AUTHOR=Schick Jan , Albert Matthias , Schmidt Matthias 

TITLE=A new approach for modeling stand height development of German forests under climate change

JOURNAL=Frontiers in Forests and Global Change

VOLUME=Volume 6 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/forests-and-global-change/articles/10.3389/ffgc.2023.1201636

DOI=10.3389/ffgc.2023.1201636

ISSN=2624-893X

ABSTRACT=We developed a new approach for site index curve models, which combines longitudinal height development patterns derived from state-space data with the broad environmental conditions covered by space-for-time data. For this, we gathered dendrometry from both inventories and research plots. Concerning environmental variables, we included soil mapping data as well as atmospheric data, i.e. precipitation, temperature and nitrogen deposition. The atmospheric data was included as a weighted mean over stand life of the sums for the dynamically determined vegetation period, or as yearly sums, in the case of nitrogen deposition, respectively. As a weight, the values of a height increment function were used. Then, we derived the basic shape of a height development curve from research plot data, and transferred said shape to a site index curve model. The model represents a substantial advancement of a previous version and was fitted as a generalized additive model (GAM). All effects were of relevant size and showed biologically feasible patterns. Though the model is biased for young ages, we could predict site index curves which, under constant environmental conditions, closely follow yield table curves and thus accurately depict stand height development. Moreover, the model does not require initial dendrometry, which broadens its applicability. Thus, the model represents a useful tool for forest management and planning under climate change.