Department of Agricultural, Food and Forest Sciences, University of Palermo, Palermo, Italy.
Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "L. Vanvitelli", Caserta, Italy.
PLoS One. 2019 Jul 24;14(7):e0220194. doi: 10.1371/journal.pone.0220194. eCollection 2019.
The occurrence of old-growth forests is quite limited in Mediterranean islands, which have been subject to particularly pronounced human impacts. Little is known about the carbon stocks of such peculiar ecosystems compared with different stages of secondary succession. We investigated the carbon variation in aboveground woody biomass, in litter and soil, and the nitrogen variation in litter and soil, in a 100 years long secondary succession in Mediterranean ecosystems. A vineyard, three stages of plant succession (high maquis, maquis-forest, and forest-maquis), and an old growth forest were compared. Soil samples at two soil depths (0-15 and 15-30 cm), and two litter types, relatively undecomposed and partly decomposed, were collected. Carbon stock in aboveground woody biomass increased from 6 Mg ha-1 in the vineyard to 105 Mg ha-1 in old growth forest. Along the secondary succession, soil carbon considerably increased from about 33 Mg ha-1 in the vineyard to about 69 Mg ha-1 in old growth forest. Soil nitrogen has more than doubled, ranging from 4.1 Mg ha-1 in the vineyard to 8.8 Mg ha-1 in old growth forest. Both soil parameters were found to be affected by successional stage and soil depth but not by their interaction. While the C/N ratio in the soil remained relatively constant during the succession, the C/N ratio of the litter strongly decreased, probably following the progressive increase in the holm oak contribution. While carbon content in litter decreased along the succession, nitrogen content slightly increased. Overall, carbon stock in aboveground woody biomass, litter and soil increased from about 48 Mg ha-1 in the vineyard to about 198 Mg ha-1 in old growth forest. The results of this study indicate that, even in Mediterranean environments, considerable amounts of carbon may be stored through secondary succession processes up to old growth forest.
在经历了特别明显的人类影响后，地中海岛屿上的古老森林的出现是相当有限的。与不同演替阶段的次生演替相比，人们对这些特殊生态系统的碳储量知之甚少。我们调查了地中海生态系统中 100 年次生演替过程中地上木质生物质、凋落物和土壤中的碳变化，以及凋落物和土壤中的氮变化。比较了一个葡萄园、三个植物演替阶段（高灌丛、灌丛-森林和森林-灌丛）和一个古老的森林。采集了两个土壤深度（0-15 和 15-30 cm）和两种凋落物类型（相对未分解和部分分解）的土壤样本。地上木质生物质的碳储量从葡萄园的 6 Mg ha-1增加到古老森林的 105 Mg ha-1。随着次生演替的进行，土壤中的碳从葡萄园的约 33 Mg ha-1显著增加到古老森林的约 69 Mg ha-1。土壤氮增加了一倍多，从葡萄园的 4.1 Mg ha-1增加到古老森林的 8.8 Mg ha-1。这两个土壤参数都受到演替阶段和土壤深度的影响，但不受它们相互作用的影响。虽然土壤中的 C/N 比在演替过程中相对保持稳定，但凋落物的 C/N 比强烈下降，可能是由于圣栎的贡献逐渐增加。随着演替的进行，凋落物中的碳含量逐渐减少，氮含量略有增加。总的来说，地上木质生物质、凋落物和土壤中的碳储量从葡萄园的约 48 Mg ha-1增加到古老森林的约 198 Mg ha-1。本研究的结果表明，即使在地中海环境中，通过次生演替过程也可以储存大量的碳，直到达到古老森林的状态。
