Key message

This study utilized dendrochronology and long-term (2003–2017) eddy covariance (EC) carbon flux data to investigate the relationships between tree growth and gross ecosystem productivity (GEP_EC) in different-age (15-, 42- and 78-year old) pine plantation forests in the Great Lakes region in eastern North America and found that tree-ring growth in these different-age pine forests was significantly (p < 0.05) correlated with observed annual GEP_EC values.

Abstract

Forests play a major role in the global carbon cycle. Understanding the dynamics of the forest carbon cycle and its driving factors is challenging. This study utilized dendrochronology and long-term (2003–2017) eddy covariance (EC) carbon flux data to investigate the relationships between tree growth and gross and net ecosystem productivities (GEP_EC and NEP_EC) in different-age (15-, 42- and 78-year old) pine plantation forests in the Great Lakes region in eastern North America. Tree growth in these different-age pine forests was significantly (p < 0.05) correlated with observed annual GEP_EC values, while coherence between tree growth and NEP_EC was relatively poor. Current-year and 1-year lagged ring-width chronologies and climate variables, including spring (April–May) temperature (T_SPR) and Standardized Potential Evapotranspiration Index (SPEI_SUM) over the summer months (June–August) were used to test ten different linear regression models to simulate tree-ring-based GEP (GEP_TR) values at all three sites. This analysis showed that current-year growth was the best predictor of GEP_TR at all three sites, when compared to observed GEP_EC, except during drought years, when GEP_TR was underestimated. Current-year tree growth models were then used to reconstruct GEP_TR over the life span of each stand. These reconstructions showed low GEP_TR values from 1978 to 1988 and from 2002 to 2007. Low GEP_TR in late 1970s occurred in response to below average temperatures when there were no major drought periods, while low GEP_TR in early 2000s occurred following drought-like conditions in 2002. However, in recent years relatively higher GEP_TR was observed at all three different-age forest sites. This interdisciplinary study will help to improve our understanding of carbon exchanges and the key environmental controls and associated uncertainties on tree growth in these different-age plantation stands in eastern North America. It will also help to determine how these forests may respond to climate change.

中文翻译：

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三种不同年龄的松树人工林林轮生长和基于涡度协方差的生态系统生产力的比较

关键信息

这项研究利用树木年代学和长期（2003-2017）涡流协方差（EC）碳通量数据研究了不同年龄（15年，42年和78年）树木生长与生态系统总生产力（GEP _EC）之间的关系。北美东部大湖地区的老松树人工林，并发现这些不同年龄的松林中的年轮增长 与观测到的年度GEP _EC值显着相关（p <0.05）。

抽象

森林在全球碳循环中起着重要作用。了解森林碳循环的动态及其驱动因素具有挑战性。本研究中使用树轮和长期（2003年至2017年）涡协方差（EC）的碳通量数据调查树木生长和毛和净生态系统的生产率（GEP之间的关系_EC和NEP _EC在不同年龄（15-），42北美东部大湖地区的78岁树龄的松树人工林。在这些不同年龄的松树林中，树木的生长 与观测到的年度GEP _EC值显着相关（p <0.05），而树木生长与NEP _EC之间的一致性相对较差。使用当年和一年的滞后环宽年表和气候变量，包括夏季（6月至8月）的春季（4月至5月）温度（T _SPR）和标准潜在蒸散指数（SPEI _SUM）进行测试十个不同的线性回归模型来模拟所有三个位置的基于树环的GEP（GEP _TR）值。该分析表明，与观察到的GEP _EC相比，在所有三个地点，当年的增长都是GEP _TR的最佳预测指标_，除了干旱年份低估了GEP _TR的干旱年份。然后使用当年的树木生长模型重建GEP _TR在每个展位的使用寿命中。这些重建呈低GEP _TR值1978至1988年以及2002年至2007年低GEP _TR在20世纪70年代末发生在响应低于平均温度时没有发生重大干旱期，而低GEP _TR在21世纪初发生以下干旱样情况在2002年有所改善。但是，近年来，在所有三个不同年龄的林地都观察到相对较高的GEP _TR。这项跨学科研究将有助于增进我们对北美东部这些不同年龄人工林林木碳交换和关键环境控制以及树木生长相关不确定性的理解。它还将有助于确定这些森林如何应对气候变化。