Variability of beetle assemblages in Mediterranean cork oak woodlands: does the higher taxa approach reliably characterize a specific response to grazing?
“…Biodiversity effects were mainly measured based on differences in species richness. Five studies with seven effect sizes used other measures, namely family richness [ 26 , 27 ], log-series [ 28 , 29 ] or Shannon index [ 30 ]. Fig.…”
Background
Agroforestry is a production system combining trees with crops or livestock. It has the potential to increase biodiversity in relation to single-use systems, such as pastures or cropland, by providing a higher habitat heterogeneity. In a literature review and subsequent meta-analysis, we investigated the relationship between biodiversity and agroforestry and critically appraised the underlying evidence of the results.
Results
Overall, there was no benefit of agroforestry to biodiversity. A time-cumulative meta-analysis demonstrated the robustness of this result between 1991 and 2019. In a more nuanced view silvopastoral systems were not more diverse in relation to forests, pastures or abandoned silvopastures. However, silvoarable systems increased biodiversity compared to cropland by 60%. A subgroup analysis showed that bird and arthropod diversity increased in agroforestry systems, while bats, plants and fungi did not.
Conclusion
Agroforestry increases biodiversity only in silvoarable systems in relation to cropland. But even this result is of small magnitude, and single-study effect sizes were heterogeneous with sometimes opposing conclusions. The heterogeneity suggests the importance of other, usually unmeasured variables, such as landscape parameters or land-use history, influencing biodiversity in agroforestry systems.
“…Biodiversity effects were mainly measured based on differences in species richness. Five studies with seven effect sizes used other measures, namely family richness [ 26 , 27 ], log-series [ 28 , 29 ] or Shannon index [ 30 ]. Fig.…”
Background
Agroforestry is a production system combining trees with crops or livestock. It has the potential to increase biodiversity in relation to single-use systems, such as pastures or cropland, by providing a higher habitat heterogeneity. In a literature review and subsequent meta-analysis, we investigated the relationship between biodiversity and agroforestry and critically appraised the underlying evidence of the results.
Results
Overall, there was no benefit of agroforestry to biodiversity. A time-cumulative meta-analysis demonstrated the robustness of this result between 1991 and 2019. In a more nuanced view silvopastoral systems were not more diverse in relation to forests, pastures or abandoned silvopastures. However, silvoarable systems increased biodiversity compared to cropland by 60%. A subgroup analysis showed that bird and arthropod diversity increased in agroforestry systems, while bats, plants and fungi did not.
Conclusion
Agroforestry increases biodiversity only in silvoarable systems in relation to cropland. But even this result is of small magnitude, and single-study effect sizes were heterogeneous with sometimes opposing conclusions. The heterogeneity suggests the importance of other, usually unmeasured variables, such as landscape parameters or land-use history, influencing biodiversity in agroforestry systems.
“…Biodiversity e ects were mainly measured based on di erences in species richness. Five studies with seven e ect sizes used other measures, namely family richness [43,44], log-series [45,46] or Shannon index [47]. 5).…”
BackgroundAgroforestry is a production system combining trees with crops or livestock. It has the potential to increase biodiversity in relation to single-use systems, such as pastures or conventional agriculture, by providing a higher habitat heterogeneity. In a literature review and subsequent meta-analysis, we investigated the relationship between biodiversity and agroforestry and critically appraise the underlying evidence of the results.ResultsBiodiversity in agroforestry was higher than in conventional agriculture, but could not outcompete pastures, forests and abandoned agroforestry systems. There was no overall biodiversity benefit in agroforestry systems. Data were available for plants, birds, bats and arthropods. Arthropods and birds were the two taxonomic groups profiting from agroforestry systems. A time-cumulative meta-analysis shows that there was no general benefit of biodiversity at any point in the past besides in early 2015. Time-cumulative meta-analysis can unravel missing robustness of meta-analytical results if conclusions alternate between significant to non-significant summary effect sizes over time.ConclusionAgroforestry increases biodiversity only in silvoarable systems compared with conventional agriculture. But even this result is based on a small magnitude and single-study effect sizes were heterogeneous with sometimes opposing conclusions. The latter suggests the importance of other usually unmeasured variables, such as landscape parameters or land-use history, influencing biodiversity in agroforestry systems.
“…Due to the great variety of ecological functions in which they intervene (Nichols et al 2008), their ability to respond in the short term to forest fragmentation (Nichols et al 2007), its developed correlation and direct dependence on the presence of mammals in the ecosystem (Nichols et al 2009;Bogoni et al 2016;Mannu et al 2018), the inclusion of the subfamily Scarabaeinae in these types of studies has been widely justified. They are well defined from a taxonomic and functional viewpoint, and methods for their sampling has been standardized (Spector 2006;Nichols and Gardner 2011).…”
Section: Monitoring and Conservationmentioning
confidence: 99%
“…The ecological functions in which these beetles are involved provide valuable ecosystem services, such as secondary seed dispersal, nutrient cycle and biological control of pests, among others (Nichols et al 2008). Moreover, different authors have indicated that these arthropods are organisms sensitive to structural changes in habitats caused by disturbances, exhibiting drastic permutations in their development and distribution in the modified landscapes (Halffter and Favila 1993;Halffter and Arellano 2002;Arellano and Halffter 2003;Reyes-Novelo et al 2007;Otavo et al 2013;Mannu et al 2018).…”
Natural Protected Areas (NPAs) are consider adequate tools for biodiversity conservation. Currently in Mexico there are 182 federal NPAs classified according to their management objectives. Chiapas is the Mexican state with the highest number of decreed NPAs and also allocates one of the largest territorial extensions for its protection. Unlike other taxa, and despite their proven ability to respond to ecosystem changes, the study of dung beetles within Mexican NPAs has been underestimated, as they are not considered as a priority group within their management and conservation programs. Based on the review of information available in publications and database on dung beetles, a list of 112 species and seven subspecies recorded in 16 of the 19 federal NPAs established in Chiapas is presented. The species recorded by each NPA show a significant correlation with the number of publications, but a low percentage of them correspond to studies with systematic samplings and most of the species reported in several of the NPAs come from sporadic records, which prevents the study of several basic and applied aspects of dung beetles in the region. Therefore, studies that extensively analyze the communities of arthropod groups, such as the Scarabaeinae, are necessary to understand their response to changes in the ecosystem at local and regional scale. It is advisable that these insects be included in the previous justifying studies for the designation or establishment of NPAs and, in turn, considered in the biological monitoring programs of these areas for their capacity as a bioindicator group.
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