Physiology-based phenology models for forest tree species in Germany

Abstract

Models of phenology are needed for the projection of effects of a changing climate on, for example, forest production, species competition, vegetation-atmosphere feedback and public health. A new phenology model for deciduous tree bud burst is developed and parameters are determined for a wide geographical range (Germany) and several forest tree species. The new model is based on considerations of simple interactions between inhibitory and promotory agents that are assumed to control the developmental status of a plant. Several alternative model structures were formulated emphasizing different hypothetical physiological processes. The new models fitted the observations better than classical models. The bias of the classical models, i.e. overestimation of early observations and underestimation of late observations, could be reduced but not completely removed. Differences in the best-fitting model equations for each species indicated that, for the late spring phases (bud burst of Fagus sylvatica and Quercus robur), the photoperiod played a more dominant role than for early spring phases (bud burst of Betula pendula and Aesculus hippocastanum). Chilling only plays a subordinate role for spring bud burst compared to temperatures preceding this event in our data. The presented modeling approach allowed for a species-specific weighting of the dominant processes. The model results are in accordance with experimental findings that indicate an important role of day length in late spring BB. Potentials for model improvement are discussed.

The shifting phenological landscape: Within‐ and between‐species variation in leaf emergence in a mixed‐deciduous woodland

“…These results support findings from a study of phenological sensitivity to temperature along altitudinal gradients in seven deciduous tree species, which found oak to be the most sensitive and beech to be the least (Vitasse et al., 2009). Beech is known to be particularly sensitive to photoperiod and is thought to require long days before bud development can begin, even in particularly warm springs (Schaber & Badeck, 2003). It is becoming clear that tree species have different cue sensitivities and requirements and that this can cause the order and distribution of species budburst throughout spring to differ considerably between years (Roberts et al., 2015).…”

Terrestrial biosphere models need better representation of vegetation phenology: results from the North American Carbon Program Site Synthesis

“…Comparative analyses of different phenological models have typically used data from only a single site (e.g., Richardson & O'Keefe, 2009), which hinders the development and parameterization of generalized models. Only in a very few studies (e.g., Schaber & Badeck, 2003) have attempts been made to constrain phenological models using data across a wide geographic range. Thus, results from most analyses reflect over-fitting of models to individuals from a particular population, when in reality there may be genetic variation across the native range of a species with respect to the phenological sensitivity to climatic drivers (Chuine et al, 1998).…”

The Role of Respiration in Estimation of Net Carbon Cycle: Coupling Soil Carbon Dynamics and Canopy Turnover in a Novel Version of 3D-CMCC Forest Ecosystem Model

“…The biggest source of uncertainty in deciduous stands was driven by the amount of degree days needed to begin vegetative period. The use of a site-specific thermal sum (GDD) to activate vegetation period is widely used, but proven to be very site sensitive, and not very effective for a regional generalization [81]. On the other hand, the processes triggering bud-burst timing are still partly unknown.…”