Title: Upscaling transpiration in diverse forests: Insights from a tropical premontane site

Abstract

Upscaling water use of individual trees to stands using sap flux techniques is a common method for partitioning site water balance, but few such studies have occurred in the tropics. Increasing interests in the role of tropical forests in global cycles have spurred upscaling studies in natural tropical forests, which present challenges from greater tree species and functional diversity, and potential factors that would reduce transpiration, such as frequent cloud cover and wet canopy conditions. In a premontane wet tropical forest in central Costa Rica, sap flow was measured in 15 trees stratified into 5 size classes based on tree diameters. None of the trees belonged to the same species, genus, or even family. Here, we also accounted for potential radial variation in sap flux density. Data were scaled to estimate transpiration within a small 2.2-ha watershed using stand surveys of sapwood area. Stand transpiration averaged only 1.4 ± 0.7 mm day ^-1 within this forested watershed due to persistent low radiation, evaporative demand, and frequent wet canopy conditions. Our systematic approach used tree size attributes to scale water use to the stand, given difficulties to quantify species differences in such a diverse ecosystem. Contrary to previous evidence on temperatemore » trees, the large trees sampled did not exhibit flow reductions in deeper sapwood, which warrants further study. Finally, these results highlight some unique aspects of measuring transpiration in wet tropical forests that are important to consider for future studies in diverse stands.« less

Authors:

Moore, Georgianne W.  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-5190-5983"
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Orozco, Graciela ^[2]; Aparecido, Luiza M. T.  ^[1];

• Search DOE PAGES for author "Aparecido, Luiza M. T."
• Search DOE PAGES for ORCID "0000-0001-8642-6632"
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Miller, Gretchen R.  ^[3]

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• Search DOE PAGES for ORCID "0000-0002-1108-0654"
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+ Show Author Affiliations

1. Texas A & M Univ., College Station, TX (United States). Dept. of Ecosystem Science and Management
2. Texas A & M Univ., College Station, TX (United States). Dept. of Ecosystem Science and Management; INVISTA S.à r.l., Orange, TX (United States)
3. Texas A & M Univ., College Station, TX (United States). Dept. of Civil Engineering

Publication Date:

2017-10-24

Research Org.:

Texas A&M Univ., College Station, TX (United States). Engineering Experiment Station

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23). Climate and Environmental Sciences Division; National Science Foundation (NSF)

OSTI Identifier:

1467894

Grant/Contract Number:  

SC0010654; EAR‐1004874

Resource Type:

Accepted Manuscript

Journal Name:

Ecohydrology

Additional Journal Information:

Journal Volume: 11; Journal Issue: 3; Journal ID: ISSN 1936-0584

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; 60 APPLIED LIFE SCIENCES; Costa Rica; radial profile; sap flow; sap flux; transitional rainforest