Early growth of different tree species on agricultural land along a latitudinal transect in Sweden

Abstract

Fast-growing tree species will be an important tool in the future production of renewables and in substituting non-renewable fossil energy sources. Sweden, like other countries around the Baltic Sea, has large areas of abandoned farmland usable for biomass production, but knowledge of growth performance of tree species candidates is insufficient. An experiment was initiated where six potentially high-producing tree species were compared. The best available plant material for each species was used on five sites over latitudes 56–64°N in Sweden. Results from the first 8–9 years are reported. Short rotation coppice willow (Salix schwerinii Wolf × S. viminalis L., clone ‘Tora’) had the fastest initial growth and production in southern Sweden. Hybrid aspen (Populus tremula L. × P. tremuloides Michx.) and poplar (Populus spp., section Tacamahaca), grown as short rotation forest, grew well over all sites and showed the highest productivity at the two northern sites. Hybrid larch (Larix ×eurolepis Henry) displayed a high potential at the two most southerly sites, whilst silver birch (Betula pendula Roth) was a medium-producing species at all sites. Norway spruce (Picea abies (L.) Karst.) started slowly, and Siberian larch (L. sukaczewii Dylis) produced poorly at the two northern sites in the initial stage. All tree species followed existing height development curves for the respective species on a high site quality level. Currently, well-growing clones of Populus spp. indicated that a wider selection of tree species can be used at high latitudes under climate change. The study showed a high growth potential for most species on former agricultural lands. However, measures to reduce climate and biological damage must be included in future efforts.

Climate and Competitive Status Modulate the Variation in Secondary Metabolites More in Leaves Than in Fine Roots of Betula pendula

“…The above-ground growth rate of sampled birches was only slightly inferior in the northern sites compared to the southern ones ( Figure 3 ). This agrees with the estimation of growth and productivity for the same plantations in Sweden ( Rytter and Lutter, 2020 ). Despite obvious growth constraints in the north (lower MAT, shorter growing season, slower N mineralization), the leaf macronutrient content was higher in the north, suggesting that N availability was not the main growth limiting factor at these sites.…”

Variation of growth and phenology traits in poplars planted in clonal trials in Northern Europe—implications for breeding

“…In Sweden, the production systems with fast-growing trees are designed to deliver wood in dimensions that are suitable for the existing pulping industry. Populus hybrids reach high growth rate in terms of mean annual increment (MAI = 15 m 3 ha −1 ) at a plantation age of 9 to 10 years in southern Sweden at 55°N [58] and 6 m 3 ha −1 in Northern Sweden at latitude 63°N [59]. MAI continues to increase after this age, and culminates with MAI = 20-30 m 3 ha −1 year −1 after 20 years in Southern Sweden [3][4][5]60].…”

Climate Benefit of Different Tree Species on Former Agricultural Land in Northern Europe

“…For example, a mean annual increment (MAI) up to 5-10 Mg of dry material ha −1 year −1 is common for the tree species mentioned. However, the species are rarely compared side-by-side on sites with homogenous growth conditions [40].…”

“…The substitution factor will largely be related to bioenergy replacing oil or gas, while the ability to create a larger average C stock might be smaller [3,5,43]. Tree species with a longer rotation cycle, such as late successional spruce, are "slow starters" in early growth in comparison with deciduous species [40]. However, slower growth and longer rotation cycle can be compensated for by a higher average CO 2 substitution effect due to a higher share of solid wood products [44] and higher average C stocks at the landscape level [41,45].…”

“…Comparison of different tree species' production by combining the studies from the literature will retain a lot of uncertainties that are biased because of the variation of pedoclimatic conditions, latitude, level of tree breeding, measurement years, management practice and land-use history. In order to overcome the uncertainties mentioned, the present study evaluates six different tree species' (silver birch, hybrid aspen, Norway spruce, poplars, larch and willow) climate benefit potential on former agricultural land by using the network of tree species comparison trials in Sweden [40,46,47]. The set-up of the experiment is replicated plots in homogenous growth conditions with a similar level of tree breeding, i.e., a tree will have an equal starting point in comparable conditions [46,47].…”