Lake landscape position: Relationships to hydrologic connectivity and landscape features

Abstract

To improve our understanding of lake landscape position, we compared four metrics based on different aspects of lake surface hydrologic connections: (1) ‘‘lake hydrology,’’ which is a general measure of lake surface hydrologic position, (2) ‘‘lake order,’’ which measures connections to streams by stream order, (3) ‘‘lake network number,’’ which measures connections to other lakes, and (4) ‘‘lake network complexity,’’ which measures the complexity of connections to other lakes (in a chain or branched). We sampled 71 lakes in northern Michigan, U.S.A. and measured lake landscape position and landscape characteristics around each lake (e.g., land use/cover and geology) to answer two questions: (1) which metric of landscape position explains the most variation in lake water chemistry/clarity? and (2) what landscape and physical features are also related to landscape position? All four landscape position metrics explained significant variation in some water chemistry/clarity variables. However, lake order, the metric based on stream order, consistently explained the most variation, ranging from 22% (dissolved organic carbon) to 53% (conductivity and calcium), with lake hydrology, the metric based on both streams and lakes, explaining similar amounts of variation to lake order, but less overall. Landscape position was also significantly related to both lake morphometry and the proportion of wetland types in buffer areas, which may help explain why landscape position is related to lake water chemistry and clarity variables.