Landscape Characteristics Affecting Small Mammal Occurrence in Heterogeneous Olive Grove Agro-Ecosystems

Isabel Barão,Hélia Vale-Gonçalves,Joana Paupério,Ricardo Pita,João Queirós

doi:10.3390/conservation2010005

Isabel Barão, Hélia Vale-Gonçalves + Show 3 more

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https://doi.org/10.3390/conservation2010005

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Abstract

Understanding how small mammals (SM) are associated with environmental characteristics in olive groves is important to identify potential threats to agriculture and assess the overall conservation value and functioning of agro-ecosystems. Here, we provide first insights on this topic applied to traditional olive groves in northeast (NE) Portugal by assessing the landscape attributes that determine SM occurrence, focusing on one species of conservation concern (Microtus cabrerae Thomas 1906) and one species often perceived as a potential pest of olives (Microtus lusitanicus Gerbe 1879). Based on SM genetic non-invasive sampling in 51 olive groves and surrounding habitats, we identified seven rodent species and one insectivore. Occupancy modelling indicated that SM were generally less detected within olive groves than in surrounding habitats. The vulnerable M. cabrerae reached a mean occupancy (95% CI) of 0.77 (0.61–0.87), while M. lusitanicus stood at 0.37 (0.24–0.52). M. cabrerae was more likely to occur in land mosaics with high density of agricultural field edges, while M. lusitanicus was more associated with high density of pastureland patches. Overall, our study suggests that the complex structure and spatial heterogeneity of traditionally managed olive grove agro-ecosystems may favor the occurrence of species-rich SM communities, possibly including well-established populations of species of conservation importance, while keeping potential pest species at relatively low occupancy rates.

Highlights

Over the past century, the transition from traditional to intensive agriculture has caused drastic changes in the environmental conditions of agricultural landscapes [1,2], being associated with a fast decline in agro-ecosystems biodiversity [3,4]
Small Mammal Detection Based on Genetic Non-Invasive Sampling
This suggests that the complex land mosaics, mostly resulting from the still predominating traditional farming in the region [31], should provide a high diversity of micro-habitats that allow the coexistence of different small mammal species, even those that might in some way overlap in their niches, such as voles, which are often associated with marginal grassland habitats in agro-ecosystems [45]

Summary

Introduction

The transition from traditional to intensive agriculture has caused drastic changes in the environmental conditions of agricultural landscapes [1,2], being associated with a fast decline in agro-ecosystems biodiversity [3,4]. In the Mediterranean region, for instance, traditional olive farming has been considered a crucial agricultural system due to its environmental, cultural and socio-economic importance [5,6,7]. In recent decades, there has been an increasing intensification in olive farming in many regions, with olive groves tending to be much larger and with less ground vegetation than traditional orchards [8,9,10]. This results in more homogeneous and simplified landscapes that likely support much lower biodiversity levels [11,12,13].

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