Responses of Sap Flux Densities of Different Plant Functional Types to Environmental Variables Are Similar in Both Dry and Wet Seasons in a Subtropical Mixed Forest

Subtropical mixed forest ecosystems are experiencing dramatic changes in precipitation and different plant functional types growing here are expected to respond differently. This study aims to unravel the water use patterns of different plant functional types and their responses to environmental changes in a typical subtropical mixed forest in southern China. Diurnal and seasonal sap flux densities of evergreen broad-leaved trees (EBL), deciduous broad-leaved trees (DBL), and conifers (CON), as well as environmental variables, were recorded simultaneously from May 2016 to March 2019. The results showed that the sap flux density of EBL was significantly higher than those of CON and DBL in all seasons, irrespective of dry or wet seasons. Path analysis revealed that seasonal differences in sap flux density were mainly due to variations in photosynthetic photon flux density (PPFD). At saturating PPFD, changes in sap flux density during the day were in response to vapor pressure deficit (VPD). Regression analyses showed that sap flux density increased logarithmically with PPFD, irrespective of functional type. The hysteresis loops of sap flux density and VPD were different among different plant functional types in wet and dry seasons. Our results demonstrated converging response patterns to environmental variables among the three plant functional types considered in this study. Our findings contribute to a better understanding of the water use strategies of different plant functional types in subtropical mixed forests.

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Assessing variation in the radial profile of sap flux density in Pinus species and its effect on daily water use

Tree Physiology ◽

10.1093/treephys/24.3.241 ◽

2004 ◽

Vol 24 (3) ◽

pp. 241-249 ◽

Cited By ~ 133

Author(s):

C. R. Ford ◽

M. A. McGuire ◽

R. J. Mitchell ◽

R. O. Teskey

Keyword(s):

Flux Density ◽

Water Use ◽

Radial Profile ◽

Sap Flux ◽

Sap Flux Density ◽

Pinus Species ◽

Daily Water

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Influence of temporospatial variation in sap flux density on estimates of whole-tree water use in Avicennia marina

Trees ◽

10.1007/s00468-014-1105-z ◽

2014 ◽

Vol 29 (1) ◽

pp. 215-222 ◽

Cited By ~ 14

Author(s):

Bart A. E. Van de Wal ◽

Adrien Guyot ◽

Catherine E. Lovelock ◽

David A. Lockington ◽

Kathy Steppe

Keyword(s):

Flux Density ◽

Water Use ◽

Avicennia Marina ◽

Sap Flux ◽

Sap Flux Density ◽

Tree Water Use ◽

Whole Tree

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Water use of interior Douglas-fir

Canadian Journal of Forest Research ◽

10.1139/x99-233 ◽

2000 ◽

Vol 30 (4) ◽

pp. 534-547 ◽

Cited By ~ 4

Author(s):

David G Simpson

Keyword(s):

Flux Density ◽

Water Use ◽

Early Summer ◽

Douglas Fir ◽

Stem Volume ◽

Curvilinear Relationship ◽

Sap Flux ◽

Sap Flux Density ◽

Sapwood Area ◽

Xylem Pressure Potential

Water use of individual Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) trees was measured in two plots at a forest site in southern British Columbia, Canada. Average daily early summer water use by trees with diameters of 7.5-70 cm varied from 1.8 to 166 L. Sap flux density (cm3 water/cm2 sapwood per hour) was linearly related to shoot xylem pressure potential and was found to increase with increasing vapour pressure deficit (VPD) and short-wave irradiance (I), reaching maximum rates with VPD > 0.6 kPa and I > 200 W·m-2. Daily sap flux density varied among trees but was not related to tree diameter, so an average value of 1137.4 L·m-2 sapwood area was used to estimate average early summer stand transpiration for the two plots of 1.08 and 1.5 mm·d-1. A close curvilinear relationship (r2 = 0.85) was found between stem cross-sectional area increment and sapwood area. The relationship was only slightly better (r2 = 0.89) between area increment and early summer individual tree water use. Stand volume growth for 1988-1998 for the two plots was 36-47 m3·ha-1. Stem volume relative growth rate over this 10-year period is estimated at 0.027 and 0.029 m3·m-3·a-1.

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Radial variations in xylem sap flux in a temperate red pine plantation forest

Ecological Processes ◽

10.1186/s13717-021-00295-4 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Alanna V. Bodo ◽

M. Altaf Arain

Keyword(s):

Flux Density ◽

Water Use ◽

Sap Flow ◽

Xylem Sap ◽

Red Pine ◽

Sap Flux ◽

Plantation Forest ◽

Sap Flux Density ◽

Flow Measurements ◽

Sapwood Area

Abstract Background Scaling sap flux measurements to whole-tree water use or stand-level transpiration is often done using measurements conducted at a single point in the sapwood of the tree and has the potential to cause significant errors. Previous studies have shown that much of this uncertainty is related to (i) measurement of sapwood area and (ii) variations in sap flow at different depths within the tree sapwood. Results This study measured sap flux density at three depth intervals in the sapwood of 88-year-old red pine (Pinus resinosa) trees to more accurately estimate water-use at the tree- and stand-level in a plantation forest near Lake Erie in Southern Ontario, Canada. Results showed that most of the water transport (65%) occurred in the outermost sapwood, while only 26% and 9% of water was transported in the middle and innermost depths of sapwood, respectively. Conclusions These results suggest that failing to consider radial variations in sap flux density within trees can lead to an overestimation of transpiration by as much as 81%, which may cause large uncertainties in water budgets at the ecosystem and catchment scale. This study will help to improve our understanding of water use dynamics and reduce uncertainties in sap flow measurements in the temperate pine forest ecosystems in the Great Lakes region and help in protecting these forests in the face of climate change.

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Effects of Wood Hydraulic Properties on Water Use and Productivity of Tropical Rainforest Trees

Frontiers in Forests and Global Change ◽

10.3389/ffgc.2020.598759 ◽

2021 ◽

Vol 3 ◽

Author(s):

Martyna M. Kotowska ◽

Roman M. Link ◽

Alexander Röll ◽

Dietrich Hertel ◽

Dirk Hölscher ◽

...

Keyword(s):

Flux Density ◽

Water Use ◽

Wood Density ◽

Wood Anatomy ◽

Tree Size ◽

Plant Performance ◽

Strong Positive Correlation ◽

Sap Flux ◽

Sap Flux Density ◽

Stem Increment

The efficiency of the water transport system in trees sets physical limits to their productivity and water use. Although the coordination of carbon assimilation and hydraulic functions has long been documented, the mutual inter-relationships between wood anatomy, water use and productivity have not yet been jointly addressed in comprehensive field studies. Based on observational data from 99 Indonesian rainforest tree species from 37 families across 22 plots, we analyzed how wood anatomy and sap flux density relate to tree size and wood density, and tested their combined influence on aboveground biomass increment (ABI) and daily water use (DWU). Results from pairwise correlations were compared to the outcome of a structural equation model (SEM). Across species, we found a strong positive correlation between ABI and DWU. Wood hydraulic anatomy was more closely related to these indicators of plant performance than wood density. According to the SEM, the common effect of average tree size and sap flux density on the average stem increment and water use of a species was sufficient to fully explain the observed correlation between these variables. Notably, after controlling for average size, only a relatively small indirect effect of wood properties on stem increment and water use remained that was mediated by sap flux density, which was significantly higher for species with lighter and hydraulically more efficient wood. We conclude that wood hydraulic traits are mechanistically linked to water use and productivity via their influence on sap flow, but large parts of these commonly observed positive relationships can be attributed to confounding size effects.

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Effect of irrigation on sap flux density variability and water use estimate in cherry (Prunus avium) for timber production: Azimuthal profile, radial profile and sapwood estimation

Agricultural Water Management ◽

10.1016/j.agwat.2015.08.019 ◽

2016 ◽

Vol 164 ◽

pp. 118-126 ◽

Cited By ~ 5

Author(s):

A.J. Molina ◽

X. Aranda ◽

G. Carta ◽

P. Llorens ◽

R. Romero ◽

...

Keyword(s):

Flux Density ◽

Water Use ◽

Prunus Avium ◽

Radial Profile ◽

Timber Production ◽

Sap Flux ◽

Sap Flux Density

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INFLUENCE OF SPATIAL VARIATION IN SAP FLUX DENSITY ON ESTIMATES OF WHOLE-TREE WATER USE IN AVICENNIA MARINA

Acta Horticulturae ◽

10.17660/actahortic.2013.991.12 ◽

2013 ◽

pp. 101-106

Author(s):

B.A.E. Van de Wal ◽

A. Guyot ◽

C.E. Lovelock ◽

D.A. Lockington ◽

K. Steppe

Keyword(s):

Spatial Variation ◽

Flux Density ◽

Water Use ◽

Avicennia Marina ◽

Sap Flux ◽

Sap Flux Density ◽

Tree Water Use ◽

Whole Tree

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Response of photosynthesis of different plant functional types to environmental changes along Northeast China Transect

Trees ◽

10.1007/s004680050211 ◽

1999 ◽

Vol 14 (2) ◽

pp. 72 ◽

Cited By ~ 23

Author(s):

G. Jiang ◽

Haiping Tang ◽

M. Yu ◽

Ming Dong ◽

Xinshi Zhang

Keyword(s):

Northeast China ◽

Environmental Changes ◽

Plant Functional Types ◽

Functional Types

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Responses of plant functional types to environmental gradients in the south-west Ethiopian highlands

Journal of Tropical Ecology ◽

10.1017/s0266467410000799 ◽

2011 ◽

Vol 27 (03) ◽

pp. 289-304 ◽

Cited By ~ 5

Author(s):

Desalegn Wana ◽

Carl Beierkuhnlein

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Relative Abundance ◽

Environmental Variables ◽

Environmental Gradients ◽

Plant Functional Types ◽

The South ◽

Ethiopian Highlands ◽

South West ◽

Functional Types

Abstract:Plant functional types across environmental gradients can be considered as a powerful proxy that reveals vegetation–environment relationships. The objectives of this study were to investigate the response in the relative abundance of plant functional types along altitudinal gradients and to examine the relationship of plant functional types to environmental variables. The study was conducted in the Gughe-Amaro Mountains, in the south-west Ethiopian highlands. We established 74 plots with an area of 400 m2(20 × 20 m) each along altitudinal ranges between 1000 and 3000 m asl. Data on site environmental conditions and on the abundance of plant functional types were analysed using the constrained linear ordination technique (RDA) in order to identify the relationships between plant functional types and environmental variables. Altitude, soil organic carbon, soil sand fraction and surface stone cover were significantly related to the relative abundance of plant functional types across the gradient. Tussocks and thorns/spines were abundant in lower altitudinal ranges in response to herbivory and drought while rhizomes and rosettes were abundant at higher altitudes in response to the cold. Generally our results show that topographic attributes (altitude and slope) as well as soil organic carbon play an important role in differentiating the relative abundance of plant functional types in the investigated gradient. Thus, considering specific plant functional types would provide a better understanding of the ecological patterns of vegetation and their response to environmental gradients in tropical regions of Africa prone to drought.

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