Influence of Water Content and Temperature on the pH values of Solution Extracted from Acidified Forest Floor Materials of Norway Spruce
- Received Date: 1997-07-22
- Available Online: 2012-03-17
Abstract: The influence of temperature and water content during incubation on the pH values of solutions extracted with saturated water content from the strongly acidified and NH4+-riched forest floor materials (OL-,OF-and OH-layers) of Norway spruce was investigated under manipulated conditions for one year.During the incubation there were no element input,element leaching and plant uptake,but the gas exchange with the atmosphere was relatively free.There were 3 temperature treatments (with annual average air temperature of 11.6,12.3 and 14.5 ℃ respectively) and 4 water content treatments (from nearly air dry to the saturation of each material).Drought led to a significant decrease of pH value.In the extreme drought treatment,the extracted H+ amounted to 2.2~2.7 times of that of the starting phase.In order to avoid a sharp decrease of pH value,a saturation degree of 60%~80% for the forest floor materials should be maintained.If it is smaller than about 30% for the OL and 50% for the OF-and OH-material,the pH value will be lowered compared with the starting phase.Surprisingly,ammonia volatilization can take place under drought conditions,even in the strongly acidified forest floor materials which have a high content of NH4+.Furthermore,ammonia volatilization plays the most important role in the decrease of pH value.On the contrary the influence of warming was not significant in the applied temperature range.