scholarly journals Using occupancy models to assess the direct and indirect impacts of agricultural expansion on species’ populations

2020 ◽  
Vol 29 (13) ◽  
pp. 3669-3688
Author(s):  
Asunción Semper-Pascual ◽  
Julieta Decarre ◽  
Matthias Baumann ◽  
Micaela Camino ◽  
Yamil Di Blanco ◽  
...  

Abstract Land-use change is a global threat to biodiversity, but how land-use change affects species beyond the direct effect of habitat loss remains poorly understood. We developed an approach to isolate and map the direct and indirect effects of agricultural expansion on species of conservation concern, using the threatened giant anteater (Myrmecophaga tridactyla) in the Gran Chaco as an example. We reconstructed anteater occupancy change between 1985 and 2015 by fitting single-season occupancy models with contemporary camera-trap data and backcasting the models to 1985 and 2000 land-cover/use maps. Based on this, we compared the area of forest loss (direct effect of agricultural expansion) with the area where forests remained but occupancy still declined (indirect effect of agricultural expansion). Anteater occupancy decreased substantially since 1985, particularly after 2000 when agriculture expanded rapidly. Between 1985 and 2015, ~ 64,000 km2 of forest disappeared, yet occupancy declined across a larger area (~ 102,000 km2), extending far into seemingly untransformed habitat. This suggests that widespread sink habitat has emerged due to agricultural land-use change, and that species may lose their habitat through direct and indirect effects of agricultural expansion, highlighting the urgent need for broad-scale conservation planning in the Chaco. Appropriate management responses could proactively protect more habitat where populations are stable, and restore habitat or address causes of mortality in areas where declines occur. Our work also highlights how occupancy modelling combined with remote sensing can help to detect the direct and indirect effects of agricultural expansion, providing guidance for spatially targeting conservation strategies to halt extinctions.

2019 ◽  
Author(s):  
Adriana De Palma ◽  
Michael Kuhlmann ◽  
William D. Pearse ◽  
Emma Flynn ◽  
Stuart P.M. Roberts ◽  
...  

AbstractBee species worldwide are facing a future of further land-use change and intensification. Populations of closely-related species with similar ecological characteristics are likely to respond similarly to such pressures. Such phylogenetic signal in species’ responses could undermine the stability of pollination services in agricultural and natural systems. We use abundance data from a global compilation of bee assemblages in different land uses to assess the sensitivity of 573 bee species to agricultural expansion, intensification and urbanization; and combine the results with the Bee Tree of Life to assess phylogenetic signal. In addition, we assess whether variation in species’ sensitivity to land-use change is better explained by phylogenetic or available functional trait differences. Bee species show strong phylogenetic signal in sensitivity to agricultural land expansion but only a weak signal in sensitivity to agricultural intensification and urbanisation. Sensitivities were usually best explained by a combination of functional and phylogenetic distances. This finding suggests that the commonly-recorded traits, despite being meaningful as functional response traits, do not capture all important determinants of bee species’ vulnerability or resistance. However, it also suggests that model-based predictions of the sensitivity of poorly known species may be sufficient to help guide conservation efforts.


Author(s):  
Yujuan Gao ◽  
Jianli Jia ◽  
Beidou Xi ◽  
Dongyu Cui ◽  
Wenbing Tan

The heavy metal pollution induced by agricultural land use change has attracted great attention. In this study, the divergent response of bioavailability of heavy metals in rhizosphere soil to different...


Author(s):  
Allison Neil

Soil properties are strongly influenced by the composition of the surrounding vegetation. We investigated soil properties of three ecosystems; a coniferous forest, a deciduous forest and an agricultural grassland, to determine the impact of land use change on soil properties. Disturbances such as deforestation followed by cultivation can severely alter soil properties, including losses of soil carbon. We collected nine 40 cm cores from three ecosystem types on the Roebuck Farm, north of Perth Village, Ontario, Canada. Dominant species in each ecosystem included hemlock and white pine in the coniferous forest; sugar maple, birch and beech in the deciduous forest; grasses, legumes and herbs in the grassland. Soil pH varied little between the three ecosystems and over depth. Soils under grassland vegetation had the highest bulk density, especially near the surface. The forest sites showed higher cation exchange capacity and soil moisture than the grassland; these differences largely resulted from higher organic matter levels in the surface forest soils. Vertical distribution of organic matter varied greatly amongst the three ecosystems. In the forest, more of the organic matter was located near the surface, while in the grassland organic matter concentrations varied little with depth. The results suggest that changes in land cover and land use alters litter inputs and nutrient cycling rates, modifying soil physical and chemical properties. Our results further suggest that conversion of forest into agricultural land in this area can lead to a decline in soil carbon storage.


Author(s):  
A. V. Prishchepov ◽  
F. Schierhorn ◽  
N. Dronin ◽  
E. V. Ponkina ◽  
D. Müller

2014 ◽  
Vol 61 ◽  
pp. 19-38 ◽  
Author(s):  
Dave Murray-Rust ◽  
Derek T. Robinson ◽  
Eleonore Guillem ◽  
Eleni Karali ◽  
Mark Rounsevell

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6255 ◽  
Author(s):  
Citlalli Castillo-Guevara ◽  
Mariana Cuautle ◽  
Carlos Lara ◽  
Brenda Juárez-Juárez

Background The discovery-dominance trade-off is the inverse relationship between the ability of a species to discover resources and the species’ dominance of those resources; a paradigm used to explain species coexistence in ant communities dependent on similar resources. However, factors such as stress (e.g., temperature) or disturbance (e.g., removal of biomass) associated with the change in land use, can modify this trade-off. Here, we aimed to determine the potential effects of land use change on dominance hierarchy, food preferences and on the discovery-dominance trade-off. Methods An experiment with baits was used to investigate the dominance hierarchies of ant communities in a temperate mountain habitat in central Mexico. We evaluated the dominance index (DI), food preferences and discovery-dominance trade-offs of ants inhabiting two types of vegetation: a native oak forest and agricultural land resulting from agricultural land use and grazing. Results The ant communities in both environments were comprised of three species of ants (Monomorium minimum, Myrmica mexicana, and Camponotus picipes pilosulus), four morphospecies (Pheidole sp.1 and Pheidole sp.2, Temnothorax sp. and Lasius sp.) and one genus (Formica spp.). All Formicidae showed values of intermediate to low DI, and this factor did not seem to be influenced by the change in land use. Ants in the modified vegetation (i.e., agricultural land) were found to be numerically greater. Overall, a higher number of visits were registered to the tuna bait, although the duration of foraging events to the honey baits was longer. However, foraging times were dependent on the species considered: the generalized Myrmicinae, M. minimum, the ant species with highest DI, foraged for longer periods of time in the agricultural land and on the tuna bait. Meanwhile, the cold-climate specialist Formica spp., with a lower DI, foraged for longer periods of time in the oak (although not significant) and on the honey bait. We found little evidence of the discovery-dominance trade-off; instead, we found considerable diversity in the strategies used by the different species to access resources. This range of strategies is well represented by the generalized Myrmicinae M. minimum, the cold-climate specialists Formica spp. and Temnothorax sp., and the rare species, as the cold climate specialist Lasius sp. (insinuators). Conclusions Our evaluation shows that transformation of the original habitat does not appear to affect the hierarchical dominance of the ant communities, but it does affect their food preferences. Species with higher DI values such as the generalized Myrmicinae are more skilled at resource acquisition in modified habitats. Our results suggest that change in land use promotes an increase in the diversity of foraging strategies used by different ant species. This diversity may contribute to resource partitioning which favors coexistence.


2018 ◽  
Vol 3 (4) ◽  
pp. 219-226
Author(s):  
Yasfir Ma'arif ◽  
Teuku Fauzi ◽  
Safrida Safrida

Abstrak  Pertumbuhan  penduduk dan dinamika pembangunan telah menggeser pemanfaatan lahan yang akhirnya menimbulkan kompleksitas permasalahan lahan yang semula berfungsi sebagai media bercocok tanam (pertanian), berangsur-angsur berubah menjadi multifungsi pemanfaatan. Berubahnya pemanfaatan lahan pertanian ke non pertanian dapat disebut juga sebagai alih fungsi lahan. Kabupaten Aceh Besar adalah salah satu kabupaten yang terus menghadapi permasalahan alih fungsi lahan, khususnya lahan sawah. Alih fungsi lahan ini mengakibatkan luas lahan sawah di Aceh Besar terus menurun. Lahan yang paling banyak mengalami alih fungsi lahan adalah jenis lahan sawah yang menjadi lahan non pertanian. Penelitian ini bertujuan untuk mengidentifikasi faktor-faktor yang menyebabkan terjadinya alih fungsi lahan sawah dan mengidentifikasi dampak sosial dan ekonomi yang dialami petani mantan pemilik lahan akibat alih fungsi lahan sawah menjadi lahan non pertanian. Berdasarkan hasil regresi secara parsial dari analisis regresi faktor harga jual, kebutuhan hidup dan kondisi lahan berpengaruh nyata terhadap konversi lahan sawah di  Kecamatan Baitussalam Kabupaten Aceh Besar. Bedasarkan hasil regresi secara serempak dari hasil regresi didapatkan bahwa harga jual, kebutuhan hidup dan kondisi lahan secara serempak mempengaruhi konversi lahan sawah di Kecamatan Baitussalam Kabupaten Aceh Besar. Berdasarkan isu dampak sosial sebagai akibat alih fungsi lahan di lihat dari keinginan kondisi lama, meningkatkan rasa kerjasama dan kekeluargaan, serta kemampuan memenuhi kebutuhan keluarga mendapatkan hasil yang positif dengan nilai ≥ 50%. Berdasarkan isu dampak ekonomi sebagai akibat alih fungsi lahan di lihat dari peningkatan pendapatan mendapatkan hasil yang positif dengan nilai ≥ 50%.Impact Of Paddy Fields Function  On Community Socio-Economic Conditions Of Baitussalam District, Aceh Besar RegencyAbstract  Population growth and the dynamics of development have shifted land use which eventually led to the complexity of the problem of land that used to function as a farming medium (agriculture), gradually becoming a multifunctional use. Changing the use of agricultural land to non-agriculture can also be referred to as land conversion. Aceh Besar District is one of the districts that continues to face the problem of land conversion, especially rice fields. The conversion of this land function has caused the area of paddy fields in Aceh Besar to continue to decline. The land that has experienced the most land use change is the type of rice field that becomes non-agricultural land. This study aims to identify the factors that cause the conversion of paddy fields and identify the social and economic impacts experienced by farmers former landowners due to the conversion of paddy fields to non-agricultural land. Based on the partial regression results from the regression analysis, the factors of selling price, life necessity and land conditions have a significant effect on the conversion of paddy fields in Baitussalam District, Aceh Besar District. Based on the simultaneous regression results from the regression results, it was found that the selling price, life needs and land conditions simultaneously affected the conversion of paddy fields in Baitussalam District, Aceh Besar District. Based on the issue of social impacts as a result of land use change seen from the desires of the old conditions, increasing the sense of cooperation and kinship, as well as the ability to meet family needs get positive results with a value of ≥ 50%. Based on the issue of economic impact as a result of the transfer of land functions, it can be seen from the increase in income that has a positive result with a value of ≥ 50%.


2018 ◽  
Vol 20 (1) ◽  
pp. 50
Author(s):  
Aziz Bahtiar Rifa’i ◽  
Fadjar Hari Mardiansjah

This study examines the impact of agricultural land use change into a petroleum mining area to farmers’ socioeconomic conditions around petroleum mining project area in Gayam District of Kabupaten Bojonegoro. The analyses used a mix method, using both quantitative and qualitative approaches. The quantitative approach is used to determine the impact of agricultural land use change on the social and economic aspects with the respondent farmers were supported with a scoring method to determine the condition of socioeconomic vulnerability of farmers, while the qualitative approach carried out through in-depth interviews to some informants who have been affected by the project. The results shows that the presence of the petroleum mining industry has not had a positive impact yet on the farmers’ socioeconomic conditions. By the 700 hectares of agricultural land conversion, the agricultural production capacity of the area tends to decrease, including by the decreasing of the productivity of some agricultural land in a radius of 500 m from the fenceof the mining area as they are affected by the fence’s spotlight. The farmers' income also tends to decrease because of the decreasing of their working hours as the big loss of agricultural land in the area. As a result, many farmers should work outside of the area to search replacement of the arable land. These situations lead to a moderate condition of social and economic vulnerability for the farmers, especially for those who still have sufficient assets to meet the needs of their economic. 


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