M Sc Dissertation(WII)

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Assessing the synergistic effect of two invasive plants on native plant communities in Kanha National Park, Central India
(Wildlife Institute of India, Dehradun, 2017) Rastogi, Rajat; Shrivastava, Aseem; Qureshi, Qamar
Over time, community assembly and functioning of native ecosystems is known to shift from native species to non-native species thus, restructuring the native community. When this shift of diverse native ecosystem interaction to less diverse invasive-centric interaction, occurs due to synergistic effect of two invasive species, it is known as ‘invasional meltdown’. Since last two decades, the effects posed by invasive species on ecosystems are widely debated. Studies across the globe have reported simplification in community structure with biological invasions, leading towards monotonous ecosystems and homogenization of biodiversity. 2. I assessed the interaction of two invasive plant species, Lantana camara complex (lantana) and Pogostemon benghalensis (pogostemon) with native understorey vegetation in Shorea robusta (Sal) forest of Kanha National Park, Central India. Here, I tested biotic homogenization, invasional meltdown and intermediate disturbance hypothesis. To achieve this, 56 km2 out of 230 km2 of Sal forest covering 5613 cells (100X100m) was extensively surveyed, to model species distribution of lantana and pogostemon using different correlative, mechanistic and ensemble models. From the surveyed area, 120 plots (10X10m) were selected based on the percent cover of invasive species, where vegetation and soil sampling was conducted. The correlations in community composition with edaphic and climatic parameters were established using nonparametric ordination, and the potential effects of single invasive species and their interaction were estimated using linear models by considering the uninvaded plots as control. 3. From the sampled area, 40 km2 (71%) and 37 km2 (66%) were found to be invaded by lantana and pogostemon respectively. Lantana presence was best explained as a function of nearby lantana density and was constrained by evapo-transpiration rate of summer, light availability and dry stress. Whereas, pogostemon presence was best explained by moistness of forest patch, lower summer temperature and habitat openings due to anthropogenic factors and was constrained due to climatic heat, edaphic dry stress, and remote deciduous forest. Study results indicate an insignificant effect of intermediate disturbances, and significant impacts of invasive species on species composition and edaphic factors, thereby affirming the biotic homogenization and invasional meltdown hypothesis and rejecting intermediate disturbance hypothesis. Present study can be used as an evidence to prioritize immediate management interventions in areas where multiple invasions are present, as the chances of extirpation of rare species is high.
A Study on Bird Communities-Habitat Structure Relationships in Pench National Park, M.P.
(Wildlife Institute of India, Dehradun, 1997) Jayapal, R.; Qureshi, Qamar
There has been a number of studies on bird communities and their relationships with habitat features of floristics and physiognomy. In particular, the spatial distribution of bird communities along the axis of structural variables of a habitat has received a wider attention in the light of recent findings on landscape behaviour. Most of these works relate to either temperate or neotropical forests and our knowledge of community dynamics of tropical deciduous forests is very limited, for there has been hardly any comprehensive study in the tropics. The present study was done in the deciduous forests of the Pench National Park, Central India (M.P) between "November, 1996 and April, 1997 covering winter (November,1996-1anuary,1997) and summer (March, 1997-April, 1997). Seven distinct habitat types were identified for the study based on floristic and structural diversity. Seasonal data on 27 habitat structural variables were collected from bird-centered sampling plots. Point count census technique was employed to study the bird population. Principal Components Analysis (PCA) was used to determine the patterns of inter-relationships among the habitat structural variables. Canonical Correspondence Analysis (CCA) was done to understand the relationships of habitat components to the distribution of bird communities. For guild analysis, two different sets criteria were used to identify the guilds among the bird populations viz., food type and foraging behaviour. Twelve guilds were recognized based on the food type and, six among the insectivores with respect to foraging behaviour. The results of the PCA showed that habitat structural variables of tropical deciduous forests have a marked pattern of inter-relationships on two axes of landscape behaviour, viz., heterogeneity and complexity. But they failed to reveal any such segregation vis-a-vis bird community structure, as the scale of measurement did not address all the members of the community. The spatial distribution pattern of bird communities in relation to habitat architecture was shown by CCA to be not very tenacious; the interactions of other extraneous factors like floristics, habitat dynamics, phenophases of vegetation, disturbance, or interactions within the community may influence the habitat selection process. There was no linear correlation observed between Foliage Height Diversity and Bird Species Diversity; possible explanations and alternative views have been discussed briefly. The response of bird communities to floristics was found to be inconsistent across habitat types as positive linear relationship was detected only for Teak-dominant forests in winter, and for Anogeiss Boswellia forests and Cleistanthus collinus woodland in summer. Guild compositions of various habitat types were not found to be significanty different from each other though the seasonal change was consistent across all the habitats.

M Sc Dissertation(WII)

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