Litter Quality and Climate Decouple Nitrogen Mineralization and Productivity in Chilean Temperate Rainforests

Abstract

We measured litter quality, N mineralization, air and soil temperatures, soil moisture, and aboveground net primary production (ANPP) at 18 plots in three forest types typical of full-stature forests found on western slopes of the Cordillera de Piuchué (CP) on Isla de Chiloé in southern Chile. The primary objectives were to examine the range of net N mineralization across forest types that have different vegetation and litter composition, assess probable controls on mineral N production and leaching, and to determine if the relationship between N mineralization and ANPP was similar to that observed in cool temperate northern hemisphere forests. Average annual litter lignin/N ratios were high in the evergreen montane broadleaf forest plots (50:1) and very high in the montane conifer plots (80:1). Net N mineralization during the summer months was correspondingly low (1.2 and 2.2 kg ha À1 , respectively). The high litter lignin content and associated low rate of N mineralization can explain the extremely low concentrations of mineral N in soils and upland streams of this region. In the broadleaf evergreen coastal forest plots, lignin/N ratio was lower (23:1) and N mineralized was considerably greater over the same measurement period than in the montane forest plots (14 kg ha À1). In contrast to findings in many cool temperate northern hemisphere forests, ANNP in the broadleaf forest type was high (average 11.1 Mg ha À1 yr À1) in spite of the low net N mineralization rates, and ANPP and net N mineralized were not correlated. Net N mineralization was best correlated with litter quality, soil temperature, and soil moisture content, and ANPP was best correlated with growing degree days. Site Description Isla de Chiloé is located off the coast of southern Chile. Low mountains of the CP run the length of the island's west

The Potential Impact of Climate Change on Soil Properties and Processes and Corresponding Influence on Food Security

“…However, the stimulated C uptake is not enough to offset the N limitation and the net result is still an increase in atmospheric CO 2 and an overall reduction in soil C levels [70]. Some researchers have reported that increasing temperatures increase N mineralization [71][72][73], which could have a positive effect on plant growth. However, a warming study by An et al [74] showed that N mineralization was stimulated in the first year but depressed afterward.…”

Soil Application of Tannery Land Plaster: Effects on Nitrogen Mineralization and Soil Biochemical Properties

“…Plant availability of organic N in a biosolid mainly depends on soil microbial processes of mineralization and immobilization whose turnover is mainly influenced by its C : N ratio, although the soil N turnover cannot be explained by this parameter alone. Soil chemical-physical characteristics and biosolid properties such as soluble C content, N biochemical quality, and phenolic content could play a crucial role in determining N mineralization [12][13][14][15][16]. Specific studies on the mineralization dynamic of the organic N in biosolids are therefore required in order to evaluate N supply to plants and to avoid leaching of N in the environment.…”

Variability of soil N cycling and N2O emission in a mixed deciduous forest with different abundance of beech

“…Taylor et al 1991;Prescott 2002;Inagaki et al 2004;Miyamoto and Hiura 2008) and soil conditions (Bengtsson et al 2003;Booth et al 2005;Kooijman et al 2008). Distinctive differences were found between conifers and hardwood species with regard to their effects on stocks, distribution and mineralization rates of soil N (Jerabkova et al 2006;Joshi et al 2006;Inagaki et al 2004). In addition, N 2 O emissions were significantly higher in deciduous than in coniferous forests (Ambus et al 2006;Butterbach-Bahl et al 2002).…”