EFFECT OF VEGETATION on SOIL WATER CHEMISTRY AT PINE LAKE, WEST DAVENPORT, NY, USA

The biology of a forest greatly impacts soil formation and soil water chemistry by affecting nutrient supplies, erosion and weathering rates. Different types of vegetation vary in nutrient demands, foliage, and microbial communities. Understanding these differences can improve reforestation efforts, remediation and sustainable forest management. The goal of this study was to examine the impact of deciduous and coniferous trees on soil water chemistry while the other soil forming factors (parent material, climate, topography, and soil development time) were kept constant. To do this, soil water samplers (lysimeters) were installed at two different depths, 30 and 90 cm, at two sites under deciduous and coniferous trees. The soils of the selected sites developed on glacial till since the last ice age, on southeast facing slopes, and were about ten meters a part. The water samples were collected every other week during the summer of 2010, and were analyzed for cation (Ca, K, Mg, Na and Mn) and anion (fluoride, chloride, nitrate, phosphate, and sulfate) concentrations by atomic absorption spectroscopy and ion chromatography, respectively. Electrical conductivity (EC) and pH of the water samples were also measured.

Considerable differences were found among the soil water samples. At a depth of 90 cm, the EC value averaged 69.0 µS under conifers and only 18.5 µS under deciduous trees (p-value of 0.001). Calcium, nitrate, sulfate and chloride concentrations were about 3-3.5 times greater under conifers than under deciduous trees (p<0.05). The pH and other measured cation and anion values of the soil water were not significantly different between the two deep samplers. At a depth of 30 cm, the values of all measured parameters, except Mg and sulfate, were significantly smaller under deciduous than under coniferous trees (p<0.05). Deciduous trees acidified the soil water to a pH of 5.3 at shallow depth, while under conifers the pH value remained 6.2. This difference could be the result of the main cation nutrient uptake process (proton exchange for cations) that also contributed to greater cation depletion under the deciduous vegetation. These results are consistent with previous studies, and support the idea that deciduous vegetation has larger nutrient demands than conifers due to physiological and life cycle differences.