Casuarina equisetifolia plantations have been widely established along tropical and subtropical coasts, where they act as a windbreak to shelter coastal areas. These shelter plantations also fulfill another important ecosystem service by sequestering large amounts of carbon (C). However, shelter plantations are usually established on nutrient-poor sand dunes, which may limit tree growth and therefore C sequestration rates. To assess whether fertilization increases the C sequestration of coastal shelter plantations, we conducted a fertilization experiment in a young C. equisetifolia plantation with four treatments: nitrogen addition (+N), phosphorus addition (+P), nitrogen and phosphorus addition (+NP), and controls (CK). We quantified nutrient availability and annual net ecosystem production (NEP) during the key early establishment phase. Fertilization with +N and +P significantly increased ammonium-N and extractable P in the surface soils and the N and P concentrations of branches, respectively. Surprisingly, the mean growth rate of C. equisetifolia plantations (24.59 ± 0.66 Mg ha⁻¹ yr⁻¹) was not affected by fertilization. The mean NEP was 6.18 ± 0.49 Mg C ha⁻¹ yr⁻¹, and there was no difference among fertilization treatments. However, soil organic C significantly increased by 41% and 36% with +N and +P, respectively, but not +NP. C. equisetifolia plantations can sequester large amounts of C in biomass on poor soils without the need for additional nutrients, although fertilization may enhance soil C storage. Considering the potential large planting area, we suggest that coastal C. equisetifolia shelter plantations could be an important nature-based solution for climate change mitigation in coastal regions.

中文翻译：

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在华南沿海避难所人工林中，添加养分可增强土壤中的碳固存，但不增强植物生物量

木麻黄种植园已在热带和亚热带海岸广泛建立，在那里它们充当防风林以保护沿海地区。这些庇护种植园还通过隔离大量碳 (C) 来实现另一个重要的生态系统服务。然而，庇护种植园通常建在营养贫乏的沙丘上，这可能会限制树木的生长，从而限制碳的固存率。为了评估施肥是否会增加沿海庇护种植园的 C 封存，我们在一个年轻的C. equisetifolia 中进行了施肥实验人工林四个处理：加氮（+N）、加磷（+P）、加氮磷（+NP）和对照（CK）。我们在关键的早期建立阶段量化了养分可用性和年度净生态系统产量 (NEP)。+N 和 +P 施肥分别显着增加了表层土壤中的铵态氮和可提取 P 以及树枝的 N 和 P 浓度。令人惊讶的是，木贼种植园的平均增长率（24.59 ± 0.66 Mg ha ^-1  yr ^-1）不受施肥的影响。平均 NEP 为 6.18 ± 0.49 Mg C ha ^-1  yr ^-1，施肥处理之间没有差异。然而，土壤有机碳在 +N 和 +P 下分别显着增加了 41% 和 36%，而不是 +NP。C. equisetifolia种植园可以在贫瘠的土壤上隔离大量的生物量碳，而无需额外的养分，尽管施肥可能会增强土壤碳的储存。考虑到潜在的大种植面积，我们建议沿海的木贼庇护种植园可能是缓解沿海地区气候变化的重要的基于自然的解决方案。