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Scientia Silvae Sinicae ›› 2020, Vol. 56 ›› Issue (1): 1-9.doi: 10.11707/j.1001-7488.20200101

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Growing-Season Transpiration of Typical Forests in Different Succession Stages in Subalpine Region of Western Sichuan, China

Lei Zhang1,Pengsen Sun2,*,Shirong Liu2   

  1. 1. Key Laboratory of Forest Silviculture of the State Forestry and Grassland Administration Research Institute of Forestry, CAF Beijing 100091
    2. Key Laboratory of Forest Ecology and Environment of State Forestry and Grassland Administration Research Institute of Forest Ecology, Environment and Protection, CAF Beijing 100091
  • Received:2018-12-12 Online:2020-01-25 Published:2020-02-24
  • Contact: Pengsen Sun
  • Supported by:
    中国林业科学研究院基本科研业务费专项资金项目(CAFYBB2017MA009);国家重点研发计划项目(2017YFC0505006);国家重点研发计划项目(2017YFC0505501)

Abstract:

Objective: In order to quantitatively reveal the patterns of transpiration and water consumption of different forests in different succession stages,we investigated the water use of representative forest types in subalpine areas of Western Sichuan,China,intending to provide a scientific basis for tree species selection for forest restoration,water holding capacity improvement and poor-efficiency forest revitalization in the subalpine areas of Western Sichuan,China. Method: In the subalpine region of western Sichuan,China,three typical forest types of old primary forest (Abies faxoniana)(PF),secondary forest (Betula albo-sinensis)(SF),and plantation forest (Picea asperata)(PL) in terms of age,forest type and area were selected from forest restoration projects for the study. We used thermal dissipation sap flow sensors to measure stem sap flow of sample trees. With sapwood area as the scaler,water use from individual trees were scaled up to estimate forest canopy transpiration for the three forest types. Next,with the relationship between daily forest transpiration and meteorological factors formulated by the random forest regression algorithm (RF),we interpolated the missing daily canopy transpiration for each forest type. Result: The maximum daily canopy transpiration observed during the growing season (May-Oct.) for PL,SF,and PF were 3.17,2.08,and 1.69 mm·day-1,respectively. RF performed well in predicting daily canopy transpiration for the three forest types. Total accumulated canopy transpiration for each forest type during the growing season was calculated based on the daily water use estimated by the RF regression algorithm. As a result,PL has the maximum canopy transpiration (314.10 mm),followed by SF (199.28 mm),and PF had the lowest canopy transpiration (125.47 mm). In comparison with previous observation of water use for the broad-leaved Quercus aquifolioides dwarf forest in this region,the canopy transpiration of the three forest types is much smaller than that of the Q. aquifolioides forest. The total canopy transpiration estimated for Q. aquifolioides is 88.77 mm in July. Conclusion: Overall,the canopy transpiration of SF in early stage of succession is higher than that of PF in late stage of succession. The canopy transpiration of plantation forest (PL) is much higher than that of natural forests (primary coniferous forest PF and natural secondary forest SF). This implies the vegetation restoration approach via large-scale spruce plantation may impose pressure on the water resources of catchment basins in the short term. The characteristics of forest transpiration and water consumption can be used as the evaluation indicators of forest restoration in this area. Finally,in combination with previous studies on forest evapotranspiration in the study area,we came up with the ecological succession hypothesis of forest water use:with the forward development of forest succession,forest water use will tend to decrease,and the zonal climax community-subalpine dark coniferous forest-has the lowest water consumption. This hypothesis can be used as a reference system for maintaining regional hydrological balance and adjusting vegetation structure in the study area.

Key words: transpiration, sap flow, natural forest, plantation, succession, random forest

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