DUGi

Assessing the structural effects of habitat on pinecone production and consumption : an integrated approach using remote sensing and vegetation indices to understand cone production and seed predation

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@28529

This study aims to understand how environmental variables and the structural complexity of Mediterranean pine forests influence cone production and their consumption by squirrels (Sciurus vulgaris). To achieve this, the availability and morphology of cones in different species and developmental stages (mature, immature, and serotinous Aleppo pine; Scots pine; and Black pine) were analysed by combining field data with structural measurements of trees and remote sensing data of vegetation indices (NDVI and EVI) and landscape structure (using LiDAR data), reflecting productivity and vegetation condition in current and past periods, with data collected from 2019 to 2024. Results show that the availability of Aleppo pine (Pinus halepensis) cones is negatively correlated with crown size and trunk diameter, suggesting a potential reproductive cost associated with competition or maintenance in larger or more competitive trees. Vegetation indices EVI from current and previous year have a positive relationship with cone production, highlighting the importance of recent favourable conditions. Interestingly, EVI with a three-year lag shows a negative influence, suggesting that adverse environmental conditions in previous years may have delayed effects on reproduction. Results also indicate that cone morphology, such as length, is a good predictor of seed production in Aleppo pine, a pattern confirmed in other pine species. Similar patterns related to availability and production were observed in other pine species and developmental stages of Aleppo pine analysed. Regarding the consumption of Aleppo pine cones by squirrels, a marginal relationship was observed with the three-year lagged EVI, indicating that past productivity influences the behaviour of seed predators. At the landscape level, fragmentation and structural heterogeneity show different effects depending on the species and developmental stage of the cone, affecting availability and reproduction. Overall, the study highlights the importance of considering cumulative environmental effects over several years and the structural complexity of forests to manage and conserve these ecosystems amid the challenges posed by climate change and environmental variability

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