© Society for Environment and Development, (India) http://www.sedindia.org Assessment of Dominant Macrophytes and Paradigm for Emerging Invasion Dynamics in Okhla Bird Sanctuary Satish Kumar # and Tuisem Shimrah * University School of Environment Management Guru Gobind Singh Indraprastha University, Sector 16C, Dwarka, New Delhi – 110078 # Email: ksatishindia@gmail.com * Email: tsshimrah@gmail.com Article history: Received 30 April2019 Received in revised form 21January 2020 Accepted 20 July2020 Available online 31 July 2020 Abstract Macrophytes plays a critical role in habitat development and influence biogeochemical process of wetland ecosystem. Invasive alien macrophytes are recognised as one of the leading threats to biodiversity. It causes significant impact on ecosystem services and associated livelihoods. Vulnerability of wetlands to invasive alien macrophytes has described a narrow and fragmented approach under the concept of environmental risk assessment. Within this context, ecological information of invasive alien macrophytes of the vegetated urban wetland namely Okhla Bird Sanctuary (OBS) was analysed through the lens of invasion dynamics on structural components of wetland ecosystem. Vegetation study of the sanctuary described that the nearly seventy percent area of the sanctuary is infested with invasive species. Eichhornia crassipes, Alternanthera philoxeroides, Typha angustata, Saccharum spontaneum and Pistia stratiotes are major invasive alien species reported in dominant macrophyte communities of the sanctuary. These species observed in almost all parts of the sanctuary including both lotic and lentic habitats from densely vegetated in summer season to disperse vegetation during winter season. Invasibility via some ecosystem attributes such as water flow, depth and quality shows significant relationship with invasion mechanisms. These aggressive tropical invasive macrophytes are causing serious problem in wetland functioning. There is a need for management prescription to be developed at several levels. Keywords: Invasive alien macrophytes; Invasion; Vulnerability; Environmental risk assessment; Invasion dynamics; Invasibility Introduction All ecosystems exhibit considerable variation in their water requirement. Presences of water throughout or parts of the year, hydric soil and plants adopted to wet condition creates wetland ecosystem. Aquatic plants grow inside or near shallow areas of wetlands referred as hydrophytes or macrophyte. According to their distribution macrophytes classified into free floating, rooted with floating leaves, submerged floating, rooted submerged and rooted emergent Environment & We An International Journal of Science & Technology Available online at www.ewijst.org ISSN: 0975-7112 (Print) ISSN: 0975-7120 (Online) Environ. We Int. J. Sci. Tech. 15 (2020) 105-115