Nutrient limitation in tropical secondary forests following different management practices

Secondary forests now make up more than half of all tropical forests, and constraints on their biomass accumulation will influence the strength of the terrestrial carbon (C) sink in the coming decades. However the variance in secondary tropical forest biomass for a given stand age and climate is high and our understanding of why is limited. We constructed a model of terrestrial C, nitrogen (N), and phosphorus (P) cycling to examine the influence of disturbance and management practices on nutrient limitation and biomass recovery in secondary tropical forests. The model predicted that N limited the rate of forest recovery in the first few decades following harvest, but that this limitation switched to P approximately 30-40 years after abandonment, consistent with field data on N and P cycling from secondary tropical forest chronosequences. Simulated biomass recovery agreed well with field data of biomass accumulation following harvest (R2=0.80). Model results showed that if all biomass re...如今次生林已占全球热带森林总量的半数以上，其生物量积累的限制条件将影响未来数十年陆地碳（C）汇的强度。然而，在既定林龄（stand age）与气候条件下，热带次生林的生物量存在显著变异，目前学界对其成因的认知仍较为有限。本研究构建了陆地碳（C）、氮（N）与磷（P）循环模型，用以探究干扰与经营措施对热带次生林养分限制及生物量恢复的影响。模型预测，采伐后的最初数十年内，森林恢复速率受氮限制，但在弃耕约30至40年后，限制因子会转为磷，这与基于热带次生林演替时间序列（chronosequences）的氮、磷循环野外观测数据相一致。模拟得到的生物量恢复结果与采伐后生物量积累的野外实测数据拟合度良好（决定系数R²=0.80）。模型结果表明，若将所有生物量重新……