Food supply and immobilizing functions on atmospheric pollutants are fundamental benefits of forest ecosystem. Diverse edible forest products provide people with basic livelihoods. This section addressed two questions: (1) understanding diversity, seasonal patterns, and food types of edible plants and macro-fungi commonly used in subtropical Guangdong Province (GP), China; and (2) evaluating utilization and conservation of food supply. Records of edible species and their illustrations were obtained from field observations, historical publications, and community surveys. Meanwhile, decrease of atmospheric SO2 concentrations was presented to show improvement of regional air quality in the Pearl River Delta (PRD), an urbanized region in GP. Five forest plots were selected along a gradient of SO2 concentrations in five cities across the PRD, containing 53 common woody species. Total carbon (C) and S contents of leaf and stem were detected, and C:S ratios were calculated for each species. Mean values of C and S contents, and C:S ratios were obtained for each plot. This section also addressed two questions: (1) S contents in diverse forest plots were correlated with SO2 concentrations to illustrate regional environmental quality; and (2) C, S contents in leaves and stems were compared to understand allocation patterns in different plant organs.
Results/Conclusions
Our results showed that 100 plant species and 20 macro-fungi were commonly used as edible forest products in subtropical GP. Species producing fruit part contributed more than 60% of the total species. Over half of the total plant species provided edible parts in summer and autumn seasons, respectively. We also found that many edible plants had multiple uses according to the supply of specific nutrient substance; specifically, 53 species were used as fruits, 27 species as medicinal & spice plants, 23 species as vegetables, 14 species as cereals & saccharides, and 12 species as oil plants. Coupling analyses showed that spatial patterns of S contents in woody species were relatively consistent with atmospheric SO2 concentrations. Mean C contents were relatively constant among all the species (44.94 ± 4.38% in leaves and 43.80 ± 3.67% in stems). However, mean S contents were much variable (0.29 ± 0.35% in leaves and 0.14 ± 0.14% in stems). C:S ratios fluctuated among different woody species and forest plots. We suggested that more non-timber forest products might be explored and domesticated from subtropical forests to support increasing demands of food, and phytoimmobilization via woody species would act as a friendly pathway to eliminate environmental pollutants.