This paper describes linguistic treasures presenting the environmental wealth of the Asahan Malay community and describes what factors underlie the shifting and shrinking of the ecolexicon. This description refers to Haugen's (1972) opinion pointing out three constituents in ecolinguistics. First, language exists only in the minds of its users and will function when its users relate to each other naturally as their natural and social environment. Second, the later part of the ecology is psychological: its interaction with other languages in the minds of bilingual or multilingual speakers. Third, sociological, namely the interaction with the community in its function as a medium of communication. Based on the results of the analysis it is concluded that there are many lexical treasures of river biota which are not known anymore. Likewise, some of the names of plants or parts are no longer known but some are still known with their general names due to the ignorance of their speakers and no entities found. A new and more modern pattern of settlement due to population growth in Asahan turned out to change the old way of setting up a house. The shape of the stone house but not wooden stairs began to be seen everywhere, including the house on the edge of the river. Ecolexicon hifting and shrinking in Malay Asahan language can be caused by two factors, namely internal factors and external factors. Internal factor is the depreciation of concept of understanding to the lexicon which tends to have no longer found and external factor such as (1) nature, (2) settlement, (3) environmental pollution, and so on