Quantifying the links between land use and population growth rate in a declining farmland bird.

Matthieu Paquet,Tomas Pärt,Matthew Low,Debora Arlt,Pär Forslund,Jonas Knape

doi:10.1002/ece3.4766

Matthieu Paquet, Tomas Pärt + Show 4 more

Open Access

https://doi.org/10.1002/ece3.4766

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Abstract

Land use is likely to be a key driver of population dynamics of species inhabiting anthropogenic landscapes, such as farmlands. Understanding the relationships between land use and variation in population growth rates is therefore critical for the management of many farmland species. Using 24 years of data of a declining farmland bird in an integrated population model, we examined how spatiotemporal variation in land use (defined as habitats with “Short” and “Tall” ground vegetation during the breeding season) and habitat‐specific demographic parameters relates to variation in population growth taking into account individual movements between habitats. We also evaluated contributions to population growth using transient life table response experiments which gives information on contribution of past variation of parameters and real‐time elasticities which suggests future scenarios to change growth rates. LTRE analyses revealed a clear contribution of Short habitats to the annual variation in population growth rate that was mostly due to fledgling recruitment, whereas there was no evidence for a contribution of Tall habitats. Only 18% of the variation in population growth was explained by the modeled local demography, the remaining variation being explained by apparent immigration (i.e., the residual variation). We discuss potential biological and methodological reasons for high contributions of apparent immigration in open populations. In line with LTRE analysis, real‐time elasticity analysis revealed that demographic parameters linked to Short habitats had a stronger potential to influence population growth rate than those of Tall habitats. Most particularly, an increase of the proportion of Short sites occupied by Old breeders could have a distinct positive impact on population growth. High‐quality Short habitats such as grazed pastures have been declining in southern Sweden. Converting low‐quality to high‐quality habitats could therefore change the present negative population trend of this, and other species with similar habitat requirements.

Highlights

Human land use and management have profound effects on populations and biodiversity
Looking into the part of the variation in realized growth rate that was explained by local demography, this showed that most of the variation was explained by demographic rates in Short habitats, with this largely driven by the contribution of fledgling recruitment from Short sites (55%; Figure 3a)
There seems to be a clear correlation, but quantifying the importance of different habitats for population growth is key for a better understanding of how land use changes affect population dynamics and could give incentives for how to reverse ongoing large‐scale population declines

Summary

| INTRODUCTION

Human land use and management have profound effects on populations and biodiversity. In particular, agricultural ecosystems are suffering from a dramatic biodiversity crisis, with many farmland bird species in Europe and North America displaying sharp declines during the last 50 years (Donald, Green, & Heath, 2001; Inger et al, 2014; Stanton, Morrissey, & Clark, 2018; Vickery et al, 2013). We have documented strong land use‐specific effects on demographic rates that could be captured by grouping land uses into two contrasting habitat types described by their vegetation structure, that is, “Short” habitats with permanently Short or sparse ground vegetation during the breeding season and “Tall” habitats with ground vegetation growing Tall (Pärt 2001; Arlt, Forslund, Jeppsson, & Pärt, 2008). These results were based on habitat‐specific population growth rates, whereas the effect of habitat and habitat use on total population growth rate was not investigated. We examined which parameters have greatest potential to change and possibly increase the population growth rate (using real‐time elasticity analysis; Haridas, Tuljapurkar, & Coulson, 2009)

| MATERIALS AND METHODS

| DISCUSSION

Findings

CONFLICT OF INTEREST