Zoonotic diseases and alien species invasion

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carbon agriculture in agricultural policies in Brazil5 (Mbow et al., 2019[22]). Low-carbon agricultural policies entail the reduction of deforestation, the restoration of degraded pasture areas, the adoption of integrated agroforestry systems6 and no-till agricultural techniques in order to reduce national GHG emissions (Oliveira and al., 2017[23]; Mozzer, 2011[24]; Mbow et al., 2019[22]).

Land use changes may exacerbate some of the consequences of climate change, such as the risk

of wildfires. Land use change influences the risk of wildfires by changing the amounts of flammable material that surrounds a fire (called fuel loads) and ignition frequency (Butsic, Kelly and Moritz, 2015[25]). For instance, changes from active agricultural fields to shrublands and increase in livestock density tend to increase fire ignition frequency (Butsic, Kelly and Moritz, 2015[25]). Decreased grazing and forest regrowth increase fuel loads (Butsic, Kelly and Moritz, 2015[25]). Biodiversity loss is also related to an increased vulnerability to wildfires that is sometimes caused by a combination of land clearing and drought, as it happened recently in Indonesia’s tropical forests (TNC, 2019[26]) and in the world’s largest tropical wetland, the Pantanal in South America (Mega, 2020[27]). Large fires have a direct negative impact on the human well-being, caused by air pollution, cost of suppression activities, and loss of property and human lives (Brockerhoff et al., 2017[28]).

Zoonotic diseases and alien species invasion

Urbanisation, deforestation, and ecosystem degradation are key drivers of the emergence and reemergence of infectious diseases (zoonoses) by altering biomes and host and pathogen population dynamics (Jones et al., 2013[29]). Land-use changes often lead to increased exposure of humans and domestic animals to pathogen-carrying wildlife (OECD, 2020[30]) and heighten the risk of virus spill-over from wildlife to domestic animals and humans, known as zoonosis (Faust et al., 2018[31]). It is estimated that about one billion people get sick and millions die every year from zoonoses (such as Chagas disease, Dengue, Ebola virus disease, Plague, Rabies) (WHO, 2014[32]). Using modelling, Faust et al. (2018[31]) found that the risk of pathogen spill-over from wildlife to domestic animals and humans, and the reverse, is highest in cases of habitat loss such as forest clearing for agriculture or mixed human use. The consequences of agricultural intensification on zoonotic diseases risks are mixed. On the one hand, agricultural intensification can reduce pressure on natural ecosystems by reducing the demand for land, thereby reducing human and livestock interaction with pathogen-carrying wildlife(OECD, 2020[3]). On the other hand, unsustainable intensification of livestock production carries a risk of zoonoses for which there are epidemiological interactions between wildlife and livestock7 (UNEP; ILRI, 2020[33]; Jones et al., 2013[29]) For instance, higher density of poultry or pig populations favours the adaptation of an introduced influenza virus and amplification for transmission between farms, to humans and to wildlife (Jones et al., 2013[29]). Land-use changes can facilitate the diffusion of invasive alien species. Ways that can link land-use to invasive alien species can be categorized as follows: Some invasive alien species can capitalize on degraded ecosystems. For instance, the tsetse fly (Glossina spp) invaded a degraded ecosystem in East Africa thanks to the newly installed Lantana camara (a neotropical shrub). This fly carries sleeping sickness (Mack and Simberloff, 2000[34]).

5 Low Carbon Agriculture Plan (ABC “Agricultura de Baixo Carbono” in Portuguese), which is based on low interest credit for investment in sustainable agricultural technologies 6 Integrated agroforestry systems are agricultural systems that strategically integrate two or more components among crops, livestock and forestry. The activities can be in consortium, succession or rotation in order to achieve overall synergy. 7 Livestock can act as an intermediate between wildlife and humans.