Montagnini F, Porras C
Yale University School of Forestry and Environmental Studies 370 Prospect New Haven, Connecticut 06511, USA
Environ Manage. 1998 May;22(3):459-70. doi: 10.1007/s002679900119.
/ Despite their fast growth, tropical plantations are a small sink of atmospheric carbon because they occupy only a small area in relation to other land uses worldwide. Proper design and management of plantations can increase biomass accumulation rates, making them more effective C sinks. However, fast-growing plantations can extract large amounts of nutrients from the soil, and site fertility declines may limit sustained plantation forestry after a few rotations. We measured aboveground biomass accumulation, carbon sequestration, and soil chemistry in three young plantations of 12 indigenous tree species in pure and mixed designs in the humid lowlands of Costa Rica. Annual biomass increments for the three mixed plantations ranged from 10-13 Mg/ha. The mixtures of four species gave higher biomass per hectare than that obtained by the sum of one fourth hectare of each species in pure plots. At this early age of the plantations, estimated annual C sequestration values were comparable to other reports from young plantations of exotic species commonly grown in the tropics. Four years after planting, decreases in soil nutrients were apparent in pure plots of some of the fastest growing species, while beneficial effects on soils were noted under other species. The mixed plots showed intermediate values for the nutrients examined and, sometimes, improved soil conditions. A mixture of fast and slower growing species yields products at different times, with the slower growing species constituting a longer term sink for fixed carbon. Examination of the role of tropical plantations as C sinks necessitates integrative approaches that consider rates of C sequestration, potential deleterious effects on ecosystem nutrients, and economic, social, and environmental constraints.KEY WORDS: Native trees; Aboveground biomass; Stem increments; Rotation length; Soil nutrients; Economics
尽管热带种植园生长迅速，但由于与全球其他土地利用方式相比，其占地面积较小，因此是大气碳的一个小汇。对种植园进行合理设计和管理可以提高生物量积累速率，使其成为更有效的碳汇。然而，速生种植园会从土壤中提取大量养分，土壤肥力下降可能会限制经过几次轮作后的可持续人工林经营。我们在哥斯达黎加湿润低地，对12种本土树种的三个纯林和混交林设计的幼龄种植园，测量了地上生物量积累、碳固存和土壤化学性质。三个混交种植园的年生物量增量范围为10 - 13 Mg/ha。四种树种的混交林每公顷生物量高于每个树种四分之一公顷纯林生物量之和。在种植园的这个早期阶段，估计的年碳固存值与热带地区常见的外来树种幼龄种植园的其他报告相当。种植四年后，一些生长最快树种的纯林中土壤养分明显下降，而在其他树种下则发现对土壤有有益影响。混交林的养分含量处于中间值，有时土壤条件有所改善。生长快和慢的树种混合种植能在不同时间产出产品，生长慢的树种构成了固定碳的长期汇。研究热带种植园作为碳汇的作用需要综合考虑碳固存速率、对生态系统养分的潜在有害影响以及经济、社会和环境限制等综合方法。关键词：本土树木；地上生物量；树干增量；轮伐期长度；土壤养分；经济学
