V. Subramanian , C. Buvaneswaran , K. Rajagopal , M. George

Abstract

Biomass production and nutrient cycling studies were carried out in a young teak (Tectona grandis L. f.) plantation of five year old (density 2,500 trees ha^-1). The trees attained an average girth and height of 23.1cm and 7.6m, respectively and the above ground biomass (agb) amounted to 76.9 t/ha, of which stem wood contributed 60%. The percentage of ischolar_main to agb was 20.5%. Investigations on nutrient content in the standing crop have shown that the per cent concentration of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg) were highest in leaf. But on unit area basis, wood accumulated the major portion (39 to 60%) of all nutrients. Among the nutrients, maximum accumulation was accounted for Ca (1,619 kg ha^-1) and the minimum for P (178 kg ha^-1). With reference to nutrient return via litter, it was observed that the total litter produced was 4,574 kg ha^-1 and the nutrients returned amounted to 46 kg ha^-1 N; 3 kg ha^-1 P; 39 kg ha^-1 K; 86 kg ha^-1 Ca and 21 kg ha^-1 Mg. Studies on interception of rainfall and nutrient return through rain-wash have shown that among the nutrients return was highest for Ca (1.87 kg ha^-1) followed by Mg (1.09 kg ha^-1), K (0.98 kg ha^-1), N (0.36 kg ha^-1) and the least for P (0.11 kg ha^-1). Nutrient cycling on an annual basis was worked out for the plantation and it was found that of the total uptake of various nutrients (178kg N ha1 yr1, 248 kg K ha^-1 yr^-1, 387 kg Ca ha^-1 yr^-1 and 109 kg Mg ha^-1 yr^-1, 74 to 91% was retained in the non-photosynthetic biomass and the rest returned to soil. These results were compared with nutrient cycling in 20-year-old teak plantation and found that at younger age teak retains more nutrients in its biomass. As the plantation gets older, it retains less and returns more quantity of nutrients. These results suggest that as the age of plantation increases, teak becomes an eco-friendly species by not adversely affecting the ecology of the site.

Keywords

Nutrient Cycling, Young Teak Plantation, Coimbatore, Tamil Nadu

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K. Rajagopal , C. Buvaneswaran , V. Subramanian , M. George

Abstract

Studies on different pathways of nutrient return through litterfall and rain-wash were carried out in a young teak (Tectona grandis L. f.) plantation at five years age (Density 2500 trees/ha). The total litter produced was 4574 kg/ha and the nutrients returned amounted to : nitrogen - 46kg/ha; phosphorus- 3 kg/ha; potassium 39kg/ha; calcium 86kg/ha; and magnesium 21kg/ha. Studies on interception of rainfall have shown that, the total incident rainfall recorded for this study during the year 2000 was 1013 mm. Of which, 28.97% was intercepted by the canopy, while 7.66% was accounted for stemflow and 63.37% for through fall. With regards to nutrients return through rain-wash, it was found that, throughfall returned more quantities of all nutrients, than stemflow. Of the total return (litter + rain wash) of various nutrients, maximum amount (kg/ha) of return was accounted for calcium (87.40) followed by nitrogen (46.56), potassium (40.31), magnesium (22.13), and the least for phosphorus (3.31). Among these two pathways of nutrients return, litterfall contributed greater amount of all nutrients (from 95 to 99%), when compared to rain wash (0.8 to 4.9%). These results were compared and discussed with nutrients return and nutrient cycling in 20 years old teak plantation and suggest intensive silvicuItural practices in teak plantations during the initial stages of growth to enhance the productivity.

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K. Rajagopal , C. Buvaneswaran , M. George , P. Manivachagam

Abstract

Comparative studies on litter decomposition employing two methods - bag and non-bag, were carried out under teak plantation of age 30 years. Though a steady decline in decomposition of the litter occurred in both the cases, the rate of decomposition was faster in the non-bag method than that of the bag. The un-decomposed litter after a period of one year was 19.43% in non-bag method against 49.8% in the bag method. The decomposition coefficient (k) was higher in non-bag (1.638) when compared to bag method (0.697). With regard to nutrients in the decomposing litter, the concentration of different nutrients differed as the decomposition progressed. Among the nutrients (N, P, K, Ca and Mg), the release of potassium was faster when compared to others. Between the two methods the decomposition co-efficient (k) was greater for all nutrients in non-bag method.

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C. Buvaneswaran , M. George , S. Mohan

Abstract

Investigations carried out on stemflow, throughfall and interception in a 30-year-old Teak plantation (density 620 trees/ha) at Coimbatore Forest Division, Tamil Nadu have shown that, out of the annual rainfall of 1966.7 mm, 7.54% was accounted as stemflow and 51.20% as tbroughfall. Remaining 41.26% was accounted as interception. While maximum stemflow (8.68% of rainfall) and throughfall (56.71%) and minimum interception loss (34.61%) was recorded during the month of November; minimum stemflow (0.25% of rainfall) and throughfall (5.0%) and maximum interception (94.75%) was recorded during March, It was also found that the seasonal variation of rainfall influenced the stemflow and throughfall. Interception during South-West monsoon (June-August) was almost at par with average annual interception. But during North-East monsoon (September-November) the interception was much below the annual average. The results of the present study show that the interrelationship between rainfall, stemflow and throughfall in Teak is similar to that of broad leaved species like Shorea robusta. It was also found that the interception depends on parameters like crown form, density of the species, external structural features like bark characteristics and branching nature as well as rainfall pattern and other meteorological factors which influence the evaporation.

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S. Varadharajan , C. Buvaneswaran , Rekha R. Warrier , R. S. C. Jayaraj

Abstract

Global warming plays a major role in climate change which is caused mainly due to increase in CO₂ level in the atmosphere. Present study attempted to evaluate four important tropical tree-species, Tectona grandis, Ailanthus excelsa, Casuanna equisetifolia and Casuarina ,Jungkuhniana for adaptation to elevated levels of CO₂ at nursery stage. The study was conducted inside the poly tunnels and CO₂ enrichment was done to double the concentration. Seedlings in poly tunnel without CO₂ enrichment served as control The short term experiments revealed that of the four species studied, casuarinas performed well under elevated CO₂ conditions in terms of all growth parameters studied. The performance of teak alone was poor indicating adverse effect of CO₂ enrichment on morphological traits of tbiB species as seen by reduced leaf area, lesser dry' matter accumulation both in shoot and ischolar_main system and poor Seedling Quality Index at elevated CO, levels. Thus, in the present study, all the species except teak showed a positive response to CO₂ enrichment in terms of morphological traits while Cuuarina equisetifolia and C. junghuhniana showed better growth and seedling quality indicating their better adaptability to elevated CO₂level.

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D. Raja Suguna Sekar , C. Buvaneswaran , P. Sornappan

Abstract

No abstract

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