RESUMO
Light availability drives vertical canopy gradients in photosynthetic functioning and carbon (C) balance, yet patterns of variability in these gradients remain unclear. We measured light availability, photosynthetic CO2 and light response curves, foliar C, nitrogen (N) and pigment concentrations, and the photochemical reflectance index (PRI) on upper and lower canopy needles of white spruce trees (Picea glauca) at the species' northern and southern range extremes. We combined our photosynthetic data with previously published respiratory data to compare and contrast canopy C balance between latitudinal extremes. We found steep canopy gradients in irradiance, photosynthesis and leaf traits at the southern range limit, but a lack of variation across canopy positions at the northern range limit. Thus, unlike many tree species from tropical to mid-latitude forests, high latitude trees may not require vertical gradients of metabolic activity to optimize photosynthetic C gain. Consequently, accounting for self-shading is less critical for predicting gross primary productivity at northern relative to southern latitudes. Northern trees also had a significantly smaller net positive leaf C balance than southern trees suggesting that, regardless of canopy position, low photosynthetic rates coupled with high respiratory costs may ultimately constrain the northern range limit of this widely distributed boreal species.
Assuntos
PiceaRESUMO
BACKGROUND: Patient-reported outcome measures (PROMs) are emerging tools used to capture a patient's daily health status and enhance communication between patients and healthcare professionals. This study examined whether PROMs can be used to predict consultation needs in an outpatient clinic setting including patients diagnosed with psoriasis. METHOD: We evaluated a nationally developed set of PROMs for psoriasis patients, which included a standard set of questionnaires that capture patients' perceptions of their experience and quality of life. Patients (n = 187) answered the psoriasis PROMs prior to an in-person consultation. Their responses were evaluated alongside patient, doctor, and nurse opinions on whether the subsequent consultation was necessary. Additionally, comments about the consultations from the patient, doctor, and nurse were collected and provided insights as to why certain consultations were deemed necessary. RESULTS: Comparing the patient, doctor, and nurse responses addressing a need for consultation compared to the coded psoriasis PROMs results (red or green/yellow outcome), 23% of the patients with a green/yellow outcome were in need of a doctor's consultation. Upon considering a subset of psoriasis PROMs questionnaires that reflect subjective responses (e.g., DLQI, PEST, MDI-2, and side effects), the proportion of patients that yielded a green/yellow outcome and were identified to require a doctor consultation increased to approximately 45%. CONCLUSIONS: The preliminary results show that the psoriasis PROMs were supportive in the consultation but alone cannot sufficiently guide healthcare professionals to determine whether in-person consultations are required.
RESUMO
Relationships between gross primary productivity (GPP) and the remotely sensed photochemical reflectance index (PRI) suggest that time series of foliar PRI may provide insight into climate change effects on carbon cycling. However, because a large fraction of carbon assimilated via GPP is quickly returned to the atmosphere via respiration, we ask a critical question-can PRI time series provide information about longer term gains in aboveground carbon stocks? Here we study the suitability of PRI time series to understand intra-annual stem-growth dynamics at one of the world's largest terrestrial carbon pools-the boreal forest. We hypothesized that PRI time series can be used to determine the onset (hypothesis 1) and cessation (hypothesis 2) of radial growth and enable tracking of intra-annual tree growth dynamics (hypothesis 3). Tree-level measurements were collected in 2018 and 2019 to link highly temporally resolved PRI observations unambiguously with information on daily radial tree growth collected via point dendrometers. We show that the seasonal onset of photosynthetic activity as determined by PRI time series was significantly earlier (p < .05) than the onset of radial tree growth determined from the point dendrometer time series which does not support our first hypothesis. In contrast, seasonal decline of photosynthetic activity and cessation of radial tree growth was not significantly different (p > .05) when derived from PRI and dendrometer time series, respectively, supporting our second hypothesis. Mixed-effects modeling results supported our third hypothesis by showing that the PRI was a statistically significant (p < .0001) predictor of intra-annual radial tree growth dynamics, and tracked these daily radial tree-growth dynamics in remarkable detail with conditional and marginal coefficients of determination of 0.48 and 0.96 (for 2018) and 0.43 and 0.98 (for 2019), respectively. Our findings suggest that PRI could provide novel insights into nuances of carbon cycling dynamics by alleviating important uncertainties associated with intra-annual vegetation response to climate change.
