Seasonal patterns of Mediterranean evergreen woodlands (Montado) are explained by long-term precipitation

Ramos, Alzira; Pereira, Maria João Veloso da Costa Ramos; Soares, Amílcar; Rosário, Lúcio do; Matos, Paula; Nunes, Alice; Branquinho, Cristina; Pinho, Pedro

doi:10.1016/j.agrformet.2014.11.021

Cited by 22 publications

(10 citation statements)

References 35 publications

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“…Since unhealthy or dead trees show, respectively, little or absent photosynthetic activity, one can conclude that this increase in the VI values results from an increase in understory production due to precipitation, which in turn causes a significant contribution of the understory (or forest floor) spectral reflectance in the NIR region. As observed by some authors [29,30], NIR rapidly increases for sparse canopy covers when the understory starts sprouting after the first rains in October/November. Healthy trees seem to be more resilient to the dry summer climate than the understory vegetation dominated by herbaceous vegetation and sparse shrubs, producing a higher contrast between tree crowns and ground.…”

Section: Resultssupporting

confidence: 63%

Assessing the Use of Sentinel-2 Time Series Data for Monitoring Cork Oak Decline in Portugal

2019

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In Portugal, cork oak (Quercus suber L.) stands cover 737 Mha, being the most predominant species of the montado agroforestry system, contributing to the economic, social and environmental development of the country. Cork oak decline is a known problem since the late years of the 19th century that has recently worsened. The causes of oak decline seem to be a result of slow and cumulative processes, although the role of each environmental factor is not yet established. The availability of Sentinel-2 high spatial and temporal resolution dense time series enables monitoring of gradual processes. These processes can be monitored using spectral vegetation indices (VI) as their temporal dynamics are expected to be related with green biomass and photosynthetic efficiency. The Normalized Difference Vegetation Index (NDVI) is sensitive to structural canopy changes, however it tends to saturate at moderate-to-dense canopies. Modified VI have been proposed to incorporate the reflectance in the red-edge spectral region, which is highly sensitive to chlorophyll content while largely unaffected by structural properties. In this research, in situ data on the location and vitality status of cork oak trees are used to assess the correlation between chlorophyll indices (CI) and NDVI time series trends and cork oak vitality at the tree level. Preliminary results seem to be promising since differences between healthy and unhealthy (diseased/dead) trees were observed.

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Section: Resultssupporting

confidence: 63%

Assessing the Use of Sentinel-2 Time Series Data for Monitoring Cork Oak Decline in Portugal

2019

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“…Particularly, to conduct the evaluation over wider areas, RS should be employed for land cover change and ecosystems' natural temporal pattern detection, land degradation assessment, and analysis of the impacts of land restoration (Zucca et al, 2015b;Ramos et al, 2015). The quantification of the photosynthetically active herbaceous and shrub biomass production in rangelands and savannahs is one of the most widely used metrics.…”

Section: Integrated Assessment Protocolsmentioning

confidence: 99%

“…The "land degradation neutrality" target promoted by the United Nations Convention to Combat Desertification (UNCCD) indicates that the progress made with restoration could compensate the impacts of degradation, stressing the importance of a quantitative evaluation process. Studies and attempts to implement restoration strategies in different dry environments are numerous, from rangelands to shrub and forest stands (Camprubi et al, 2015;Cortina et al, 2009;Fuentes et al, 2010;Roa-Fuentes et al, 2015;Zucca et al, 2015a, b), from agricultural ecosystems to mining sites and brownfields (Dickinson et al, 2005;de Moraes Sá et al, 2015;Hasanuzzaman et al, 2014;Oliveira et al, 2011;Stroosnijder, 2009;Toktar et al, 2016;Wong et al, 2015). Though restoring degraded drylands is also a complex issue, it can be pursued by means of several strategies, all of which consider soil characteristics, either directly or indirectly.…”

Section: Introductionmentioning

confidence: 99%

Soil indicators to assess the effectiveness of restoration strategies in dryland ecosystems

Costantini¹,

et al. 2016

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Abstract. Soil indicators may be used for assessing both land suitability for restoration and the effectiveness of restoration strategies in restoring ecosystem functioning and services. In this review paper, several soil indicators, which can be used to assess the effectiveness of ecological restoration strategies in dryland ecosystems at different spatial and temporal scales, are discussed. The selected indicators represent the different viewpoints of pedology, ecology, hydrology, and land management. Two overall outcomes stem from the review. (i) The success of restoration projects relies on a proper understanding of their ecology, namely the relationships between soil, plants, hydrology, climate, and land management at different scales, which are particularly complex due to the heterogeneous pattern of ecosystems functioning in drylands.(ii) The selection of the most suitable soil indicators follows a clear identification of the different and sometimes competing ecosystem services that the project is aimed at restoring.

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“…Furthermore, we observe that the temperature control on phenology is generally stronger at the colder sites (Figure 4). The influence of precipitation on vegetation change is expected to be stronger in dry areas than humid areas (Ramos et al, 2015;Tao et al, 2017), for example, a stronger influence of precipitation than that of temperature was discovered in water-limited biomes such as the arid desert and dry steppe (Zhu and Meng, 2014). In this study, precipitation influence was not evident at most of these northern catchments; however, the pre-season precipitation influence on SOS is positive at the cold sites (Wolf Creek, Krycklan and Dorset), indicating that more winter precipitation is correlated with a delayed start of growing season.…”

Section: Vegetation Phenology In Response To Climatic Factorsmentioning

confidence: 99%

Climate-phenology-hydrology interactions in northern high latitudes: Assessing the value of remote sensing data in catchment ecohydrological studies

Wang

Tetzlaff

Buttle

et al. 2019

Science of The Total Environment

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We assessed the hydrological implications of climate effects on vegetation phenology in northern environments by fusion of data from remote-sensing and local catchment monitoring. Studies using satellite data have shown earlier and later dates for the start (SOS) and end of growing seasons (EOS), respectively, in the Northern Hemisphere over the last 3 decades. However, estimates of the change greatly depend on the satellite data utilized. Validation with experimental data on climate-vegetationhydrology interactions requires long-term observations of multiple variables which are rare and usually restricted to small catchments. In this study, we used two NDVI (normalized difference vegetation index) products (at ~25 & 0.5 km spatial resolutions) to infer SOS and EOS for six northern catchments, and then investigated the likely climate impacts on phenology change and consequent effects on catchment water yield, using both assimilated data (GLDAS: global land data assimilation system) and direct catchment observations. The major findings are: (1) The assimilated air temperature compared well with catchment observations (regression slopes and R 2 close to 1), whereas underestimations of summer rainstorms resulted in overall underestimations of precipitation (regression slopes of 0.3-0.7, R 2 ≥ 0.46). (2) The two NDVI products inferred different vegetation phenology characteristics. (3) Increased mean pre-season temperature significantly influenced the advance of SOS and delay of EOS. The precipitation influence was weaker, but delayed SOS corresponding to increased preseason precipitation at most sites can be related to later snow melting. (4) Decreased

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Seasonal patterns of Mediterranean evergreen woodlands (Montado) are explained by long-term precipitation

Cited by 22 publications

References 35 publications

Assessing the Use of Sentinel-2 Time Series Data for Monitoring Cork Oak Decline in Portugal

Assessing the Use of Sentinel-2 Time Series Data for Monitoring Cork Oak Decline in Portugal

Soil indicators to assess the effectiveness of restoration strategies in dryland ecosystems

Climate-phenology-hydrology interactions in northern high latitudes: Assessing the value of remote sensing data in catchment ecohydrological studies

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