Eddy Covariance vs. Biometric Based Estimates of Net Primary Productivity of Pedunculate Oak (Quercus robur L.) Forest in Croatia during Ten Years

Forests

Alessandro Peressotti¹  Giorgio Alberti¹  Mislav Anić²  MašaZorana Ostrogović Sever²  Goran Tijan²  Hrvoje Marjanović²  Elvis Paladinić²  Dijana Vuletić²  Ivan Balenović²  Željko Večenaj³ 

[1] Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Via Delle Scienze 206, 33100 Udine, Italy;Department of Forest Management and Forestry Economics, Croatian Forest Research Institute, Cvjetno Naselje 41, 10450 Jastrebarsko, Croatia;Department of Geophysics, Faculty of Science, University of Zagreb, Horvatovac 95, 10000 Zagreb, Croatia;

关键词: carbon flux;    carbon balance;    net ecosystem exchange;    dendrometers;    tree biomass;    litterfall;    logistic model;   

DOI  :  10.3390/f9120764

来源: DOAJ

【 摘 要 】

We analysed 10 years (2008⁻2017) of continuous eddy covariance (EC) CO₂ flux measurements of net ecosystem exchange (NEE) in a young pedunculate oak forest in Croatia. Measured NEE was gap-filled and partitioned into gross primary productivity (GPP) and ecosystem reparation (R_ECO) using the online tool by Max Planck Institute for Biogeochemistry in Jena, Germany. Annual NEE, GPP, and R_ECO were correlated with main environmental drivers. Net primary productivity was estimated from EC (NPP_EC), as a sum of −NEE and R_h obtained using a constant R_h:R_ECO ratio, and from independent periodic biometric measurements (NPP_BM). For comparing the NPP at the seasonal level, we propose a simple model that aimed at accounting for late-summer and autumn carbon storage in the non-structural carbohydrate pool. Over the study period, Jastrebarsko forest acted as a carbon sink, with an average (±std. dev.) annual NEE of −319 (±94) gC m⁻² year⁻¹, GPP of 1594 (±109) gC m⁻² year⁻¹, and R_ECO of 1275 (±94) gC m⁻² year⁻¹. Annual NEE showed high inter-annual variability and poor correlation with annual average global radiation, air temperature, and total precipitation, but significant (R² = 0.501, p = 0.02) correlation with the change in soil water content between May and September. Comparison of annual NPP_EC and NPP_BM showed a good overall agreement (R² = 0.463, p = 0.03), although in all years NPP_BM was lower than NPP_EC, with averages of 680 (±88) gC m⁻² year⁻¹ and 819 (±89) gC m⁻² year⁻¹, respectively. Lower values of NPP_BM indicate that fine roots and grasses contributions to NPP, which were not measured in the study period, could have an important contribution to the overall ecosystem NPP. At a seasonal level, two NPP estimates showed differences in their dynamic, but the application of the proposed model greatly improved the agreement in the second part of the growing season. Further research is needed on the respiration partitioning and mechanisms of carbon allocation.

【 授权许可】

Unknown