Browsing by Author "Karunakaran, P.V."

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Ecological studies on the grassland of Eravikulam National Park, Kerala.
(Wildlife Institute of India, Dehradun, 1998) Karunakaran, P.V.; Rawat, G.S.
An ecological study on the. montane grasslands of Eravikulam National Park (ENP), the Western Ghats, was conducted during 1992-1996, with the following objectives: (i). to prepare a complete floristic inventory of the grasslands of ENP, (ii). to identify the grassland communities, their structure, function and successional trends along the anthropogenic gradient, (iii). to determine the forage quantity in different ecological conditions and (iv). to study the effect of fire and tree plantations on the grasslands. 2. The ENP lies between 10° 5’ to 10°20’ N and 77° to 77°10’ E with an area of 97 km2 in the Southern Western Ghats. The study recommends the following research and management strategies for the long term conservation of Shola-Grassland ecosystems and endangered Nilgiri tahr: (a) inclusion of adjecent reserved forests with shola-graslands in the park, (b) boundary verification and better patrolling to check the illegal activities and fire hazards, (c) early burning in selected areas on experimental basis, (d) control of black wattle spreading, (e) ecodevelopment measures for the Lakkamkudi village, (f) better tourism management and (g) long term monitoring of exclosures and representative shola-grassland patches.
Ecology and conservation of the Grasslands of Eravikulam National Park, Western Ghats
(Wildlife Institute of India, Dehradun, 1998) Karunakaran, P.V.; Rawat, G.S.; Uniyal, V.K.
An ecological study on the montane grasslands of Eravikulam National Park (ENP), the Western Ghats, was conducted during 1992-1996, with the following objectives: (i). to prepare a complete floristic inventory of the grasslands of ENP, (ii). to identify the grassland communities, their structure, function and successional trends along the anthropogenic gradient, (iii). to determine the forage quantity in different ecological conditions and (iv). to study the effect of fire and tree plantations on the grasslands. : The ENP lies between 10° 5' to 10°20' N and 77° to 77°10' E with an area of 97 km? in the Southern Western Ghats. The average altitude of the plateau is 2000 m and the highest peak, Anamudi, reaches 2695 m. Soil was acidic with pH ranging from 4.6 to 4.8. The climate was dominated by monsoon. During the study period the annual rainfall ranged from 4697 to 5540 mm. Winter days (Nov- Jan) were cooler and frost was common. The two distinct physiognomic units of vegetation are grasslands and sholas, unique to the Western Ghats. 3: The study area was stratified into eight landscape units viz., slope without rocky outcrops, slope with rocky outcrops, flat top, valley, bog, shola-grassland edge, cattle grazed and scraped areas. Systematic surveys and vegetation parameters such as species association, frequency, diversity, evenness and richness were studied in each landscape unit by laying 5 m radius. 4. 308 plant species were collected from the grasslands, adding 106 new species to the earlier list. 51 species were found to be endemic to the grasslands and 29 were listed as rare and endangered species. There were 64 species common with Eastern Ghats, 30 species with Patanas of Sri Lanka, 35 with Western Himalaya and 35 with Naga and Khasi hills indicating phytogeographical affinities with different biogeographic zones. D! Vegetation association was derived using ‘TABLE TRANSFER METHOD’ and TWINSPAN (computer packages). TABLE TRANSFER method identified 23 vegetation associations and TWINSPAN identified 15 associations. In both the analyses it was found that Chrysopogon zeylanicus and Sehima nervosum were the two dominant species. The diversity index (H’) of the associations ranged from 1.38 in the Artemisia nilagirica-Heteropogon contortus-Cymbopogon flexuosus (cattle grazed area) to 2.90 in Agrostis peninsularis-Eulalia phaeothrix-Chrysopogon zeylanicus in the shola-grassland edges. Vegetation ordination i.e., Canonical Correspondance Analysis (CANOCO) indicated that clay, pH and sand were important environmental factors which determined the species distribution and abundance.6. Biomass study was conducted at three sites in three dominant communities viz., Chrysopogon zeylanicus, Sehima nervosum and Cymbopogon flexuosus. Clipping was done both inside the exclosure and outside to obtain net primary productivity (NPP). The NPP values showed that these grasslands are between tropical and temperate grasslands . Outside the exclosures NPP was maximum at Eravikulam and minimum at Lakkamkudi. But inside the exclosures all the three sites were having nearly equal amount of NPP. Above ground biomass (ANP) was maximum at Eravikulam inside the exclosures and less at Rajamala, where as below ground (BNP) biomass was more at Rajamala and less at Lakkamkudi. Rate of biomass production was more (3.1 g m day!) at Eravikulam inside the exclosure and less (0.8 gm? day!) at Lakkamkudi outside the exclosures. In all the communities monocots contributed more to the ANP (59-97 %) than dicots (3-41%). In Lakkamkudi Pteridium aquilinum (fern) contributed 10 % to the ANP. Sehima nervosum, Heteropogon contortus and Chrysopogon zeylanicus were the three dominant grass species according to ANP. The annual removal of ANP by cattle and wild ungulate from Lakkamkudi was 68 %. Z. Burning (early and late) was done in S. nervosum (Anamudi) and C. zeylanicus (Rajamala) community. It was found that both in the early and late burnt areas no significant changes were noticed on species diversity, richness and evenness. Regarding the structure of the vegetation, cover value of dicots showed significant difference between early and late burnt in different months. Both early and late burning affected the regeneration of Phlebophyllum kunthianum. 8. A comparison of various sites with different density and age of wattle plantations with unplanted area showed that the number of endemic species and food species of Nilgiri tahr decreased with increase in the age of plantation. The increase in weed abundance with the age of plantation indicated more harm to the natural vegetation. The diversity index (H’) was 2.64 in 10 year old plantation and 1.87 in 3 year old. TWINSPAN identified two plant species associations each in unplanted, 3 year old and five year old plantations, and four in 10 year old plantation. 9. The study recommends the following research and management strategies for the long term conservation of Shola-Grassland ecosystems and endangered Nilgiri tahr: (a) inclusion of adjecent reserved forests with shola-graslands in the park, (b) boundary verification and better patrolling to check the illegal activities and fire hazards, (c) early burning in selected areas on experimental basis, (d) control of black wattle spreading, (e) eco-development measures for the Lakkamkudi village, (f) better tourism management and (g) long term monitoring of exclosures and representative shola-grassland patches.
Influence of invasive plant species on native plant-flower visitor interactions in a scrub forest of Anaikatty, Nilgiri Biosphere Reserve
(Wildlife Institute of India, Dehradun, 2025) Akilan, K P; Ramesh, C.; Gautam, Ritesh Kumar; Karunakaran, P.V.
Invasive alien species are one of the top five drivers of biodiversity loss globally. Invasive alien species are known to cause changes to the biotic interactions in the invaded regions. Pollination is an important limiting process in the life cycle of plants and the pollinators potentially mediate the process of invasion through novel interactions. Invasive plants can have an impact on the native plant-pollinator interactions. 2. I studied the influence of invasive plants on the native plant-flower visitor interactions in the scrub forests of Anaikatty, Nilgiri Biosphere Reserve. I determined the change in flower visitor diversity along an invasion gradient. I also compared the visitation between native and invasive plants, by looking at the difference in composition of insect interactions with native and invasive plants. I used 20 min zigzag walks in 26 plots across three months looking at insects interacting with flowers. I also estimated the density of flowers in each plot. 3. I used generalised linear mixed effects models to draw the relationship between insect richness and the proportion of invasive flowers, and between number of visits and proportion of invasive flowers. To compare the difference in composition of flower visitors between the plant species, I performed permutational multivariate analysis of variance (PERMANOVA) with bray-curtis dissimilarity index. 4.I observed 191 unique plant-flower visitor interactions of a total of 813 plant-flower visitor interactions, formed by 68 insect visitors and 28 flowering plants. Native plants, Sida cordifolia (25%), Tephrosia purpurea (20%) and Glycosmis mauritiana (13%) and invasive plants Parthenium hysteriphorus (8%) and Ageratum conyzoides (6%) formed majority of the interactions. Hymenoptera and Lepidoptera are the insect orders with the most number of interactions. 5. The richness and number of flower visitors increase with increasing flower density. The richness and number of flower visitors show a negative relationship with proportion of invasive flowers. The composition of visitors is significantly ifferent among all native flowers and between native flowers and invasive flowers.6.This is the first study in the Nilgiris Biosphere Reserve looking at plant-flower visitor interactions in wild flowers, with a focus on the influence of invasive species. Visitation of insects to a plot has a weak negative relationship with proportion of invasive species, in this context. This study sets the baseline for future studies that could look at explaining the patterns seen, looking at relationship between the functional diversity of flowers and insects.
Understanding the influence of tourism on behaviour and habitat use of Nilgiri tahr (Nilgiritragus hylocrius Ogilby, 1838) in Eravikulam National Park, Kerala
(Wildlife Institute of India, Dehradun, 2024) Mohammed, Aslam; Chinnasamy, Ramesh; Ramesh, K.; Karunakaran, P.V.
Eravikulam National Park is the home for the largest number of Endangered Nilgiri tahr in the world (Predit et al, 2015; Saju,2012) and the park is also having an ecotourism programme dedicated for observing tahr at closer distance (Saju,2012). This population in the tourism area have high human interaction and have become habituated to the presence of humans. Habituation is known to influence the wild behaviour and instincts of animals (Shackley,1996; Knight,2009; Mazur, 2006; Marler & Hamilton,1966; Hingham & Shelton,2011) and this study was intended to understand the influence of tourism on the behaviour and habitat use of Nilgiri tahr in the Eravikulam National Park.The field work was carried for four months from January 2024 to April 2024, of which tourism was closed during the months of February and March, creating three sampling seasons: preclosing, closing and reopening season with varying human presence. Scan sampling and focal sampling (Altman, 1974) were carried out and observations of the population in tourism area were compared to the populations in Varattukulam region of core area which have minimum human interaction. The result showed a significant difference in the behaviour and habitat use between tourism and core area and also across tourism season. The activity pattern in the tourism zone is different from that of the core. Habitat use was also different as most of the behaviour in tourism area were not showing any significant relationship with a particular habitat unlike the population in core area. The flight distance in tourism area was also found to be very much shorter (1.8m) in compared to core area(118m) which is evidence for the extend of habituation tahr has gone through. Interestingly, the tourism adjacent hills which belonged to the same landscape as that of the tourism zone showed higher flight distance. The tourism zone also had high density of predators (Tiger and leopard) and there was spatial overlap between tahr and predators. Study was not able to prove the existence of human shield hypothesis (HSH) (Berger, 2007) as large carnivores were still present in the tourism area and even when tourism was closed, which reduced the number of people on the road, tahr were still coming to tourism area. However, tahrs were observed to be avoiding the carnivore by temporal separation as all camera trapping of predators happened during night time but no tahr was active at that time in tourism road.