Over the last a few decades, Professor Khan has made outstanding contributions to the understanding of forest regeneration dynamics, population biology of rare endangered threatened (RET) plant species, ecosystem services, and threat status assessments of forests in the Eastern Himalayas and Central India. He has enhanced ongoing efforts toward the in-situ conservation of RET tree species through the mapping of plant biodiversity over different landscapes. He has used ecological niche modeling as a tool for locating new populations and identified niches and guilds influencing the regeneration processes of these tree species. In addition to furthering our understanding of key forest processes, these contributions have also served as the foundation for forest management policies. Through his studies on the interactive influence of various factors prevailing in forests, he has suggested several measures to augment forest regeneration. He highlighted the role of seed energy reserves on seedlings establishment. Seedlings from seeds with greater initial reserves gain a temporal advantage in competitive interactions as well as resistance against the herbivory. His studies on Rudraksh tree demography across disturbance gradients demonstrated that approximately 80% of the fruit produced by the trees disappeared from the forest floor or were severely damaged by insects, reducing the available seed bank of the species. With its natural populations in Arunachal Pradesh threatened by household and industrial uses, these findings outlined a critical aspect of the Rudraksh regeneration process and are vital to the conservation of this species. He also developed an easy and cheap technique to germinate Rudraksh nuts, which is now widely adopted by the Forest Department and other user groups to raise seedlings. He conducted detailed studies on the biodiversity of sacred forests within the northeastern and central regions of India and suggested conservation measures. He developed a database of the floristic status of the state of Meghalaya, Arunachal Pradesh, and Central India. Database being used to assess the effectiveness of existing protected area networks in conserving the floristic biodiversity. He explored germplasm of Bamboo, Ratan, Banana, Citrus, Primula and many other ecologically/socially important species. He also studied genetic diversity of Rice. He identified several new species of Rhododendron, many of which he later identified as being vulnerable, and offered insight into effective measures for their conservation. His research provided critical insights on population dynamics, plant diversity, carbon sequestration, disturbance ecology and ecosystem services of different landscapes in Indian forests. He has assessed the diversity, carbon storage in several sacred groves of the country and proposed their management and conservation strategies. He also assessed the impacts of plant invasion and forest fires on soil nutrient dynamics, diversity, structural, and functional attributes in the tropical forests of Central India, Western Ghats, and temperate forests of north-eastern Himalayan biodiversity hotspot. His current research also focuses on community phylogenetics, modelling species distribution and nature-based solutions. Professor Khan has contributed 205 peer-reviewed papers and 63 book chapters. Three books have been authored/edited by him and have an impressive citation index. Having published several articles in prestigious journals such as Nature, PNAS (USA), Nature Ecology and Evolution, Nature Scientific Report, Critical Review in Biotechnology, Science of the Total Environment, his articles in Nature and PNAS elevated Dr. Harisingh Gour Central University to number one out of all Indian institutions listed on the Global Nature Index during 2020-21. He also featured in the list of 2% Scientists published by Stanford University, USA. He has received many awards in recognition to his contributions to the Science and Society, the latest and most prestigious one is the 7th Visitor Award for Research in Biological Sciences to be conferred soon by President of India. He has been elected the Fellow of National Academy of Agricultural Sciences, Royal Society of Biology, London, UK and many other scientific societies. He has been able to attract the research funding from different national and international agencies (43 research grants; 42 completed, 01 ongoing). In view of outstanding research contribution in the field of Ecology and Environment, he has been included as an expert in the committee constituted by the Office of the Principal Scientific Adviser to the Government of India to draft the Mega Science Vision-2035 of India. Further, he is the partner to setup the Long-Term Ecological Observatories (LTEO, a programme of MoEF & Climate Change, GoI) at different landscapes of India.