Data from: The oldest, slowest forests in the world? Exceptional biomass and slow carbon dynamics of Fitzroya cupressoides temperate rainforests in southern Chile

Old-growth temperate rainforests are, per unit area, the largest and most long-lived stores of carbon in the terrestrial biosphere, but their carbon dynamics have rarely been described. The endangered Fitzroya cupressoides forests of southern South America include stands that are probably the oldest dense forest stands in the world, with long-lived trees and high standing biomass. We assess and compare aboveground biomass, and provide the first estimates of net primary productivity (NPP), carbon allocation and mean wood residence time in medium-age stands in the Alerce Costero National Park (AC) in the Coastal Range and in old-growth forests in the Alerce Andino National Park (AA) in the Andean Cordillera. Aboveground live biomass was 113–114 Mg C ha-1 and 448–517 Mg C ha-1 in AC and AA, respectively. Aboveground productivity was 3.35–3.36 Mg C ha-1 year-1 in AC and 2.22–2.54 Mg C ha-1 year-1 in AA, values generally lower than others reported for temperate wet forests worldwide, mainly due to the low woody growth of Fitzroya. NPP was 4.21–4.24 and 3.78–4.10 Mg C ha-1 year-1 in AC and AA, respectively. Estimated mean wood residence time was a minimum of 539–640 years for the whole forest in the Andes and 1368–1393 years for only Fitzroya in this site. Our biomass estimates for the Andes place these ecosystems among the most massive forests in the world. Differences in biomass production between sites seem mostly apparent as differences in allocation rather than productivity. Residence time estimates for Fitzroya are the highest reported for any species and carbon dynamics in these forests are the slowest reported for wet forests worldwide. Although primary productivity is low in Fitzroya forests, they probably act as ongoing biomass carbon sinks on long-term timescales due to their low mortality rates and exceptionally long residence times that allow biomass to be accumulated for millennia.温带古老雨林（old-growth temperate rainforests）单位面积的碳储量为陆地生物圈（terrestrial biosphere）之最，且存续周期极长，但其碳动态（carbon dynamics）却极少被系统描述。南美南部濒危的智利柏（Fitzroya cupressoides）林包含可能是全球现存最古老的密林立木群落，其树木寿命悠长，现存生物量（standing biomass）极高。我们对沿海山脉的沿海阿尔塞国家公园（Alerce Costero National Park, AC）内的中龄林分，以及安第斯山脉（Andean Cordillera）的安第斯阿尔塞国家公园（Alerce Andino National Park, AA）内的古老林分的地上生物量（aboveground biomass）开展评估与对比，并首次给出了其净初级生产力（Net Primary Productivity, NPP）、碳分配（carbon allocation）模式以及木材平均滞留时间（mean wood residence time）的估算结果。沿海阿尔塞国家公园的地上活生物量为113–114 Mg C ha⁻¹，安第斯阿尔塞国家公园则为448–517 Mg C ha⁻¹。其地上生产力为3.35–3.36 Mg C ha⁻¹·a⁻¹，安第斯阿尔塞国家公园则为2.22–2.54 Mg C ha⁻¹·a⁻¹；这一数值普遍低于全球温带湿林的已有研究报道值，主要归因于智利柏的木质生长速率偏低。该区域的净初级生产力（NPP）为4.21–4.24 Mg C ha⁻¹·a⁻¹，安第斯阿尔塞国家公园则为3.78–4.10 Mg C ha⁻¹·a⁻¹。估算得到的安第斯区域全林分木材平均滞留时间最低为539–640年，该区域内智利柏单优种群的木材平均滞留时间则达1368–1393年。我们针对安第斯区域林分的生物量估算结果表明，此类生态系统已跻身全球生物量最丰厚的森林群落之列。不同样地间的生物量生产差异，主要体现为碳分配模式的差异，而非生产力水平的不同。智利柏的木材平均滞留时间估算值为所有树种之首，此类森林的碳动态速率也为全球湿林领域已有报道中最低者。尽管智利柏林的初级生产力偏低，但得益于其极低的死亡率与极长的碳滞留时间，生物量可历经数千年持续累积，因此从长期尺度来看，此类森林仍是持续运作的生物量碳汇。