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Savi T, Casolo V, Dal Borgo A, Rosner S, Torboli V, Stenni B, Bertoncin P, Martellos S, Pallavicini A, Nardini A. Drought-induced dieback of Pinus nigra: a tale of hydraulic failure and carbon starvation. Conserv Physiol 2019; 7:coz012. [PMID: 31198559 PMCID: PMC6541882 DOI: 10.1093/conphys/coz012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/22/2019] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
Ongoing climate change is apparently increasing tree mortality rates, and understanding mechanisms of drought-induced tree decline can improve mortality projections. Differential drought impact on conspecific individuals within a population has been reported, but no clear mechanistic explanation for this pattern has emerged. Following a severe drought (summer 2012), we monitored over a 3-year period healthy (H) and declining (D) Pinus nigra trees co-occurring in a karstic woodland to highlight eventual individual-specific physiological differences underlying differential canopy dieback. We investigated differences in water and carbon metabolism, and xylem anatomy as a function of crown health status, as well as eventual genotypic basis of contrasting drought responses. H and D trees exploited the same water pools and relied on similar hydraulic strategies to cope with drought stress. Genetic analyses did not highlight differences between groups in terms of geographical provenance. Hydraulic and anatomical analyses showed conflicting results. The hydraulic tracheid diameter and theoretical hydraulic conductivity were similar, but D trees were characterized by lower water transport efficiency, greater vulnerability to xylem conduit implosion and reduced carbohydrate stores. Our results suggest that extreme drought events can have different impacts on conspecific individuals, with differential vulnerability to xylem embolism likely playing a major role in setting the fate of trees under climate change.
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Affiliation(s)
- Tadeja Savi
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia
- Division of Viticulture and Pomology, Department of Crop Sciences, University of Natural Resources and Life Sciences, Konrad Lorenz Strasse 24, Tulln, Austria
| | - Valentino Casolo
- Dipartimento di Scienze Agro-Alimentari, Ambientali e Animali, Università di Udine, Via delle Scienze 91, Udine, Italia
| | - Anna Dal Borgo
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia
| | - Sabine Rosner
- Institute of Botany, University of Natural Resources and Life Sciences, Gregor Mendel Strasse 33, Vienna, Austria
| | - Valentina Torboli
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia
| | - Barbara Stenni
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca’ Foscari Venezia, Via Torino 155, Venezia Mestre, Italia
| | - Paolo Bertoncin
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia
| | - Stefano Martellos
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia
| | - Alberto Pallavicini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia
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Savi T, Dal Borgo A, Love VL, Andri S, Tretiach M, Nardini A. Drought versus heat: What's the major constraint on Mediterranean green roof plants? Sci Total Environ 2016; 566-567:753-760. [PMID: 27239718 DOI: 10.1016/j.scitotenv.2016.05.100] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/12/2016] [Accepted: 05/15/2016] [Indexed: 06/05/2023]
Abstract
Green roofs are gaining momentum in the arid and semi-arid regions due to their multiple benefits as compared with conventional roofs. One of the most critical steps in green roof installation is the selection of drought and heat tolerant species that can thrive under extreme microclimate conditions. We monitored the water status, growth and survival of 11 drought-adapted shrub species grown on shallow green roof modules (10 and 13cm deep substrate) and analyzed traits enabling plants to cope with drought (symplastic and apoplastic resistance) and heat stress (root membrane stability). The physiological traits conferring efficiency/safety to the water transport system under severe drought influenced plant water status and represent good predictors of both plant water use and growth rates over green roofs. Moreover, our data suggest that high substrate temperature represents a stress factor affecting plant survival to a larger extent than drought per se. In fact, the major cause influencing seedling survival on shallow substrates was the species-specific root resistance to heat, a single and easy measurable trait that should be integrated into the methodological framework for screening and selection of suitable shrub species for roof greening in the Mediterranean.
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Affiliation(s)
- Tadeja Savi
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy.
| | - Anna Dal Borgo
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy.
| | - Veronica L Love
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy; Department of Landscape, University of Sheffield, Western Bank, Sheffield, South Yorkshire S10 2TN, United Kingdom.
| | - Sergio Andri
- Harpo seic verdepensile, Via Torino 34, 34123 Trieste, Italy.
| | - Mauro Tretiach
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy.
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy.
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Nardini A, Casolo V, Dal Borgo A, Savi T, Stenni B, Bertoncin P, Zini L, McDowell NG. Rooting depth, water relations and non-structural carbohydrate dynamics in three woody angiosperms differentially affected by an extreme summer drought. Plant Cell Environ 2016; 39:618-27. [PMID: 26437327 DOI: 10.1111/pce.12646] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 09/22/2015] [Accepted: 09/22/2015] [Indexed: 05/17/2023]
Abstract
In 2012, an extreme summer drought induced species-specific die-back in woody species in Northeastern Italy. Quercus pubescens and Ostrya carpinifolia were heavily impacted, while Prunus mahaleb was largely unaffected. By comparing seasonal changes in isotopic composition of xylem sap, rainfall and deep soil samples, we show that P. mahaleb has a deeper root system than the other two species. This morphological trait allowed P mahaleb to maintain higher water potential (Ψ), gas exchange rates and non-structural carbohydrates content (NSC) throughout the summer, when compared with the other species. More favourable water and carbon states allowed relatively stable maintenance of stem hydraulic conductivity (k) throughout the growing season. In contrast, in Quercus pubescens and Ostrya carpinifolia, decreasing Ψ and NSC were associated with significant hydraulic failure, with spring-to-summer k loss averaging 60%. Our data support the hypothesis that drought-induced tree decline is a complex phenomenon that cannot be modelled on the basis of single predictors of tree status like hydraulic efficiency, vulnerability and carbohydrate content. Our data highlight the role of rooting depth in seasonal progression of water status, gas exchange and NSC, with possible consequences for energy-demanding mechanisms involved in the maintenance of vascular integrity.
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Affiliation(s)
- Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Valentino Casolo
- Dipartimento di Scienze Agrarie e Ambientali, Università di Udine, Sezione di Biologia Vegetale, Via delle Scienze 91, Udine, 33100, Italy
| | - Anna Dal Borgo
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Tadeja Savi
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Barbara Stenni
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari Venezia, via Torino 155, Venezia Mestre, 30170, Italy
- Dipartimento di Matematica e Geoscienze, Università di Trieste, Via Weiss 2, Trieste, 34127, Italy
| | - Paolo Bertoncin
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Luca Zini
- Dipartimento di Matematica e Geoscienze, Università di Trieste, Via Weiss 2, Trieste, 34127, Italy
| | - Nathan G McDowell
- Los Alamos National Laboratory, Earth and Environmental Sciences Division, Los Alamos, NM, 87545, USA
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