Estimating spatial variation in the effects of climate change on the net primary production of Japanese cedar plantations based on modeled carbon dynamics

Jumpei Toriyama,Aleksi Lehtonen,Shinji Sawano,Tatsuya Tsurita,Takanori Shimizu,Shigehiro Ishizuka,Naoyuki Yamashita,Taku M Saitoh,Shoji Hashimoto,Yoko Osone,Sophan Chhin

doi:10.1371/journal.pone.0247165

Jumpei Toriyama, Aleksi Lehtonen + Show 9 more

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https://doi.org/10.1371/journal.pone.0247165

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Abstract

Spatiotemporal prediction of the response of planted forests to a changing climate is increasingly important for the sustainable management of forest ecosystems. In this study, we present a methodology for estimating spatially varying productivity in a planted forest and changes in productivity with a changing climate in Japan, with a focus on Japanese cedar (Cryptomeria japonica D. Don) as a representative tree species of this region. The process-based model Biome-BGC was parameterized using a plant trait database for Japanese cedar and a Bayesian optimization scheme. To compare productivity under historical (1996–2000) and future (2096–2100) climatic conditions, the climate scenarios of two representative concentration pathways (i.e., RCP2.6 and RCP8.5) were used in five global climate models (GCMs) with approximately 1-km resolution. The seasonality of modeled fluxes, namely gross primary production, ecosystem respiration, net ecosystem exchange, and soil respiration, improved after two steps of parameterization. The estimated net primary production (NPP) of stands aged 36–40 years under the historical climatic conditions of the five GCMs was 0.77 ± 0.10 kgC m-2 year-1 (mean ± standard deviation), in accordance with the geographical distribution of forest NPP estimated in previous studies. Under the RCP2.6 and RCP8.5 scenarios, the mean NPP of the five GCMs increased by 0.04 ± 0.07 and 0.14 ± 0.11 kgC m-2 year-1, respectively. The increases in annual NPP were small in the southwestern region because of the decreases in summer NPP and the small increases in winter NPP under the RCP2.6 and RCP8.5 scenarios, respectively. Under the RCP2.6 scenario, Japanese cedar was at risk in the southwestern region, in accordance with previous studies, and monitoring and silvicultural practices should be modified accordingly.

Highlights

At present, spatiotemporal prediction of the response of planted forests to a changing climate is increasing in importance
The modeled gross primary production (GPP) in the Takayama coniferous forest (TKC) exhibited a sharp decrease followed by an increase in the daily time step during summer in STEP-0, and these variations were removed in STEP-2 (Fig 3A)
The parameterization conducted in this study improved the estimation of the physiological responses of Japanese cedar plantations growing under humid climatic conditions in East Asia

Summary

Introduction

Spatiotemporal prediction of the response of planted forests to a changing climate is increasing in importance. The planted forest area worldwide reached 293.9 million ha, which is 7% of total forest area, by 2020 [1]. This increase has highlighted the importance of predicting the spatial responses of planted forests to changing climatic conditions in terms of material and energy flows in terrestrial ecosystems. Predicting the future risk of decreasing productivity and carbon (C) sequestration in planted forests and modeling of C dynamics [2] are expected play important roles. Prediction of a planted forest’s response to climate change through modeling of C dynamics depends strongly on the climate scenarios employed. Several process-based models, including ORCHIDEE [3], LPJ-GUESS [4] and 3-PG [5], have been applied to planted forests, and Biome-BGC (BBGC) has been used to model various tree species in Europe [6, 7] and East Asia [8, 9]

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