Abstract: Since the establishment of plant mineral nutriology, it has been well believed that plants mainly absorb inorganic nitrogen. With the improvement of research means and contents, it was approved that some vascular plants with no mycorrihiza could absorb soluble organic nitrogen, especially small molecular amino acids, which aroused the attentions on plant organic nutrition and its diverse modes. Relative researches suggested that amino acids could be released into soil by various means, while microbes, plants, animals, and their metabolites were the main sources. The contents of amino acids in soil were affected by soil temperature, moisture, applied organic fertilizer, plant species, and their growth stages. The uptake of amino acids by plants was an active process regulated by the carriers, energy status, and media pH and temperature. The mechanisms of amino acid uptake by plants and the related ecological processes are needed to be studied further.

Key words: camera trap, population ecology, field survey, density estimation, occupancy.