Comparing invasiveness of native and non-native species under changing climate in North-East India: ecological niche modelling with plant types differing in biogeographic origin

Ecology, Biology, Environmental Impacts, and Management of an Agro-Environmental Weed Ageratum conyzoides

Ageratum conyzoides L. (Billy goat weed; Asteraceae) is an annual herbaceous plant of American origin with a pantropical distribution. The plant has unique biological attributes and a raft of miscellaneous chemical compounds that render it a pharmacologically important herb. Despite its high medicinal value, the constant spread of the weed is noticeable and alarming. In many countries, the weed has severely invaded the natural, urban, and agroecosystems, thus presenting management challenges to natural resource professionals and farmers. Its interference with agricultural crops, grassland forbs, forest ground flora, and its ability to replace native plant species are of serious concern. Therefore, it is pertinent to monitor its continuous spread, its entry into new geographic regions, the extent of its impact, and the associated evolutionary changes. While management strategies should be improvised to control its spread and reduce its adverse impacts, the possible utilization of this noxious weed for pharmacological and agronomic purposes should also be explored. The objective of this review is to provide a detailed account of the global distribution, biological activities, ecological and environmental impacts, and strategies for the management of the agro-environmental weed A. conyzoides.

Multi-Decadal Mapping and Climate Modelling Indicates Eastward Rubber Plantation Expansion in India

Automated long-term mapping and climate niche modeling are important for developing adaptation and management strategies for rubber plantations (RP). Landsat imageries at the defoliation and refoliation stages were employed for RP mapping in the Indian state of Tripura. A decision tree classifier was applied to Landsat image-derived vegetation indices (Normalized Difference Vegetation Index and Difference Vegetation Index) for mapping RPs at two-three years intervals from 1990 to 2017. A comparison with actual plantation data indicated more than 91% mapping accuracy, with most RPs able to be identified within six years of plantation, while several patches were detected after six years of plantations. The RP patches identified in 1990 and before 2000 were used for training the Maxent species distribution model, wherein bioclimatic variables for 1960–1990 and 1970–2000 were used as predictor variables, respectively. The model-estimated suitability maps were validated using the successive plantation sites. Moreover, the RPs identified before 2017 and the Shared Socioeconomic Pathways (SSP) climate projections (SSP126 and SSP245) were used to predict the habitat suitability for 2041–2060. The past climatic changes (decrease in temperature and a minor reduction in precipitation) and identified RP patches indicated an eastward expansion in the Indian state of Tripura. The projected increase in temperature and a minor reduction in the driest quarter precipitation will contribute to more energy and sufficient water availability, which may facilitate the further eastward expansion of RPs. Systematic multi-temporal stand age mapping would help to identify less productive RP patches, and accurate monitoring could help to develop improved management practices. In addition, the existing RP patches, their expansion, and the projected habitat suitability maps could benefit resource managers in adapting climate change measures and better landscape management.

Predicting shifts in distribution range and niche breadth of plant species in contrasting arid environments under climate change

Arid environments face extreme risk from contemporary climate change; therefore, predicting the shifts in species distribution range and niche breadth in these environments assumes urgent research priority. Here we report the potential distribution and predict future distribution range of two model plant species typically representing contrasting environments across Asia and Africa: hot-arid Ephedra foliata and cold-arid E. gerardiana. We adopted a comparative modelling approach and used occurrence points from extensive field surveys, supplemented with herbaria records and publicly available distribution data. Our study reveals that currently an area of 8.797334 × 10⁶ km² (8.8%) is potentially suitable for E. foliata and nearly half 4.759326 × 10⁶ km² (4.8%) for E. gerardiana. Under future climate change scenarios, distribution range of E. foliata is predicted to expand but contract in E. gerardiana. Similarly, E. foliata showed broader niche breadth which is predicted to increase under B1 (0.097-0.125) and B2 (0.878-0.930) climatic change scenarios. In contrast, E. gerardiana had narrower niche breadth and expected to further decrease under B1 (0.081-0.078) and B2 (0.878-0.854). The most influential bioclimatic variable governing the potential distribution and niche breadth of E. foliata was the precipitation of warmest quarter, whereas that of E. gerardiana was temperature seasonality. The results from our study can help in developing potential indicator plant species for assessment and monitoring of distribution range shifts in response to changing climate in the arid environments.

Advances in terrestrial and ocean dynamics studies in India

The land, oceans, and atmosphere are tightly linked and form the most dynamic component of the climate system. Studies on terrestrial and ocean science enhance the understanding on the impacts of climate change. Across India and the world over, human-driven land use and climate changes are altering the structure, function, and extent of natural terrestrial ecosystems and in turn regional biogeochemical feedbacks. In this special issue, we present 29 manuscripts; those discuss wide-ranging aspects of terrestrial and oceanic characterization and dynamics. These contributions are based on selected presentations made at the 2nd International Workshop on Biodiversity and Climate Change (BDCC-2018) held on 24-27 February 2018 at the Indian Institute of Technology Kharagpur, India. The manuscripts are arranged in five sections such as Ecological Assessment, Plant Invasion, Carbon Dynamics, Ecosystem Characterization, and Ocean Dynamics. We realized that the utility of satellite remote sensing data has been emerging as a dominant trend in environmental monitoring and assessment studies in India.