Analysis of Petiole Sap Nutrients Using Rapid and Standard Methods and Its Relation to Leaf Analysis of Fertilized Malus domestica cv. Gala Mariana Mota, M. João Martins, Layanne Sprey, Anabela Maurício, Cristina Rosa, João Faria, Miguel B. Martins, Miguel L. de Sousa, Ricardo Santos, Rui M. de Sousa, Henrique Ribeiro, Cristina M. Oliveira Horticulturae, 2024 Currently, fertilization decisions in apple orchards are based on soil and leaf analyses while the leaf material is sampled after the growing season, usually in June–July (90–110 days after full bloom). This approach is inefficient, as the information becomes available later than the growing season and is therefore only useful in supporting fertilization decisions for the next year, not the current one. To establish a method that provides useful information for fertilization decisions earlier in the growth cycle, our research focused on the assessment of the nutrient content of petiole sap using different methods, the standard method and the rapid method using a reflectometer. For this study, in 2021, four ‘Gala’ orchards were fertilized with different N–P–K levels. Macro and micronutrients were determined in leaves and petiole sap at 45 and 90–110 days after full bloom (DAFB) using standard laboratory methods and the reflectometer. When leaf analysis at 45 and 90–110 DAFB was compared with petiole sap analysis at the same time point, no significant correlations were found between the nutrient contents in leaf material and petiole sap, with the exception of calcium. However, positive results were obtained regarding the correlation between reflectometer determination and standard laboratory analyses. The regression analysis revealed high determination coefficients for N-NO3− (R2 = 0.703), K+ (R2 = 0.705), Ca2+ (R2 = 0.715), and Mg2+ (R2 = 0.780) between standard laboratory methods and the reflectometer. These results suggest that the reflectometer enables a real-time diagnostic tool for monitoring nutrient status throughout the growth cycle, particularly key nutrients related to fruit quality. The N–P–K fertilization strategies had no influence on the nutrient content of leaves or petiole sap. The nutrient content of both sample types varied depending on the orchard.
The max-out min-in problem: A tool for data analysis Jorge Orestes Cerdeira, Maria João Martins, Marcos Raydan Computers and Operations Research, 2023 Consider a graph with vertex set V and non-negative weights on the edges. For every subset of vertices S, define ϕ(S) to be the sum of the weights of edges with one vertex in S and the other in V∖S, minus the sum of the weights of the edges with both vertices in S. We consider the problem of finding S⊆V for which ϕ(S) is maximized. We call this combinatorial optimization problem the max-out min-in problem (MOMIP). In this paper we (i) present a linear 0/1 formulation and a quadratic unconstrained binary optimization formulation for MOMIP; (ii) prove that the problem is NP-hard; (iii) report results of computational experiments on simulated data to compare the performances of the two models; (iv) illustrate the applicability of MOMIP for two different topics in the context of data analysis, namely in the selection of variables in exploratory data analysis and in the identification of clusters in the context of cluster analysis; and (v) introduce a generalization of MOMIP that includes, as particular cases, the well-known weighted maximum cut problem and a novel problem related to independent dominant sets in graphs.
Prediction scenarios of past, present, and future environmental suitability for the Mediterranean species Arbutus unedo L. Alice Maria Almeida, Maria João Martins, Manuel Lameiras Campagnolo, Paulo Fernandez, Teresa Albuquerque, Saki Gerassis, José Carlos Gonçalves, Maria Margarida Ribeiro Scientific Reports, 2022 Climate change is a challenge for forests in the coming decades, with a major impact on species adaptation and distribution. The Mediterranean Basin is one of the most vulnerable hotspots for biodiversity conservation under climate change in the world. This research aimed at studying a Mediterranean species well adapted to the region: the Arbutus unedo L. (strawberry tree). The MaxEnt, a presence-only species-distribution software, was used to model A. unedo’s environmental suitability. The current species potential distribution was accessed based on actual occurrences and selected environmental variables and subsequently projected for the Last Glacial Maximum (LGM), the Mid-Holocene (MH), and the years 2050 and 2070, considering the two Representative Concentration Pathways: RCP4.5 and RCP8.5. Results from the LGM projection suggest the presence of refugia in the core of the Mediterranean Basin, in particular the Iberian Peninsula (IP). The projections for the MH indicate increasing climatic suitability for the species and an eastward expansion, relatively to LGM. The predicted future environmental changes will most likely act as a catalyst for suitable habitat loss and a range shift towards the North is likely to occur.
Nutrient Content with Different Fertilizer Management and Influence on Yield and Fruit Quality in Apple cv. Gala Mariana Mota, Maria João Martins, Gonçalo Policarpo, Layanne Sprey, Mafalda Pastaneira, Patrícia Almeida, Anabela Maurício, Cristina Rosa, João Faria, Miguel B. Martins, Miguel L. de Sousa, Ricardo Santos, Rui M. de Sousa, Anabela B. da Silva, Henrique Ribeiro, Cristina M. Oliveira Horticulturae, 2022 Assessing a plant’s nutritional status and fertilizer rates and types that can optimize fruit quality and yield are critical in intensive apple orchards. The aim of this work was to identify correlations between nutrients in the different organs that allow the early diagnosis of the nutritional status and to assess the impact on the optimal nutrient content in apple leaves, as well as in the yield and quality of chemical and organic fertilization. Five orchards of ‘Gala’ were fertilized with different levels of NPK over a period of four years. Macro and micronutrients of buds, flowers, 45 and 90–110 days after full bloom (DAFB) leaves and 60 DAFB and 15 days before harvest (DBH) fruits were determined. Boron was the only element for which strong correlations, 0.7 < r < 0.9, were observed between all organ pairs. The fertilization treatments did not affect the nutrient concentrations in the leaves of 90–110 DAFB other than P, Ca and Mg and did not affect the macronutrients in the fruit. In one of the five orchards, the yield increased by 26% with double fertilization compared to standard fertilization and, for the other four orchards, the impact depended on the year. Fruit size was more related to crop load than to fertilization and TSS and firmness were not affected by the type or amount of fertilizers. Replacing part of the chemical fertilizer with organic materials did not affect productivity or fruit quality.
Functional Diversity of Riparian Woody Vegetation Is Less Affected by River Regulation in the Mediterranean Than Boreal Region Ivana Lozanovska, María Dolores Bejarano, Maria João Martins, Christer Nilsson, Maria Teresa Ferreira, Francisca C. Aguiar Frontiers in Plant Science, 2020 River regulation may filter out riparian plants often resulting in reduced functional diversity, i.e., in the range of functions that organisms have in communities and ecosystems. There is, however, little empirical evidence about the magnitude of such reductions in different regions. We investigated the functional diversity patterns of riparian woody vegetation to streamflow regulation in boreal Sweden and Mediterranean Portugal using nine plant functional traits and field data from 109 sampling sites. We evaluated changes in mean plant functional traits as well as in indices of multidimensional functional traits, i.e., functional richness (FRic) and functional redundancy (FRed) within regions and between free-flowing and regulated river reaches. We found that regulation significantly reduced functional diversity in Sweden but not in Portugal. In Sweden, the increased magnitude of variations in water flow and water level in summer, the prolonged duration of extreme hydrological events, the increased frequency of high-water pulses, and the rate of change in water conditions were the likely main drivers of functional diversity change. Small riparian plant species with tiny leaves, poorly lignified stems, and shallow root systems were consistently associated with regulated sites in the boreal region. In Portugal, the similar functional diversity values for free-flowing and regulated rivers likely stem from the smaller streamflow alterations by regulation combined with the species legacy adaptations to the Mediterranean natural hydrological regimes. We conclude that streamflow regulation may reduce the functional diversity of riparian woody vegetation, but the magnitude of these effects will vary depending on the adaptations of the local flora and the patterns of streamflow disturbances. Our study provides insights into functional diversity patterns of riparian woody vegetation affected by regulation in contrasting biomes and encourages further studies of the functional diversity thresholds for maintaining ecosystems.
Long-term human-generated alterations of Tagus River: Effects of hydrological regulation and land-use changes in distinct river zones Maria Rosário Fernandes, Francisca C. Aguiar, Maria João Martins, Rui Rivaes, Maria Teresa Ferreira Catena, 2020 Large rivers on the Iberian Peninsula reflect a long-history of human interventions and natural disturbances in the fluvial corridors and on the surrounding valleys. In this study we aim to characterize the river morphology in pre-regulation times and understand the morphological changes of the large river Tagus (Central Portugal), across space and time. For this, we used comparable military thematic maps from three dates (1855, 1940 and 2000) and evaluated the river landforms, including sinuosity, aquatic, geomorphic and riparian aspects, in three geomorphological zones (Upland, Middle, and Lowland) using a Geographic Information System (GIS). We related the landform variations to the hydrological alterations and to Land-use Land-Cover (hereinafter LULC) changes at valley level. Hydrological data were achieved by simulating river flow regime using the Soil and Water Assessment Tool (SWAT) model. LULC data was obtained by on-screen digitizing of the military thematic maps complemented with ancillary bibliographic information. Metrics for channel form, aquatic and riparian features were quantified in 51 sampling units of 2500 m-long river sections for each period to describe the river morphology. Shannon-Wiener Index (H’) was applied as a descriptor of the morphological diversity. Data analysis revealed a narrowing of the main channel, an overall reduction of the sinuosity, a smaller number of instream geomorphic units and abandoned lateral channels on the most recent period. Morphological alterations were driven primarily by the reduction of floods and sediment inputs, caused by streamflow regulation, while the agricultural intensification, the augment of forest plantations and the reduction of the Mediterranean scrublands induced changes in sediment dynamics and altered the riparian connectivity. The Upland zone showed the highest morphological alterations switching from a historical high-energy section to a low-dynamic zone. We also observed a high morphological variability in the Middle course exhibiting multifaceted gradients of change, while the Lowland zone reflected continuous but less pronounced modifications. River management planning should express the insights of how past and present human alterations affect morphological processes in river-floodplain systems, particularly taking into account river zones’ specificities and how they may react or constrain potential restoration processes.
Carbon stock estimations in a mediterranean riparian forest: A case study combining field data and UAV imagery Maria Rosário Fernandes, Francisca C. Aguiar, Maria João Martins, Nuno Rico, Maria Teresa Ferreira, Alexandra C. Correia Forests, 2020 This study aims to estimate the total biomass aboveground and soil carbon stocks in a Mediterranean riparian forest and identify the contribution of the different species and ecosystem compartments to the overall riparian carbon reservoir. We used a combined field and object-based image analysis (OBIA) approach, based on unmanned aerial vehicle (UAV) multispectral imagery, to assess C stock of three dominant riparian species. A linear discriminator was designed, based on a set of spectral variables previously selected in an optimal way, permitting the classification of the species corresponding to every object in the study area. This made it possible to estimate the area occupied by each species and its contribution to the tree aboveground biomass (AGB). Three uncertainty levels were considered, related to the trade-off between the number of unclassified and misclassified objects, leading to an error control associated with the estimated tree AGB. We found that riparian woodlands dominated by Acacia dealbata Link showed the highest average carbon stock per unit area (251 ± 90 tC ha−1) followed by Alnus glutinosa (L.) Gaertner (162 ± 12 tC ha−1) and by Salix salviifolia Brot. (73 ± 17 tC ha−1), which are mainly related to the stem density, vegetation development and successional stage of the different stands. The woody tree compartment showed the highest inputs (79%), followed by the understory vegetation (12%) and lastly by the soil mineral layer (9%). Spectral vegetation indices developed to suppress saturation effects were consistently selected as important variables for species classification. The total tree AGB in the study area varies from 734 to 1053 tC according to the distinct levels of uncertainty. This study provided the foundations for the assessment of the riparian carbon sequestration and the economic value of the carbon stocks provided by similar Mediterranean riparian forests, a highly relevant ecosystem service for the regulation of climate change effects.
Effects of a large irrigation reservoir on aquatic and riparian plants: A history of survival and loss Francisca C. Aguiar, Maria Rosário Fernandes, Maria João Martins, Maria Teresa Ferreira Water Switzerland, 2019 Dammed rivers have unnatural stream flows, disrupted sediment dynamics, and rearranged geomorphologic settings. Consequently, fluvial biota experiences disturbed functioning in the novel ecosystems. The case study is the large irrigation reservoir Alqueva in Guadiana River, Southern Iberia. The study area was divided into three zones: upstream and downstream of the dam and reservoir. For each zone, species composition and land use and land cover (LULC) were compared before and after the Alqueva Dam implementation. Data consist of aquatic and riparian flora composition obtained from 46 surveys and the area (%) of 12 classes of LULC obtained in 90 riverine sampling units through the analysis of historical and contemporary imagery. There was an overall decrease of several endemic species and on the riparian shrublands and aquatic stands, although differences in the proportion of functional groups were not significant. Nevertheless, compositional diversity shows a significant decline in the upstream zone while landscape diversity shows an accentuated reduction in the reservoir area and downstream of the dam, which is likely related to the loss of the rocky habitats of the ‘old’ Guadiana River and the homogenization of the riverscape due to the irrigation intensification. The mitigation of these critical changes should be site-specific and should rely on the knowledge of the interactions between surrounding lands, ecological, biogeomorphologic, and hydrological components of the fluvial ecosystems.
Combining social media photographs and species distribution models to map cultural ecosystem services: The case of a Natural Park in Portugal Pedro Clemente, Marta Calvache, Paula Antunes, Rui Santos, Jorge Orestes Cerdeira, Maria João Martins Ecological Indicators, 2019 Developing spatially explicit models of Ecosystem Services (ES) distribution and diversity across the territory has been increasingly attracting the interest of researchers and policy-makers due to its potential to operacionalize and mainstream the ES concept into existing planning and policy tools. In this paper we explore the use of social media photographs to model the spatial distribution of people preferences for cultural ecosystem services (CES), map their hotspots, identify the determinant variables as well as the spatial correlation between CES. This research was applied in the Sudoeste Alentejano and Costa Vicentina Natural Park (PNSACV) located in Southwestern Alentejo, Portugal. A collection of 1378 geo-tagged digital images taken inside the Park and posted in the Flickr web platform between 2004 and 2015 were analyzed and classified according to a tailored list of CES. To model CES spatial distribution it was used a species distribution model – Maxent – adapted to combine the observation of CES occurrence with biophysical and infrastructural variables. This method allowed us to identify and map the social preferences for CES in this area. The distance to the ocean and distance to touristic and cultural infrastructure were the most determinant variables to explain CES distribution in PNSACV. Another relevant result of this study was the identification of pairs of CES (such as Recreation & Aesthetics services) with a significant spatial overlap. Using social media data can be an expedite and cost-effective way to identify and map CES, although this approach embodies some challenges and biases that need to be considered. The use of species distribution models, such as Maxent, can be particularly valuable to support the design of future scenarios and assist decision-making on land use planning.
Paddy rice stored under hermetic conditions: The effect of relative humidity, temperature and storage time in suppressing Sitophilus zeamais and impact on rice quality Maria Otilia Carvalho, Patrícia Fradinho, M. João Martins, Ana Magro, Anabela Raymundo, Isabel de Sousa Journal of Stored Products Research, 2019 The aim of this study was to analyse the effect of relative humidity in suppressing Sitophilus zeamais, in paddy rice stored under hermetic conditions, during four and seven months, at different average temperatures, as well as the impact on rice quality. Hermetic bags, GrainPro® SuperGrainbag® Farm™, were used to store two rice varieties under three different relative humidities: 67%, 75% and 85% RH, and average temperatures of 14 °C, 17 °C and 24 °C, both monitored by Hobo® Data loggers, with the probe placed inside the bags. CheckpointII Portable O2 and CO2 Gas Analyzer was used to assess gas contents on the top and bottom of each bag. At the end of the trials, paddy samples were collected to estimate water activity (aw). The rheology behaviour of rice pastes prepared with race flour obtained from the different treatments was also evaluated, using a controlled stress rheometer. The results showed that the response of the stored-product insects changes with environmental conditions, O2 and CO2 contents. Other parameters were considered; aw increased with relative humidity and temperature, but decreased with storage time. The relative humidity played an important role, together with the increase of temperature, in suppressing insect populations. A modified atmosphere was naturally produced inside the hermetic bag, under 85% RH, with low O2 and high CO2 contents, at different average temperatures, 14 °C and 17 °C. These results demonstrated that S. zeamais can survive, but has no progeny. Under the same conditions, but at the higher average temperature of 24 °C, S. zeamais attained 100% mortality before producing progeny. The increase on respiration rate, registered by CO2 increase and O2 decrease, for higher RH values, reduced the viscoelastic functions and changed the starch gelatinization point of Indica and Japonica rice. The results obtained showed that storing paddy hermetically, at low relative humidity, did not change atmospheric content and maintained the viscoelastic functions of the rice pastes.
Revisiting niche fundamentals with Tukey depth Jorge Orestes Cerdeira, Tiago Monteiro‐Henriques, Maria João Martins, Pedro C. Silva, Diogo Alagador, Aldina M. A. Franco, Manuel L. Campagnolo, Pedro Arsénio, Francisca C. Aguiar, Mar Cabeza Methods in Ecology and Evolution, 2018
Resampling methodologies and reliable tail estimation South African Statistical Journal, 2015
Data depth for the uniform distribution Pedro C. Silva, J. Orestes Cerdeira, M. João Martins, T. Monteiro-Henriques Environmental and Ecological Statistics, 2014
