Distinct genecological patterns in seedlings ofNorway spruce and silver fir from a mountainous landscape

Abstract

Abstract. Understanding the genecology of forest trees is critical for gene conservation, for predicting the effects of climate change and climate change adaptation, and for successful reforestation. Although common genecological patterns have emerged, species-specific details are also important. Which species are most vulnerable to climate change? Which are the most important adaptive traits and environmental drivers of natural selection? Even though species have been classified as adaptive specialists vs. adaptive generalists, large-scale studies comparing different species in the same experiment are rare. We studied the genecology of Norway spruce (Picea abies) and silver fir (Abies alba), two co-occurring but ecologically distinct European conifers in Central Europe. For each species, we collected seed from more than 90 populations across Switzerland, established a seedling common-garden test, and developed genecological models that associate population variation in seedling growth and phenology to climate, soil properties, and site water balance. Population differentiation and associations between seedling traits and environmental variables were much stronger for Norway spruce than for silver fir, and stronger for seedling height growth than for bud phenology. In Norway spruce, height growth and second flushing were strongly associated with temperature and elevation, with seedlings from the lowlands being taller and more prone to second flush than seedlings from the Alps. In silver fir, height growth was more weakly associated with temperature and elevation, but also associated with water availability. Soil characteristics explained little population variation in both species. We conclude that Norway spruce has become an adaptive specialist because trade-offs between rapid juvenile growth and frost avoidance have subjected it to strong diversifying natural selection based on temperature. In contrast, because silver fir has a more conservative growth habit, it has evolved to become an adaptive generalist. This study demonstrates that co-occurring tree species can develop very different adaptive strategies under identical environmental conditions, and suggests that Norway spruce might be more vulnerable to future maladaptation due to rapid climate change than silver fir.

A review and meta‐analysis of intraspecific differences in phenotypic plasticity: Implications to forecast plant responses to climate change

“…Despite the ubiquity and eco‐evolutionary implications of P × E , a considerable proportion of studies (>20%) were performed in only one test environment, which prevents its calculation (e.g., Alberto et al, ; Hernandez‐Serrano et al, ; Sebastian‐Azcona, Hacke, & Hamann, ). For instance, only one test environment is used in most studies using F ST – Q ST comparisons (e.g., Frank, Sperisen, et al, ; Hernandez‐Serrano et al, ; Santiso et al, ); Q ST measures population differentiation in functional traits, and may be compared to F ST , a metric widely used to measure population differentiation in neutral molecular markers. Their comparison informs on the role of divergent natural selection in the functional differentiation of populations (see Merilä & Crnokrak ).…”

“…Their comparison informs on the role of divergent natural selection in the functional differentiation of populations (see Merilä & Crnokrak ). The few instances where Q ST has been calculated in several environments show that Q ST values are not always consistent across test environments, which has important implications for our understanding of the evolutionary forces shaping population differentiation patterns (Frank, Sperisen, et al, ; Ramírez‐Valiente et al, ). Our results thus call for caution on the use of single‐environment studies to infer adaptive divergence among populations.…”

Recovery of Abies alba and Picea abies saplings to browsing and frost damage depends on seed source

“…Environmental variables considered at the seed sources included the following: mean annual temperature ( MAT ); mean spring temperature (March – May, MTsp ); continentality (interannual temperature variance, that is, maximum of warmest month minus minimum of coldest month); average maximum diurnal amplitude of temperature during spring (March – May, DTAsp ); sum of growing degree days (based on a threshold of 5°C, DDEG ); average numbers of days during the vegetation season (March – November) with frost ( SFROv ); mean annual precipitation sum ( PREC ); absolute maximum drought ( PREC < 0.01 mm) period length in summer (June – August, DRYPsu ); and annual aridity index ( DMI = PREC / MAT *10 (Martonne, )). All variables were calculated for the period 1931–1960 for each seed source (Frank et al, ). Physical and chemical soil properties—including the available water capacity of 1 m soil depth ( AWC )—were derived from local soil pits that were located within a few meters of one of the three mother trees at each seed source (details see appendix in Frank et al, ).…”

Growth and quality of Fagus sylvatica saplings depend on seed source, site, and browsing intensity

“…These values represent best linear unbiased predictions of population means (Frank et al. ). The environmental variables included temperature variables, such as mean annual temperature (MAT), and precipitation variables for the time period 1931–1960 that were approximated for each seed source (Frank et al.…”

“…The environmental variables included temperature variables, such as mean annual temperature (MAT), and precipitation variables for the time period 1931–1960 that were approximated for each seed source (Frank et al. : Table A1). In addition, elevation was recorded at each seed source.…”