In recent decades, in marginal areas of Mediterranean Europe, there has been a "migration" process of local populations towards more urbanized areas, coastal or valley floors, with a consequent abandonment of primary activities linked to the mountain territory. One of the consequences was the progressive renaturalization of the agro-pastoral areas in which the woods are reoccupying the ancient areas of their relevance. This study, limited to a side of the Marche sector of the Laga Mountains (Macera della Morte), aims to evaluate both the variations of the forest cover along an altitude gradient (from 1000 to 1700 meters above sea level), and the space-time dynamisms of the clearings (gap) and the upper limit of the forest, from the mid-20th century. to date. The work was performed through a multi-temporal analysis. For this purpose, images from 1954 (Volo GAI), 1978 (Volo Marche) and 2017 (Google satellite images) were used. The three images were classified into five different land use classes (forest - grassland - cultivated - non-vegetated - artificial). At the end of the classification, a validation and post-processing was performed through the application of low-pass filters. The variations in land use were quantified through the creation of the respective transition matrices. Finally, for each landscape some metrics were calculated (Edge density, Number of patches, Mean patch area, Patch density) and the Shannon, Evenness and Simpson diversity indices for the three images. Finally, the forest gaps for each classified image were highlighted and analysed, divided by altitudinal bands. At the upper limit of the forest, coverage variation analyses were carried out in 30 circular plots with a radius of 50 m and related to the main pedo-morphological factors. The changes in land use and consequently in the forest landscape testify to a progressive renaturalization of the coenosis, tending to a relative structural homogeneity in favour of the forest classes. The increase in wooded area in the two time periods analysed is significantly higher in the first period (1954-1978) than in the second (1978-2017), passing from a rate of change of 16.5 to 4.3 ha / respectively. year. At the landscape level, from 1954 to 2017 there was a progressive decrease in the surface and fragmentation of the "non-wooded" areas transformed into small isolated "pieces" embedded in a forest matrix. These processes have had greater rhythms and intensities in the higher sectors with a greater decrease in both the number of non-wooded patches and their average extent. All this testifies to a progressive homogenization of the landscape, which passes from a high level of mixing and interconnectivity between habitats to greater ecological uniformity and simplification. Similar results were obtained from the analysis of the upper limit of the forest. Probably, following a decrease in anthropogenic pressure, there has been a progressive densification of the high-altitude forests and the definition of a closed forest limit. The current state of the landscape is characterized by few and small residual non-wooded patches, set in the forest matrix, which soon could be destined to disappear in the absence of interventions aimed at limiting the vegetation dynamics. It is therefore essential to ask we which management strategies to support, or whether it is better to lose an articulated mosaic that allows the mixing of different habitats in favour of a more "natural" but homogeneous landscape, or to resume the various agro-forestry-pastoral activities to restore / maintain greater landscape variability.
Negli ultimi decenni in aree marginali dell’Europa mediterranea, si è assistito ad un processo “migratorio” delle popolazioni locali verso le aree maggiormente urbanizzate, costiere o di fondovalle, con un conseguente abbandono delle attività primarie legate al territorio montano. Una delle conseguenze, è stata la progressiva rinaturalizzazione delle aree agro-pastorali nelle quali i boschi stanno rioccupando gli antichi areali di loro pertinenza. Questo studio, limitato ad un versante del settore marchigiano dei Monti della Laga (Macera della Morte), si propone di valutare sia le variazioni della copertura forestale lungo un gradiente altitudinale (dai 1000 a 1700 m.s.l.m. circa), sia i dinamismi spazio-temporali delle radure (gap) e del limite superiore del bosco, dalla metà del XX sec. ad oggi. Il lavoro è stato eseguito mediante un’analisi multi-temporale. A tale scopo sono state utilizzate immagini del 1954 (Volo GAI), del 1978 (Volo Marche) e del 2017 (Immagini satellitari Google). Le tre immagini sono state classificate in cinque diverse classi di uso del suolo (bosco – prateria - coltivi – non-vegetato - artificiale). Al termine della classificazione, è stata eseguita una validazione ed un post-processamento attraverso l’applicazione di filtri passa-basso. Le variazioni di uso del suolo sono state quantificate attraverso la realizzazione delle rispettive matrici di transizione. Infine, per ogni paesaggio sono state calcolate alcune metriche (Edge density, Number of patch, Mean patch area, Patch density) e gli indici di diversità di Shannon, Evenness e Simpson per le tre immagini. Infine, sono stati messi in evidenza ed analizzati i gap forestali per ogni immagine classificata, suddivisi per fasce altitudinali. Nel limite superiore del bosco, sono state effettuate delle analisi di variazione di copertura in 30 plot circolari di raggio 50 m e messe in relazione con i principali fattori pedo-morfologici. I cambiamenti di uso del suolo e conseguentemente del paesaggio forestale, testimoniano una progressiva rinaturalizzazione delle cenosi, tendenti ad una relativa omogeneità strutturale a favore delle classi forestali. L’incremento della superficie boscata nei due periodi temporali analizzati è nettamente superiore nel primo periodo (1954-1978) rispetto al secondo (1978-2017), passando da un tasso di cambiamento rispettivamente di 16,5 ad uno di 4,3 ha/anno. A livello paesaggistico, dal 1954 al 2017 c’è stata una progressiva diminuzione superficiale e frammentazione delle aree “non boscate” trasformate in piccoli “tasselli” isolati incastonati in una matrice forestale. Questi processi hanno avuto ritmi ed intensità maggiori nei settori più elevati con una maggiore diminuzione sia del numero delle patch non boscate sia della loro estensione media. Tutto questo testimonia una progressiva omogeneizzazione del paesaggio, che passa da un elevato livello di mescolanza e interconnettività fra habitat ad una maggiore uniformità e semplificazione ecologica. Risultati simili sono stati ottenuti dall’analisi del limite superiore del bosco. Probabilmente, a seguito di una diminuzione della pressione antropica, si è verificata una progressiva densificazione dei boschi di alta quota e la definizione di un limite del bosco chiuso. Lo stato attuale del paesaggio è caratterizzato da poche e piccole patch residuali non boscate, incastonate nella matrice forestale, che in un futuro prossimo potrebbero essere destinati a scomparire in assenza di interventi mirati a limitare le dinamiche vegetazionali. È fondamentale quindi interrogarsi su quali strategie gestionali assecondare, ovvero se sia meglio perdere un mosaico articolato che permette la mescolanza di habitat diversi a favore di un paesaggio più “naturale” ma omogeneo, oppure riprendere le varie attività agro-silvo-pastorali al fine di ripristinare/mantenere una maggior variabilità paesaggistica.
Dinamismi spazio-temporali del paesaggio forestale in un versante dei Monti della Laga (AP)
CALANDRA, LUCA
2019/2020
Abstract
In recent decades, in marginal areas of Mediterranean Europe, there has been a "migration" process of local populations towards more urbanized areas, coastal or valley floors, with a consequent abandonment of primary activities linked to the mountain territory. One of the consequences was the progressive renaturalization of the agro-pastoral areas in which the woods are reoccupying the ancient areas of their relevance. This study, limited to a side of the Marche sector of the Laga Mountains (Macera della Morte), aims to evaluate both the variations of the forest cover along an altitude gradient (from 1000 to 1700 meters above sea level), and the space-time dynamisms of the clearings (gap) and the upper limit of the forest, from the mid-20th century. to date. The work was performed through a multi-temporal analysis. For this purpose, images from 1954 (Volo GAI), 1978 (Volo Marche) and 2017 (Google satellite images) were used. The three images were classified into five different land use classes (forest - grassland - cultivated - non-vegetated - artificial). At the end of the classification, a validation and post-processing was performed through the application of low-pass filters. The variations in land use were quantified through the creation of the respective transition matrices. Finally, for each landscape some metrics were calculated (Edge density, Number of patches, Mean patch area, Patch density) and the Shannon, Evenness and Simpson diversity indices for the three images. Finally, the forest gaps for each classified image were highlighted and analysed, divided by altitudinal bands. At the upper limit of the forest, coverage variation analyses were carried out in 30 circular plots with a radius of 50 m and related to the main pedo-morphological factors. The changes in land use and consequently in the forest landscape testify to a progressive renaturalization of the coenosis, tending to a relative structural homogeneity in favour of the forest classes. The increase in wooded area in the two time periods analysed is significantly higher in the first period (1954-1978) than in the second (1978-2017), passing from a rate of change of 16.5 to 4.3 ha / respectively. year. At the landscape level, from 1954 to 2017 there was a progressive decrease in the surface and fragmentation of the "non-wooded" areas transformed into small isolated "pieces" embedded in a forest matrix. These processes have had greater rhythms and intensities in the higher sectors with a greater decrease in both the number of non-wooded patches and their average extent. All this testifies to a progressive homogenization of the landscape, which passes from a high level of mixing and interconnectivity between habitats to greater ecological uniformity and simplification. Similar results were obtained from the analysis of the upper limit of the forest. Probably, following a decrease in anthropogenic pressure, there has been a progressive densification of the high-altitude forests and the definition of a closed forest limit. The current state of the landscape is characterized by few and small residual non-wooded patches, set in the forest matrix, which soon could be destined to disappear in the absence of interventions aimed at limiting the vegetation dynamics. It is therefore essential to ask we which management strategies to support, or whether it is better to lose an articulated mosaic that allows the mixing of different habitats in favour of a more "natural" but homogeneous landscape, or to resume the various agro-forestry-pastoral activities to restore / maintain greater landscape variability.| File | Dimensione | Formato | |
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Tesi_Calandra_Luca_1091519_Dinamismi_spazio-temporali_del_paesaggio_forestale_in_un_versante_dei_Monti_della_Laga(AP).pdf
Open Access dal 12/02/2023
Descrizione: Tesi di Laurea Magistrale di Calandra Luca, matricola 1091519
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https://hdl.handle.net/20.500.12075/4676