Experimental warming studies on tree species and forest ecosystems: a literature review

Abstract

Temperature affects a cascade of ecological processes and functions of forests. With future higher global temperatures being inevitable it is critical to understand and predict how forest ecosystems and tree species will respond. This paper reviews experimental warming studies in boreal and temperate forests or tree species beyond the direct effects of higher temperature on plant ecophysiology by scaling up to forest level responses and considering the indirect effects of higher temperature. In direct response to higher temperature (1) leaves emerged earlier and senesced later, resulting in a longer growing season (2) the abundance of herbivorous insects increased and their performance was enhanced and (3) soil nitrogen mineralization and leaf litter decomposition were accelerated. Besides these generalizations across species, plant ecophysiological traits were highly species-specific. Moreover, we showed that the effect of temperature on photosynthesis is strongly dependent on the position of the leaf or plant within the forest (canopy or understory) and the time of the year. Indirect effects of higher temperature included among others higher carbon storage in trees due to increased soil nitrogen availability and changes in insect performance due to alterations in plant ecophysiological traits. Unfortunately only a few studies extrapolated results to forest ecosystem level and considered the indirect effects of higher temperature. Thus more intensive, long-term studies are needed to further confirm the emerging trends shown in this review. Experimental warming studies provide us with a useful tool to examine the cascade of ecological processes in forest ecosystems that will change with future higher temperature.

Forest Insects and Climate Change

“…Physiological changes in insects in response to temperature can facilitate changes in their distribution patterns [21]. Field-based experimental manipulations of host plants [36] and insects to determine their relative responses to changes in temperature [37][38][39] can help predict the nature and extent of range shifts and to better understand how forest ecosystems will respond to climate change [40].…”

Positive effects of night warming on physiology of coniferous trees in late growing season: Leaf and root

“…Alteration in plant phenology is one of the most sensitive and observable Abbreviations: AQE, apparent quantum efficiency; Fv/Fm, maximum quantum efficiency of PS II; NR, nitrate reductase; NSC, non-structural carbohydrate; PAR, photosynthetically active radiation; P max , light-saturated rate of photosynthesis; P n , net photosynthesis rate; R d , dark respiration rate; SLA, specific leaf area; SRA, root specific surface area; SRL, specific root length; TF, triphenylformazan; TTC, triphenyltetrazolium chloride.biological response to global warming (Bronson et al, 2009;Morin et al, 2010;Polgar and Primack, 2011). Some field (Rollinson and Kaye, 2012) and modeling studies (Lebourgeois et al, 2010) have illuminated that warm temperature would expand plant growing season due to early onset and later end (Parmentier et al, 2011;Chung et al, 2013). Previous studies about the effect of experimental warming on tree species have focused primarily on net mineralization, net nitrification and denitrification rates, ectomycorrhizal colonization and root exudation in early growing season, peak of growing season and non-growing season (Zhao and Liu, 2009;Yin et al, 2012Yin et al, , 2013Yin et al, , 2014.…”

Species-specific growth and photosynthetic responses of first-year seedlingsof four coniferous species to open-field experimental warming

“…Open-field experimental warming is an effective method to examine the ecosystem responses to temperature rise with minimal confounding effects (Chung et al, 2013) and to temperature ranges higher than those of past observations (Saxe et al, 2001). However, relatively few studies have been conducted in forest ecosystems (Wu et al, 2011).…”