Soil warming alters nitrogen cycling in a New England forest: implications for ecosystem function and structure

Abstract

Global climate change is expected to affect terrestrial ecosystems in a variety of ways. Some of the more well-studied effects include the biogeochemical feedbacks to the climate system that can either increase or decrease the atmospheric load of greenhouse gases such as carbon dioxide and nitrous oxide. Less well-studied are the effects of climate change on the linkages between soil and plant processes. Here, we report the effects of soil warming on these linkages observed in a large field manipulation of a deciduous forest in southern New England, USA, where soil was continuously warmed 5°C above ambient for 7 years. Over this period, we have observed significant changes to the nitrogen cycle that have the potential to affect tree species composition in the long term. Since the start of the experiment, we have documented a 45% average annual increase in net nitrogen mineralization and a three-fold increase in nitrification such that in years 5 through 7, 25% of the nitrogen mineralized is then nitrified. The warming-induced increase of available nitrogen resulted in increases in the foliar nitrogen content and the relative growth rate of trees in the warmed area. Acer rubrum (red maple) trees have responded the most after 7 years of warming, with the greatest increases in both foliar nitrogen content and relative growth rates. Our study suggests that considering species-specific responses to increases in nitrogen availability and changes in nitrogen form is important in predicting future forest composition and feedbacks to the climate system.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-011-2133-7) contains supplementary material, which is available to authorized users.

Combined effect of atmospheric nitrogen deposition and climate change on temperate forest soil biogeochemistry: A modeling approach

“…Indeed, soil biogeochemistry is directly and strongly affected by climate since climate influences soil temperature and moisture conditions, which themselves are a major driver of the decomposition of soil organic matter and consequently of soil nitrogen availability (Rustad et al, 2001;Ge et al, 2010;Butler et al, 2012;Guntinas et al, 2012). Therefore the expected temperature increase due to future climate change could also affect soil nitrogen processes.…”

Historic nitrogen deposition determines future climate change effects on nitrogen retention in temperate forests

“…N deposition between 1990 and 2010 explained 41% of this variation showing that future warming induced tree growth might be higher in sites with high N deposition in the past. Though this relationship was only marginally significant (p = 0.088) and strongly controlled by only one site (ZB00) tree fertilization due to enhanced N mineralization rates under warming has been shown experimentally (Butler et al 2012), and it is likely that the stimulation of tree growth is higher in sites with low N limitation as a result of higher N loads in the past. N deposition during the period 1990-2010 also controlled future N retention in humus.…”

“…Soil organic matter (SOM) decomposition is temperature sensitive (Davidson and Janssens 2006) and soil warming leads to enhanced N mineralization and nitrification (Butler et al 2012), though the latter strongly depends also upon the availability of NH 4 + (Butterbach-Bahl and Gundersen 2011). Furthermore, soil water content affects the temperature sensitivity of SOM decomposition (Davidson and Janssens 2006) and controls gaseous N efflux (Butterbach-Bahl et al 2013).…”

“…Enhanced tree growth has been observed during the last decades (Fang et al 2014;McMahon et al 2010;Pretzsch et al 2014a;Pretzsch et al 2014b). Warming can increase tree growth directly or via the enhancement of N availability by increasing rates of N mineralization and nitrification (Butler et al 2012). Enhanced tree growth can cause soil nutrient depletion (N, phosphor and base cations) rendering limitations in tree growth (Jonard et al 2015;Templer 2013).…”

Effects of soil warming and nitrogen foliar applications on bud burst of black spruce

“…Previous soil warming experiments revealed an increase in the rate of nitrogen mineralization (Butler et al, 2012;Campbell et al, 2009;Melillo et al, 2011) and, especially with the current climate change, an increase of this nutrient may affect tree growth. In addition, to overcome the limited availability of nitrogen in the soil, trees have recourse to the absorption of this element directly at the canopy level.…”