Biodiversity of soil algae in the farmlands of mid-Taiwan

Very little information is available about soil algae in Taiwan. In this study, we investigated for the first time the soil algae inhabiting five types of farmland in mid-Taiwan: rice paddies, vegetable farms, tea plantations, sugar cane farms, and orchards. Sixty-four taxa belonging to 33 genera of cyanobacteria, diatoms, green algae, and euglenoids were identified on the basis of fine structures observed under optical and electron microscopes and rDNA sequencing. The majority of the isolates were of the genera Oscillatoria, Navicula, Nitzschia, and Pinnularia. Five species were reported for the first time in Taiwan, namely Microcoleus paludosus, M. subtorulosus, Navicula subminuscula, Nitzschia levidensis, and Ni. pusilla. The distribution and diversity of these species was shown to be strongly dependent on habitat, with the highest diversity of green algae in the orchards, a fairly high diversity of diatoms and cyanobacteria in the rice paddies, and a relatively low diversity in the tea plantations and sugar cane farms. The humidity and acidity were the most important environmental factors influencing the diversity of soil algae in these farmlands.