Assessing the effects of agricultural intensification on natural habitats and biodiversity in Southern Amazonia

expressed by the population impact, a factor that summarizes the total impact of the anthropo- genic interference in natural ecosystems [43]. Main objective of the paper is to assess the potential effects of future agricultural intensifica- tion on habitat and biodiversity loss in the federal states Mato Grosso (MT) and Para´ (PA) in Brazil. For this purpose, we analyze a set of spatially explicit LULCC scenarios with a time horizon until 2030, characterized by different assumptions regarding agricultural and socio- economic development in the region as well as by different environmental policies. The first part of our study determines the effects of the loss of natural habitat due to the expansion of agricultural area on the distribution ranges of vertebrate species. In the second part of our analysis we use the BII as an indicator to evaluate the combined effects of expansion and inten- sification of agriculture. 2. Material and methods 2.1. Study area This study focusses on the two Brazilian federal states MT and PA (see Fig 1). These states dif- fer greatly in respect to their recent agricultural developments and their level of exploitation of natural habitats due to the Brazilian agricultural development frontier running through this region [44, 45]. PA has an area of 1.25 million km2 and a population of 8 million people [46]. Only 11,969 km2 of the land is used for soybean cultivation [46]. In 2015 1,881 km2 were deforested which is about the same amount of deforestation as in 2014 [6]. The dominant land use sector is cattle

ranching with a total herd size of 19.2 million animals [46]. A hot spot of LULCC is along the Cuiaba´-Santarem highway (BR-163), the most recent of the “development highways” which are used to acquire the agriculturally rather underdeveloped northern parts of Brazil for crop cultivation and cattle ranching [47]. The natural vegetation is dominated by dense rainforest [11] covering about 77.6% of the state’s area according to MODIS land cover data [48]. More than 40,000 vascular plant species can be found here, of which 30,000 are endemic [11]. Over 1,000 bird species are harbored in the Amazon biome [11] as well as a high concentration of mammals, of which many are endemic, especially along the courses of the rivers crossing this biome [5]. Of the 875 amphibian species in the country, approximately 50% are concentrated in the Amazon biome [5]. Especially here the potential for a loss of vertebrate diversity is high due to a high density of endemic, threatened, and small ranged species [5] as well as ongoing and expected future agricultural expansion [15]. MT has an area of 907,000 km2 and a population of 3.2 million inhabitants [46]. 69,807 km2 of land is used for soybean cultivation [46] and 1,508 km2 were deforested in 2015 which con- stitutes an increase of 16% in comparison to 2014 [6]. Another dominant land use sector is cat- tle ranching with a total herd size of 28.4 million animals [46]. Here the expansion of area used for soybean cultivation and cattle ranching could be identified as the primary cause of conver-

sion of natural ecosystems to agricultural land [49, 50]. In comparison to PA, MT is more con- solidated in terms of agricultural expansion. In recent years, the steep decline of availability of highly productive farmland, policies to curb deforestation and rising land prices have led to a development toward agricultural intensification and away from agricultural expansion [18, 51, 52]. MT is covered by two Brazilian biomes, the Brazilian Cerrado and the Amazon rainforest [5, 45]. Here, 7,000 plant species, of which 44% are endemic to the Cerrado, can be found. The Cerrado biome is especially rich in bird diversity with 837 species, which resembles 49% of all bird species found in Brazil. Also 150 reptile species (50% of all Brazilian reptile species) and 180 amphibian species (28% endemic to the Cerrado) are found here. The Cerrado biome and its waterways are home to 1,400 fish species, 40% of all fish species occurring in Brazil [53]. PLOS ONE Agricultural intensification effects on natural habitats and biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0225914 November 25, 2020 3 / 21