Artificial recharge of groundwater through sprinkling infiltration: impacts on forest soil and the nutrient status and growth of Scots pine.
We studied the chemical changes in forest soil and the effects on Scots pine trees caused by continuous sprinkling infiltration over a period of two years, followed by a recovery period of two years. Infiltration increased the water input onto the forest soil by a factor of approximately 1000. After one year of infiltration, the pH of the organic layer had risen from about 4.0 to 6.7. The NH(4)-N concentration in the organic layer increased, most probably due to the NH(4) ions in the infiltration water, as the net N mineralization rate did not increase. Sprinkling infiltration initiated nitrification in the mineral soil. Macronutrient concentrations generally increased in the organic layer and mineral soil. An exception, however, was the concentration of extractable phosphorus, which decreased strongly during the infiltration period and did not show a recovery within two years. The NO(3)-N and K concentrations had reverted back to their initial level during the two-year recovery period, while the concentrations of Ca, Mg and NH(4)-N were still elevated. Nutrient concentrations in the pine needles increased on the infiltrated plots. However, the needle P concentration increased, despite the decrease in plant-available P in the soil. Despite the increase in the nutrient status, there were some visible signs of chlorosis in the current-year needles after two years of infiltration. The radial growth of the pines more than doubled on the infiltrated plots, which suggests that the very large increase in the water input onto the forest floor had no adverse effect on the functioning of the trees. However, a monitoring period of four years is not sufficient for detecting potential long term detrimental effects on forest trees.
Nöjd
Pekka
P
Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland. pekka.nojd@metla.fi
Lindroos
Antti-Jussi
AJ
Smolander
Aino
A
Derome
John
J
Lumme
Ilari
I
Helmisaari
Heljä-Sisko
HS
D001673:Biodegradation, Environmental; D003247:Conservation of Natural Resources; D005374:Filtration; D028223:Pinus / Q000502:physiology*; D012987:Soil / Q000032:analysis; D014197:Trees; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
D012987:Soil; D014874:Water Pollutants, Chemical