Temel Sariyildiz

Effects of Ips typographus (L.) damage on litter quality and decomposition rates of Oriental Spruce [Picea Orientalis (L.) Link.] in Hatila Valley National Park, Turkey

This study investigated the effects of Ips typographus (L.) damage on initial litter quality parameters and subsequent decomposition rates of oriental spruce tree species [Picea orientalis (L.) Link]. The needle litter was collected from highly damaged, moderately damaged and control stands on two aspects (north and south) and two slope position (top and bottom) on each aspect. The litter was analyzed for initial total carbon, lignin and nutrient (nitrogen, phosphorus, potassium, calcium, magnesium and manganese) concentrations. The variability in nitrogen and calcium concentrations and ratios of C:N, lignin:N and lignin:Ca was significantly affected by the insect damaged levels. While nitrogen concentrations in needle litter increased with increasing insect damage (and consequently the ratios of C:N and lignin:N decreased), calcium concentrations decreased (and consequently the ratio of lignin:Ca increased). Aspect and slope positions explained most of the variability in carbon, lignin, phosphorus, potassium, magnesium and manganese concentrations and lignin:P ratio between all studied stands. Litter decomposition was studied in the field using the litterbag technique. The litter from highly damaged stands showed highest decomposition rates followed by moderately damaged and control stands. The mass loss rates were significantly positively correlated with initial nitrogen concentration and negatively with C:N and lignin:N ratios. The effects of microclimate resulting from canopy damage on litter decomposition was also examined at the same time using standard litter with the same litter quality parameters, but they showed no significant differences among the insect damage levels indicating that alteration of the litter quality parameters produced by I. typographus damage played a more important role than altered microclimate in controlling needle litter decomposition rates. However, changes in microclimate factors due to topography influenced decomposition rates.

Effects of tree canopy on litter decomposition rates of Abies nordmanniana, Picea orientalis and Pinus sylvestris

Abstract Effects of tree canopy (distance from the stem) on litter decay rates were investigated in the field for 4 years. Needle litter of Nordmann fir [Abies nordmanniana (Stev.) Spach.], Oriental spruce [Picea orientalis (L.) Link] and Scots pine (Pinus sylvestris L.) species were placed at three distances from their stems (<1 m, 1–2 m and >2 m). The litter showed highest decomposition rates at the distance of >2 m and lowest rates at <1 m for all species. Initial lignin concentrations were most strongly correlated with the decay rates, but among the microclimatic and soil factors, forest floor moisture content was the best predictor. The results showed that litter quality variables define the potential rates of microbial decomposition rates within and between trees, but adverse environmental conditions created by a tree canopy can also significantly affect decomposition rates. The closer distance to the stem significantly reduces litter decay rates by changing environmental conditions (especially forest floor moisture content) which can reduce microbial activity, and thus, the effects of tree canopy on litter decomposition rates should be taken into an account when calculating or comparing litter decomposition dynamics of forest ecosystems.