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2020 - 20223
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Subject: Silviculture and Agroforestry × Author: KAU × Start date: 2020 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Growth and productivity as function of site quality and age in teak plantations of Nilambur, Kerala
    (Department of Silviculture and Agroforestry, College of Forestry, Vellanikkara, 2022) Sankar Thampuran, M V; KAU; Kunhamu, T K
    Teak has been one among the principal timber species widely used across the world due to its matchless combination of qualities. Kerala has around 76,710 ha of pure teak and 14,440 ha of teak with softwood plantation making up 49.08 and 9.24 per cent respectively of the total plantation area in the state. Despite having the largest share of plantations under teak, the productivity of teak plantations of Kerala are under serious decline and has been a matter of concern in the scientific parlance. Evidences suggest that even in Nilambur, the celebrated land of teak, there has been large scale decline in productivity of teak plantations. However, quantitative aspects of the productivity of teak and the drivers of changes especially in the best teak growing region in Kerala such as Nilambur, is lacking. In this backdrop, a field study entitled “Growth and productivity as function of site quality and age in teak plantations of Nilambur, Kerala” was conducted in selected plantations from Nilambur North and Nilambur South Forest Divisions. The plantations were selected based on the information available from Kerala Forest Department on their age and site quality. Four site qualities (SQ I, SQ II, SQ III and SQ IV) and five age classes (10-20, 20-30, 30-40, 40-50 and 50+) were considered for the study forming a total of 20 plantations (4 site qualities x 5 age classes = 20 plantations). Five sample plots, each of size 24m x 24m were laid out randomly in each of the selected plantations and parameters like total tree height, bole height, diameter at breast height, diameter at crown point and crown width were measured in the field. Also, soil sampling was done in four plantations of different site qualities falling in the mature age class of 40-50. For this, 1 m deep soil pits were dug, one each inside the plantation and in the respective contiguous treeless open. Sampling was done in five depth intervals (0-20, 20-40, 40-60, 60- 80 and 80-100 cm). Thus, a total of 120 samples of soil were collected for analysis. The collected soil was analysed for physical properties like bulk density and particle size distribution/ texture and chemical properties like pH, total Nitrogen, organic Carbon content, available Phosphorus and exchangeable Potassium following standard procedures. 122 The results showed that among the plantations studied in Nilambur, the SQ I plantations showed dominance in all growth parameters of teak while a predictable pattern of change was lacking across the subsequent site qualities. There was large heterogeneity among the plantations in terms of management that had a confounding effect on the potential exploitation of the site resources for optimal growth of teak. Many of the plantations had high density of invaded miscellaneous trees which have increased the effective density and seriously affected the growth of teak. The density of miscellaneous trees varied from 0 to 694 trees per hectare among the studied plantations. The competition with miscellaneous species has created large scale variability within each stand in growth attributes. Normal distribution of diameter classes was observable in the plantations studied due to high effective density. Stand density being a critical factor that decide productivity and product quality in teak plantations, the observed variability in productivity could be attributed to poor adherence to proper density regulation. Also, the productivity of the plantations has been considerably influenced by poor adherence to timely plantation management practices. The Mean Annual Increment varied from 0.56 to 8.70 m3ha-1yr-1 among all the plantations studied. On comparing with the All-India yield table for teak, the plantations showed growth and productivity estimates that were quite different from their assigned site quality. In the age class 40-50, the SQ I plantation showed a height that was corresponding to SQ III according to the yield table, while the SQ IV plantation height corresponded to the SQ II. All the observed soil parameters with in the experimental plots were well within the range required for the optimal growth of teak. However, except for SQ1, we could not observe any predictable change in soil properties across the remaining site qualities. The Bulk density of soil increased with depth, both inside and outside the plantations. The rate of increase of bulk density was higher in the treeless open areas compared to the plantations. Th soil texture remained as sandy loam or loamy sand for all the analysed soil samples. The soil pH varied from 5.17 to 5.98 between the soil samples that were analysed. The organic Carbon content in various layers of plantation soil varied from 0.58 to 2.07 %. Total Nitrogen varied from 0.077 to 123 0.223 %. Available Phosphorus varied from 2.10 to 17.33 kgha-1. Exchangeable potassium varied from 51.82 to 488.30 kgha-1. Attempts to relate the soil properties with the site productivity could not derive meaningful correlations suggesting that the productivity decline might be an effect of poor management rather than depletion of nutrient status. The study suggests that there is an urgent need to revisit and reassess the site quality of the plantations in Nilambur and to give utmost concern for adhering to scientific stand management in timebound manner for deriving optimal productivity from teak plantations of Nilambur.
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    ThesisItemOpen Access
    Evaluation of biodegradable containers for seedling production in tree nurseries
    (Department of Silviculture and Agroforestry ,College of Forestry, Vellanikkara, 2020) Subhasmita, Parida; KAU; Kunhamu, T K
    A nursery trial titled ‘Evaluation of biodegradable containers for seedling production in tree nurseries’ was conducted to develop alternate eco-friendly plant container as substitute for conventional polythene bag based containers at College of Forestry, Kerala Agricultural University, Thrissur. The study involved a three month long preliminary trial to explore the efficacy of various locally available materials for use as container for tree species. Based on the preliminary trial, five better performing container types were screened for detailed nursery trial to further examine their efficiency as containers for tree seedling production. Teak (Tectona grandis) being the widely produced forest planation species in Kerala, the nursery trials were performed with teak as test crop. The locally available materials used as containers for the preliminary trial included cow dung pot, sugarcane bagasse, arecanut sheath, mud pots, bamboo splits, bamboo basket, coco pot, cloth bag, nonwoven bag, bioplastic bag and treated card board. The containers were evaluated for their durability, physical stability to management practices such as irrigation and manuring, survival percent, height and collar diameter of the teak seedlings. It was observed that the bamboo splits based containers had the highest durability and can be used for two seasons while containers made from arecanut sheath, cow dung pot, sugarcane bagasee pot, bamboo basket, bioplastic bag and cloth bag totally degraded within two months suggesting their unsuitability for tree seedling production. In general, the better container types in terms of overall seedling growth performance and physical soundness were nonwoven bag, bamboo split, coco pot, treated cardboard pot and mud pot. These five container types along with coir root trainer (CRT) supplied by Kerala Forest Department were subjected to detailed nursery trial. It was observed that considerable variability existed in seedling growth characters such as height, collar diameter, number of leaves, leaf area, number of secondary and tertiary roots, lateral root length, root length: shoot length ratio, root and shoot dry and total dry weight. Among all container types studied, nonwoven bag grown seedlings showed better growth performance followed by seedlings grown in bamboo split containers while mud pot raised seedlings showed the lowest performance during all the stages of seedling growth. The overall performance of the container types followed the order: nonwoven bag > bamboo split > coco pot > treated cardboard > Coir root trainer (CRT) > mud pot. The cost of production per seedling was Rs 8.3 for non-woven bag, Rs 60.2 for coco pot, Rs 62.0 for mud pot, Rs 11.0 for bamboo split, Rs 12.8 for treated cardboard pot and Rs 25.8 for Coir root trainer (CRT). The Benefit: Cost ratio of raising 3- month old teak seedling ranged from 0.32 – 2.45. The value was highest for seedlings raised in bamboo split pot (2.45) followed by nonwoven bag (2.41) and cardboard (1.56) while it was less than one for all the remaining container types. The trial suggest that further studies are required to develop protocols for the reinforcement of biodegradable containers for increased phys ical strength and durability.
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    ThesisItemOpen Access
    Floristic diversity and regeneration status of moist deciduous forests in Thrissur district, Kerala :reassessment after three decades
    (Department of Silviculture and Wildlife Science, College of Forestry, Vellanikkara, 2020) Abhi, Jamatia; KAU; Kunhamu, T K
    Moist deciduous forests in Kerala constitute one of the most degraded forest ecosystems consequent to demographic pressure and other bio- physical factors. Field investigation was carried out to study the changes in phytosociology and vegetation dynamics of Moist Deciduous Forests in selected locations in Thrissur Forest Division, Kerala during 2018-19. The primary objective of the study was to assess the changes in floristic diversity, structure and regeneration status of moist deciduous forests compared to a similar study carried out in the same locations prior to three decades. The selected three locations were Karadippara and Kalluchal in Peechi WL sanctuary and Kuthiran in Pattikkad range. The vegetation attributes subjected to detailed assessment included species diversity, density, relative density, basal area, relative basal area, relative frequency and Importance Value Index and size class distribution of vegetation. A total of 51 species have been reported in various study locations in the Moist Deciduous Forests of Thrissur Forest Division. Kalluchal represented the highest number of woody species (48 species) followed by Karadippara (37 species) and Kuthiran recording the lowest with 26 species. Tree density showed profound variation across sites with Kalluchal giving the highest number (691 stems ha-1) followed by Karadippara (688 stems ha-1) and lowest for Kuthiran (516 stems ha-1). Xylia xylocarpa contributed the maximum number of stems in all the three sites followed by Wrightia tinctoria and Holarrhena antidysentrica. Mean relative density was highest for upper stratum (44.62%) and 33.07% for the lower stratum and lowest for the middle stratum (22.30%). Karadippara, Kalluchal and Kuthiran sites represented 30, 45 and 20 species within frequency class I (within 1-20%) and there was conspicuous absence of species in the higher frequency class in all the three sites. All the three sites had similar total IVI around 300. The major share of the IVI was confined to the species in the upper stratum (58 to 60%) while the middle and lower stratum has a lower and similar trend in IVI distribution (20% each). Size class distribution of among various social l classes ii showed conspicuous absence of majority of tree species in the higher size class suggesting a skewed distribution pattern. Almost 85% of individuals in each species belonged to lower size classes (h50 and h100) which drastically declined with increase in size class. A comparison with the study in the same sites three decades back indicates variable results. There was overall improvement in species diversity and phyto-sociological attributes in the Kalluchal region particularly, the species density and regeneration patterns. However, the number of individuals in the present study at Karadippara and Kuthiran sites, especially in the lower size classes were far lower compared to the previous study implying that the regeneration patterns of many tree species have been seriously affected by the undesirable changes in the past three decades. Probably, apart from human influences, the impact of changing climate may also have affected the regeneration ecology and vegetation dynamics of the MDF forests in Thrissur District which necessitate further detailed investigation in this line.