Productivity of local Norway spruce clones relates to weather sensitivity of height increment in the eastern Baltic region

In the eastern Baltic region, Norway spruce (Picea abies) is predicted to decrease in abundance, resulting in substantial economic consequences. Such predictions have been based on distribution, as well as the sensitivity of growth, largely neglecting the adaptive potential of local populations. Under such circumstances, information on growth sensitivity and its genetic control, as well as productivity-sensitivity relationships is necessary to evaluate the adaptability of populations. Radial increment, which is highly sensitive to local conditions has been mainly used for weather-growth analysis, while height increment, which is a better proxy of productivity due to lower dependence on local density, has been neglected due to laborious gathering of data. Long-term weather sensitivity of annual height increment to weather fluctuations and anomalies (extremes) was estimated by the time series decomposition and multiple regression techniques. Clones of plus-trees from a local population differing by productivity at the age of 55 years growing in an experimental plantation in Latvia were studied. Meteorological conditions prevailingly had carry-over effects on height increment. Thermal regime in winter was the primary driver of height increment with moisture availability in summer showing secondary effects, presuming a positive effect of warming on growth. Abrupt changes in annual increment were related to the co-occurrence of a few weather anomalies, suggesting robustness of height growth. Height increment showed explicit sensitivity-productivity relationships with more productive genotypes being more tolerant and resistant to weather fluctuations. Considering that narrow spatial scale and climatic gradient were analysed, linear and nonlinear responses to weather conditions were estimated implying local adaptation and varying phenotypic plasticity of the genotypes, thus suggesting the persistence of adaptive potential of the local non-marginal population.