Multi-scale prediction of landscape resistance for tiger dispersal in central India

Context

Connectivity models for animal movement frequently use resistance surfaces, but rarely incorporate actual movement data and multiple scale drivers of landscape resistance.

Objectives

Using GPS data, we developed a multi-scale model of landscape resistance for tiger (Panthera tigris) dispersal in central India and evaluated the performance, interpretation and predictions against single scale models.

Methods

Six dispersing tiger paths were subjected to a path level analysis with conditional logistic regression to parameterize a resistance surface. We evaluated for 21 scales of available habitat and selected the best scale for each variable. We derived a scale-optimized multivariate path selection function and predicted landscape resistance across the landscape.

Results

The tigers preferred to move along areas with forest cover at relatively high elevations along the ridges with rugged topography at broad scale, while avoiding areas with agriculture-village matrix at fine scale. We found that the scale that was most supported by Akaike’s information criterion was not always the scale that maximized the magnitude (effect size) of the relationship. Further, the multi-scale optimized model differed substantially from the single scale models in terms of variable importance, magnitude of coefficients and predictions of connectivity.

Conclusions

Our results demonstrate that the variables in landscape resistance models produce markedly different predictions of population connectivity depending on the scales of analyses and interpretation. Thus, scale optimization in parameterization is critical for appropriate inferences and sound management strategies.

     

Assemblages and species diversity of wood destroying termites in different land use systems in Western Ghat, India

Spatial distribution, abundance and assemblage of termites depend mainly on the local conditions and habitats in which they thrive. Striking differences are observed in the species richness, number of clades and functional diversity of termite assemblage between different habitats. This study aim was to examine effect of human interference in the diversity of wood destroying termite in forest areas as well as managed and unmanaged plantations in South India. Termites attacking trees and wooden logs were collected from forest areas, managed plantations and unmanaged plantations. The termites collected were identified and compared for species abundance, richness and species diversity. Results show that the species composition and species diversity of the wood destroying termites vary according to the conditions. The species diversity measures revealed that there is a significance variation among the forest fauna and plantations. The forest areas have the highest species composition compared to plantations. Species richness is high forest areas. Even though the abundance of termites are more in unmanaged plantations, there is no significant difference related to species diversity among the managed and unmanaged plantations.     

Effect of pre‐storage seed treatments on adult mortality,oviposition and development of Callosobruchus chinensis L. (Bruchidae: Coleoptera), and the viability of mungbean (Vigna radiata (L.) Wilczek) in India

Abstract

The adult mortality of Callosobruchus chinensis L. was 100% within 24 h after artificially infesting seeds pretreated with inert clay and stored for 12 months under ambient conditions. Pre‐treatment with thiram and delsan‐30 (TCMTB) were also effective in controlling the adults by impairing oviposition. The seeds maintained over 80% germination up to 12 months of storage under all the treatments.     

Effect of iron supplementation on physical growth in children: systematic review of randomised controlled trials

OBJECTIVE: To evaluate the effect of iron supplementation on physical growth in children through a systematic review of randomised controlled trials (RCTs). DATA SOURCES: Electronic databases, personal files, and hand search of reviews, bibliographies of books, abstracts and proceedings of international conferences. REVIEW METHODS: RCTs evaluating change in anthropometry with interventions that included oral or parenteral iron supplementation, or iron-fortified formula milk or cereals, were analysed. RESULTS: Twenty-five trials (26 cohorts) had relevant information. There was no evidence of publication bias. The pooled estimates (random effects model) did not document a statistically significant (P>0.05) positive effect of iron supplementation on any anthropometric variable (weight-for-age, weight-for-height, height-for-age, mid upper-arm circumference, skinfold thickness, head circumference). Significant heterogeneity was evident, and its predictors included greater weight-for-age in supplemented children in malaria hyperendemic regions and greater weight-for-height for children above 5 years of age, but a negative effect on linear growth in developed countries and with supplementation for 6 months or longer. CONCLUSIONS: This review did not document a positive effect of iron supplementation on the physical growth of children. The identified predictors of heterogeneity should be considered as exploratory and requiring confirmation, not conclusive.     

Investment decision model for drip irrigation system

Drip irrigation is becoming popular in India although the decision to shift to drip irrigation from surface irrigation is not backed up by solid economic factors. It is not that the factors do not justify the shift, but that insufficient study has been done to document the conditions under which a change is justified. The investment decision for shifting to drip irrigation will depend upon many factors; including cost of cultivation, productivity, yield gain factor, cost of produce, electricity charges, depth of groundwater and irrigation requirement. These parameters vary from crop to crop, place to place, size of plot, and farmer to farmer. Therefore a sweeping recommendation suitable for all conditions cannot be made. In view of this, a software program has been developed for estimating the threshold economic value of the investment cost of drip irrigation. In addition to the threshold value of investment cost, the software provides information on energy consumption and net return. The software can be used both for annual crops such as sugarcane or seasonal crops such as vegetable rotations (winter–summer). To demonstrate the interdependence of various input parameters, an analysis has been made using local data in this software. The analysis has provided the relationship between the investment cost and the yield gain factor, the returns from the crop, as well as the savings in energy and the size of the prime mover with regard to the size of the farm.     

Application of Isozyme Data in Fingerprinting Napier Grass (Pennisetum purpureum Schum.) for Germplasm Management

Sixty-four accessions of Napier grass (Pennisetum purpureum Schum.), a forage crop of tropics and subtropics, were assessed for polymorphism in isozymes and total proteins (TP). The national germplasm collection exhibited polymorphism in all the three isozymes viz., malate dehydrogenase, glutamate oxaloacetate transaminase and peroxidase (POX) besides TP profile. Though POX and TP showed comparatively higher polymorphism, the study indicated the efficiency of three-enzyme system in identifying more than 90% of the accessions. The combination of TP and three-enzyme systems provided unique isozyme/TP banding patterns for all the 64 accessions leading to development of accession specific profile/fingerprints. In Napier, which is perennial with long vegetative phase, it is difficult to discriminate germplasm accessions based only on morphology. Thus biochemical markers could be efficiently utilized to complement morphological evaluations, in maintaining identity and purity of germplasm for proper conservation and management, for better use in breeding and for proprietary reasons.     

Mineralization-immobilization of soil organic S and oxidation of elemental S in subtropical soils under flooded and nonflooded conditions

Information on the influence of soil moisture on elemental sulphur (S⁰) oxidation and transformation into organic S in semi-arid subtropical soils is scarce. We studied the impact of three moisture regimes on the mineralization of soil organic S, and the oxidation and immobilization of S⁰ in acidic (pH 4.9), neutral (pH 7.1) and alkaline (pH 10.2) subtropical soils. Repacked soil cores were incubated under aerobic (40% and 60% water-filled pore space, WFPS) and flooded soil conditions (120% WFPS) for 0, 14, 28 and 42 days with and without incorporated S⁰ (500 µg g^-1 soil). Soil moisture had profound effects on these processes and the mineralization of native soil organic S, oxidation of applied S⁰ and transformation of S⁰ into soil organic S proceeded most rapidly at 60% WFPS, irrespective of soil pH. Mineralization of native soil organic S resulted in the accumulation of 34, 49 and 44 g SO₄^2--S g^-1 soil in acidic, neutral and alkaline soil in a 42-day period at 60% WFPS. The oxidation rate of added S⁰ during the initial 14-day period at 60% WFPS was highest in alkaline soil (428 µg S cm^-2 day^-1), followed by neutral soil (326 µg S cm^-2 day^-1), and lowest in acidic soil (235 µg S cm^-2 day^-1). These rates are several folds higher than those reported in earlier studies because now we computed the oxidation rates by including the amount of S⁰ that was immobilized to organic S. Of the applied S⁰ at 40% and 60% WFPS, 2.6% and 6.0%, 3.4% and 10.0%, and 9.4% and 14.4% oxidized to SO₄^2-, and 15.0% and 17.6%, 17.6% and 19.6%, and 17.6% and 23.6% transformed into organic S in the 42-day period in acidic, neutral and alkaline soil, respectively. These results suggest that in order to synchronize the availability of S with plant need, S⁰ may be applied well before the seeding of crops especially in acidic soils and in rainfed regions where soil moisture remains at less than 60% WFPS. Apparently no oxidation of S⁰ and significant reduction of SO₄^2--S (7, 53 and 78 µg SO₄^2--S g^-1 in acidic, neutral and alkaline soil, respectively) under flooded conditions suggest that S⁰ is least effective for correcting S deficiency in flooded soil systems such as rice fields.     

Arbuscular mycorrhizae and phosphate solubilising bacteria of the rhizosphere of the mangrove ecosystem of Great Nicobar island, India

Mangroves form an important ecosystem of Great Nicobar, a continental island in the Bay of Bengal with luxuriant tropical rainforests. The rhizosphere of the mangrove plants of Great Nicobar was investigated for the presence of arbuscular mycorrhizal fungus (AMF) and phosphate solubilising bacteria (PSB). The soils of the Great Nicobar mangroves were silt–clays and were poor in phosphate content. Five species of AMF belonging to the genus Glomus were isolated. The %AMF colonization in the mangrove plants was between 0 and 17%, and the presence of AMF in the aerenchymatous cortex suggests that the mangrove plants may be aiding in AMF survival by providing oxygen. Two strains of phosphate solubilising Pseudomonas aeruginosa were found in the mangrove soils of Great Nicobar. Phosphate solubilisation by the two isolated strains was almost 70% under in vitro conditions. PSB may play a role in the mangrove ecosystems of Great Nicobar by mobilising insoluble phosphate. The plant roots could pick up the released phosphate directly or with the aid of AMF hyphae.