Climate Warming Impacts on Distributions of Scots Pine (Pinus sylvestris L.) Seed Zones and Seed Mass across Russia in the 21st Century

Abstract

Research highlights: We investigated bioclimatic relationships between Scots pine seed mass and seed zones/climatypes across its range in Russia using extensive published data to predict seed zones and seed mass distributions in a changing climate and to reveal ecological and genetic components in the seed mass variation using our 40-year common garden trial data. Introduction: seed productivity issues of the major Siberian conifers in Asian Russia become especially relevant nowadays in order to compensate for significant forest losses due to various disturbances during the 20th and current centuries. Our goals were to construct bioclimatic models that predict the seed mass of major Siberian conifers (Scots pine, one of the major Siberian conifers) in a warming climate during the current century. Methods: Multi-year seed mass data were derived from the literature and were collected during field work. Climate data (January and July data and annual precipitation) were derived from published reference books on climate and climatic websites. Our multiple regression bioclimatic models were constructed based on the climatic indices of growing degree days > 5 °C, negative degree days < 0 °C, and annual moisture index, which were calculated from January and July temperatures and annual precipitation for both contemporary and future climates. The future 2080 (2070–2100) January and July temperatures and annual precipitation anomalies were derived from the ensemble of twenty CMIP5 (the Coupled Model Intercomparison Project, Phase 5) global circulation models (GCMs) and two scenarios using a mild RCP (Representative Concentration Pathway) 2.6 scenario and an extreme RCP 8.5 scenario. Results: Site climate explained about 70% of the seed mass variation across the Scots pine range. Genetic components explained 30% of the seed mass variation, as per the results from our common garden experiment in south central Siberia. Seed mass varied within 3.5 g (min) and 10.5 g (max) with the mean 6.1 g (n = 1150) across Russia. Our bioclimatic seed mass model predicted that a July temperature elevated by 1 °C increased seed mass by 0.56 g, and a January temperature elevated by 5 °C increased seed mass by 0.43 g. The seed mass would increase from 1 g to 4 g in the moderate RCP 2.6 and the extreme RCP 8.5 climates, respectively. Predicted seed zones with heavier seed would shift northwards in a warming climate. However, the permafrost border would halt this shifting due to slower permafrost thawing; thus, our predicted potential for Scots pine seed zones and seed mass would not be realized in the permafrost zone in a warmed climate. Our common garden experiment in central Siberia showed that trees of northerly origins produced lighter seeds than local trees but heavier ones than the trees at the original site. Trees of southerly origins produced heavier seeds than local trees but lighter seeds than the trees at the original site. Conclusions: The findings from this study could serve as blueprints for predicting new landscapes with climatic optima for Pinus sylvestris to produce better quality seeds to adjust to a warming climate.

The VIS-Spectrometric Data of Scots Pine Individual Seed Reveal Forecasting Potential for Container-Grown Germination and Seedling’s Dickson Quality Index

“…Currently, there is a tendency to move [233] seeds of Scots pine (P. sylvestris L.) for growth experiments in the gradation function of the accumulated annual precipitation (mm) depending on the accumulated degree days [234] of the region. The current experiment is no exception: 1200 varietal (P. sylvestris L., variety "Negorelskaya") seeds were moved from the collection area (1731 degreedays, 722 mm) to the experimental area (2326 degree-days; 786 mm).…”

Climatic Stress Test of Scots Pine Provenances in Northeastern Europe Reveals High Phenotypic Plasticity and Quasi-Linear Response to Warming

“…The xeric (trailing) limit is a critical boundary for the functioning of the manifold services the forest cover provides [23]. Although it marks significant changes in land cover and landmass carbon balance [24][25][26][27], its importance in research and forest and land management remains underestimated [10]. Local site conditions may influence the presence and survival of populations in this border zone [28].…”

Genetic Resources and Adaptive Management of Conifers in a Changing World

“…Seed weight increases with the warming climate, improving seedling survival. This trait should also be considered, especially on extreme sites [8]. Some further queries for assisted migration are the transfer of populations outside their current natural distribution, selective breeding for disease-resistant trees, differentiation of measures according to the position in the range of the species, or the invasive potential of transferred species, etc.…”