Feral pigs in a temperate rainforest ecosystem: disturbance and ecological impacts

• Published in: Biological invasions Vol. 15; no. 10; pp. 2193 - 2204
• Main Authors: Krull, Cheryl R., Choquenot, David, Burns, Bruce R., Stanley, Margaret C.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-10-2013; Springer; Springer Nature B.V
• Subjects: Abundance; Biological and medical sciences; Biomedical and Life Sciences; Decomposition; Developmental Biology; Disturbance; Ecology; Ecosystems; Environmental changes; Environmental impact; Forestry; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Hogs; Invasive species; Life Sciences; Litter; Mammalia; Nitrates; Nitrogen dioxide; Original Paper; Plant Sciences; Planting density; Rainforests; Seedlings; Soil nutrients; Species composition; Species richness; Sus scrofa; Swine; Temperature effects; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Regeneration; Impacts; Feral hog; Exclosure; Disturbance; Natural population; Rain forest; Perturbation; Temperate zone; Disturbed ecosystem; Pig; Vertebrata; Mammalia; Environment impact; Temperate climate; Artiodactyla; Sus scrofa; Ungulata
• ISSN: 1387-3547; 1573-1464
• DOI: 10.1007/s10530-013-0444-9

Feral pigs (
Sus scrofa
) are a widespread invasive species, and cause biotic disturbance. This study evaluated the impacts associated with ground disturbance by feral pigs in the North Island of New Zealand. Exclosure cages were erected over feral pig-disturbed ground and visually undisturbed ground (the latter as controls). Buried resin bags and litter bags were located in these plots to examine differences in soil nutrients and decomposition rates and seedling/sapling recruitment (abundance, species composition and richness) was monitored over 21 months. No difference was found in the litter decomposition between the disturbed and visually undisturbed plots. Significantly more nitrate (NO
3
-N/NO
2
-N) was found in the disturbed exclosures. Seedling density was not significantly affected by feral pig disturbance. However, seedling/sapling species richness was lower in disturbed areas. Species composition changes occurred at disturbed sites with species increasing and decreasing in density after feral pig disturbance. However, no pattern was observed between species that were negatively affected by feral pig disturbance. This study shows that feral pig disturbance affects vegetation through direct removal, but also indirectly through increased nitrate, potentially leading to seedling and sapling species composition changes. Feral pigs are known to return to previously disturbed areas to re-disturb. These areas may remain in a re-disturbed state if not protected, and through continued disturbance and increased nitrate, ecosystem changes may occur, especially in characteristically nutrient poor environments.