How can higher-yield farming help to spare nature? Phalan, Ben; Green, Rhys E.; Dicks, Lynn V. ...
Science (American Association for the Advancement of Science),
01/2016, Letnik:
351, Številka:
6272
Journal Article
Recenzirano
Odprti dostop
Mechanisms to link yield increases with conservation
Expansion of land area used for agriculture is a leading cause of biodiversity loss and greenhouse gas emissions, particularly in the tropics. One ...potential way to reduce these impacts is to increase food production per unit area (yield) on existing farmland, so as to minimize farmland area and to spare land for habitat conservation or restoration. There is now widespread evidence that such a strategy could benefit a large proportion of wild species, provided that spared land is conserved as natural habitat (
1
). However, the scope for yield growth to spare land by lowering food prices and, hence, incentives for clearance (“passive” land sparing) can be undermined if lower prices stimulate demand and if higher yields raise profits, encouraging agricultural expansion and increasing the opportunity cost of conservation (
2
,
3
). We offer a first description of four categories of “active” land-sparing mechanisms that could overcome these rebound effects by linking yield increases with habitat protection or restoration (table S1). The effectiveness, limitations, and potential for unintended consequences of these mechanisms have yet to be systematically tested, but in each case, we describe real-world interventions that illustrate how intentional links between yield increases and land sparing might be developed.
Conversion of grasslands into crops is a major factor leading to the decline of grassland birds. Cattle ranching represents another disturbance to natural grasslands, but may be less detrimental to ...grassland birds. We studied the diversity, density, and composition of bird species in Brazilian and Uruguayan grasslands under two different land use types: cattle ranching on seminatural grasslands, and soybean fields with interspersed patches of grassland. Cattle sites had higher species richness (n = 75 species) than soybean sites (n = 57 species). Most birds showed higher densities in cattle sites, but some common and habitat-generalist species were more abundant in soybean sites. Species composition did not differ significantly with land use. The generalist Eared Dove (Zenaida auriculata), however, was strongly associated with soybean sites. Among species of conservation interest, either regionally or globally, all had higher densities in cattle sites, highlighting the importance of maintaining these ranching areas. The persistence of grassland birds in soybean fields may be related to the presence of seminatural grassland patches within soybean crops.
A bacia do Rio Corumbataí é composta por um mosaico de ambientes, fortemente antropizado, com predominância de pastagens e plantações de cana-deaçúcar, além de florestas plantadas de eucalipto e ...fragmentos de floresta estacional semidecidual. Esta bacia, principal fonte de abastecimento de água da região metropolitana de Campinas, pode ser considerada como um modelo conveniente para o estudo da conservação da diversidade biológica. Subdivide-se em cinco sub-bacias, sendo que a maior, e que apresenta os maiores fragmentos florestais remanescentes, é a do Rio Passa-Cinco. Para verificar a diversidade e a abundância de espécies de mamíferos de médio e grande porte, bem como a utilização que fazem deste mosaico agroflorestal, foram realizados censos por meio de transectos, buscando-se todos os possíveis tipos de registro - diretos e indiretos - como observação direta, fezes, pegadas, arranhões e carcaças. Entre julho de 2003 e junho de 2004 foram percorridos 284,4 km ao todo, e registradas 25 espécies silvestres nativas e duas exóticas, além de seis espécies domésticas. Na floresta nativa foram registradas 23 espécies, no canavial 20, no eucaliptal 17 e nas áreas de pastagem 12. O estimador não-paramétrico Bootstrap calculou 25 espécies para a floresta nativa, 22 para o canavial, 18 para o eucalipto e 13 para o pasto, indicando que o esforço amostral não foi suficiente para a estabilização da curva de esforço. Os índices de Diversidade (H e 1/D), bem como Pielou (J), mostraram ambientes similares, e o ajuste das curvas de distribuição de espécies ao modelo de séries logarítmicas mostra uma comunidade com uma estrutura composta por poucas espécies abundantes e muitas espécies raras. Quanto à freqüência de ocorrência e à abundância relativa nos quatro ambientes amostrados, as únicas espécies que apresentaram diferenças entre os ambientes foram o cachorro-do-mato (Cerdocyon thous) e a lebre européia (Lepus europaeus), ambas com hábitos generalistas, as duas com maior freqüência no canavial, e a lebre-européia também com maior abundância no canavial. Já em relação à comunidade de mamíferos como um todo, o pasto apareceu como o ambiente com menor riqueza de espécies e com o menor freqüência de ocorrência, enquanto que o canavial obteve a maior freqüência de ocorrência. A análise de correspondência mostrou sete espécies mais relacionadas à floresta nativa, cinco ao eucalipto e nove às áreas abertas (pastagem e canavial). Os resultados obtidos sugerem que a comunidade de mamíferos de médio e grande porte da Bacia do Rio Passa-Cinco é sujeita às modificações ambientais que a região vem sofrendo, e que as espécies de hábitos mais generalistas são as que estão conseguindo se manter com maior facilidade, devido, possivelmente, a seus menores requerimentos de habitat.
The Corumbataí river basin is a landscape with great human influence, with the most relevant agroecosystems of São Paulo. It has been used as one of the major water supplies for the metropolitan region of Campinas. This basin is formed by five subbasins, where the Passa-Cinco river basin is the largest, with the most native remaining fragments. This basin could be considered as a convenient model for the study of biodiversity conservation in agroecosystems. In order to evaluate the distribution and abundance of medium and large-sized mammals, 284,4 km of transects were censused from July 2003 to June 2004 in Semideciduous native forest, eucalyptus plantations, sugar-cane plantations and pastures. All possible records were recorded such as direct observation, faeces, tracks, scratches, and carcasses. I found 25 native species and two exotic species, besides six domestic species. On the native forest I recorded 23 species, on sugar cane 20, on eucalypt forest 17, and on the pasture areas 12. The diversity and the evenness index suggested that environments were similar, and the distribution species curve (Log-series model) showed few abundant and a majority of rare species. Crab-eating fox and European hare were the only species with differences among habitats in frequency of occurrence, and European hare was the only one with difference among habitats in relative abundance. The results suggested that this mammalian community has been influenced by the environmental alteration that this region has been suffering, and the current community is basically formed by generalist species what enhanced its adaptation to an anthropogenic landscape. In such conditions, current environmental laws should be enforced in order to improve forest conservation and mitigate the impacts of agriculture, paper industry, and livestock production.
We explored how grassland birds responded to three different managements in grassland areas. Moreover, we examined whether bird's communities were different depending on the biome grasslands were ...inserted. We carried out bird surveys in six private farms in the Upland grasslands (Atlantic Forest biome) and the Pampas grasslands (Pampa biome). Land use included: (1) natural grasslands – paddocks with cattle stocking around 0.8animal units/ha, without improvement/crop plantation in the last four years; (2) improved grasslands – grasslands with usage of fertilizers and forage improvement with exotic species, and (3) cultivated fields – forage/crop plantations. Threatened and restricted grassland birds were found in natural grasslands areas while more common species occurred in improved grasslands and cultivated fields. Bird community was different in the biomes with some species more related to the Upland grasslands and others to the Pampas. We highlighted the importance of natural grasslands and its management in private farms to maintain grassland bird species richness and their abundance in south Brazil.
Livestock production and the replacement of semi-natural grasslands by crops result in land use changes and as consequence some habitat is no longer suitable for all species of grassland birds. ...Although some generalist species could benefit from such changes, habitat alteration is detrimental to the populations of most sensitive species. In this study, we investigated the patterns of habitat use by breeding grassland birds through the assessment of their presence/absence and abundance in a landscape composed of semi-natural grasslands and croplands in southern Brazil and Uruguay. We sampled grassland birds in 160 100-m radius point counts: 80 in a semi-natural grassland dominated landscape and 80 in soybean fields with grassland patches. We classified vegetation cover on a 100-m radius buffer following three classes of land use: semi-natural grasslands, wet grasslands, and soybean fields. We used GLMM to analyze presence/absence and abundance of grassland birds found in the region. Nine species showed a positive response to the semi-natural grasslands and/or wet grassland vegetation cover categories. Five species recorded are of conservation concern. Most of the grassland bird species preferred sites with high semi-natural grassland cover and only one species used primarily soybean fields. Grassland birds required around 80% of semi-natural grassland cover to maintain larger abundances. Research across landscapes and a better understanding of the responses of grassland birds to habitat modification are still needed to establish conservation practices of natural grasslands and their avifauna in southern Brazil and Uruguay.
Mammals play an important role in the maintenance and regeneration of tropical forests since they have essential ecological functions and can be considered key-species in structuring biological ...communities. In landscapes with elevated anthropogenic pressure and high degree of fragmentation, species display distinct behavioral responses, generally related to dietary habits. The landscape of Passa-Cinco river basin, in the central-eastern region of Sao Paulo State, shows a high degree of anthropogenic disturbance, with sugar cane plantations, eucalyptus forests, native semideciduous forest remnants and pastures as the key habitat types in the region. We surveyed medium to large mammals in those habitats and determined species richness and relative abundance for each of the following trophic categories: Insectivore/Omnivores, Frugivore/Omnivores, Carnivores, Frugivore/Herbivores and Herbivore/Grazers. Differences in species richness and relative abundance among habitats were tested using one-way analysis of variance, followed by Tukey test, considering 1) each of the trophic categories individually and 2) the set of categories together. Between July 2003 and June 2004, 284.4 km were walked and 22 species were recorded (20 native and two exotics). Analysis of variance did not detect differences in species richness for any of the trophic categories or for the assemblage. Considering relative abundance, the analysis detected significant differences only for the whole assemblage, with the assemblage being more abundant in sugar cane plantations compared to pastures. Our results indicate that the heterogeneous landscape of the study area is dominated by generalist species adapted to use different habitat types and food items.
Conversion of grasslands into crops is a major factor leading to the decline of grassland birds. Cattle ranching represents another disturbance to natural grasslands, but may be less detrimental to ...grassland birds. We studied the diversity, density, and composition of bird species in Brazilian and Uruguayan grasslands under two different land use types: cattle ranching on seminatural grasslands, and soybean fields with interspersed patches of grassland. Cattle sites had higher species richness (n = 75 species) than soybean sites (n = 57 species). Most birds showed higher densities in cattle sites, but some common and habitat-generalist species were more abundant in soybean sites. Species composition did not differ significantly with land use. The generalist Eared Dove (Zenaida auriculata), however, was strongly associated with soybean sites. Among species of conservation interest, either regionally or globally, all had higher densities in cattle sites, highlighting the importance of maintaining these ranching areas. The persistence of grassland birds in soybean fields may be related to the presence of seminatural grassland patches within soybean crops.
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