2022
Autores
Monteiro, AT; Alves, P; Carvalho Santos, C; Lucas, R; Cunha, M; da Costa, EM; Fava, F;
Publicação
DIVERSITY-BASEL
Abstract
The spatial monitoring of plant diversity in the endangered species-rich grasslands of European mountain pastoral systems is an important step for fairer and more efficient Agri-Environmental policy schemes supporting conservation. This study assessed the underlying support for a spatially explicit monitoring of plant species richness at parcel level (policy making scale) in Southern European mountain grasslands, with statistical models informed by Sentinel-2 satellite and environmental factors. Twenty-four grassland parcels were surveyed for species richness in the Peneda-Geres National Park, northern Portugal. Using a multi-model inference approach, three competing hypotheses guided by the species-scaling theoretical framework were established: species-area (P1), species-energy (P2) and species-spectral heterogeneity (P3), each representing a candidate spatial pathway to predict species richness. To evaluate the statistical support of each spatial pathway, generalized linear models were fitted and model selection based on Akaike information criterion (AIC) was conducted. Later, the performance of the most supported spatial pathway(s) was assessed using a leave-one-out cross validation. A model guided by the species-energy hypothesis (P2) was the most parsimonious spatial pathway to monitor plant species richness in mountain grassland parcels (P2, AICc = 137.6, increment AIC = 0.0, wi = 0.97). Species-area and species-spectral heterogeneity pathways (P1 and P3) were less statistically supported (Delta AICc values in the range 5.7-10.0). The underlying support of the species-energy spatial pathway was based on Sentinel-2 satellite data, namely on the near-infrared (NIR) green ratio in the spring season (NIR/Green(spring)) and on its ratio of change between spring and summer (NIR/Green(change)). Both predictor variables related negatively to species richness. Grassland parcels with lower values of near-infrared (NIR) green ratio and lower seasonal amplitude presented higher species richness records. The leave-one-out cross validation indicated a moderate performance of the species-energy spatial pathway in predicting species richness in the grassland parcels covered by the dataset (R-2 = 0.44, RMSE = 4.3 species, MAE = 3.5 species). Overall, a species-energy framework based on Sentinel 2 data resulted in a promising spatial pathway for the monitoring of species richness in mountain grassland parcels and for informing decision making on Agri-Environmental policy schemes. The near-infrared (NIR) green ratio and its change in time seems a relevant variable to deliver predictions for plant species richness and further research should be conducted on that.
2022
Autores
Guo, YH; Chen, SZ; Li, XX; Cunha, M; Jayavelu, S; Cammarano, D; Fu, YS;
Publicação
REMOTE SENSING
Abstract
Precisely monitoring the growth condition and nutritional status of maize is crucial for optimizing agronomic management and improving agricultural production. Multi-spectral sensors are widely applied in ecological and agricultural domains. However, the images collected under varying weather conditions on multiple days show a lack of data consistency. In this study, the Mini MCA 6 Camera from UAV platform was used to collect images covering different growth stages of maize. The empirical line calibration method was applied to establish generic equations for radiometric calibration. The coefficient of determination (R-2) of the reflectance from calibrated images and ASD Handheld-2 ranged from 0.964 to 0.988 (calibration), and from 0.874 to 0.927 (validation), respectively. Similarly, the root mean square errors (RMSE) were 0.110, 0.089, and 0.102% for validation using data of 5 August, 21 September, and both days in 2019, respectively. The soil and plant analyzer development (SPAD) values were measured and applied to build the linear regression relationships with spectral and textural indices of different growth stages. The Stepwise regression model (SRM) was applied to identify the optimal combination of spectral and textural indices for estimating SPAD values. The support vector machine (SVM) and random forest (RF) models were independently applied for estimating SPAD values based on the optimal combinations. SVM performed better than RF in estimating SPAD values with R-2 (0.81) and RMSE (0.14), respectively. This study contributed to the retrieval of SPAD values based on both spectral and textural indices extracted from multi-spectral images using machine learning methods.
2022
Autores
Afonso, S; Dias, MI; Ferreira, ICFR; Arrobas, M; Cunha, M; Barros, L; Rodrigues, MA;
Publicação
HORTICULTURAE
Abstract
The interest in expanding the production of hops outside the traditional cultivation regions, mainly motivated by the growth of the craft brewery business, justifies the intensification of studies into its adaptation to local growing conditions. In this study, four field trials were undertaken on a twenty-year-old hop garden, over periods of up to three years to assess the effect of important agro-environmental variation factors on hop phenol and phenolic composition and to establish its relationship with the elemental composition of hop cones. All the field trials were arranged as factorial designs exploring the combined effect of: (1) plots of different vigour plants x year; (2) plots of different plant vigor x algae- and nutrient-rich foliar sprays x year; (3) plot x liming x year; and (4) cultivars (Nugget, Cascade, Columbus) x year. Total phenols in hops, were significantly influenced by most of the experimental factors. Foliar spraying and liming were the factors that least influenced the measured variables. The year had the greatest effect on the accumulation of total phenols in hop cones in the different trials and may have contributed to interactions that often occurred between the factors under study. The year average for total phenol concentrations in hop cones ranged from 11.9 mg g(-1) to 21.2 mg g(-1). Significant differences in quantity and composition of phenolic compounds in hop cones were also found between cultivars. The phenolic compounds identified were mainly flavonols (quercetin and kaempferol glycosides) and phenolic carboxylic acids (p-coumaric and caffeic acids).
2022
Autores
Marcos, B; Gonçalves, J; Alcaraz-Segura, D; Cunha, M; Honrado, JP;
Publicação
Advances in Forest Fire Research 2022
Abstract
2022
Autores
Melo, P; Arrais, R; Teixeira, S; Veiga, G;
Publicação
2022 IEEE 20TH INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS (INDIN)
Abstract
Modern software engineering practices to enable reproducible and easy to deploy robotics solutions have been embraced in recent years, leading to an increasing adoption of container technologies within the Robot Operating System (ROS) community. However, there is still no common procedure or tools for creating, testing, and deploying containerized ROS packages. A common way to work with containerized ROS applications would prove beneficial by increasing even more the level of collaboration among development teams, help in reusing existing solutions, and automate the development of new ones. This paper presents a software framework to support the development of ROS applications using Docker containers, across all its stages. Besides containerizing ROS packages, the presented tool also assists in the deployment of containerized solutions as well as the creation of complex simulation environments for testing. The tool also provides a way for these simulations to be assessed at run-time using a property-specific language targeting ROS applications. An industrial and a scientific scenario are presented to portray the usage of the proposed tool.
2022
Autores
Santos, MG; Moreira, GS; Pereira, R; Carvalho, SMP;
Publicação
AGRICULTURAL WATER MANAGEMENT
Abstract
Cascade cropping systems in soilless horticulture (where drainage collected from the main crop is used in fertigation of secondary crops) are potentially interesting for Mediterranean countries as they enhance water and nutrient use efficiency. However, their agronomic and long-term environmental impact has been poorly addressed. In this case study, lettuce grown hydroponically or in soil (previously exposed to drainage for five years) was fertigated, throughout the cultivation period, with a nutrient solution composed of 0, 25, 50 or 100 % of drainage (0D, 25D, 50D and 100D) mixed with a fresh nutrient solution. Plant performance analysis included growth parameters and leaf mineral composition. Drainage was analyzed for nutrients and Plant Protection Products (PPP) residues, and bioassays were performed exposing aquatic organisms (Raphidocelis subcapitata, Aliivibrio fischeri and Daphnia magna) to drainage and soil elutriate. When analyzing plant performance in both cultivation systems, a significant effect was only found at 100D in hydroponics, resulting in 41 % less leaf area, 20 % smaller head diameter and 43 % lower yield. Drainage analysis showed high nutrient content, presence of PPP residues (up to 6 substances, reaching 3.29 mu g.L-1 in total) and revealed toxicity to D. magna (EC50 = 66.6 %). Moreover, soil elutriate presented toxicity to R. subcapitata (EC50 = 20.6 %) and to A. fischeri (EC50 = 14.9 %). This study demonstrates the potential of using relatively high drainage percentages (up to 50 %) from soilless cultivation systems if applied to hydroponically-grown secondary crops. However, attention should be paid to the use of cascade cropping systems when drainages are applied to fertigate soil-grown crops, as it may contribute to soil degradation and environmental pollution on a long run.
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