Effect of fire severity on physical and biochemical soil properties in Zagros oak (<Emphasis Type="Italic">Quercus brantii</Emphasis> Lindl.) forests in Iran     

M. Heydari  A. Rostamy  F. Najafi  D. C. Dey 《林业研究》2017,28(1):95-104

Fire affects the physical and chemical properties and soil biological activity of natural ecosystems. This study was conducted in the Miyan Tang region, Ilam Province in western Iran. The study site was 110 hectares, where we sampled soils in areas that were classified by fire severity: low (LS), high (HS) and medium severity (MS), and unburned (UB), which served as the control. In each severity class, 25 transect points were randomly selected for measurement. Around each transect plot center, 3 soil samples were selected randomly and soils collected from the 0 to 20 cm depth were combined into a composite sample that was used in laboratory analysis to represent conditions at that point. Plots in the UB and LS fire classes had similar soil conditions and had higher values of factors such as saturated moisture, organic carbon, carbon dioxide, and silt and clay content. In contrast, plots in the HS and MS fire severity classes were clustered in the positive direction along the first axis that represented gradients in soil acidity, electrical conductivity, cation exchange capacity, accessible phosphorus, accessible potassium, bulk density, and sand. Soil attributes were similar in areas of HS and MS fire severity classes, whereas soil conditions in the LS class and UB controls were most similar. Fire in the LS areas either did not significantly alter the physical–chemical soil properties and microbial basal respiration, or soils were able to recover quickly after being burned.  相似文献   

Quantifying flooding effects on hardwood seedling survival and growth for bottomland restoration     

John M. Kabrick  Daniel C. Dey  J. W. Van Sambeek  Mark V. Coggeshall  Douglass F. Jacobs 《New Forests》2012,43(5-6):695-710

Growing interest worldwide in bottomland hardwood restoration necessitates improved ecological understanding of flooding effects on forest tree seedlings using methodology that accurately reflects field conditions. We examined hardwood seedling survival and growth in an outdoor laboratory where the timing, depth, duration, and flow rate of flood water can be carefully controlled while simulating natural soil conditions occurring in floodplains. Flooding treatments were initiated in mid-May and included partial inundation (15–20?cm) during the growing season for 5-week flowing, 5-week standing, 3-week flowing, and control. We monitored the vigor, survival, and growth (changes in basal diameter and stem length) of six hardwood species representing a wide range in expected flood tolerance including eastern cottonwood (Populus deltoides Bartr. Ex Marsh.), pin oak (Quercus palustris Muenchh.), swamp white oak (Q. bicolor Willd.), bur oak (Q. macrocarpa Michx.), black walnut (Juglans nigra L.), and pecan [Carya illinoensis (Wangenh.) K. Koch]. All stock was 1-0 bareroot except that cuttings were used for eastern cottonwood. Five species—eastern cottonwood, bur oak, swamp white oak, pin oak, and pecan—exhibited high survival probabilities (>0.62 for cottonwood; >0.77 for the others) regardless of flood treatment. But of the survivors, only eastern cottonwood and swamp white oak maintained positive growth and healthy green foliage. Despite high survival, bur oak and pin oak suffered stem growth losses and exhibited chlorotic foliage in flood treatments suggesting greater vulnerability to other abiotic or biotic stresses if outplanted on flood-prone sites. Pecan also suffered stem dieback in controls suggesting vulnerability to competition and browsing when outplanted despite high survival after flooding. Our quantitative data helps to confirm and/or refine previously published qualitative flood tolerance ratings for these species, and describes operation of an in situ outdoor flood experiment laboratory that may prove effective in guiding future flood tolerance research.  相似文献   

A scanning electron microscope study of Raillietascaris varani (Baylis et Daubney, 1922) (Nematoda: Ascaridioidea).     

N C De  J Dey 《Folia parasitologica》1992,39(2):145-151

The Raillietascaris varani (Baylis et Daubney, 1922), parasitic in the Indian monitor lizard, Varanus monitor (L.), was studied by scanning electron microscopy (SEM). A surface topography of the worm, especially the head and male tail, were described, illustrated and discussed with regard to the available data on this species, and also other species of ascaridoid nematodes. The present study confirms the previous observations from Sprent (1985), and also provides some additional information concerning the microtopography of the worm which might be useful in comparative studies on the Ascaridoidea.  相似文献   

The effects of PPR on the reproductive health of Black Bengal goats and the possible role played by oxidative stress     

Pankaj Kumar  Amitava Dey  Abhay Kumar  Pradeep Kumar Ray  Poolangulam Chinnakkan Chandran  Rashmi Rekha Kumari  Manish Kumar 《Tropical animal health and production》2018,50(7):1441-1447

Outbreaks of Peste des petits ruminants (PPR) viral disease in Black Bengal goats were investigated from the middle Indo-Gangetic Plains of India. Clinical profile of PPR-affected flocks was recorded from four different outbreak sites of the region. The PPR outbreak was diagnosed serologically using commercially available sandwich ELISA kit. Relatively, low mortality rate (mean 26.75%) for PPR outbreak was recorded due to the endemic status of the disease. To understand the role of oxidative stress in PPR virus pathogenesis, various oxidant and antioxidant parameters in goats infected with PPR were estimated and compared with the uninfected/healthy goats of the same flock. The measured high level of pro-oxidant malondialdehyde (MDA) obtained from lipid peroxidation along with lower levels of anti-oxidants viz. superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) in PPR-affected Black Bengal goats suggests oxidative stress as one of the mechanism of pathogenesis of PPR virus. In addition, the correlation of oxidative stress due to PPR and the resulting reproductive disorders in the female goats were evaluated. The abortion in pregnant does observed during PPR outbreak was proportional to debility and oxidative stress manifested during PPR infection. The reproductive performance of recovered female goats in the period of 18 months of monitoring was significantly compromised in terms of kidding and twinning frequency. The mortality rate in kids born from PPR-recovered goats was significantly higher compared to those from health goats in the first 9 months post-recovery. From the present study, it may be concluded that together with the PPR virus, infection in goats and the resulting oxidative stress play a vital role for abortion and reduced post-reproductive performance in Black Bengal female goat.  相似文献   

Effect of midstory and understory removal on the establishment and development of natural and artificial pin oak advance reproduction in bottomland forests   总被引：1，自引：1，他引：0  

Jonathan R. Motsinger  John M. Kabrick  Daniel C. Dey  Dawn E. Henderson  Eric K. Zenner 《New Forests》2010,39(2):195-213

Regenerating oaks (Quercus L.) on mesic and hydric sites has remained a problem largely because of inadequate density and poor distribution of large oak advance reproduction prior to harvesting. We examined the effect of midstory and understory removal on the establishment and 3-year development of natural and artificial sources of pin oak (Q. palustris Muenchh.) advance reproduction in bottomland forests in southeastern Missouri, USA. Midstory and understory removals increased the photosynthetically-active radiation (PAR) reaching the seedling layer from about 3 to 15%. This increased light did not increase the density of natural pin oak advance reproduction compared to control, but it increased the survival and nominally increased the growth of the natural pin oak advance reproduction. Where the midstory and understory had been removed, underplanted RPM^® container stock and bareroot pin oak stock maintained high survival, but of the two only the RPM^® stock maintained positive height and diameter growth while bareroot stock suffered some growth reductions. Pin oaks originating from the direct seeding of stratified acorns sown in the spring had low germination and survival, but the survivors had growth rates similar to those of natural seedlings in thinned stands. Applying triclopyr to competitors in the ground flora layer only nominally increased PAR but reduced the percent survival and marginally increased the growth of natural and artificial pin oak. We conclude that artificial reproduction may be used to further increase the probability of achieving adequate numbers of the desired species in the future. Bareroot seedlings may not perform as well as RPM^® seedlings and natural seedlings already present. However, bareroot and RPM^® seedlings remained significantly larger than the natural seedlings after 3 years.  相似文献   

River dolphin distribution in regulated river systems: implications for dry‐season flow regimes in the Gangetic basin     

Sunil Choudhary  Sushant Dey  Subhashish Dey  Viveksheel Sagar  Tarun Nair  Nachiket Kelkar 《水产资源保护:海洋与淡水生态系统》2012,22(1):11-25

Optimizing protocol for efficient microspore embryogenesis and doubled haploid development in different maturity groups of cauliflower (B. oleracea var. botrytis L.) in India     

R. Bhatia  S. S. Dey  Shritika Sood  Kanika Sharma  V. K. Sharma  Chander Parkash  Raj Kumar 《Euphytica》2016,208(3):439-451

  相似文献   

DISAGGREGATED ANALYSIS OF FISH SUPPLY,DEMAND, AND TRADE IN ASIA: BASELINE MODEL AND ESTIMATION STRATEGY     

Madan M. Dey  Roehlano M. Briones  Mahfuzzudin Ahmed 《Aquaculture Economics & Management (Blackwell Science)》2013,17(1-2):113-139

ABSTRACT

Quantitative modeling of fish supply, demand and trade is a useful tool for analyzing recent structural changes, such as the rapid development of aquaculture. Existing models are, however, limited by their use of highly aggregated fish categories and assumed (rather than estimated) elasticities. This paper outlines an estimation strategy and a multiproduct equilibrium model for disaggregated analysis of fish supply, demand, and trade. The model is composed of a producer, consumer and trade core, and is specified to accommodate special features of the fish sector. The estimation and modeling strategy also address common data problems, such as heterogeneity of fish types, diversity of production categories, and so forth. The model has been applied to nine major fish producers in developing Asia.  相似文献   

FOOD SAFETY STANDARDS AND REGULATORY MEASURES: IMPLICATIONS FOR SELECTED FISH EXPORTING ASIAN COUNTRIES     

Madan M. Dey  M. A. Rab  K. M. Jahan  A. Nisapa  A. Kumar  M. Ahmed 《Aquaculture Economics & Management (Blackwell Science)》2013,17(1-2):217-236

ABSTRACT

Developing Asian countries continue to record an impressive trade surplus in fish products. However, raising consumer concerns about a range of food safety matters and increasingly stringent regulatory standards related to fish product supply pose on-going challenges to the sustained international market access of many developing country suppliers. This paper provides an overview of emerging trade patterns in fish products and the trade regime in which this is occurring. It then reviews the implementation of various food safety standards on fish and seafood exports in the major fish-exporting countries in Asia, and analyzes the costs and benefits of compliance with these standards and regulations in these countries. Results show that, at the factory level, implementation of the standards has significantly increased the cost of processing, and the cost per unit of fish processed is higher for the smaller plants. These economies of scale could exclude small operators in developing countries. Continued competitiveness of small plants would seem to require government policies and support designed to minimize the cost of compliance with international standards.  相似文献   

THE SOCIAL AND ECONOMIC IMPACTS OF SEMI-INTENSIVE AQUACULTURE ON BIODIVERSITY     

Robert Pomeroy  Madan M. Dey  Nataliya Plesha 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):303-324

As a result of the concern and debate about the impacts of intensive aquaculture development on biodiversity, semi-intensive aquaculture is being considered as an alternative. Although the biophysical impacts of aquaculture on biodiversity have been examined, there is only limited understanding of the social and economic impacts of aquaculture on biodiversity, and especially the impacts of the shift from intensive to semi-intensive systems. The purposes of this article are twofold: (1) to identify and discuss the social and economic impacts of aquaculture on biodiversity, and (2) to examine the impacts while moving from intensive to semi-intensive systems. After discussing the findings of our study, we provide some recommendations as to how to minimize social and economic impacts of aquaculture on biodiversity by moving to a lower intensity aquaculture system. The integrated agriculture-aquaculture farming systems, stakeholder involvement in management, and well defined basic rights are aquaculture systems that contribute to conservation of biodiversity.  相似文献