| Summary: | Forest inventory data (FID) are important resources for understanding the dynamics of forest carbon cycling at regional and global scales. Developing carbon storage growth models and analyzing the difference and climate effect on carbon sequestration capacity have a great importance in practice, which can provide a decision-making basis for promoting high-quality development of forestry and implementing the carbon emission peak and carbon neutralization strategy. Based on the carbon storage dataset of 2680 sample plots from the ninth national forest inventory (NFI) of China, the carbon storage growth models and climate-sensitive variable-parameter carbon storage growth models for three major coniferous plantations (<i>Larix</i> spp., <i>Pinus massoniana</i>, and <i>Pinus tabuliformis</i>) were developed by using weighted nonlinear regression method. The effects of two climate factors (mean annual temperature (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>M</mi><mi>A</mi><mi>T</mi></mrow></semantics></math></inline-formula>) and mean annual precipitation (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>M</mi><mi>A</mi><mi>P</mi></mrow></semantics></math></inline-formula>)) on carbon storage growth and carbon sequestration capacity were analyzed and compared. The mean prediction error (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>M</mi><mi>P</mi><mi>E</mi></mrow></semantics></math></inline-formula>) of carbon storage growth models for three major coniferous plantations was less than 5%, and total relative error (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>T</mi><mi>R</mi><mi>E</mi></mrow></semantics></math></inline-formula>) was approximately less than 2% for self- and cross- validation. The maximum current annual increment of carbon storage for <i>P. massoniana</i>, <i>Larix</i>, and <i>P. tabuliformis</i> was 2.29, 1.89, and 1.19 t/(ha·a), respectively, and their corresponding age of inflection point was 9a, 14a, and 30a, respectively. The maximum average increment of carbon storage for <i>P. massoniana</i>, <i>Larix,</i> and <i>P. tabuliformis</i> was 1.85, 1.50, and 0.94 t/(ha·a), respectively, and their corresponding age of quantitative maturity was 16a, 24a, and 53a, respectively. The maximum average increment of carbon storage for the <i>P. massoniana</i> and <i>Larix</i> plantations was approximately 1.97 and 1.60 times, respectively, that of <i>P. tabuliformis</i> plantation. The average increment of carbon storage for the <i>P. massoniana</i> and <i>Larix</i> plantations reduced approximately by 4.5% and 3.8%, respectively, when the <i>MAT</i> decreases by 1 °C. The average increment of carbon storage for the <i>Larix</i> and <i>P.</i><i>tabuliformis</i> plantations decreased by approximately 6.5% and 3.6%, respectively, when the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>M</mi><mi>A</mi><mi>P</mi></mrow></semantics></math></inline-formula> decreases by 100 mm. Our findings suggest that: the carbon sequestration capacity is from highest to lowest in the <i>P. massoniana</i>, <i>Larix</i>, and <i>P. tabuliformis</i> forests. <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>M</mi><mi>A</mi><mi>T</mi></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>M</mi><mi>A</mi><mi>P</mi></mrow></semantics></math></inline-formula> have different effects on the carbon growth process and carbon sequestration capacity of these plantations. The greatest impact on carbon sequestration capacity was detected in the <i>Larix</i> plantation, followed by the <i>P. massoniana</i> and <i>P. tabuliformis</i> plantations. It is essential to coordinate regional development and employ scientific management strategies to fully develop the maximum carbon sequestration capacity in terms of plantations in China. In the present study, we estimate the carbon storage in major coniferous plantations in China and describe a useful methodology for estimating forest carbon storage at regional and global levels.
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