Effects of nutrition and soil warming on stemwood production in a boreal Norway spruce stand

Abstract

The boreal forest is expected to experience the greatest warming of all forest biomes. The extent of the boreal forest, the large amount of carbon contained in the soil, and the expected climate warming, make the boreal forest a key biome to understand and represent correctly in global carbon models. It has been suggested that an increase in temperature could stimulate the release of CO2 caused by an increased decomposition rate, more than biomass production, which could convert current carbon sinks into carbon sources. Most boreal forests are currently carbon sinks, but it is unclear for how long in the future the carbon sink capacity of the boreal forest is likely to be maintained. The impact of soil warming on stem volume growth was studied during 6 years, in irrigated (I) and irrigated‐fertilized (IL) stands of 40‐year‐old Norway spruce in Northern Sweden. From May to October heating cables were used to maintain the soil temperature on heated‐irrigated plots (Ih and ILh) 5 °C above that on unheated control plots (Ic and ILc). After six seasons' warming, stem volume production (m3 ha−1 a−1) was 115% higher on Ih than on unheated (Ic) plots, and on heated and irrigated‐fertilized plots (ILh) it was 57% higher than on unheated plots (ILc). The results indicate that in a future warmer climate, an increased availability of nitrogen, combined with a longer growing season, may increase biomass production substantially, on both low‐ and high‐fertility sites. It is, however, too early to decide whether the observed responses are transitory or long lasting. It is therefore crucial to gain a better understanding of the responses of boreal forest ecosystems to climate change, and to provide data to test and validate models used in predicting the impact of climate change.

Abundance and community structure of ammonia oxidizing bacteria and archaea in a Sweden boreal forest soil under 19-year fertilization and 12-year warming

“…In addition, soil moisture has been reported as a major factor affecting soil N mineralization, which influences the N availability, along a temperature gradient in four European shrubland ecosystems (Beier et al 2008). This mechanism was unlikely to be significant in our study area, where soil moisture was relatively similar among all treatments (Strömgren and Linder 2002). In boreal forest ecosystems, growth of soil microorganisms was found to primarily be controlled by C rather than N availability (Ekblad and Nordgren 2002).…”

“…In late autumn, when soil temperature on the control plots approached 0°C, the soil temperature of warmed plots was reduced by 1°C per week until they were the same as unheated control plots. Detailed descriptions of design and performance of the soilwarming system are found in and Strömgren and Linder (2002).…”

“…The unit of replication for the heating factor was the blocks (n 02) (Strömgren and Linder (2002). Multivariate analyses were performed using canonical correspondence analysis (CCA) with Brodgar version 2.6.6 (Highland Statistics Ltd. UK); P values≤0.05 were considered significant.…”

Plant-soil interactions and acclimation to temperature of microbial-mediated soil respiration may affect predictions of soil CO2 efflux

“…At the ecosystem level, several studies have observed a decrease in soil respiration in association with metabolic down-regulation at warmer temperatures (Luo et al 2001;Stromgren and Linder 2002;Giardina and Ryan 2000;Misson et al 2007). However a number of studies have attributed this apparent acclimation to other factors; as temperature increases the imbalance arises between the supply (photosynthesis) and the utilization (respiration) of the most labile C fraction, product of plant activity (Rustad et al 2001;Kirschbaum 1995Kirschbaum , 2004Gu et al 2004;Eliasson et al 2005;Hartley et al 2007).…”

Soil temperature responses to climate change along a gradient of upland–riparian transect in boreal forest

“…Change in soil freeze-thaw cycles as a result of alterations in energy flow could have large effects on hydrological and biogeochemical processes (Euskirchen et al 2007) and must be accounted for to constrain uncertainty in biogeochemical modeling of future conditions. Warmer soil temperature could have positive impacts on boreal forest productivity (Strömgren and Linder 2002) as well as plant community and soil composition (Charles and Dukes 2009;Pumpanen et al 2012;Thakur et al 2014). However, adverse effects of changes in soil temperature have also been reported on below-ground processes including decreased soil aggregate stability (Oztas and Fayetorbay 2003), increased nutrient leaching ), higher root mortality , greater rates of soil organic matter mineralization (Davidson and Janssens 2006), hydrological flow path alteration, increased soil microbial respiration, and cell wall lysis ) among others.…”