scholarly journals Airborne Tree Crown Detection for Predicting Spatial Heterogeneity of Canopy Transpiration in a Tropical Rainforest

2020 ◽  
Vol 12 (4) ◽  
pp. 651
Author(s):  
Joyson Ahongshangbam ◽  
Alexander Röll ◽  
Florian Ellsäßer ◽  
Hendrayanto ◽  
Dirk Hölscher
Keyword(s):  
Spatial Heterogeneity ◽  
Water Use ◽  
Tropical Rainforests ◽  
Sap Flux ◽  
Tree Crown ◽  
Individual Tree ◽  
Canopy Transpiration ◽  
Tree Water Use ◽  
Climate Regulation ◽  
The Relationship

Tropical rainforests comprise complex 3D structures and encompass heterogeneous site conditions; their transpiration contributes to climate regulation. The objectives of our study were to test the relationship between tree water use and crown metrics and to predict spatial variability of canopy transpiration across sites. In a lowland rainforest of Sumatra, we measured tree water use with sap flux techniques and simultaneously assessed crown metrics with drone-based photogrammetry. We observed a close linear relationship between individual tree water use and crown surface area (R2 = 0.76, n = 42 trees). Uncertainties in predicting stand-level canopy transpiration were much lower using tree crown metrics than the more conventionally used stem diameter. 3D canopy segmentation analyses in combination with the tree crown–water use relationship predict substantial spatial heterogeneity in canopy transpiration. Among our eight study plots, there was a more than two-fold difference, with lower transpiration at riparian than at upland sites. In conclusion, we regard drone-based canopy segmentation and crown metrics to be very useful tools for the scaling of transpiration from tree- to stand-level. Our results indicate substantial spatial variation in crown packing and thus canopy transpiration of tropical rainforests.

scholarly journals Coordination of leaf area, sapwood area and canopy conductance leads to species convergence of tree water use in a remnant evergreen woodland

2008 ◽  
Vol 56 (2) ◽  
pp. 97 ◽  
Author(s):  
Melanie Zeppel ◽  
Derek Eamus
Keyword(s):  
Leaf Area ◽  
Water Use ◽  
Canopy Conductance ◽  
Evaporative Demand ◽  
Sapwood Area ◽  
Huber Value ◽  
Tree Water Use ◽  
Decoupling Coefficient ◽  
The Relationship ◽  
Daily Total

This paper compares rates of tree water use, Huber value, canopy conductance and canopy decoupling of two disparate, co-occurring tree species, in a stand of remnant native vegetation in temperate Australia in order to compare their relative behaviour seasonally and during and after a drought. The study site was an open woodland dominated by Eucalyptus crebra F.Muell. (a broad-leaved species) and Callitris glaucophylla J.Thompson & L.A.S. Johnson (a needle-leaved tree species). Tree water use was measured with sapflow sensors and leaf area and sapwood area were measured destructively on felled trees. The Huber value was calculated as the ratio of sapwood area to leaf area. Diameter at breast height (DBH) of the stem was used as a measure of tree size. Canopy conductance was calculated with an inversion of the Penman–Monteith equation, whereas canopy decoupling) was calculated as described by Lu et al. (2003). The relationship between DBH and daily total water use varied during the four measurement periods, with largest rates of water use observed in summer 2003–2004, following a large rainfall event and the smallest maximum water use observed in winter 2003 when monthly rainfall was much less than the long-term mean for those months. Despite differences in the relationship between sapwood area and DBH for the two species, the relationship between daily total water use and DBH did not differ between species at any time. The same rates of water use for the two species across sampling periods arose through different mechanisms; the eucalypt underwent significant changes in leaf area whereas the Callitris displayed large changes in canopy conductance, such that tree water use remained the same for both species during the 2-year period. Canopy conductance and the decoupling coefficient were both significantly larger in winter than summer in both years. The generally low decoupling coefficient (0.05–0.34) reflects the low leaf area index of the site. When evaporative demand was small (winter), the degree of stomatal control was small and the decoupling coefficient was large. There was no relationship between tree size and either canopy conductance or the decoupling coefficient. Transpiration rates generally showed little variation between seasons and between species because of the balance between changes in leaf area, canopy conductance and evaporative demand. The occurrence of a significant drought did not appear to prevent these coordinated changes from occurring, with the result that convergence in water use was observed for these two disparate species.

Scaling theory to extrapolate individual tree water use to stand water use

1995 ◽  
Vol 9 (5-6) ◽  
pp. 527-540 ◽  
Author(s):  
Thomas J. Hatton ◽  
Hsin-I Wu
Keyword(s):  
Water Use ◽  
Scaling Theory ◽  
Individual Tree ◽  
Tree Water Use

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

Trees ◽  
2014 ◽  
Vol 29 (1) ◽  
pp. 215-222 ◽  
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

scholarly journals Rainfall pattern greatly affects water use by Mongolian Scots pine on a sandy soil, in a semi-arid climate

2017 ◽  
Author(s):  
Hongzhong Dang ◽  
Lizhen Zhang ◽  
Wenbin Yang ◽  
Jinchao Feng ◽  
Hui Han ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Sandy Soil ◽  
Heavy Rainfall ◽  
Rainfall Pattern ◽  
Severe Drought ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Tree Water Use ◽  
Moderate Drought

Abstract. We report new information on tree water use by Mongolian Scots pine (Pinus sylvestris var. mongolica) growing on a sandy soil, in a region characterised by an erratic rainfall pattern. Measurements were made over three successive years of contrasting annual rainfall – a wet year (2013), a dry year (2014), and a second dry year (2015). The result was the development of worsening levels of drought year by year. Over the three years, sap flux density (Js) was measured at individual tree level in up to 25 trees. The sap flux density values were up-scaled to estimate tree water use at plot level (Ts). Our measurements follow forest plot response to increasing levels of drought which developed over a three-year period as soil moisture conditions gradually worsened from wet, to moderate-drought, to severe-drought, to extreme-drought, in response to the dynamics of a variable rainfall pattern. Values of Ts did not exceed 3.03 mm day−1 (2013), 1.75 mm day−1 (2014) and 1.59 mm day−1 (2015) during the three growing seasons. Total annual stand transpiration over the same three years declined progressively from 290 mm (2013), to 182 mm (2014) and to 175 mm (2015). Satisfactory power-function relationships (R2 = 0.64) between daily Ts and the product of ET0 and the relative extractable soil water (REW) were found. This study helps elucidate the interplay between the effects of the atmosphere and soil moisture on tree water use. Tree water use responded to drought, with daily Ts values decreasing by 5–46 % in response to moderate drought, by 48–62 % in response to severe drought and by 65 % in response to extreme drought. Upon release of moderate drought by heavy rainfall in 2013, daily Ts recovered completely. However, under the severe and extreme droughts in the subsequent dry years, recovery of Ts following heavy rainfall was incomplete (57–58 %). Our results highlight the negative effects of water stress on the growth of mature forest trees, in a sandy soil, in a climate characterised by large intra- and inter-annual variances in rainfall. When the erratic rainfall and sandy soil were also coupled with a declining groundwater table, the result was tree water use fluctuated widely over quite short time scales (months or weeks). Overall, our findings account for the observed premature degradation of these MP plantations in terms of an eco-hydrological perspective.

scholarly journals Linking leaf and tree water use with an individual-tree model

2007 ◽  
Vol 27 (12) ◽  
pp. 1687-1699 ◽  
Author(s):  
B. E. Medlyn ◽  
D. A. Pepper ◽  
A. P. O'Grady ◽  
H. Keith
Keyword(s):  
Water Use ◽  
Tree Model ◽  
Individual Tree ◽  
Tree Water Use ◽  
Individual Tree Model

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

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

scholarly journals Optimizing Grain Yield and Water Use Efficiency Based on the Relationship between Leaf Area Index and Evapotranspiration

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 313
Author(s):  
Guoqiang Zhang ◽  
Bo Ming ◽  
Dongping Shen ◽  
Ruizhi Xie ◽  
Peng Hou ◽  
...  
Keyword(s):  
Grain Yield ◽  
Water Use Efficiency ◽  
Leaf Area Index ◽  
Water Use ◽  
Plant Density ◽  
Maize Yield ◽  
Area Index ◽  
Irrigation Level ◽  
Use Efficiency ◽  
The Relationship

Achieving optimal balance between maize yield and water use efficiency is an important challenge for irrigation maize production in arid areas. In this study, we conducted an experiment in Xinjiang China in 2016 and 2017 to quantify the response of maize yield and water use to plant density and irrigation schedules. The treatments included four irrigation levels: 360 (W1), 480 (W2), 600 (W3), and 720 mm (W4), and five plant densities: 7.5 (D1), 9.0 (D2), 10.5 (D3), 12.0 (D4), and 13.5 plants m−2 (D5). The results showed that increasing the plant density and the irrigation level could both significantly increase the leaf area index (LAI). However, LAI expansion significantly increased evapotranspiration (ETa) under irrigation. The combination of irrigation level 600 mm (W3) and plant density 12.0 plants m−2 (D4) produced the highest maize yield (21.0–21.2 t ha−1), ETa (784.1–797.8 mm), and water use efficiency (WUE) (2.64–2.70 kg m−3), with an LAI of 8.5–8.7 at the silking stage. The relationship between LAI and grain yield and evapotranspiration were quantified, and, based on this, the relationship between water use and maize productivity was analyzed. Moreover, the optimal LAI was established to determine the reasonable irrigation level and coordinate the relationship between the increase in grain yield and the decrease in water use efficiency.

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