Biochemical analysis of three red grapevine varieties during three phenological periods grown under Mediterranean climate conditions.

In Mediterranean regions, severe summers are becoming more common, leading to restrictions to vine productivity and yield quality, requiring sustainable practices to support this sector. We assessed the behaviour of three red grapevine varieties from the Douro Region to examine their tolerance to summer climate stress from the perspective that the less common varieties may have potential for increased use in a climate change scenario. Leaf and fruit biochemical profile, antioxidant activity and fruit colorimetric parameters were assessed at different phenological stages in Aragonez (AR), Tinto Cão (TC) and Touriga Nacional (TN) grape varieties. All three varieties exhibit significant variability in phenological timing, influenced by genetic and environmental factors. Photosynthetic pigment strategies differed among varieties. Chlorophyll content in AR was high to cope with high radiation, while TN displaying a balanced approach, and TC had lower pigment levels, with higher levels of phenolics, antioxidants, and soluble sugars, particularly during stress. The variations in berry biochemical profile highlight the distinct characteristics of the varieties. TC and TN show potential for coping with climate change, having elevated total acidity, while AR has larger and heavier berries with distinct coloration. These findings reinforce the need to study the behaviour of different varieties in each Terroir, to understand their diverse strategies to deal with summer climate stress. This will help in selecting the most suitable variety for these conditions under vineyard management in the Douro Region.

Spatio-temporal monitoring of marsh vegetation phenology and its response to hydro-meteorological factors using CCDC algorithm with optical and SAR images: In case of Honghe National Nature Reserve, China.

Vegetation phenology is a sensitive indicator which can comprehensively reflect the response of wetland vegetation to external environment changes. However, the time-series monitoring wetland vegetation phenological changes and clarifying its response to hydrology and meteorology still face great challenges. To fill these research gaps, this paper proposed a novel time-series approach for monitoring phenological change of marsh vegetation in Honghe National Nature Reserve (HNNR), Northeast China, using continuous change detection and classification (CCDC) algorithm and Landsat and Sentinel-1 SAR images from 1985 to 2021. We evaluated the spatio-temporal response relationship of phenological characteristics to hydro-meteorological factors by combining CCDC algorithm with partial least squares regression (PLSR). Finally, this study further explored the intra-annual loss and restoration of marsh vegetation in response to hydro-meteorological factors using the transfer entropy (TE) and CCDC-MLSR model constructed by CCDC and Multiple Linear Stepwise Regression (MLSR) algorithms. We found that the bimodal trajectory of phenology reflects two growth processes of marsh vegetation in one year, and high-frequency and high-amplitude loss occurred in shallow-water and deep-water marsh vegetation from April to October, resulting in the loss area within the year was significantly greater than the recovery area. We confirmed that the CCDC algorithm could track the evolution trajectory of time-series phenology of marsh vegetation. We further revealed that precipitation, temperature and frequency of water-level changes are the main driving factors for the spatio-temporal phenological evolution of different marsh vegetation. This study verified the effect of alternative changes of hydrology and climate on loss and recovery of marsh vegetation in each growth stage. The results of this study provide a scientific basis for wetland protection, ecological restoration, and sustainable development.

Land Use and Environmental Variability Impacts on the Phenology of Arid Agro-Ecosystems.

The overexploitation of water resources in arid environments often results in abandonment of large extensions of agricultural lands, which may (1) modify phenological trends, and (2) alter the sensitivity of specific phenophases to environmental triggers. In Mexico, current governmental policies subsidize restoration efforts, to address ecological degradation caused by abandonments; however, there is a need for new approaches to assess their effectiveness. Addressing this, we explore a method to monitor and assess (1) land surface phenology trends in arid agro-ecosystems, and (2) the effect of climatic factors and restoration treatments on the phenology of abandoned agricultural fields. We used 16-day normalized difference vegetation index composites from the moderate resolution imaging spectroradiometer from 2000 to 2009 to derive seasonal phenometrics. We then derived phenoclimatic variables and land cover thematic maps, to serve as a set of independent factors that influence vegetation phenology. We conducted a multivariate analysis of variance to analyze phenological trends among land cover types, and developed multiple linear regression models to assess influential climatic factors driving phenology per land cover analyzed. Our results suggest that the start and length of the growing season had different responses to environmental factors depending on land cover type. Our analysis also suggests possible establishment of arid adapted species (from surrounding ecosystems) in abandoned fields with longer times since abandonment. Using this approach, we were able increase our understanding on how climatic factors influence phenology on degraded arid agro-ecosystems, and how this systems evolve after disturbance.