Potential Carbon Storage of Rubber Plantations.

The study was conducted at the three Municipalities of Cotabato province Southern Philippines between January to May 2011. The study aimed at determining the Carbon budget of the different age rubber plantation through field sampling and modeling. Actual field measurement of dbh, were done for the estimation of above-below ground biomass. The major carbon pools, such as above-ground biomass, below-ground biomass, litter and understory vegetation were added and multiplied with 45% default value by IPCC to obtained the carbon density in Mt/ha. The total estimated biomass of the rubber plantation in Antipas were 103.91Mt/ha (10 years) and 573.21Mt/ha (20 years) with carbon density of 46.79Mt/ha and 257.95mt/ha respectively. For the Arakan plantation, the following were revealed in the estimation: (a). the 40 year plantation has total biomass of 1041.54Mt/ha biomass (468.69Mt/ha C), (b). the 11 year plantation has 158.79Mt/ha biomass (71.46Mt/ha C), (c). the 35 year plantation has total biomass of 246.23Mt/ha (110.8Mt/ha Carbon density), and (d). the 12 year plantation has 355.60Mt/ha biomass (160.02Mt/ha C). In Matalam Cotabato, the two different age rubber plantations has an estimated biomass density of 149.47Mt/ha in 8 years with 67.26 Mt/ha C and 70.82Mt/ha biomass density for the 6 year old plantation with 31.87 Mt/ha C.The soil organic carbons found in each plantation were: Antipas; 100.25t/ha (10 years) and 203.54t/ha (20 years), Arakan; 202.55t/ha (40 years), 142.67t/ha (11 years), 86.1t/ha (35 years) and 129.53t/ha (12 years), Matalam; 53.32t/ha (8 years) and 62.04t/ha in the 6 year plantation. T-test reveals significant differences of the biomass and carbon density of the rubber plantation with respect to age range (6-12 years and 20-40 years). This implies that biomass production and carbon storage potentials of rubber plantation is very much dependent on plantation age. Pearson regressioncorrelation analysis of the carbon density of each plantation with carbon pools found to be highly significant.

Impact of age of rubber (Hevea brasiliensis) plantation on earthworm communities of West Tripura (India).

A comparative analysis of earthworm communities was carried out in the rubber plantations (Hevea brasiliensis) of different age groups in West Tripura to understand the impact of such exotic and monoculture plantation in biodiversity conservation. Earthworm communities were studied on monthly basis over a period of one year (2006-2007) in the 3, 10, 14, 20 and 25 year-old plantations. Among twelve earthworm species collected from the studied sites, six species belonged to Octochaetidae [Eutyphoeus assamensis Stephenson, Eutyphoeus comillahnus Michaelsen, Lennogaster chittagongensis (Stephensen), Octochaetona beatrix Gates, Dichogaster affinis Michaelsen, Lennogaster yeicus (Stephensen)], two species each to Megascolecidae [Metaphire houlleti (Perrier), Kanchuria sp. 1] and Moniligastridae [Drawida nepalensis Michaelsen, Drawida papillifer papillifer Stephenson], one species each to Glossoscolecidae [Pontoscolex corethrurus (Muller)] and Ocnerodrilidae [Gordiodrilus elegans Beddard]. Exotic species P. corethrurus, M. houlleti and native peregrine species like D. nepalensis and D. papillifer papillifer were distributed in all the age groups of plantation, while other species showed restricted distribution. P. corethrurus contributed more than 60% biomass and 70% density of earthworm communities in rubber plantation. With aging of rubber plantations both the densities and biomasses of earthworms increased. High contents of polyphenol, flavonoid and lignin in the litters of 3 and 10 year-old-rubber plantations through their effects on food intake, probably resulted to low biomass values of earthworms in those age groups of plantation. With further increase in the age of plantations beyond 10 years, polyphenol, flavonoid and lignin contents decreased. Accordingly the biomass of earthworms increased with increase in the age of plantation. Soil moisture increased with increase in the age of plantation and there was a good positive correlation between soil moisture and earthworm biomass (p<0.01). Density, biomass and dominance of earthworms increased while species diversity, species richness and species evenness of earthworm community were decreased with increase in the age of rubber plantation.

Effects of five earthworm species on some physico-chemical properties of soil.

An incubation experiment was conducted to study the changes that occur in organic carbon content, phosphorous and potassium availability and other soil properties with ingestion of soil mixed with rubber leaf litter and cow dung by five earthworm species viz. Pontoscolex corethrurus, Drawida assamensis, Drawida papillifer papillifer, Eutyphoeus comillahnus and Metaphire houlleti of rubber plantation in Tripura (India). Due to earthworm activity organic C (1.56-1.63%) and available P (14.71-27.60 mg 100 g-1) and K (43.50-49.0 mg 100 g-1) content of the soil increased significantly (p<0.05) in most of the earthworm species studied. M. houlleti and D. papillifer papillifer had the highest P (27.60 mg 100 g-1) and K (49.0 mg 100 g-1) mobilization capacity, respectively. Earthworms, irrespective of the species, increased the pH (7.05-7.17) and electrical conductivity (663-1383 µS cm-1) of the soil significantly (p<0.05).

Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV) during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8 percent suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG)] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68 percent of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002). Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019) and 31-40 (χ2 = 5.84; p = 0.016) years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

Community structure of earthworms under rubber plantations and mixed forests in Tripura, India.

Studies on community structures of earthworms of rubber (Hevea brasiliensis) plantations and their adjacent mixed forests in West Tripura (India) revealed that both the studied sites harvoured 10 earthworm species. Nine species (Pontoscolex corethrurus, Kanchuria sp 1, Metaphire houlleti, Drawida papillifer papillifer, Drawida assamensis, Gordiodrilus elegans, Eutyphoeus assamensis, Eutyphoeus comillahnus and Eutyphoeus gigas) were common to both. While Octochaetona beatrix was found only in the rubber plantations, Dichogaster affinis was restricted to the mixed forest only. Earthworms were found mostly within 15 cm depth of soils having mean temperature of 27ºC, moisture of 23%, pH of 4.57, organic matter of 1.34% and water holding capacity of 36%. Mean earthworm density in rubber plantations (115 ind. m-2) was significantly higher (p = 0.003, t = 3.83) than that in the mixed forests (69 ind. m-2) due to dominance of Pontoscolex corethrurus, an exotic species. Numbers of dominant species were two (P. corethrurus and D. assamensis) in the rubber plantations and five (P. corethrurus D. assamensis, D. papillifer papillifer, M. houlleti and Kanchuria sp 1) in the mixed forests. Compared to the mixed forests, significantly low (p<0.05) Shannon diversity index (H) and species evenness and high index of dominance in the rubber plantation were evaluated.