The expected production, dissemination, and planting of blight-resistant hybrid chestnut seedlings calls for anticipatory studies to establish optimal management practices. To test phytotoxic potential of a site preparation herbicide, seedling growth and physiological function were measured for potted American chestnut (Castanea dentata [Marsh.] Borkh.). Six concentrations (0.0, 0.026, 0.053, 0.105, 0.158, and 0.210 kg active ingredient [ai] ha−1) of sulfometuron methyl (Oust) were applied to pots in April 2008, which were planted with 1 + 0 seedlings in May, and grown until November 2008. Changes in height, rootcollar diameter, and root volume and length were measured. A portable photosynthesis system was used to measure net photosynthesis, stomatal conductance, and transpiration. Seedlings treated with label-recommended doses (0.105‐0.210 kg [ai] ha−1) showed growth and leaf function suppression, including 55, 71, and 82% reductions in height growth, root volume, and net photosynthesis, respectively. These results indicate that a strong need exists for field trials, with various dose regimes, to be conducted to refine an application rate that minimizes phytotoxic damage while still providing suitable control of competition vegetation.
Summary
Shifts in the age or turnover time of non‐structural carbohydrates (NSC) may underlie changes in tree growth under long‐term increases in drought stress associated with climate change. But NSC responses to drought are challenging to quantify, due in part to large NSC stores in trees and subsequently long response times of NSC to climate variation.
We measured NSC age (Δ14C) along with a suite of ecophysiological metrics in Pinus edulis trees experiencing either extreme short‐term drought (−90% ambient precipitation plot, 2020–2021) or a decade of severe drought (−45% plot, 2010–2021). We tested the hypothesis that carbon starvation – consumption exceeding synthesis and storage – increases the age of sapwood NSC.
One year of extreme drought had no impact on NSC pool size or age, despite significant reductions in predawn water potential, photosynthetic rates/capacity, and twig and needle growth. By contrast, long‐term drought halved the age of the sapwood NSC pool, coupled with reductions in sapwood starch concentrations (−75%), basal area increment (−39%), and bole respiration rates (−28%).
Our results suggest carbon starvation takes time, as tree carbon reserves appear resilient to extreme disturbance in the short term. However, after a decade of drought, trees apparently consumed old stored NSC to support metabolism.
Abreviaturas y siglas vi Agradecimientos ix Resumen ejecutivo x Capítulo 1: Introducción 1.1. Antecedentes del estudio 1.2. ¿En qué consisten los pagos por servicios ambientales? 1.3. El contexto boliviano 1.4. Resumen de características de los estudios de caso Capítulo 2: Estudios de caso -Bosques para fijación de carbono 2.1. Introducción 2.2. Proyecto de Acción Climática Noel Kempff Mercado 2.3. Iniciativas en ciernes para la fijación de carbono Capítulo 3: Estudios de caso -Protección de cuencas 3
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