Reclamation with alder plantation may caused more loss of nutrients from the soil in comparison unreclaimed succession sites after coal mining (Czech Republic)
Abstract
Restoration by afforestation of post mi ning site belongs to the most popular way how to restore of the ecosystem functions and return the landscpae to productive use reasonably fast with moderate cost and effort. But the productivity of forest ecosystems is closely related to the availability and demand for available nutrients.
A popular strategy to speed up soil development is a planting of N2 fixing plants. Alders and other N2 fixing plants can be useful in the contribution of N2 to the soil.
But in recent studies has been shown that using N2 fixing plant can also have a disadvantage because higher input of N in the ecosystem leads to more open biogeochemical cycling which may result in a nutrient loss from the system. The aim of this study was to find out how adding of nitrogen in the system by planting N2 fixing plant will make nutrient cycling faster and more open which may promote nutrient losses from the system.
Both types of sites were about the same age about 25 years old. Reclaimed sites were afforested by alders (Alnus glutinosa, Alnus incana) and characteristic vegetation at unreclaimed sites with spontaneous succession are a dominance of aspen poplar (Populus tremula), and willow goat (Salix caprea).
Data about nutrient concentration in throughfall, lysimetric leachates, plant litter, and tree biomass were collected during 2 years. At each site, selected trees were harvested and basic nutrient (Ctot, Ntot, Ptot, Catot, Mgtot, Ktot) were analyzed in biomass compartments.
In result, the higher stock of nutrient in biomass and production of the plant litter with higher nutrient quality (except Ntot) was at unreclaimed sites. Litter fall at unreclaimed site decomposed slowly, which leads to less loss of nutrient from the soil.
The higher nutrient loss indicated by lysimetric leachate was observed at reclaimed sites with alder due to a low allocation of nutrients in tree biomass and plant litter.Higher loss of nutrients from the ecosystem can lead to earlier depletion of nutrients at site on bedrock with a poor stock of nutrients and consequent soil acidification due to high N input and eutrophication with the decreasing variability of the ecosystem. While on unreclaimed sites there was found more suitable use of nutrients because more nutrients are stocked in tree biomass, and plant litter (litter fall and fine roots) decomposed slowly and released nutrients are not leached in large quantities such as at reclaimed sites with alder stands.
This study has shown that for further reclamation technic will be useful to focus on planting mixed stands not only on alder plantations.