The relationship between sap flow density and environmental factors in the Yangtze River Delta region
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Abstract
Transpiration is an important component of the water balance in forest ecosystems. Quercus acutissima and Cunninghamia lanceolata are two important, fast-growing and commercial tree species that have been extensively used for vegetation restoration, water conservation and building artificial forests in the Yangtze River Delta Region of China. The primary objective of this study was to characterize sap flow densities of the two species by comparing diurnal, nocturnal and seasonal sap flow patterns and their relationships with environmental factors. Sap flow densities (Sd) were measured between September 2012 and August 2013 using the commercially-available thermal dissipation probes. Hourly meteorological data were measured in an open field, located 200 m away from the study site. Standard meteorological data were logged hourly at this site, including photosynthetically active radiation (Par), air temperature (Ta), relative air humidity (Rh), vapor pressure deficit (Vpd) and precipitation (P). Soil water content (Swc) data were logged hourly in different layers at Q.acutissima and C.lanceolata forests. Results indicated that the mean Sd in summer was higher than that in spring and autumn, and was lowest in winter. The Sd of Q. acutissima showed distinct diurnal patterns during the growth period (between May and October), and C. lanceolata followed similar sap flow patterns in all months except February. Nocturnal sap flow densities (Sdn) were noticeable and both species followed similar patterns during the growth period, in which Q. acutissima followed a power function from April to November and C. lanceolata followed similar patterns in all months except February. Pearson correlation analysis suggested that the sap flow density responded to environmental factors differently among each of the growing stages. The diurnal sap flow density (Sdd) was more sensitive to environmental factors than Sdn. The Sd during the growth period was more sensitive to environmental factors than in the dormant period. Par, Vpd and Ta were significantly correlated with Sdd in the whole year. In the nighttime, the sap flow density was also effected by the Vpd, Ta and Rh. The results of this study can be used to estimate the transpiration of Q. acutissima and C. lanceolata.
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2016. The relationship between sap flow density and environmental factors in the Yangtze River Delta region. PeerJ Preprints 4:e2516v1 https://doi.org/10.7287/peerj.preprints.2516v1Author comment
This is a submission to PeerJ for review.
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Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Xin Liu conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables.
Bo Zhang conceived and designed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, reviewed drafts of the paper.
Donald L DeAngelis analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, reviewed drafts of the paper.
Jinchi Zhang conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, reviewed drafts of the paper.
Jiayao Zhuang conceived and designed the experiments, performed the experiments, reviewed drafts of the paper.
Cheng Han conceived and designed the experiments, performed the experiments.
Lu Zhai contributed reagents/materials/analysis tools, reviewed drafts of the paper.
Wenrui Zhao conceived and designed the experiments, performed the experiments.
Ling Wang conceived and designed the experiments, performed the experiments.
Data Deposition
The following information was supplied regarding data availability:
The raw data has been supplied as a supplementary file.
Funding
This study was financially supported by the National Natural Science Foundation of China (Grant No. 31470709), the National Special Fund for Forestry Scientific Research in the Public Interest (Grant No. 201504406), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and the Doctorate Fellowship Foundation of Nanjing Forestry University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
