RESUMO
Phenology has been useful to better understand the climate-vegetation relationship, and it is considered an indicator of climate change impact. Phenological data have been generated through multiple remote sensing techniques and ground-based observations through professional or citizen science. The combination of both techniques is known as cross-scale phenological monitoring. However, no comparative analysis has been carried out to assess the advantages and disadvantages of each of these techniques to characterize the phenological cycle of forest ecosystem species. This work is a content-analysis-based review of scientific literature published between 2000 and 2018 related to cross-scale monitoring methods, to estimate the phenological variation in different forest ecosystems worldwide. For this study, 97 publications related to cross-scale phenological monitoring were selected. We found that 71% of the articles aimed to corroborate the data generated through satellite imagery using surface data from either phenocams, flux towers, or from citizen science networks. More publications were published by authors in the USA (30%), Canada (8%), and China (7%). The most commonly used vegetation index was the normalized difference vegetation index (65%). Some deficiencies in the evaluation of the phenological phases of autumn when compared with surface observations were found. Flux towers and phenocams were included as alternatives for ground-based monitoring. Cross-scale phenological monitoring has the potential to characterize the phenological response of vegetation accurately due to data combinations at two different observation scales. This work contributes to specifying the methodologies used in gathering phenological parameters of the world's forest ecosystems.
Assuntos
Ecossistema , Florestas , Mudança Climática , Imagens de Satélites , Estações do AnoRESUMO
RESUMEN Objetivo. Estimar el número de días no productivos (DNP) de por vida, la proporción de DNP (%DNP) y días no productivos por cerda por año (DNP/Y), y determinar el efecto de factores de hato y cerda sobre las características aquí estudiadas en tres granjas comerciales en el trópico mexicano. Materiales y métodos. Los datos de 6703 cerdas de tres granjas comerciales fueron usados. El modelo que describió las características de interés incluyeron los efectos fijos de granja, año de primer parto, época de primer parto, edad al primer parto, causa de desecho, interacción de año por época y error residual. Resultados. Las medias de DNP de por vida, %DNP y DNP/Y fueron 64 días, 12% y 39.3 días, respectivamente. Todos los factores tuvieron efectos significativos (p<0.01) en todas las características. Las cerdas con primer parto a mayor edad y las eliminadas por razones reproductivas tuvieron más DNP en el hato. Además, las cerdas eliminadas en el primer parto tuvieron menor DNP y mayor %DNP que las cerdas desechadas en partos subsecuentes. Conclusiones. La eliminación temprana de cerdas incrementó la proporción de días no productivos, que a su vez podrían reducir la rentabilidad de las granjas.
ABSTRACT Objectives. To estimate the lifetime non-productive days (NPD), lifetime proportion of NPD (%NPD) and non-productive days per sow per year (NPD/Y), and to determine the effect of herd and sow level factors on the traits here studied in three pig farms in the Mexican tropics. Materials and methods. Data from 6703 sows from three commercial farms were used. The model that described the traits studied comprise the fixed effects of farm, year and season of first farrowing, age at first parity, reasons of removal of sows, year x season interaction and the residual error. Results. The means for lifetime NPD, %NPD and NPD/Y were 64 days, 12.0% and 39.3 days, respectively. All fixed factors had significant effects (p<0.01) on the characteristics evaluated. Sows having their first parity at an old age and sows culled because of reproductive reasons had the highest lifetime NPD. In addition, sows culled at first parity had lower lifetime NPD and higher %NPD than sows culled in subsequent farrowing. Conclusions. The early culling of sows increased the percentage of non-productive days, which in turn is expected to reduce the profit of farms.