Agroforestry practices, such as hedgerow planting, are widely encouraged for climate change mitigation and there is an urgent need to assess their contribution to national ‘net-zero’ targets. This study examined the impact that planting hedgerows at different rates could make to UK net-zero goals over the next 40 years, with a focus on 2050. We analysed the carbon (C) content of native hedgerow species and determined hedge aboveground biomass (AGB) C stock via destructive sampling of hedges of known ages. AGB C stocks ranged from 8.34 Mg C ha−1 in the youngest hedges, to 40.42 Mg C ha−1 in old ones. Knowing the age of the hedgerows, we calculated their annual average AGB C sequestration rate, which was highest in young hedges (2.09 Mg C ha−1 yr−1), and lowest in 39 year old mature, regularly trimmed hedgerows (0.86 Mg C ha−1 yr−1). We present a time series of the annual AGB C sequestration rate change between hedge age categories, which increases from 2.09 Mg C ha−1 yr−1 in the first 6 years after planting, to 2.26 Mg C ha−1 yr−1 in the next 6 years, and then decreases to 0.43 Mg C ha−1 yr−1 between years 13 and 40. Our results indicate that, if encouraged widely, hedgerow planting can be a valuable tool for atmospheric CO2 capture and storage, contributing towards net-zero targets. However, current planting rates (1778.8 km yr−1) are too low to reach the net-zero goal set by the UK Climate Change Committee of increasing hedgerow length by 40 % by 2050. An increased planting rate of 7148.1 km yr−1 will achieve this goal by 2050, and, over 40 years, store 3.41 Tg CO2 in hedge AGB, or 10.13 Tg CO2 in hedge total biomass and in the soil, annually offsetting 1.5 %–4.5 % of UK annual agricultural CO2 emissions.

中文翻译：

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种植树篱：生物质碳封存和对净零目标的贡献


广泛鼓励种植树篱等农林业实践以缓解气候变化，迫切需要评估它们对国家“净零”目标的贡献。这项研究考察了以不同速度种植树篱可能对未来 40 年英国净零目标产生的影响，重点是 2050 年。我们分析了本地树篱物种的碳 （C） 含量，并通过对已知年龄的树篱进行破坏性采样来确定树篱地上生物量 （AGB） C 存量。AGB C 存量范围从最年轻的树篱的 8.34 Mg C ha-1 到老树篱的 40.42 Mg C ha-1 不等。了解树篱的年龄后，我们计算了它们的年平均 AGB C 封存率，其中在年轻的树篱中最高 （2.09 Mg C ha-1 yr-1），在 39 年成熟、定期修剪的树篱中最低 （0.86 Mg C ha-1 yr-1）。我们提出了树篱年龄类别之间年度 AGB C 封存率变化的时间序列，从种植后前 6 年的 2.09 Mg C ha-1 yr-1 增加到接下来 6 年的 2.26 Mg C ha-1 yr-1，然后在 13 年至 40 年之间下降到 0.43 Mg C ha-1 yr-1。我们的结果表明，如果得到广泛鼓励，树篱种植可以成为大气二氧化碳捕获和储存的宝贵工具，有助于实现净零目标。然而，目前的种植率（1778.8 公里 yr-1）太低，无法实现英国气候变化委员会设定的到 2050 年将树篱长度增加 40% 的净零目标。到 2050 年，增加 7148.1 公里/年-1 的种植率将实现这一目标，并且在 40 年内，在树篱 AGB 中储存 3.41 Tg CO2，或在树篱总生物量和土壤中储存 10.13 Tg CO2，每年抵消 1.5 %-4.5% 的英国农业 CO2 排放量。