SIGEEI

EICAT ASSESSMENT SHEET

Environmental Impact Classification for Alien Taxa

Equus caballus

Linnaeus, 1758

CATEGORIA EICAT: MODERATE (MO) - MODERADO

Herbivoria sobre espécies nativas da flora e mudanças estruturais no ambiente que impactam indiretamente espécies nativas da fauna.

IDENTIFICATION AND CLASSIFICATION

Scientific name

Equus caballus

Autoria

Linnaeus, 1758

Nomes comuns

cavalo

Data da avaliação

03/05/2021

Avaliação

Global, independente de unidade de conservação

Resultado

MODERATE (MO) - MODERADO

NOMENCLATURA E CLASSIFICAÇÃO

Kingdom

Animalia

Phylum

Chordata

Class

Mammalia

Order

Perissodactyla

Family

Equidae

Genus

Equus

PROVENIÊNCIA E REGISTRO

Pessoa responsável pela análise

Rafael Dudeque Zenni

Verificação

Verificado

Verificado por

Não informado

Data da verificação

Não informada

Data de publicação

03/05/2021

Número da versão

Editor da versão atual

Rafael

RESUMO DA AVALIAÇÃO EICAT

Confiança EICAT

Alta

Justificativa da confiança

Há muitos artigos sugerindo o nível de impacto negativo da espécie para a biodiversidade nativa registrado nessa análise.

Países/regiões de maior impacto

Argentina; Austrália; Canadá; Nova Zelândia; Estados Unidos

Locais de maior impacto

Unidades de Conservação, ambientes planos.

Espécies impactadas

Não há

SÍNTESE DOS IMPACTOS

Herbivoria sobre espécies nativas da flora e mudanças estruturais no ambiente que impactam indiretamente espécies nativas da fauna.

AVALIAÇÃO COMPLETA CONFORME O EICAT

As respostas, os mecanismos, as evidências e as referências abaixo preservam a estrutura da avaliação registrada no SIGEEI.

00. O táxon exótico causou impactos ambientais?

Resposta

Sim

Mecanismo(s)

Não informado

Evidência

Não informado

Referências

Não informado

01. O táxon exótico causou reduções no desempenho de indivíduos na biota nativa?

Resposta

Sim

Mecanismo(s)

(8) Pastoreio / Herbivoria / Alimentação,(9) Impacto químico no ecossistema,(11) Impacto estrutural no ecossistema

Evidência

Pastoreio / herbivoria / alimentação: This study shows that horses cause considerable direct environmental impact in central Australia and suggests that they also cause significant indirect changes such as accelerated erosion and restriction of suitable habitat for large macropods. (Berman, 1991) We detected a significant effect of treatments on plant growth where horses were present (F ¼ 5.14, df = 2,421 p= 0.0063); the raised exclosure (p =0.004) and the complete exclosure (p < 0.04) were significantly different from the control, the complete exclosure was similar to the raised exclosure (p=0.60). We detected a total length reduction of 0.59 m for Vaccinium spp., which indicated a biomass loss between 2.4% to 12.5% [...] Our study demonstrated a marked increase in disturbances where horses were present compared to areas where they were excluded. […] Additionally, horses may have been responsible for six of the seven disturbances in the excluded area due to a two-week power outage. We detected few disturbances from white-tailed deer and none from feral pigs. Our results indicated that treatment had a positive effect on growth of vegetation on the side of the fence where horses were present.. […] Despite the short time period between the end of the fence construction and the start of our sampling, we documented significant differences in plant growth between treatments in areas where horses were present. (Porter et al. 2014) Impacto químico no ecossistema: This study suggests that trampling may be the more destructive component of grazing by large ungulates in the marsh. Horses have a strong impact on large portions of the high marsh. Horse grazing pressure is not uniform, but varies from intense near the upland to light further into the marsh. The upland area of marsh is by far the area most severely affected. Some heavily grazed areas are already withstanding very intense grazing pressures. In these areas, standing stocks of live biomass never exceed 40 g m -2 dry mass. Heavily grazed marshes may be more susceptible to erosion and storm damage, since accretion of sediment in marshes is a function of the density of grasses present to trap particles (Gleason et al. 1979). [...] Densities of the salt marsh periwinkle (Littorina irrorata) were highly variable among experimental plots. The south plots contained higher densities of snails than did the north plots; in fact, densities were too low in the north for treatment effects to be observed. Snails on the south plots responded to perturbations, but only during the second grow- ing season. The trend was similar to that seen in the aboveground vegetation. (Turner, 1987) Impacto estrutural no ecossistema: In Tornquist Park this results in great changes in vegetation structure, which, in extreme cases turns into grassy meadows 15 cm high in contrast to grasslands free from exotic herbivores that are over 1 m high. These variations reflect on the richness and diversity of birds, which are greatest in areas subject to moderate levels of grazing, slightly lower in the enclosures and much lower under high grazing pressure, coinciding with changes in the diversity of habitats. In particular it is interesting that the richness and diversity of species are slightly greater in areas of moderate grazing than in the enclosures, as predicted by the theory of intermediate disturbance. […] The presence of feral horses was associated with an increase in the rate of predation of eggs which varied from 12.5% within the enclosures to 70% in grazed areas. It is suggested that the increase in predation rate was due to the increased visibility of the nests and an increase in the density of opportunist carnivores. [...] Our work suggests that there are consistent differences in the composition of bird communities according to grazing intensity, with some species preferring areas of intense grazing and others found exclusively, or more abundantly, in areas with a low density of feral horses. (Zalba et al, 2004)

Referências

Zalba, S. M., & Cozzani, N. C. (2004). The impact of feral horses on grassland bird communities in Argentina. Animal Conservation, 7(1), 35-44. Berman, D. M. (1991). The ecology of feral horses in central Australia. PhD dissertation. University of New England: Armidale, NSW. Porter, K. M., DePerno, C. S., Krings, A., Krachey, M., & Braham, R. (2014). Vegetative impact of feral horses, feral pigs, and white-tailed deer on the Currituck National Wildlife Refuge, North Carolina. Castanea, 79(1), 8-17. Turner, M. G. (1987). Effects of grazing by feral horses, clipping, trampling, and burning on a Georgia salt marsh. Estuaries, 10(1), 54-60.

02. O táxon exótico causou declínio no tamanho da população de alguma espécie nativa?

Resposta

Sim

Mecanismo(s)

(8) Pastoreio / Herbivoria / Alimentação,(10) Impacto físico no ecossistema,(11) Impacto estrutural no ecossistema

Evidência

Bioincrustação: Our results suggest that feral horse grazing can affect some aspects of semi-arid ecosystems. […] At higher levels of horse use there was about half the perennial grass cover in grazed compared to ungrazed exclosures; however, herbaceous cover and density were generally not different between horse grazed and ungrazed areas in our study […] In contrast to the lack of measured effects of feral horse grazing exclusion on herbaceous vegetation abundance, sagebrush density was two-fold higher in horse exclosures suggesting sagebrush recruitment may be limited by feral horses, probably though physical damage of sagebrush. [...] Our results suggest effects of feral horses on species richness and diversity may vary by plant community and site characteristics (grazingplant coevolution, climate, soils, etc.). Plant species diversity was greater in exclosures than feral horse grazed areas in our study. (Davis et al. 2014) Pastoreio / herbivoria / alimentação: The impact of horses was assessed from an existing network of permanent grassland plots and three ungulate exclosure plots established in 1982 to assess vegetation condition and the impact of large grazjng herbivores. [...] In the control plot, continued grazing pressure led to a significant decline in individuals of the highly palatable grass, hair fescue, and also in Festuca nigrescens, Geranium sessilif1orum, Yorkshire fog, Rytidosperma gracile, Stackhousia minima, and Wahlenbergia albomarginata. (Rogers, 1991) Colorinfrared imagery from 1998 and field measurements from 2001 indicated that there was a significant difference in vegetation cover between the fenced and unfenced plotpairs over the study period. Fenced plots contained a higher percentage of vegetation cover that was dominated by American beachgrass (Ammophila breviligulata). [...] Field measurements of vegetation cover from 2001 showed fenced plots averaging between 25% and 50% vegetation cover, whereas unfenced plots contained between 1% and 5% vegetation cover [...] (De Stoppelaire et al. 2004) Ammophila breviligulata, American beachgrass, and Spartina patens, salt meadow hay, have been grazed by feral horses on the dunes of Assateague Island for hundreds of years; however, because of a significant increase in the horse population since the 1960s, overgrazing and dune erosion have become problems. Grazing was assessed on foredunes of four different morphologies along a 21- km stretch of the Maryland portion of the island using 17 exclosure plot pairs. In addition to decreased cover and biomass of the two species, plant structure was significantly affected by grazing. Leaf length and width, stem diameter, and stem density of A. breviligulata and stem diameter of S. patens were reduced in the grazed plots. (Seliskar, 2003) Impacto estrutural no ecossistema: We selected as our study sites six marsh islands of about 10 km 2 each that were adjacent to Shackleford Banks. Three of these islands were accessible to horses [...] Three islands were not visited by horses because of deeper water that deterred horses. [...] To document bird usage and density on each island, we performed scan samples using binoculars from a stationary boat. [...] Using conical, galvanized-steel, wire-mesh minnow traps (42 cm long, 22.5 cm maximum diameter, 3.5 cm entrance diameter), we sampled fish at the marsh surface. [...] Fish abundance and species richness were significantly higher in ungrazed marshes than in grazed marshes ( Fig. 2). Two fish species, mummichogs and pinfish, dominated our samples (18% and 76%, respectively). Adult mummichog abundance averaged 14 times higher in ungrazed than in horse-grazed marshes (Fig. 2), although juvenile mummichogs were captured only in ungrazed marshes (x=1.11 per pit trap; SE = 0.56). Similarly, pinfish were completely absent from grazed marshes (Fig. 2). […] Laughing Gulls (Larus atricilla) and Forster’s Terns (Sterna fosteri) nested in great abundance in ungrazed marshes and dominated the avian assemblage there (96% of the total). However, Laughing Gulls were virtually absent and Forsters’ Terns significantly reduced in numbers on marshes grazed by horses (Table 2; Fig. 1). [...] Experiments manipulating marsh vegetation indicated that the potential for predation on fishes in ungrazed marshes was higher than in grazed marshes. [...] Thus, it appears that when horses remove the shelter provided by Spartina , mummichogs seek shelter in the burrows of xanthid crabs and then become easy prey for the crabs. We did not investigate the mechanisms by which grazing affected pinfish abundance, although it is conceivable that the same processes affecting mummichogs affect pinfish. (Levin et al. 2002)

Referências

Rogers, G. M. (1991). Kaimanawa feral horses and their environmental impacts. New Zealand journal of ecology, 49-64. De Stoppelaire, G. H., Gillespie, T. W., Brock, J. C., & Tobin, G. A. (2004). Use of remote sensing techniques to determine the effects of grazing on vegetation cover and dune elevation at Assateague Island National Seashore: impact of horses. Environmental Management, 34(5), 642-649. Seliskar, D. M. (2003). The response of Ammophila breviligulata and Spartina patens (Poaceae) to grazing by feral horses on a dynamic mid-Atlantic barrier island. American Journal of Botany, 90(7), 1038-1044. Levin, P. S., Ellis, J., Petrik, R., & Hay, M. E. (2002). Indirect effects of feral horses on estuarine communities. Conservation Biology, 16(5), 1364-1371. Davies, K. W., Collins, G., & Boyd, C. S. (2014). Effects of feral free‐roaming horses on semi‐arid rangeland ecosystems: an example from the sagebrush steppe. Ecosphere, 5(10), 1-14.

03. O táxon exótico causou a extinção local de pelo menos uma população de alguma espécie nativa?

Resposta

Não

Mecanismo(s)

Não informado

Evidência

Não informado

Referências

Não informado

04. A extinção local observada é reversível ou irreversível se o táxon exótico for removido?

Resposta

Nenhuma extinção registrada

Mecanismo(s)

Não informado

Evidência

Não informado

Referências

Não informado

INFORMAÇÕES ADICIONAIS DA AVALIAÇÃO

Vias de introdução/dispersão

Introdução deliberada

Comentários e informações adicionais

Não há

Referências adicionais sobre impactos

Volery, L. et al. (2020) Ranking alien species based on their risks of causing environmental impacts: A global assessment of alien ungulates. Global Change Biology https://doi.org/10.1111/gcb.15467 https://onlinelibrary.wiley.com/doi/10.1111/gcb.15467

Bases de dados consultadas

GISD,GRIIS,CABI Invasive Species Compendium

Comentários taxonômicos

Não informado

NOTAS DE INTERPRETAÇÃO PARA O SIGEEI

PRESENÇA NÃO É IMPACTO LOCAL

Esta ficha representa uma avaliação global da espécie. Ela não declara, por si só, que Equus caballus esteja estabelecida, invasora ou causando impacto em uma unidade de conservação específica. Essa distinção deve ser registrada separadamente pelos gestores e especialistas responsáveis pela unidade.

REFERÊNCIAS

Volery, L. et al. (2020) Ranking alien species based on their risks of causing environmental impacts: A global assessment of alien ungulates. Global Change Biology https://doi.org/10.1111/gcb.15467 https://onlinelibrary.wiley.com/doi/10.1111/gcb.15467
Zalba, S. M., & Cozzani, N. C. (2004). The impact of feral horses on grassland bird communities in Argentina. Animal Conservation, 7(1), 35-44. Berman, D. M. (1991). The ecology of feral horses in central Australia. PhD dissertation. University of New England: Armidale, NSW. Porter, K. M., DePerno, C. S., Krings, A., Krachey, M., & Braham, R. (2014). Vegetative impact of feral horses, feral pigs, and white-tailed deer on the Currituck National Wildlife Refuge, North Carolina. Castanea, 79(1), 8-17. Turner, M. G. (1987). Effects of grazing by feral horses, clipping, trampling, and burning on a Georgia salt marsh. Estuaries, 10(1), 54-60.
Rogers, G. M. (1991). Kaimanawa feral horses and their environmental impacts. New Zealand journal of ecology, 49-64. De Stoppelaire, G. H., Gillespie, T. W., Brock, J. C., & Tobin, G. A. (2004). Use of remote sensing techniques to determine the effects of grazing on vegetation cover and dune elevation at Assateague Island National Seashore: impact of horses. Environmental Management, 34(5), 642-649. Seliskar, D. M. (2003). The response of Ammophila breviligulata and Spartina patens (Poaceae) to grazing by feral horses on a dynamic mid-Atlantic barrier island. American Journal of Botany, 90(7), 1038-1044. Levin, P. S., Ellis, J., Petrik, R., & Hay, M. E. (2002). Indirect effects of feral horses on estuarine communities. Conservation Biology, 16(5), 1364-1371. Davies, K. W., Collins, G., & Boyd, C. S. (2014). Effects of feral free‐roaming horses on semi‐arid rangeland ecosystems: an example from the sagebrush steppe. Ecosphere, 5(10), 1-14.