Abstract
In an Athens Co., Ohio, salt pan, there were four vegetation zones: the Meadow, H or deum, Atriplex and Pan zones. These constituted a salinity gradient from the nonsaline Meadow to the highly saline Pan. The phenology, survival and distribution of the halophyte, Atriplex triangularis Willd., within this salt pan were investigated. The life cycle of A. triangularis spanned 9 months from February to October. The germination period extended from February to May. Flowers appeared in mid-July; seed development began in September. Senescence and death followed in late October. The population dynamics of A. triangularis were related to three main factors: soil temperature, soil moisture and soil salinity. Soil temperatures of 15 C appeared to trigger germination. High soil moisture values with consequent low soil salinity were prevalent during the winter-early spring germination period. Seedling establishment was particularly sensitive to salinity with severe mortality occurring in late spring and early summer when soil moisture values started to decline and salinity began to climb. The highest concentration of soil salts coincided with the flowering stage in July and August when soil moisture values dropped severely due to low rainfall and high evaporation. By the seed development and maturation stage in September, soil moisture levels had begun to rise due to heavy autumn rains and decreased evaporation which led to a decrease in total soil salts. The germination and survival of Atriplex triangularis were restricted in the main to the Atriplex zone. The relative absence of A. triangularis in the Meadow zone stemmed from the interference from the existing meadow vegetation. The rapid growth of Hordeum jubatum hindered the establishment of A. triangularis in the H or deum zone. High soil salinity within the Pan zone prevented the germination of A. triangularis.
Published Version
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