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

negatively, especially endemic amphibians and endemic birds as well as threatened birds and threatened mammals. 3.3.3. The combined effects of agricultural expansion and intensification on vertebrate diversity: A scenario comparison. In general, when looking at sections 3.3.1. and 3.3.2. as well as the following discussion of the illustrated results, one has to keep in mind that the BII values in MT are on average 0.14 points below those calculated for PA as MT is more consoli- dated in agricultural terms [51, 52]. Newbold et al. [7] calculated BII values of around 70% for the Brazilian Cerrado (mainly located in MT) as well as 85% for the Amazon biome (mainly located in PA). This agrees well with our calculation for the year 2010 of 0.59–0.68 (MT) and 0.65–0.86 (PA) respectively (see Tables 4 and 5). The fact that the estimates found in our study are slightly lower than those estimated by Newbold et al. [7] is explained by taking into account that they focused on the whole Cerrado and Amzonia region. We assess a sub-region that is and was characterized by especially strong LULCC dynamics. Interestingly in PA, the negative effect in the case of the Illegal Intensification Scenario is lower compared to the Legal Intensification Scenario. This can be explanied by the consider- ation of the 216,022 km2 of rainforest share of the total Legal Reserve area (270,027 km2) in PA as affected area with a population impact of 0.83 (see Table 3). Here, the fragmentation of the total Legal Reserve area by small scale agriculture, and consequently the degradation of rain-

forest habitats e.g. [88, 89], has a negative impact that leads to a stronger decrease of the BII as compared to the Illegal Intensification Scenario. This is true despite the fact that in the Illegal Intensification Scenario a larger amount of natural habitat area is actualy converted into man- aged land with a higher impact of either 0.15 for cropland or 0.6 for extensive pasture. In the case of the Sustainable Development Scenario in PA, the impact of a conversion on natural hab- itats, distribution ranges of vertebrate species and, thus calculated BII values could be reduced substantially in comparison to all other scenarios. This effect is attributable to a substantial reduction of the global meat intake which leads to a significant reduction of pasture area which, in turn, can be utilized for an expansion of cropland area. A total of 94% of the crop- land expansion was realized on released pasture area (see Table 3), thus decreasing the amount of transformed natural habitat area considerably. Alkimim et al. come to a similar conclusion in their study [87]. In PA, strong decreases of the BII can be witnessed. In the case of the Illegal Intensification Scenario in MT strongly decreasing BII value for threatened vertebrate species and especially small-ranged amphibian species can be observed due to the opening up of protected areas for agricultural expansion. Especially the Pantanal, known for its species richness in regard to birds and amphibians [90], is affected by the dis- placement of managed land into formerly protected areas. Moreover, we see decreasing BII

values for all taxa and categories except endemic vertebrate species which either remain con- stant or even increase slightly. This can be attributed to the fact that some natural habitat areas that are domiciling endemic vertebrate species are found rather in natural habitats that are not within the protected areas [5]. Since large portions of natural habitats within protected areas are favored for conversion (higher possible crop yield), natural habitats outside these protected areas can be spared from conversion to cultivated land or are converted from cropland to pas- ture cells due to cropland being relocated to areas within protected habitats (see Table 3). Moreover, the overall higher BII values in the Legal Intensification Scenario, compared to the Illegal Intensification Scenario, shows that effective conservation of existing protected areas can further enhance biodiversity in MT in 2030 [91]. This observation is confirmed by Sparovek et al. who found the legal command and control frameworks were the most important deter- minants of conservation outcomes, protecting at least 80% of the existing natural vegetation, and thus biodiversity, in all of their simulated future land use scenarios [85]. In the case of the Legal Intensification Scenario in MT, current protected areas are assumed being effectively PLOS ONE Agricultural intensification effects on natural habitats and biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0225914 November 25, 2020 14 / 21