Nutrient cycling indicators in different models of successional groups and spacing for forest restoration

The increasing demand for forest restoration necessitates new strategies and assessments of nutrient returns to support functional restoration. This study aims to evaluate the production, nutrient cycling, and litter decomposition in different restoration models using both different seedling densities and varying proportions of pioneer and non-pioneer species. The experiment was established in 2012, with litter collection occurring in the sixth and seventh years; the leaf fraction was used for chemical analysis. To assess decomposition, litterbags were installed and collected monthly for six months, and climatic data were recorded during this period. The annual litter production in the sixth and seventh years was 7255 and 7953 kg ha-1, respectively. The decomposition process was unaffected by the treatments but was influenced by the microclimate, with minimum temperature showing the strongest correlation. Litter input and nutrient release (kg ha-1) varied significantly only with plant spacing, with the highest releases observed at 1 × 0.3 m spacing. The P, K, and S contents were not affected by either successional groups or plant spacing, while only calcium content varied significantly with the proportion of successional groups. Plant density was linked to higher litter and nutrient production in the system. The highest plant density was more effective at promoting short-term nutrient cycling at the beginning of the restoration process.