Vegetation composition, chemical element flows and their interactions in the forested riparian zone: An example from a small stream in Latvia

Riparian vegetation plays amajor role inmaintaining biodiversity and reducing the negative impact ofnutrient leaching into aquatic ecosystems. However, the knowledge onthe interactions between riparian vegetation and other environmental factors isstill incomplete for planning sustainable riparian forest management. The aim ofthis study was toexplore interactions between riparian forest ecosystem components along asmall stream. Interactions between vegetation structure, chemical composition ofsoil and groundwater, aswell aschemical element flows via litterfall and precipitation were studied inseven 50 m long transects located inthe riparian forest ofdifferent characteristics along a1.4 km river section inthe northern part ofLatvia. Our results showed that throughfall input oftotal nitrogen (TN) and potassium (K) was higher intransects with predominantly deciduous tree stands, but the concentration ofTNinforest floor was higher inconiferous tree stands. Atsome soil layers, apositive correlation between organic soil carbon (OC) and the concentration ofTNingroundwater was detected. The concentration ofTNand nitrate-nitrogen (N-NO3–) in groundwater correlated positively with the deciduous tree basal area. The obtained results suggested that element flows are strongly dependent on tree species' composition and a comparatively small riparian area is able to provide diverse ecological conditions.