Chin J Plant Ecol ›› 2011, Vol. 35 ›› Issue (12): 1310-1317.DOI: 10.3724/SP.J.1258.2011.01310

• Research Articles • Previous Articles    

Contribution of stem water storage to daily transpiration of three temperate trees in northeastern China

JIN Ying, WANG Chuan-Kuan*(), SANG Ying   

  1. Center for Ecological Research, Northeast Forestry University, Harbin 150040, China
  • Received:2011-07-14 Accepted:2011-09-27 Online:2011-07-14 Published:2011-12-15
  • Contact: WANG Chuan-Kuan

Abstract:

Aims Stem water storage plays a significant role in maintaining a favorable leaf water and carbon balance and minimizing temporal imbalances between water supply and demand. Few measurements, however, have been made on the daily dynamics of discharge and recharge of stem water storage, especially for Chinese temperate trees. Our objectives were to (1) examine diurnal courses of stem water storage of three temperate trees with different characteristics in Northeast China, i.e., coniferous needle-leaved Korean pine (Pinus koraiensis), broadleaved diffuse-porous aspen (Populus davidiana) and ring-porous Mongolian oak (Quercus mongolica), (2) quantify the contribution of stem water storage to the daily transpiration loss for these trees and (3) explore biotic factors influencing stem water storage.
Methods Sapflow was measured simultaneously at the crown base and trunk base with calibrated thermal dissipation probes from mid-August to late-September 2010. The daily stem water storage was calculated by comparing the diurnal patterns of trunk basal and crown basal sapflow for each of three replicated trees per species.
Important findings Crown basal sapflow started earlier than trunk basal sapflow in the morning for all trees, and a distinct time lag existed during the daytime. This suggested stem water storage was significant in regulating tree transpiration losses. The diurnal course of stem water storage was divided into four stages, i.e., full discharge, mainly discharge supplemented with recharge, mainly recharge supplemented with discharge, and saturated steady stages. However, the duration and pattern of each stage varied with species. The pine experienced two periods of discharge and recharge of stem water storage, while the two broad-leaved species experienced only one. The daily amount of water withdrawn from storage and subsequently replaced that was normalized to the mean sapwood volume (0.29 m3) was (3.4 ± 1.5), (2.4 ± 0.6) and (1.5 ± 0.4) kg·d -1 (mean ± SD) for the pine, aspen, and oak, respectively, accounting for 18.9%, 17.1% and 8.8% of the total daily water loss, respectively. Use of stem-stored water exponentially increased with daily water loss, and was positively correlated with the basal sapwood area and tree height. These results emphasize the effects of tree size (i.e., tree height and sapwood area) and timber properties on stem water storage and its contribution to daily water losses.

Key words: diurnal course, sapflow, transpiration, water storage, water use