RESUMEN
Forest ecosystems face increasing drought exposure due to climate change, necessitating accurate measurements of vegetation water content to assess drought stress and tree mortality risks. Although Frequency Domain Reflectometry offers a viable method for monitoring stem water content by measuring dielectric permittivity, challenges arise from uncertainties in sensor calibration linked to wood properties and species variability, impeding its wider usage. We sampled tropical forest trees and palms in eastern Amazônia to evaluate how sensor output differences are controlled by wood density, temperature and taxonomic identity. Three individuals per species were felled and cut into segments within a diverse dataset comprising five dicotyledonous tree and three monocotyledonous palm species on a wide range of wood densities. Water content was estimated gravimetrically for each segment using a temporally explicit wet-up/dry-down approach and the relationship with the dielectric permittivity was examined. Woody tissue density had no significant impact on the calibration, but species identity and temperature significantly affected sensor readings. The temperature artefact was quantitatively important at large temperature differences, which may have led to significant bias of daily and seasonal water content dynamics in previous studies. We established the first tropical tree and palm calibration equation which performed well for estimating water content. Notably, we demonstrated that the sensitivity remained consistent across species, enabling the creation of a simplified one-slope calibration for accurate, species-independent measurements of relative water content. Our one-slope calibration serves as a general, species-independent standard calibration for assessing relative water content in woody tissue, offering a valuable tool for quantifying drought responses and stress in trees and forest ecosystems.
Asunto(s)
Bosques , Árboles , Clima Tropical , Agua , Madera , Madera/química , Agua/metabolismo , Árboles/fisiología , Ecosistema , Sequías , Arecaceae/fisiología , Arecaceae/metabolismo , BrasilRESUMEN
The efficacy of captopril 25 mg/day as monotherapy or when necessary, in association with hydrochlorothiazide 25 mg/day, was studied during three months in 472 patients, average age 45 (17-59) years, 51% males with mild (73%) 95 less than PAD less than 104 mmHg, and moderate (27%) arterial hypertension 104 less than PAD less than 114 mmHg. Were included in the study hypertensive patients with previous antihypertensive therapy or when in the course of any previous antihypertensive treatment (52.4%) blood pressure control were not observed and side effects compromised patient's compliance. Captopril 25 mg/day was used once a day as single dose or subdivided in two daily doses (12.5 mg b.i.d.), during 30 days. If blood pressure was not normalized or dyastolic blood pressure drop was not equal or bigger than 10% after this period, it was added hydrochlorothiazide 25 mg/day. After three months under treatment, 411 (87%) patients normalized their dyastolic blood pressure DBP (less than 90 mmHg), from them, 273 (57.6%) had received only captopril and the others 138 (29.4%) with the addition of hydrochlorothiazide. The drop of mean arterial pressure, MAP = 2 DBP + 1 SBP was in average, 17.3 mmHg, in the 3 patients whose blood pressure normalized with captopril alone, and in average of 18.5 mmHg in those patients requiring addition of hydrochlorothiazide (difference without statistical significance). A small decrease of body weight, but with statistical significance (p less than 0.001) were observed during the use of captopril as monotherapy. Expressive reduction of side effects were observed during the period under captopril related to the period with previous antihypertensive therapy.