Examinando por Autor "Thomas, Evert"

Mostrando 1 - 4 de 4

Climate change impact on cultivated and wild cacao in Peru and the search of climate change-tolerant genotypes
(Wiley, 2021-05-21) Ceccarelli, Viviana; Fremout, Tobias; Zavaleta, Diego; Lastra, Sphyros; Imán Correa, Sixto Alfredo; Arévalo Gardini, Enrique; Rodriguez, Carlos Armando; Cruz Hilacondo, Wilbert Eddy; Thomas, Evert
Aim: Cacao (Theobroma cacao L.) is expected to be vulnerable to climate change. The objectives of this study were to (a) assess the future impact of climate change on cacao in Peru and (b) identify areas where climate change-tolerant genotypes are potentially present. Methods: Drawing on 19,700 and 1,200 presence points of cultivated and wild cacao, respectively, we modelled their suitability distributions using multiple ensemble models constructed based on both random and target group selection of pseudo-absence points and different resolutions of spatial filtering. To estimate the uncertainty of future predictions, we generated future projections for all the ensemble models. We investigated the potential emergence of novel climates, determined expected changes in ecogeographical zones (zones representative for particular sets of growth conditions) and carried out an outlier analysis based on the environmental variables most relevant for climate change adaptation to identify areas where climate change-tolerant genotypes are potentially present. Results: We found that the best modelling approaches differed between cultivated and wild cacao and that the resolution of spatial filtering had a strong impact on future suitability predictions, calling for careful evaluation of the effect of model selection on modelling results. Overall, our models foresee a contraction of suitable area for cultivated cacao while predicting a more positive future for wild cacao in Peru. Ecogeographical zones are expected to change in 8%–16% of the distribution of cultivated and wild cacao. We identified several areas where climate change-tolerant genotypes may be present in Peru. Main conclusions: Our results indicate that tolerant genotypes will be required to facilitate the adaptation of cacao cultivation under climate change. The identified cacao populations will be target of collection missions.
Co-benefits of soil carbon protection for invertebrate conservation
(EL SEVIER, 2020-11-13) Flores Rios, Angelli; Thomas, Evert; Peri, Pablo P.; Amelung, Wulf; Duarte Guardia, Sandra; Borchard, Nils; Lizárraga Travaglini, Alfonso Diulio; Vélez Azañero, Armando; Sheil, Douglas; Tscharntke, Teja; Steffan Dewenter, Ingolf; Ladd, Brenton
The global decline in invertebrate diversity requires urgent conservation interventions. However, identifying priority conservation areas for invertebrates remains a significant challenge. We hypothesized that aligning the conservation of invertebrate biodiversity with climate change mitigation ofer offers a solution. As both soil carbon storage and invertebrate biodiversity are positively influenced by plant diversity and productivity, a positive correlation can also be expected between SOC and invertebrate biodiversity. Drawing on >10,000 invertebrate observations organized into functional groups, and site-specific soil organic Carbon (SOC) measurements from Patagonia, the Peruvian Andes, and montane tropical rainforest, we examined the role of climate, soil, topographical position and land use for prediction of invertebrate biodiversity. We found that taxonomic and functional invertebrate diversity and abundance closely correlate with SOC stocks within ecosystems. Topographical position of sites, which was partly associated with SOC, was also important, whereas land use was of subordinate importance. We conclude that recent advances in predicting and mapping SOC can guide the identification of habitats within landscapes with high biodiversity and conservation value for invertebrates. Our findings stress the importance of linking global climate change mitigation initiatives that aim to preserve and restore SOC to efforts aimed at improving the conservation of invertebrates and the ecosystem services they provide, for the realization of mutual climate and biodiversity benefits.
The distribution of cadmium in soil and cacao beans in Peru
(Elsevier, 2023-04-11) Thomas, Evert; Atkinson, Rachel; Zavaleta, Diego; Rodriguez, Carlos; Lastra Paucar, Sphyros Roomel-Luciano; Yovera, Fredy; Arango, Karina; Pezo, Abel; Aguilar, Javier; Tames, Miriam; Ramos, Ana; Cruz, Wilbert; Cosme, Roberto; Espinoza, Eduardo; Chavez, Carmen Rosa; Ladd, Brenton
Peru is the eighth largest producer of cacao beans globally, but high cadmium contents are constraining access to international markets which have set upper thresholds for permitted concentrations in chocolate and derivatives. Preliminary data have suggested that high cadmium concentrations in cacao beans are restricted to specific regions in the country, but to date no reliable maps exist of expected cadmium concentrations in soils and cacao beans. Drawing on >2000 representative samples of cacao beans and soils we developed multiple national and regional random forest models to develop predictive maps of cadmium in soil and cacao beans across the area suitable for cacao cultivation. Our model projections show that elevated concentrations of cadmium in cacao soils and beans are largely restricted to the northern parts of the country in the departments of Tumbes, Piura, Amazonas and Loreto, as well as some very localized pockets in the central departments of Huánuco and San Martin. Unsurprisingly, soil cadmium was the by far most important predictor of bean cadmium. Aside from the south-eastern to north-western spatial trend of increasing cadmium values in soils and beans, the most important predictors of both variables in nation-wide models were geology, rainfall seasonality, soil pH and rainfall. At regional level, alluvial deposits and mining operations were also associated with higher cadmium levels in cacao beans. Based on our predictive map of cadmium in cacao beans we estimate that while at a national level <20 % of cacao farming households might be impacted by the cadmium regulations, in the most affected department of Piura this could be as high as 89 %.
Diversidad genética de cacao en el Perú
(Bioversity International, 2023-09-30) Thomas, Evert; Imán Correa, Sixto Alfredo; Atkinson, Rachel; Zavaleta, Diego; Rodriguez, Carlos; Lastra, Sphyros; Murrieta, Edgardo; Farfán, Abel; Castro, Juan; Ramírez, José; Samanamud Curto, Angelo Francisco; Paredes Meneses, Cleydi; Arango, Karina; Cruz, Wilbert; Ramírez, Marleni; Zhang, Dapeng
El principal objetivo de este capítulo es dar a conocer la gran diversidad de cacaos que existen en el Perú para promover tanto su uso como su conservación. El capítulo demuestra que la mayoría de los diferentes cultivares tradicionales y grupos genéticos silvestres tienen una coherencia geográfica que permitirá la implementación de un sistema de denominación de origen para el cacao nativo peruano. Para poner en práctica dicho sistema es crítico tener identificado y tener acceso a materiales puros de cada grupo genético, para así poder apoyar a los agricultores, cooperativas y asociaciones, compradores, inversionistas o autoridades públicas, entre otros, en sus esfuerzos de producir y marquetear cacaos de calidad de origen nativo puro.