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林业科学 ›› 2020, Vol. 56 ›› Issue (1): 1-9.doi: 10.11707/j.1001-7488.20200101

• 论文与研究报告 • 上一篇    下一篇

川西亚高山森林不同恢复阶段生长季蒸腾特征

张雷1,孙鹏森2,*,刘世荣2   

  1. 1. 中国林业科学研究院林业研究所 国家林业和草原局森林培育重点实验室 北京 100091
    2. 中国林业科学研究院森林生态环境与保护研究所 国家林业和草原局森林生态环境重点实验室 北京 100091
  • 收稿日期:2018-12-12 出版日期:2020-01-25 发布日期:2020-02-24
  • 通讯作者: 孙鹏森
  • 基金资助:
    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)

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)

摘要:

目的: 定量揭示我国川西亚高山地区不同恢复阶段森林的蒸腾耗水特征,为当地森林恢复树种选择、水源涵养功能提升与低效林改造等提供科学参考。方法: 选择川西亚高山地区植被恢复系列中无论是林龄、类型还是面积都具有典型代表性的岷江冷杉老龄原始林、红桦次生林和粗枝云杉人工林作为研究对象,利用热扩散技术监测生长季树木蒸腾量;利用林分边材面积进行尺度上推,估算林分冠层蒸腾耗水量。基于机器学习技术(随机森林回归算法)估算整个生长季(5-10月)的林分冠层蒸腾耗水量。结果: 各森林类型平均日冠层蒸腾量表现为粗枝云杉林>红桦林>岷江冷杉林;在整个生长季观测到的粗枝云杉林、红桦林和岷江冷杉林日最大冠层蒸腾量分别为3.17、2.08和1.69 mm;基于多气象因素,随机森林回归算法可有效估算森林蒸腾耗水量;整个生长季的林分冠层蒸腾总量估算结果表现为粗枝云杉林(314.1 mm)>红桦林(199.3 mm)>岷江冷杉林(125.5 mm)。结论: 处在演替早期的红桦次生林冠层蒸腾耗水量明显高于处于演替晚期的岷江冷杉原始林;人工林蒸腾耗水量明显高于天然林(岷江冷杉原始林和红桦次生林),因此可将森林蒸腾耗水特征作为研究区森林恢复度的评价指标。该区大量营造的粗枝云杉人工林已步入中龄林阶段,高蒸腾特征可能会对流域产水量构成压力,建议进行抚育性结构调整。通过综合分析多项研究结果,本文提出一个"森林水分利用生态演替"假说:伴随着亚高山森林植被自然恢复进程(正向演替),林地蒸腾耗水量趋于减少,地带性演替顶级群落亚高山暗针叶林具有最低蒸腾耗水特征。这个假说可作为川西亚高山区区域水文平衡维持和植被结构调整的参照体系。

关键词: 蒸腾液流, 天然林, 人工林, 演替, 随机森林

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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