Litterfall production and fine root dynamics in cool-temperate forests.

Ji Young An,Akira Osawa,Jung Hwa Chun,Luitgard Schwendenmann,Byung Bae Park

doi:10.1371/journal.pone.0180126

Abstract

Current understanding of litterfall and fine root dynamics in temperate forests is limited, even though these are the major contributors to carbon and nutrient cycling in the ecosystems. In this study, we investigated litterfall and fine root biomass and production in five deciduous and four coniferous forests at the Gwangneung Experimental Forest in Korea. We used ingrowth cores to measure fine root production and root turnover rate. The litterfall was separated into leaves, twigs, and others, and then leaves were further separated according to species. Annual litterfall mass was not significantly different between the years, 360 to 651 g m-2 in 2011 and 300 to 656 g m-2 in 2012. Annual fine root (<5 mm) production was significantly higher in 2012 (421 to 1342 g m-2) than in 2011 (99 to 872 g m-2). Annual litterfall mass was significantly different among the stands, while fine root production did not statistically differ among the stands. The average fine root turnover rate, calculated by dividing the annual fine root production by the maximum standing fine root biomass, was 1.65 for deciduous forests and 1.97 for coniferous forests. Fine root production constituted 18–44% of NPP, where NPP was the sum of woody biomass production, litterfall production, and fine root production. Belowground production was a greater fraction of NPP in more productive forests suggesting their greater carbon allocation belowground.

Highlights

Tree roots and aboveground vegetation are huge carbon and nutrient sinks, and they play an important role in the carbon and nutrient cycles of forest ecosystems
The soil bulk density was significantly higher in the B than in the A horizon, while chemical properties such as organic matter (OM), Total nitrogen (TN), AP, and cation exchange capacity (CEC) were higher in the A than in the B horizon (p < 0.05)
Our results showed that fine roots constituted 18–44% of the annual net primary production (NPP) and the fraction was higher in deciduous forests than in coniferous forests, but was not significantly different (p = 0.29)

Summary

Introduction

Tree roots and aboveground vegetation are huge carbon and nutrient sinks, and they play an important role in the carbon and nutrient cycles of forest ecosystems. Our knowledge on the belowground sink strength of forest ecosystems is still limited due to relatively poor knowledge on the process of fine root production [2,3,4]. This may lead to unreliable estimates of carbon budget and uncertainties in forest simulation models [5,6,7]. Aboveground litterfall is a key process regulating the carbon and nutrient cycling in forests, but the quantity of fallen leaves greatly depends on spatiotemporal factors and is determined by climate, topography, species composition, and soil fertility [8,9,10]. Zhang et al [11]

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