Short Legacy Effects of Growing Season Nitrogen Addition and Reduced Precipitation alter Soil Respiration during Nongrowing Season

Abstract

The short legacy effects of growing season nitrogen (N) addition and reduced precipitation on nongrowing season soil respiration (Rs), autotrophic respiration (Ra), and heterotrophic respiration (Rh) are still unclear. Therefore, a field manipulative experiment to determine the responses of nongrowing season Rs and its components to growing season N addition and reduced precipitation was conducted in a temperate forest. The results show that growing season N addition and reduced precipitation significantly increased nongrowing season Rs by regulating the response of Ra and Rh. The combination of N addition and reduced precipitation also showed a much stronger effect on Rs and its components, but the magnitude and direction largely depended on the snowpack thickness. The effects of growing season N addition and reduced precipitation on nongrowing season Rs and its components were mediated by different sampling periods. N addition significantly decreased Rs by decreasing Rh in early winter and significantly increased Rs by increasing Ra in deep winter and late winter. All treatments decreased temperature sensitivity (Q10) of Rs and Rh. Our findings contribute to a better understanding of how nongrowing season Rs and its components will change under growing season N addition and reduced precipitation and could improve predictions of the future states of the soil C cycle in response to climate change.

Long‐term manipulation of mean climatic conditions alters drought effects on C‐ and N‐cycling in an arable soil

“…The estimation of Q 10 values support this speculation; long‐term reduction of the precipitation amount significantly decreased Q 10 within our soils throughout the drought experiment. This is in line with Yan et al (2020), who also observed lower Q 10 as a response to reduced precipitation in the previous year before sampling. However, more field studies targeting legacy effects on microbial C allocation during drought and after rewetting are needed to improve our mechanistic understanding of historical precipitation regimes’ influence on the effects of soil warming.…”

Increased Litter Greatly Enhancing Soil Respiration in Betula platyphylla Forests of Permafrost Region, Northeast China

“…Q 10 , the temperature sensitivity index for Rs, refers to the ratio between the value of Rs at a given temperature to its value at a temperature 10 • C lower than the given temperature. Q 10 is generally expressed as follows [2,41]:…”

“…where b is the fitted parameter obtained from Equation (2). A one-way ANOVA analysis followed by post hoc LSD tests were performed to determine the differences in the effect size of Rs between groups in each stand age in the whole study period.…”

“…Soil respiration (Rs) is a key process of biochemical activity in soil, during which carbon dioxide is produced as a result of metabolism of free-living soil microorganisms and of roots or root-associated microorganisms [1][2][3]. Total Rs is the sum of all CO 2 effluxes originating from litter, soil organic matter and roots [4,5].…”

“…Three stand age classes, namely, 25-, 40-, and 61-year-old Betula platyphylla, stands (hereafter called 25 a, 40 a and 61 a, respectively) were selected, and the Rs under litter exclusion (no-litter, NL), litter addition (litter doubling, DL) and control litter (CK) were measured at monthly intervals from May to October in 2018. The objective of this study was (1) to determine the seasonal dynamics of Rs under litter manipulation and its correlated factors in different-aged stands; (2) to investigate the contribution of litter to Rs under different-aged stands; and (3) to assess the main driving factors affecting Rs under litter manipulation in different-aged Betula platyphylla forests of the permafrost region, Northeast China.…”