Presentation Type
Poster
Faculty Mentor’s Full Name
Anna Sala
Faculty Mentor’s Department
Biological Sciences
Abstract / Artist's Statement
The frequency, distribution and intensity of drought is expected to increase with climate change. Drought decreases water availability and the production of carbohydrates, both of which reduce growth. Reduced growth is an indicator of future tree death. However, the relative impacts of carbohydrate limitation versus water stress on tree growth is poorly understood. As part of a broader project in the Sala lab, I examined how reduced water and carbohydrate availability individually and in combination affect ponderosa pine growth during and after a stress event. In the summer of 2022, we subjected ponderosa pine to drought to reduce water and carbohydrate availability. We also subjected saplings to shade to test carbohydrate limitation individually. In the fall of 2023, I explored treatment effects on growth. The drought treatment consisted of drought (D) and Ambient (A); The shade treatment consisted of shade (S) and a no shade control (C), resulting in four treatment combinations with five replicates each: (1) Drought-No shade (DC), (2) Drought-Shade (DS), (3) No drought-No shade (AC), (4) No drought-Shade (AS). To test growth effects, I sampled three branches per tree. On each branch I measured three years of growth: before treatment (2021, as a reference), during treatment (2022), and after treatment (2023). For each year of growth, I measured wood radial growth, needle biomass, and shoot length. I found that drought has a very strong negative effect on growth and that this effect carries over subsequent years. Carbohydrate limitation alone (shade) has mild impacts on growth, and they do not carry over. The addition of further carbohydrate limitation to drought only mildly worsens the negative effects of water limitation on growth. This shows that water limitation is a much stronger stressor than carbohydrate limitation. These results highlight the danger that increased drought frequency and intensity pose to ponderosa pine forests.
Category
Life Sciences
Individual and combined effects of drought and shade on growth in ponderosa pines
UC South Ballroom
The frequency, distribution and intensity of drought is expected to increase with climate change. Drought decreases water availability and the production of carbohydrates, both of which reduce growth. Reduced growth is an indicator of future tree death. However, the relative impacts of carbohydrate limitation versus water stress on tree growth is poorly understood. As part of a broader project in the Sala lab, I examined how reduced water and carbohydrate availability individually and in combination affect ponderosa pine growth during and after a stress event. In the summer of 2022, we subjected ponderosa pine to drought to reduce water and carbohydrate availability. We also subjected saplings to shade to test carbohydrate limitation individually. In the fall of 2023, I explored treatment effects on growth. The drought treatment consisted of drought (D) and Ambient (A); The shade treatment consisted of shade (S) and a no shade control (C), resulting in four treatment combinations with five replicates each: (1) Drought-No shade (DC), (2) Drought-Shade (DS), (3) No drought-No shade (AC), (4) No drought-Shade (AS). To test growth effects, I sampled three branches per tree. On each branch I measured three years of growth: before treatment (2021, as a reference), during treatment (2022), and after treatment (2023). For each year of growth, I measured wood radial growth, needle biomass, and shoot length. I found that drought has a very strong negative effect on growth and that this effect carries over subsequent years. Carbohydrate limitation alone (shade) has mild impacts on growth, and they do not carry over. The addition of further carbohydrate limitation to drought only mildly worsens the negative effects of water limitation on growth. This shows that water limitation is a much stronger stressor than carbohydrate limitation. These results highlight the danger that increased drought frequency and intensity pose to ponderosa pine forests.