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In a climate change scenario, Mediterranean forest species such as pines may be endangered by rising temperatures and reduced precipitation, thus calling for studies on the transpiration and water balance in pines. In this paper, the response of young plants of Pinus sylvestris L., Pinus pinea L. and Pinus halepensis Mill. to different irrigation treatments has been studied. Significant differences were found in water potential, sap flow, leaf-level gas exchange and spectral variables. P. sylvestris had higher pre-dawn and midday water potentials, sap flow rates and leaf-level gas exchange rates compared to the other two species in well-watered conditions. Vapor pressure gradient correlated with stomatal conductance, net assimilation and transpiration, but the association between stomatal conductance and sap flow was weak. The environmental variables more strongly associated with sap flow were solar radiation and reference evapo-transpiration, especially in the well-watered plants, but those associations were weaker in the stressed plants. All three pine species showed the isohydric, drought-avoiding strategy common in the genus Pinus, maintaining relatively high water potentials in dry conditions. Nevertheless, P. halepensis showed a water-saving strategy, with a stomatal closure behavior under drought. Stomatal regulation was less strict in P. sylvestris, closer to a water-spending pattern, while P. pinea showed an intermediate behavior. Significant differences were recorded among species in spectral reflectance in the visible and infra-red regions. Photochemical Reflectance Index, Normalized Difference Vegetation Index and combinations of other ratios permitted the discrimination among the three pine species. These spectral variables showed association with sap flow rate, water potential and leaflevel gas exchange variables. Both cluster analysis and k-means classification discriminated Scots pine and Aleppo pine in two different groups. On the other hand, Stone pine showed differences in spectral behavior depending on the hydric status of the plants. Well-watered Stone pine plants had the same spectral behavior as Scots pine, while the plants subjected to drought stress were closer to Aleppo pine plants in spectral response. These findings may help to quantify the impacts of early and mid-summer water deficit on Mediterranean pines in future climate regimes.

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“…1). The model response of gs to VPG described by Eamus & Shanahan (2002) resembles our model in eqn. 5.…”

Section: Discussionmentioning

confidence: 99%

Sap flow, leaf-level gas exchange and spectral responses to drought in Pinus sylvestris, Pinus pinea and Pinus halepensis

Manzanera¹,

Gómez-Garay²,

Pintos³

et al. 2017

iForest

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“…This implies that tropical trees had a conservative water use strategy when exposed to short-term drought [36,37]. High sensitivity of canopy stomatal control to VPD has been linked to conditions of water stress [38,39]. This result could be explained by consequent drought stress in S. wallichii and C. lanceolata during the dry season.…”

Section: Discussionmentioning

confidence: 99%

Assessing Environmental Control of Sap Flux of Three Tree Species Plantations in Degraded Hilly Lands in South China

Wang

Lintunen

Zhao

et al. 2020

Forests

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Prerequisite for selection of appropriate tree species in afforestation programs is to understand their water use strategy. Acacia mangium Willd., Schima wallichii Choisy, and Cunninghamia lanceolata (Lamb.) Hook are the three main vegetation restoration pioneer species in southern China, but no comparative research on the water use strategy of these three tree species have been reported. Our objective was to gain a detailed understanding of how photosynthetically active radiation (PAR), vapor pressure deficit (VPD), and soil water content (SWC) at different soil depths control the sap flux density (Js) in the dry and wet seasons. We measured the Js of these three tree species by using the thermal dissipation method in low subtropical China. We found that both S. wallichii and C. lanceolata differed clearly in their stomatal behavior from one season to another, while A. mangium did not. The canopy conductance per sapwood area of S. wallichii and C. lanceolata was very sensitive to VPD in the dry season, but not in the wet season. The Js of A. mangium was negatively correlated to SWC in all soil layers and during both seasons, while the other two species were not sensitive to SWC in the deeper layers and only positively correlated to SWC in dry season. Our results demonstrate that the three species have distinct water use strategies and may therefore respond differently to changing climate.

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“…Again, based on UV values, first day measurements should be more stressful than the second. Decrease in relative humidity (RH), in other words, the increase of vapor pressure difference between plant and air expedites water lose due to transpiration and again, the plant enters to a state of water stress (Eamus and Shanahan, 2002). The average RH of M1 and M2 (14:00-15:00) are 48.14% and 62.23% respectively, thus first day measurements should be more stressful than the second based on the RH as well.…”

Section: Lwp Measurement Methodsmentioning

confidence: 99%

Asma Su Stresinin Hiperspektral Analizi

Özelkan

Karaman

Candar³

et al. 2020

ÇOMÜ Ziraat Fakültesi Dergisi

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Viticulture is very sensitive to water stress, which is critical and influenced by all environmental factors, relating to the crop quality and productivity of vineyards. In this study, water stress was examined in veraison and harvest stages for nine different species with spectroradiometric measurements. Leaf water potential (LWP) values from field measurements and original spectra-based (OSB) and continuum removed spectra-based (CRSB) curves were analyzed with correlation and regression analysis to find the highest related wavelengths. The analysis was done for both specific dates of field measurements (i.e. 08.08.2012 and 06.09.2012) and also in aggregate i.e. all measured data. The specific date wavelength-based analysis revealed the "red edge region" as a major water stress indicator. The highest correlated wavelength was found to be 684 nm of CRSB curves with R=0.988. For the aggregate wavelength-based water stress analysis, the "violet and green regions" were identified as the best indicators. The highest correlated wavelength was found to be 410 nm of OSB curves with R=0.820. Furthermore, the Analysis of Variance (ANOVA) testing indicates that the results are significant at relatively high confidence levels. The spectral-based method performed in this study provides fast, flexible, and non-destructive water stress measurements of grapevines when compared to classical methods.

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Cited by 30 publications

References 36 publications

Sap flow, leaf-level gas exchange and spectral responses to drought in Pinus sylvestris, Pinus pinea and Pinus halepensis

Sap flow, leaf-level gas exchange and spectral responses to drought in Pinus sylvestris, Pinus pinea and Pinus halepensis

Assessing Environmental Control of Sap Flux of Three Tree Species Plantations in Degraded Hilly Lands in South China

Asma Su Stresinin Hiperspektral Analizi

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