of genes for combating biotic and abiotic stresses. The natural diversity of these genetic resources is shrinking at alarming rate due to large scale deforestation, shifting cultivation practiced in these areas and climate change scenario in this important hotspot of biodiversity. Socio-economic importance of each species have been studied during surveys and interesting domestication trends were observed based on their cultural and economic significance, which led to “in situ on farm” conservation of C. indica, C. macroptera and threat to C. megaloxycarpa and C. ichangensis. Consequently, genetic resources of most of these species are facing severe threat of extinction necessitating policy interventions and adoption of dynamic conservation and management strategies. Species specific conservation strategy especially through “in situ on farm” conservation has been proposed with suitable sites in Northeastern Indian states based on population structure and suitability of habitat. Farmers’ support through “The Biological Diversity Act, 2002” and “The Protection of Plant Varieties and Farmers’ Rights Act, 2001” of India would bring the required impact on management of these complex genetic resources of Citrus. In the present study, we have documented the current status, socio-economic potential, domestication trends and associated traditional knowledge of these wild and semi-wild Citrus species occurring in Northeast India and enumerated suitable conservation strategies and desired policy interventions for their dynamic conservation and sustainable utilization.  相似文献   

2.
The North-eastern region of India is rich treasure of various Citrus species. A vast reservoir of Citrus diversity exists in wild, semi wild form and is found scattered here and there without commercial cultivation and much care. The edaphic and climatic set up as well as the physiographic condition of the region makes it possible to grow a number of species, landraces and probable hybrids of Citrus without any care. But of now with the population increase, changing attitude of the farmers towards some newly introduced cash crops there is genetic erosion of the valuable resources and most of them are in verge of extinction. So, it is the high time for the scientific community to exploit all the rare and endangered resources of Citrus of north eastern region and for their conservation. In addition molecular and morphological characterization of the reported germplasm, evaluation and screening against biotic and abiotic stresses should also be needed to safeguard the existing population of Citrus and for future Citrus improvement programme.  相似文献   

3.
人多地少是中国的基本国情,人均耕地面积大约只有世界平均水平的1/3。突破现有耕地保护内涵对重新认识耕地保护具有重要意义,能更大程度保障国家粮食安全。该研究界定可耕地内涵,运用生态位模型和GIS空间分析法对全国范围内的土地开展可耕性评价,测算可耕地规模和空间布局,分析可耕地与现状耕地空间冲突,并提出耕地保护转型策略。结果表明:1)可耕地数量充足,约为现状耕地的2.05倍,主要分布在胡焕庸线以东区域。2)可耕地质量从东南向西北呈阶层分布,质量逐渐降低。3)可耕地与现状耕地存在空间错配,16.83%的现状耕地分布在不可耕作区。可耕地的提出为耕地保护转型提供了方向,可耕性评价有助于摸清中国可以耕作的土地资源本底,开展可耕地分级分区保护并依据分级分区结果适当调整现状耕地、新增耕地布局,进而实现良田粮用,确保国家粮食出现危机时及时提供足量的耕地投入农业生产。  相似文献   

4.
Cambodia forms part of the Indo-Burma hotspot. Its extent of biodiversity, however, is subject to considerable uncertainty, as there has been little systematic collection of flora and fauna. During the Khmer Rouge regime institutions were banned, academics were prosecuted and written documentation systematically destroyed. Compared with neighbouring countries Cambodia has a low population density and relatively large natural areas that are still intact. However, deforestation is expanding rapidly and a significant but un-estimated area of forest has been degraded by development of agro-industries, encroachment, illegal logging, over-harvesting and forest fire as well as the use of chemicals during war. The purpose of the paper is to: (i) apply reserve selection methods to design more robust conservation networks when knowledge of species occurrence is incomplete and habitat is threatened, and (ii) evaluate the usefulness of systematic conservation planning in a developing country where data are limited and institutions for implementation are weak. This study investigates the performance of four non-probabilistic strategies: (i) a so-called ‘rule of thumb’, (ii) hotspot, (iii) minimum cost representation, and (iv) maximum coverage; and one probabilistic design strategy, i.e. maximum expected coverage. The maximum expected coverage approach is between 15% and 24% more efficient than the non-probabilistic strategies. Finally, the relevance of such tools to real-world conservation planning in Cambodia is investigated. By incorporating experts in the generation of data, running the models and setting up premises, they acknowledge that it is possible to contribute to more systematic conservation planning in developing countries.  相似文献   

5.
Illegal hunting poses a dual threat to large carnivores through direct removal of individuals and by prey depletion. We conducted a camera-trapping survey in the Namdapha National Park, north-east India, conducted as part of a programme to evaluate carnivore and prey species abundance. Clouded leopard (Neofelis nebulosa) was the only large carnivore detected by camera-trapping. Indirect evidences indicated the presence of the wild dog (Cuon alpinus) and leopard (Panthera pardus), however, there was no evidence of tigers (Panthera tigris), suggesting their possible extinction from the lower elevation forests. Of the major ungulate prey species, sambar (Cervus unicolor) and wild pig (Sus scrofa) were the only large prey detected, while the Indian muntjac (Muntiacus muntjak) was the only small prey species detected. Relative abundances of all species were appreciably lower than estimates from other tropical forests in south-east Asia. We suspect that illegal hunting may be the cause for the low carnivore and prey species abundance. An ongoing community-based conservation programme presents an opportunity to reduce local people’s dependence on hunting by addressing their socio-economic needs and for using their skills and knowledge of the landscape for wildlife conservation. However, long-term wildlife monitoring is essential to assess the efficacy of the socio-economic interventions in bringing about wildlife recovery.  相似文献   

6.
The use of predictive habitat distribution models by land managers in the conservation management of threatened species is increasing. Few models, however, are subsequently field-checked and evaluated. This study evaluates the statistical strength and usefulness for conservation purposes of three predictive habitat models developed for a threatened stag beetle, Hoplogonus simsoni, found in the wet eucalypt forests and mixed/rainforests of north-east Tasmania. The relationship between various environmental variables for which spatial (GIS) information was available and the density, frequency of occurrence and presence/absence of the species was investigated using generalised linear modelling. Models developed were coupled with the GIS data to develop maps of predicted occurrence within the species’ range, grouped into categories of habitat quality. The models found that altitude, aspect, slope, distance to nearest stream and overstorey tree height were significantly associated with the occurrence of the species. Evaluation of the statistical strength of the models with independent data of species’ occurrence collected at 95 sites found that the density model performed poorly with little correlation between predicted and observed densities of the species. The frequency of occurrence model, however, showed a moderate ability to predict both species’ abundance and presence/absence. The presence/absence model had a similar discriminatory ability in predicting presence or absence of H. simsoni, but also showed some potential as an indirect predictor of species’ abundance. Assuming a correlation between relative abundance and habitat quality, the frequency of occurrence predictive model appeared to be the better and more direct discriminator of high quality habitat relative to the other models. The value of species’ habitat models and the need to evaluate their utility in the development of conservation strategies are discussed.  相似文献   

7.
In 26 crops specific and several multicrop explorations, 2592 germplasm representing diversity in cruciferous oilseeds namely Brassica juncea (L.) Czern., B. rapa L. ssp. trilocularis (Roxb.) Hanelt, B. rapa L. ssp. dichotoma (Roxb.) Hanelt, B. rapa L. ssp. oleifera (DC) Metzg.; B. nigra (L.) Koch, B. tournefortii Gouan and Eruca sativa Mill, and wild related genera-Lepidium, Sisymbrium, Crambe, Arabis, Barbarea etc. have been collected by the National Bureau of Plant Genetic Resources since 1976, independently as well as in collaboration with crop based institutes and projects, state agricultural universities and departments and foreign universities. The variability has been collected through random sampling in diverse habitats in 20 states of India. The indigenous collections exhibited facinating variability in important morphological, economic and resistance traits. Tarai region in Gorakhpur and Deoria for B. rapa L. ssp. trilocularis (Roxb.) Hanelt, local – yellow sarson; diara lands in Budaun for B. rapa L. ssp. oleifera (DC) Metzg., local – toria; central parts of Uttar Pradesh for B. rapa L. ssp. dichotoma (Roxb.) Hanelt, local – brown sarson; Tibbi area in Ganganagar for B. tournefortii Gouan; Mewat region and Chambal ravines for Eruca sativa Mill. have been identified as the hot spots of variability in respective species. These areas still hold a lot of variability worth utilizing, even through direct selection by the breeders. A general pattern of variability indicated that early dwarf types are distributed in the eastern parts of the country with frequency increasing towards the border areas facing Bangladesh. Whereas tall, late, robust, high bearing and/or high yielding types are concentrated in the western parts of the country, particularly in Haryana and Rajasthan. To broaden germplasm base further, over 2000 accessions of different types have been introduced from 22 countries and promising lines identified for further uses. 4589 lines representing diversity in cruciferous oilseeds have been conserved in the National Gene Bank for posterity and gaps in collection have been discussed.  相似文献   

8.
Hunting is one of the greatest conservation challenges facing tropical wildlife. Wildlife in Indian tropical forests are vulnerable to hunting, although data on hunting impacts from the region are limited. We use a meta-analysis of 143 hunting studies from India to identify the species and geographic regions most at risk, and to assess their legal protection. We found evidence of hunting in 114 mammal species, with larger-bodied mammals being particularly vulnerable. Although 75% of all studies focused on mammals, few actually quantified hunting impacts. Further, among studies of all terrestrial vertebrates where hunting was mentioned, only 6% focused exclusively on hunting. With further research, we expect that the suite of species known to be exploited by hunters will increase. We conclude that the Eastern Himalaya and Indo-Myanmar biodiversity-hotspot complex is particularly vulnerable to hunting. Quantitative studies of hunting impacts are urgently needed across India, especially in this biodiversity-hotspot complex.  相似文献   

9.

The state of Kerala in India, a part of the Western Ghats–Sri Lanka biodiversity hotspot, is blessed with rich biodiversity including agrobiodiversity. Richness in crop diversity is attributed to the wide topographic and climatic niches, long history of outside contacts, personal craving for experimenting new crops, practice of high-density multi-species cropping system, etc. Evidence from several field exploration trips, herbarium survey, reliable literature and other sources has revealed that 306 crop taxa (excluding medicinal and aromatic plants, ornamentals and forestry species) belonging to 290 species coming under 179 genera and 61 families, are being cultivated in different areas of this state. This includes crops belonging to crop-groups—cereals and millets (11), pseudocereals (2), pulses (7), oilseeds (7), fibres (3), forages (14), fruits and nuts (107), vegetables (86; 18-being tuber crops), spices and condiments (20), plantation crops (10) and others (29). Of 306 taxa, 63 occur in the wild state as well; 43 are of only recent cultivation (<?15 years) or under trial cultivation by innovative farmers; and 43 are confined only in (sub)temperate hills. This is more than double (104% increase) the earlier estimate of crops made during 2011, which also included species of medicinal/aromatic/ornamental value (5), not under cultivation in Kerala (3), mistaken identity (3) and synonym (1). We provide here user-friendly crop-group wise categorization of taxa with their vernacular names for easy cross reference. This communication also discusses about the issue of botanical misidentification of crop plants, species of doubtful cultivation status, specialty crops, potential exotic crops, etc.

  相似文献   

10.
NE India is considered as one of the centre of diversity of gingers having a total account of 24 species out of the 65 valid species found in the world. Manipur is one of the seven states of NE India with a mere area of 0.7% out of the total area of India. This paper focuses on the distribution, classification and evaluation of Hedychium species collected from Manipur. A total of 11 species were collected, identified and classified based on their morphological characteristics. The species are identified as Hedychium rubrum A.S. Rao et Verma, H. coronarium Koenig, H. chrysoleucum Hook., H. coccineum Buch.-Ham., H. thrysiforme Ker-Gawl., H. flavescens Carey ex Roscoe, H. stenopetalum Lodd., H. urophyllum Lodd., H. marginatum Clarke, H. villosum Wall. and H. elatum R. Brown. Evaluation of its botanical characteristics are also conducted. Analytical hierarchy process method is used in this paper to address the possibility of analysing the potential of these diverse Hedychium resources based on their ornamental, adaptability and utilisation potential which was evaluated on 12 indicator points. H. elatum scored the highest overall index making it the most potential species for sustainable exploitation followed by H. coronarium while H. villosum ranked the lowest.  相似文献   

11.
Conservation agriculture(CA)-based best-bet crop management practices may increase crop and water productivity, while conserving and sustaining natural resources. We evaluated the performance of rainy season maize during 2014 under an ongoing long-term trial(established in 2008) with three tillage practices, i.e., permanent bed(PB), zero tillage(ZT), and conventional tillage(CT) as main plots, and four intensified maize-based cropping systems, i.e., maize-wheat-mungbean, maize-chickpea-Sesbania(MCS), maizemustard-mungbean, and maize-maize-Sesbania) as subplot treatments. In the seventh rainy season of the experiment, maize growth parameters, yield attributes, yield, and water-and energy-use efficiency were highest at fixed plots under ZT. Maize growth parameters were significantly(P 0.05) superior under ZT and PB compared with CT. Maize yield attributes, including cobs per m~2(7.8), cob length(0.183 m), grain rows per cob(13.8), and grains per row(35.6), were significantly higher under ZT than CT; however, no significant effect of cropping systems was found on maize growth and yield attributes. Zero tillage exhibited the highest maize productivity(4 589 kg ha~(-1)). However, among the cropping systems, MCS exhibited the highest maize productivity(4 582 kg ha~(-1)). In maize, water use was reduced by 80.2–120.9 mm ha-1under ZT and PB compared with CT, which ultimately enhanced the economic water-use efficiency by 42.0% and 36.6%, respectively. The ZT and PB showed a 3.5%–31.8% increase in soil organic carbon(SOC) at different soil depths(0–0.45 m), and a 32.3%–39.9% increase in energy productivity compared with CT. Overall, our results showed that CA-based ZT and PB practices coupled with diversified maize-based cropping systems effectively enhanced maize yield and SOC,as well as water-and energy-use efficiency, in northwestern India.  相似文献   

12.
Field trials have been carried out to determine the variability of residue levels of fenitrothion and its main metabolites fenitrothion-oxon and 3-methyl-4-nitrophenol in individual kaki fruits versus composite samples, in peel versus flesh, and in whole uncooked versus whole cooked fruits. Residue levels have been determined by gas chromatography with thermionic specific detection after extraction with ethyl acetate and without further cleanup. At harvest, residue levels of fenitrothion were below maximum residue levels (MRLs) and the two metabolites 3-methyl-4-nitrophenol and fenitrothion-oxon could be quantified with average amounts of 0.080 and 0.012 mg/kg, respectively. Levels of fenitrothion decreased 88% after peeling, whereas temperature did not result in a high variation. The ratios of the highest residue level in the individual fruits to the corresponding mean of residue levels in the composite samples for fenitrothion were <3. This value is lower than that recommended by the World Health Organization as default value for consumer risk assessment.  相似文献   

13.
There are about 800 different species of wild edible crops in India, out of which about 300 species are used mostly by the tribal and rural population of the North-eastern region alone. This region is the natural reservoir of a number of wild edible fruits. These naturally occurring fruit are not only nutritionally and medicinally rich but also thrive well under adverse climatic conditions and are resistant to biotic and abiotic stresses. In spite of their potential, these fruits are unattended both at scientific and farmers level. Due to lack of proper documentation, the information about the ethno-botanical uses of these fruits have been lost at an alarming rate. Therefore, an attempt has been made during 2015–16 at to enumerate the ethno-medicinal uses and socio-economic importance of wild edible fruits of Mokokchung district of Nagaland, India. In the present study, altogether 55 wild edible fruit species belonging to 29 families have been enumerated. These fruits are used traditionally for the treatment of gastro-intestinal disorders, respiratory ailments, urogenital problems, dermatological problems, fever, cuts and wounds, diabetes, jaundice, cardiovascular problems, nutritional disorders, antidote, bone diseases, cancer, toothache, opthalmia, ENT, food poison, malaria and allergy. In addition, these fruits have also been use in the socio-economic life of the rural people as constructional timber, firewood, fodder, charcoal, fish poisoning, dyes, oil etc. Although, these fruits play an important role in the social and cultural life of rural people, but most of them are going to be extinct due to a number of factors. Therefore, there is urgent need to conserve these species for livelihood security of rural people.  相似文献   

14.
Soil erosion is a major land degradation problem in South Africa (SA) that has economic, social and environmental implications due to both on-site and off-site effects. High rates of soil erosion by water are causing rapid sedimentation of water bodies, ultimately leading to water crisis in SA. Lots of financial and human resources are channelled towards controlling of soil erosion but unfortunately with little success. The level of soil erosion in a particular area is governed by the site properties. Therefore, it is inappropriate to generalize data on soil erosion at a large-scale spatial context. The literature on soil erosion in SA classifies Eastern Cape Province as a high-erosion-potential area using data collected at a large-scale spatial context. Collecting soil erosion data at a large spatial scale ignores site-specific properties that could influence soil erosion and has resulted in failure of many traditional soil erosion control measures applied in the province. Moreover, scientific principles underlying the processes and mechanisms of soil erosion in highly erodible soils are missing in SA. This review was to find effective soil erosion control measures by having an insight on what happens during soil erosion and how soil erosion occurs in Ntabelanga. The literature suggested that erosion in Ntabelanga could be influenced by both the erosivity and erodibility factors though the erodibility factors being more influential. Soil permeability contrast between the horizons could be influencing the rate and nature of soil erosion. To mitigate the impact of soil erosion in Ntabelanga, efforts should aim to improve the vertical flow capacity in the B horizon. Clay spreading, clay delving, addition of gypsum, deep ploughing and mulching could aid the water permeability problems of the subsurface horizons. However for effective soil management and control option, detailed studies of specific site properties are needed. The generated information can assist in formulating soil erosion policies and erosion control strategies in the Ntabelanga area and SA at large.  相似文献   

15.
16.
We determined the food habits of the endangered Indian wolf Canis lupus pallipes in the Bhal region of Gujarat, western India by analyzing 1246 wolf scats from five packs by estimating prey availability and by monitoring radio-tagged wolves from three packs for 1994 hour. The frequency of occurrence of blackbuck Antelope cervicapra remains in scats was 55.5%, followed by cattle (25.7%), nilgai Boselaphus tragocamelus (6.3%); and as others (<5%). The frequency of food items in scats of different wolf packs reflected their relative availability. For cattle the distinction between scavenging and predation was only possible through continuous monitoring. The average feeding interval obtained from monitoring was 3.6± 0.7 (S.E.) days and the average consumption/wolf/day was 1.8± 0.3 (S.E.) Kg. Adult male blackbuck formed most (70%) of the biomass consumed by wolves whereas cattle carcasses and cattle actually killed by wolves contributed 14 and 8%, respectively. Predation on cattle therefore was low and translated in an estimated loss of Rs. 821 (US$ 17) per village per annum. We propose that landscapes such as the Bhal with high wolf densities, high natural prey availability and consequently low human-wolf conflict levels should be prioritized as prime sites for wolf conservation efforts.  相似文献   

17.
Planners of Marine Protected Areas (MPAs) commonly use maps of habitat types when choosing areas to conserve. This assumes that habitats are homogeneous, and therefore, that any area of habitat will represent the full spectrum of ecological diversity within that habitat. Here, we report that macrobenthic assemblages in tidal flat habitats were spatially heterogeneous in terms of beta diversity (taxonomic turnover), abundance, taxonomic richness and Shannon-Wiener H′ Diversity. Importantly, the patterns of heterogeneity were scale dependent for the three spatial scales we examined; plots (20 m), sites (100s of m) and estuaries (<30 km). The three estuaries in the study were compositionally similar as they shared the same dominant taxa, although one estuary had significantly more taxa and a higher abundance of macrobenthos. Assemblages within tidal flats differed at scales of 100s of m for all ecological measures. Most notably, beta diversity was highest at this scale. Assemblages were relatively more homogeneous at the 20-m scale. These findings highlight the value of examining more than one ecological measure and estimating magnitude of effects across a variety of scales. This work presents two important considerations for MPAs. First, although tidal flats in different estuaries are compositionally similar for dominant taxa, rarer taxa and high heterogeneity in abundance should influence the choice and number of tidal flats in MPAs. Second, strong compositional heterogeneity within individual tidal flats implies that conservation of whole habitat, rather than sections of a tidal flat, is essential if this habitat type is to be used to represent taxonomic diversity.  相似文献   

18.
With growing pressure for conservation to pay its way, the merits of compensation for wildlife damage must be understood in diverse socio-ecological settings. Here we compare compensation programs in Wisconsin, USA and Solapur, India, where wolves (Canis lupus) survive in landscapes dominated by agriculture and pasture. At both sites, rural citizens were especially negative toward wolves, even though other wild species caused more damage. Wisconsin and Solapur differ in payment rules and funding sources, which reflect distinct conservation and social goals. In Wisconsin, as wolves recolonized the state, some periodically preyed on livestock and hunting dogs. Ranchers and some hunters were more likely to oppose wolves than were other citizens. The Wisconsin compensation program aimed to restore an iconic species by using voluntary contributions from wolf advocates to pay affected individuals more for wolf losses than for other species. By contrast, wolves had been continuously present in Solapur, and damages were distributed amongst the general populace. Government-supported compensation payments were on offer to anyone suffering losses, yet claims registered were low. There were no significant differences in attitudes of any particular segment of the population, but those losing high value livestock applied for compensation. Residents at both sites did not report (Wisconsin) or expect (Solapur) a change in attitude towards wolves as a result of compensation, yet they support the existence of such programs. To assess the merits of any compensation program, one must disentangle the multiple goals of compensation, such as reducing wolf killing or more fairly sharing the costs of conserving large carnivores.  相似文献   

19.
A simple, specific, and rapid analytical method for determining seven largely used carbamate insecticides in tomato, spinach, lettuce, zucchini, pear, and apple is here presented. This method is based on the matrix solid-phase dispersion technique, with heated water as extractant followed by liquid chromatography (LC)-mass spectrometry (MS) equipped with a single quadrupole and an electrospray ion source. Target compounds were extracted from the vegetal matrixes by water heated at 50 degrees C. After acidification and filtration, 0.25 mL of any aqueous extract was injected in the LC column. MS data acquisition was performed in the selected ion monitoring mode, selecting three ions for each target compound. Heated water appeared to be an excellent extractant because recovery data ranged between 76 (carbaryl in spinach) and 99% (pirimicarb in spinach), with RSDs not larger than 10%. Using trimethacarb (an obsolete carbamate insecticide) as a surrogate internal standard, the accuracy of the analysis varied between 84 and 110%, with RSDs not larger than 9%. On the basis of a signal-to-noise ratio of 10, limits of quantification were estimated to range between 2 (pirimicarb) and 10 ppb (oxamyl) and were not influenced by the type of matrix. When trying to fractionate analytes by using a short chromatographic run time, marked weakening of the ion signals for oxamyl, methomyl, and aldicarb were observed. This effect was traced to polar endogenous co-extractives eluted in the first part of the chromatographic run that interfered with gas-phase ion formation for carbamates. Adopting more selective chromatographic conditions eliminated this effect.  相似文献   

20.
 基于联合国粮农组织对农业可持续发展的定义,采用社会经济统计学法,建立水土保持型生态农业可持续性评价多指标模型,并利用此模型对陕西省安塞县纸坊沟流域水土保持型生态农业实体模式进行评价与分析。结果显示:纸坊沟流域水土保持型生态农业的可持续生产性指数、经济活性指数、保护性指数、稳定性指数和社会接受性指数分别为69.5、56.8、62.5、86.8和52.8;综合可持续发展指数为65.4,离可持续发展目标仍有较大的差距。  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