J Plant Ecol ›› 2020, Vol. 13 ›› Issue (3): 266-272.DOI: 10.1093/jpe/rtaa010

• Research Articles • Previous Articles     Next Articles

Quantifying the interannual litterfall variations in China’s forest ecosystems

Bingrui Jia1, *, Hongru Sun1,2, Wenying Yu3 and Guangsheng Zhou1,4, *   

  1. 1 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, 2 University of Chinese Academy of Sciences, Beijing 100049, China, 3 Institute of Atmospheric Environment, China Meteorological Administration, Shenyang 110166, China, 4 Chinese Academy of Meteorological Sciences, Beijing 100081, China

    *Corresponding author. E-mail: jiabingrui@ibcas.ac.cn (B.J.); gszhou@ibcas.ac.cn (G.Z.)
  • Received:2019-08-21 Revised:2020-02-17 Accepted:2020-03-11 Online:2020-03-14 Published:2020-06-01

Abstract:

Aims

Litterfall is a key parameter in forest biogeochemical cycle and fire risk prediction. However, considerable uncertainty remains regarding the litterfall variations with forest ages. Quantifying the interannual variation of forest litterfall is crucial for reducing uncertainties in large-scale litterfall prediction.

Methods

Based on the available dataset (N = 318) with continuous multi-year (≥2 years) measurements of litterfall in Chinese planted and secondary forests, coefficient of variation (CV), variation percent (VP), and the ratio of next-year litterfall to current-year litterfall were used as the indexes to quantify the interannual variability in litterfall.

Important Findings

The interannual variations of litterfall showed a declining trend with increasing age from 1 to 90 years. The litterfall variations were the largest in 1–10 years (mean CV = 23.51% and mean VP = −28.59% to 20.89%), which were mainly from tree growth (mean ratio of next-year to current-year = 1.20). In 11–40 years, the interannual variations of litterfall gradually decreased but still varied widely, mean CV was ~18% and mean VP ranged from −17.69% to 21.19%. In 41–90 years, the interannual variations minimized to 8.98% in mean CV and ~8% in mean VP. As a result, forest litterfall remained relatively low and constant when stand age was larger than 40 years. This result was different from the previous assumptions that forest litterfall reached relatively stable when stand age was larger than 30, 20 or even 15 years. Our findings can improve the knowledge about forest litter ecology and provide the groundwork for carbon budget and biogeochemical cycle models at a large scale.

Key words: annual litterfall production, China, forest, interannual variation, coefficient of variation, stand age

摘要:

凋落物是森林生物地化学循环和火险预测的关键参数。然而,森林凋落物如何随林龄变化仍不清楚。因此,量化森林生态系统凋落物年际变化对减少大尺度凋落物预测的不确定性至关重要。本论文基于中国人工林和次生林凋落物连续多年(≥2年)测定的数据集(N = 318),采用变异系数(CV)、变化百分比(VP)和年际间比率量化凋落物的年际变化。研究结果表明,凋落物的年际变化随林龄增加(1–90年生)而呈下降趋势。其中,1–10年林龄的凋落物年际变化最大(平均CV = 23.51%,平均VP= -28.59%~20.89%),其主要原因在于树木早期快速生长,即下一年与当年凋落物比率平均为1.20。11–40年林龄的凋落物年际变化逐渐减小,但CV平均值仍在18%左右,VP平均值在-17.69%~21.19%之间。41–90年林龄的凋落物年际变化最小,CV平均值仅为8.98%,VP平均值维持在8%左右。因此,大于40年林龄的凋落物量较低且稳定。这一结果与已有研究的认知不同:即当林龄大于30年、20年甚至15年时,森林凋落物量达到相对稳定。本研究结果将有助于我们深入理解森林凋落物生态学,并为大尺度碳收支和生物地化学循环模型提供基础。

关键词: 年凋落物产量, 中国, 森林, 年际变化, 变异系数, 林龄