The habitat selection by the wild boar was studied in the Ticino Valley Regional Park. The study was carried out collecting data on distribution and abundance of presence signs along 30 itineraries (average length 8.02 km, SD = 2.97) surveyed in autumn-winter and spring. We firstly compared the use of the different habitat types with their availability by the Manly-Chesson α index. To estimate the effect of habitat composition on wild boar presence we formulated a Resource Selection Probability Function (RSPF) by Binary Logistic Regression Analysis (BLRA). To analyse the attendance of the different type of habitats by the species we carried out correlation and regression analyses between the Index of Kilometric Abundance (IKA) and the percentage of habitat types on the itineraries. Wild boar mainly selected woodland during the whole year, coniferous forests are used as availability while rice fields and urbanized areas avoided. The meadows are mainly used during autumn and winter while in spring the presence of wild boar was higher in areas where the length of the forest edges is greater. The logistic model formulated show that high-density deciduous forests positively affected the probability of wild boar presence. Meadows and fields instead showed a negative influence. The Special Protection Area “Risaie della Lomellina” was the subject of a study that aimed to determine the impact of wild boar on croplands and to formulate a risk prediction model through a binary logistic regression analysis. Damage events almost exclusively involved maize, and were concentrated in spring and summer. Sporadic cases of damage concerned rice, soybean and sorghum fields. The risk of damage was higher in fields close to forests, far from main roads, urban areas and continuous hedgerows, and in areas with low human population densities. In the Ticino Valley Natural Park, from 2010 to 2017, 49% of the complaints report an event of damage to maize and 43% to meadows. The total expense for reimbursements of the maize amounted to € 439,341.52, with damages concentrated in May, after sowing period and between August and September, during the milky stage of maize. For meadows, reimbursements amounted to € 324,768.66, with damage events concentrated in February and March. To reduce damage to crops, the Park administration carried out lethal control of the wild boar population. From 2006 to 2017, the most used control method was culling from hides. In our analysis, we did not find significant relationships between the number of shot boars and the amount of damage. The factors that determine the decrease in the probability of damage to crops are mainly related to human disturbance and the characteristics of the fields. The predictive model of damage risk showed a good predictive ability. The Population Viability Analyses showed that it is not possible to obtain a drastic reduction with the current harvest rate. By tripling it and focusing on the females and sub-adult a numerical reduction of 50% of the population would be achievable in 7 years and the probability of population survival would be halved in 3 years. Between March and August 2019 we investigated the factors influencing feeding habitat selection of the wild boar, and the impact of rooting on nemoral flora. Feeding during spring and summer seems concentrated in wooded areas characterized by fresh soils, where the thickness of the litter is greater and the mast content, especially acorns, is greater. We found a significant correlation between the intensity of rooting and the presence of nemoral species, it does not seem to have a significant and negative effect on the number of species present or their abundance in the sampled areas. The floristic diversity and the dominance ratios are not influenced by the rooting intensity.

La selezione degli habitat del cinghiale è stata studiata nel Parco Regionale della Valle del Ticino, raccogliendo dati sulla distribuzione e abbondanza dei segni di presenza lungo 30 itinerari (lunghezza media 8,02 km, SD = 2,97) rilevati in autunno-inverno e primavera. Abbiamo confrontato l'uso dei diversi tipi di habitat con la loro disponibilità dall'indice α di Manly-Chesson. Per stimare l'effetto della composizione dell'habitat sulla presenza di cinghiali, abbiamo formulato una funzione di probabilità di selezione delle risorse (RSPF) mediante analisi di regressione logistica binaria (BLRA). Per analizzare la presenza nei diversi tipi di habitat, abbiamo effettuato analisi di correlazione e regressione tra l'Indice di Abbondanza Chilometrica (IKA) e la percentuale di tipi di habitat sugli itinerari. Il cinghiale principalmente seleziona i boschi decidui durante tutto l'anno, le foreste di conifere sono utilizzate secondo la loro disponibilità mentre le risaie e le aree urbanizzate vengono evitate. I prati sono prevalentemente utilizzati durante l'autunno e l'inverno mentre in primavera la presenza del cinghiale è più alta nelle zone dove la lunghezza dei margini del bosco è maggiore. Il modello logistico formulato mostra che le foreste decidue ad alta densità hanno influenzato positivamente la probabilità di presenza di cinghiali. Prati e campi hanno invece mostrato un'influenza negativa. La Zona di Protezione Speciale “Risaie della Lomellina” è stata oggetto di uno studio per determinare l'impatto del cinghiale sui terreni coltivati e formulare un modello di previsione del rischio attraverso un'analisi di regressione logistica binaria. I danni hanno riguardato quasi esclusivamente il mais e si sono concentrati in primavera ed estate. Casi sporadici di danni hanno riguardato campi di riso, soia e sorgo. Il rischio di danni è risultato maggiore nei campi vicini alle foreste, lontano dalle strade principali, dalle aree urbane e dalle siepi continue, e nelle aree a bassa densità di popolazione umana. Nel Parco Naturale della Valle del Ticino, dal 2010 al 2017, il 49% delle denunce riporta un evento di danno al mais e il 43% ai prati. La spesa complessiva per rimborsi del mais è stata pari a 439.341,52 euro, con danni concentrati a maggio e tra agosto e settembre. Per i prati i rimborsi sono stati pari a 324.768,66 euro, con eventi di danno concentrati nei mesi di febbraio e marzo. Per ridurre i danni alle colture, l'amministrazione del Parco ha effettuato un controllo letale della popolazione di cinghiali. Dal 2006 al 2017, il metodo di controllo più utilizzato è stato l'abbattimento da altana. Non abbiamo trovato relazioni significative tra il numero di cinghiali abbattuti e l'entità del danno. I fattori che determinano la diminuzione della probabilità di danni alle colture sono principalmente legati al disturbo antropico e alle caratteristiche dei campi e il modello predittivo del rischio di danno ha mostrato una buona capacità predittiva. Le analisi della vitalità della popolazione hanno mostrato che non è possibile ottenere una riduzione drastica con l'attuale tasso di prelievo. Triplicandolo e concentrandolo sulle femmine e sui subadulti si otterrebbe una riduzione numerica del 50% della popolazione in 7 anni e la probabilità di sopravvivenza della popolazione sarebbe dimezzata in 3 anni. Tra marzo e agosto 2019 abbiamo studiato i fattori che influenzano la selezione dell'habitat alimentare del cinghiale e l'impatto del grufolamento sulla flora nemorale. L'alimentazione durante la primavera e l'estate sembra concentrata nelle zone boschive caratterizzate da suoli freschi, dove lo spessore della lettiera è maggiore e il contenuto di frutti, soprattutto ghiande, è maggiore. Nonostante la correlazione significativa tra rooting e presenza delle nemorali non sembra esserci un effetto significativo e negativo sul numero e l'abbondanza di specie presenti.

(2021). Wild boar impacts on crops and nemoral flora in lowland areas of northern Italy. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2021).

Wild boar impacts on crops and nemoral flora in lowland areas of northern Italy

CAPPA, FABRIZIO
2021

Abstract

The habitat selection by the wild boar was studied in the Ticino Valley Regional Park. The study was carried out collecting data on distribution and abundance of presence signs along 30 itineraries (average length 8.02 km, SD = 2.97) surveyed in autumn-winter and spring. We firstly compared the use of the different habitat types with their availability by the Manly-Chesson α index. To estimate the effect of habitat composition on wild boar presence we formulated a Resource Selection Probability Function (RSPF) by Binary Logistic Regression Analysis (BLRA). To analyse the attendance of the different type of habitats by the species we carried out correlation and regression analyses between the Index of Kilometric Abundance (IKA) and the percentage of habitat types on the itineraries. Wild boar mainly selected woodland during the whole year, coniferous forests are used as availability while rice fields and urbanized areas avoided. The meadows are mainly used during autumn and winter while in spring the presence of wild boar was higher in areas where the length of the forest edges is greater. The logistic model formulated show that high-density deciduous forests positively affected the probability of wild boar presence. Meadows and fields instead showed a negative influence. The Special Protection Area “Risaie della Lomellina” was the subject of a study that aimed to determine the impact of wild boar on croplands and to formulate a risk prediction model through a binary logistic regression analysis. Damage events almost exclusively involved maize, and were concentrated in spring and summer. Sporadic cases of damage concerned rice, soybean and sorghum fields. The risk of damage was higher in fields close to forests, far from main roads, urban areas and continuous hedgerows, and in areas with low human population densities. In the Ticino Valley Natural Park, from 2010 to 2017, 49% of the complaints report an event of damage to maize and 43% to meadows. The total expense for reimbursements of the maize amounted to € 439,341.52, with damages concentrated in May, after sowing period and between August and September, during the milky stage of maize. For meadows, reimbursements amounted to € 324,768.66, with damage events concentrated in February and March. To reduce damage to crops, the Park administration carried out lethal control of the wild boar population. From 2006 to 2017, the most used control method was culling from hides. In our analysis, we did not find significant relationships between the number of shot boars and the amount of damage. The factors that determine the decrease in the probability of damage to crops are mainly related to human disturbance and the characteristics of the fields. The predictive model of damage risk showed a good predictive ability. The Population Viability Analyses showed that it is not possible to obtain a drastic reduction with the current harvest rate. By tripling it and focusing on the females and sub-adult a numerical reduction of 50% of the population would be achievable in 7 years and the probability of population survival would be halved in 3 years. Between March and August 2019 we investigated the factors influencing feeding habitat selection of the wild boar, and the impact of rooting on nemoral flora. Feeding during spring and summer seems concentrated in wooded areas characterized by fresh soils, where the thickness of the litter is greater and the mast content, especially acorns, is greater. We found a significant correlation between the intensity of rooting and the presence of nemoral species, it does not seem to have a significant and negative effect on the number of species present or their abundance in the sampled areas. The floristic diversity and the dominance ratios are not influenced by the rooting intensity.
MERIGGI, ALBERTO
BANI, LUCIANO
Sus scrofa; Crop damages; Undergrowth flora; Biodiversity; Prelievo selettivo
Sus scrofa; Danni agricoli; Flora di sottobosco; Biodiversità; Prelievo selettivo
BIO/05 - ZOOLOGIA
English
11-feb-2021
SCIENZE CHIMICHE, GEOLOGICHE E AMBIENTALI
33
2019/2020
open
(2021). Wild boar impacts on crops and nemoral flora in lowland areas of northern Italy. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2021).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/305594
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