corniculatus and C. epigejos) used as independent variables. A two-way anova was performed to establish significant interactions between the harvesting time and treatment. Significant selleck compound differences for specific variables were identified using Duncan’s post hoc test at P<0.05 following a one-way anova. Exponential curve fitting (Fig. 1) was performed using sigma plot 11.2. A principal component analysis (PCA)
was performed on the variance–covariance matrix using the statistical software r. Data illustration was performed using adobe illustrator cs3 and s-plus 8.1. Results are presented as means with SDs given in parentheses; the PCA plots are based on individual replicates. As expected, the N content of C. epigejos plant litter was significantly lower compared with L. corniculatus, which resulted in a C/N ratio of 40.46 (± 1.14) for C. epigejos compared with 14.24 (± 0.79) for L. corniculatus (data not shown). Plant litter of both L. corniculatus and C. epigejos decreased significantly during the 40-week experimental Natural Product Library clinical trial period (Fig. 1a). However, significantly higher decomposition rates (P<0.0001) were obtained for the L. corniculatus litter material. This result is in accordance with Hopkins
et al. (2007), who found a faster decomposition rate of plant litter with higher nutritional quality, in volcanic soils of initial nature with a low nutrient status, which was comparable to the substrate used in the present experiment. After 40 weeks of litter incubation, litter residues of 36.2% (± 1.7) and 25.4% (± 2.4) of the initial amounts of C. epigejos and L. corniculatus litter, respectively, Bay 11-7085 were measured. The decomposition rates of litter generally depend on the litter quality, which is usually linked to easily available nutrients (e.g. sugars or amino acids), recalcitrant C compounds (e.g. lignin or suberin) and substances
with antimicrobial properties (such as certain phenolic compounds or long-chain alkanes; Berg, 2000; Palosuo et al., 2005). Therefore, the initial mass loss of plant litter during the first 4 weeks of incubation observed in the present study can be attributed to the large amounts of water soluble plant litter components (e.g. proteins, sugars, amino acids) that are used by microorganisms colonizing the litter material to increase their activity patterns and to accumulate biomass (Aneja et al., 2006; Poll et al., 2008). A significant decrease in the content of N was detected after 4 weeks (P<0.05) for both types of litter material (Fig. 1b). According to Fioretto et al. (2005), high N availability is a major driver for litter decomposition in the early stages of litter degradation. Originating from the labelling procedure, plants were harvested at a very young stage (after 6–8 weeks), which might have resulted in a higher litter quality compared with in situ plant litter, especially with respect to the N content.