The effect of altitude on the distribution of aquatic plants in some lakes of New Hampshire, U. S. A.

Summary

The benthic aquatic vegetation and hydrographic features were studied with SCUBA in five lakes, all within a radius of 24 km and ranging in altitude from 257 m to 1542 m in the White Mountains of New Hampshire. The vegetation along traverse lines was noted with respect to depth and distance from the shore. No rooted hydrophytes were observed deeper than 6.5 m in any lake, and the general limit appeared to be correlated with the depth of the thermocline in summer.

The number of genera and species decreased with increased altitude. Temperature, rather than light seemed to limit the distribution, density and vigor of benthic plants both between lakes with respect to altitude, and within lakes with respect to depth. The composition and aspect of the substrate appeared to influence the distribution of plants, but the degree of slope had little effect on their distribution.