The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine Species
High temperatures threaten tree survival and regeneration. A few pine species, such as <i>Pinus oocarpa</i> and <i>Pinus canariensis</i>, resprout after complete defoliation, a likely consequence of evolving in volcanic environments. <i>Pinus pinea</i> and <i&g...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-11-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/14/11/2174 |
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| author | Pilar Pita Rosana López Luis Gil |
| author_facet | Pilar Pita Rosana López Luis Gil |
| author_sort | Pilar Pita |
| collection | DOAJ |
| description | High temperatures threaten tree survival and regeneration. A few pine species, such as <i>Pinus oocarpa</i> and <i>Pinus canariensis</i>, resprout after complete defoliation, a likely consequence of evolving in volcanic environments. <i>Pinus pinea</i> and <i>Pinus pinaster</i> rely on other mechanisms to survive wildfires. We hypothesized that the needle water potential (Ψ) and needle osmotic potential (Ψ<sub>s</sub>) would decrease more under hot wind in resprouting species, a strategy of needle sacrifice in accordance with the hydraulic segmentation hypothesis. We submitted two-year-old seedlings to a two-phase hot wind treatment, consisting of one hour at 39 °C followed by five minutes at 70 °C. Phase 2 killed all needles. In non-resprouting species, Ψ decreased steeply at the beginning of Phase 1 and remained between −2 MPa and −4 MPa afterward, maintaining the loss of stem hydraulic conductance below the 50% threshold. On average, resprouting species had 15% lower wood densities and kept 51% higher stem water contents than non-resprouting species after Phase 2. The loss of hydraulic conductance did not affect resprouting. The increase in hydraulic conductance toward the base of the stem was lowest in <i>P. canariensis</i>, suggesting a lower degree of conduit tapering in the only species that had not undergone heteroblastic change. We measured the lowest Ψ and highest Ψ<sub>s</sub> in the most xeric <i>P. canariensis</i> and the opposite in the most mesic <i>P. oocarpa</i>, highlighting the roles of xylary and extra-xylary hydraulic resistances in compartmentalizing the needle to preserve the stem. The measurement of both Ψ and Ψ<sub>s</sub> allowed us to characterize the strategies of response to hot wind in resprouting and non-resprouting pine species. |
| first_indexed | 2024-03-09T16:50:03Z |
| format | Article |
| id | doaj.art-941350d31e4d4d85b70d62f059fc2761 |
| institution | Directory Open Access Journal |
| issn | 1999-4907 |
| language | English |
| last_indexed | 2024-03-09T16:50:03Z |
| publishDate | 2023-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Forests |
| spelling | doaj.art-941350d31e4d4d85b70d62f059fc27612023-11-24T14:42:34ZengMDPI AGForests1999-49072023-11-011411217410.3390/f14112174The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine SpeciesPilar Pita0Rosana López1Luis Gil2Departamento de Sistemas y Recursos Naturales, Universidad Politécnica de Madrid, José Antonio Novais 10, 28040 Madrid, SpainDepartamento de Sistemas y Recursos Naturales, Universidad Politécnica de Madrid, José Antonio Novais 10, 28040 Madrid, SpainDepartamento de Sistemas y Recursos Naturales, Universidad Politécnica de Madrid, José Antonio Novais 10, 28040 Madrid, SpainHigh temperatures threaten tree survival and regeneration. A few pine species, such as <i>Pinus oocarpa</i> and <i>Pinus canariensis</i>, resprout after complete defoliation, a likely consequence of evolving in volcanic environments. <i>Pinus pinea</i> and <i>Pinus pinaster</i> rely on other mechanisms to survive wildfires. We hypothesized that the needle water potential (Ψ) and needle osmotic potential (Ψ<sub>s</sub>) would decrease more under hot wind in resprouting species, a strategy of needle sacrifice in accordance with the hydraulic segmentation hypothesis. We submitted two-year-old seedlings to a two-phase hot wind treatment, consisting of one hour at 39 °C followed by five minutes at 70 °C. Phase 2 killed all needles. In non-resprouting species, Ψ decreased steeply at the beginning of Phase 1 and remained between −2 MPa and −4 MPa afterward, maintaining the loss of stem hydraulic conductance below the 50% threshold. On average, resprouting species had 15% lower wood densities and kept 51% higher stem water contents than non-resprouting species after Phase 2. The loss of hydraulic conductance did not affect resprouting. The increase in hydraulic conductance toward the base of the stem was lowest in <i>P. canariensis</i>, suggesting a lower degree of conduit tapering in the only species that had not undergone heteroblastic change. We measured the lowest Ψ and highest Ψ<sub>s</sub> in the most xeric <i>P. canariensis</i> and the opposite in the most mesic <i>P. oocarpa</i>, highlighting the roles of xylary and extra-xylary hydraulic resistances in compartmentalizing the needle to preserve the stem. The measurement of both Ψ and Ψ<sub>s</sub> allowed us to characterize the strategies of response to hot wind in resprouting and non-resprouting pine species.https://www.mdpi.com/1999-4907/14/11/2174heathydraulic segmentationosmotic potentialrelative water contentembolismheteroblasty |
| spellingShingle | Pilar Pita Rosana López Luis Gil The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine Species Forests heat hydraulic segmentation osmotic potential relative water content embolism heteroblasty |
| title | The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine Species |
| title_full | The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine Species |
| title_fullStr | The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine Species |
| title_full_unstemmed | The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine Species |
| title_short | The Effect of Hot Wind on Needle and Stem Water Status: Response Strategies in Resprouting and Non-Resprouting Pine Species |
| title_sort | effect of hot wind on needle and stem water status response strategies in resprouting and non resprouting pine species |
| topic | heat hydraulic segmentation osmotic potential relative water content embolism heteroblasty |
| url | https://www.mdpi.com/1999-4907/14/11/2174 |
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