Why non-native grasses pose a critical emerging threat to biodiversity conservation, habitat connectivity and agricultural production in multifunctional rural landscapes

Robert Godfree,Jennifer Firn,Nunzio Knerr,Jacqui Stol,Stephanie Johnson,Veronica Doerr

doi:10.1007/s10980-017-0516-9

Abstract

ContextLandscape-scale conservation planning is key to the protection of biodiversity globally. Central to this approach is the development of multifunctional rural landscapes (MRLs) that maintain the viability of natural ecosystems and promote animal and plant dispersal alongside agricultural land uses.ObjectivesWe investigate evidence that non-native grasses (NNGs) in rangelands and other low-intensity agricultural systems pose a critical threat to landscape conservation initiatives in MRLs both in Australia and globally.MethodsWe first establish a simple socio-ecological model that classifies different rural landscape elements within typical MRLs based on their joint conservation and agro-economic value. We then quantify the impacts of eight Australian NNGs (Andropogon gayanus, Cenchrus ciliaris, Eragrostis curvula, Hyparrhenia hirta, Nassella neesiana, Nassella trichotoma, Phalaris aquatica and Urochloa mutica) on different landscape elements and then classify and describe the socio-ecological transformations that result at the MRL scale.ResultsOur data indicate that two broad classes of NNGs exist. The first reduces both conservation and agro-economic value (‘co-degrading’ species) of invaded landscapes, while the second improves agro-economic value at the expense of conservation value (‘trade-off’ species). Crucially, however, both classes cause hardening of the landscape matrix, agricultural intensification, reduced habitat connectivity, and the loss of multi-value land use types that are vital for landscape conservation.ConclusionsNNGs drive socio-ecological transformations that pose a growing threat to landscape-scale connectivity and conservation initiatives in Australia and globally. There is an urgent need for further research into the impacts of NNGs on habitat connectivity and biodiversity within multifunctional landscapes, and the socio-ecological goals that can be achieved when landscape transformation and degradation by these species is unavoidable.

Highlights

The invasion of new habitats by non-native grasses (NNGs) can have profound implications for community dynamics, abiotic–biotic interactions, and the structure and provision of ecosystem processes and services (Strayer 2012)
We quantify the impacts of eight Australian NNGs (Andropogon gayanus, Cenchrus ciliaris, Eragrostis curvula, Hyparrhenia hirta, Nassella neesiana, Nassella trichotoma, Phalaris aquatica and Urochloa mutica) on different landscape elements and classify and describe the socio-ecological transformations that result at the multifunctional rural landscapes (MRLs) scale
The first reduces both conservation and agro-economic value (‘co-degrading’ species) of invaded landscapes, while the second improves agroeconomic value at the expense of conservation value (‘trade-off’ species). Both classes cause hardening of the landscape matrix, agricultural intensification, reduced habitat connectivity, and the loss of multi-value land use types that are vital for landscape conservation

Summary

Introduction

The invasion of new habitats by non-native grasses (NNGs) can have profound implications for community dynamics, abiotic–biotic interactions, and the structure and provision of ecosystem processes and services (Strayer 2012). Others quickly colonise and dominate disturbed systems (Firn et al 2010; D’Antonio et al 2011), and when coupled with anthropogenic drivers that increase their dispersal and fitness (e.g., MacDougall and Turkington 2005; MacDougall et al 2014), have become major degraders of agricultural production systems The role of such species as drivers of global environmental change and biodiversity decline is long recognised (Franklin et al 2006; Friedel et al 2011; Firn et al 2013). We believe the potentially serious consequences of these impacts for biodiversity conservation and habitat connectivity at the landscape scale remains poorly recognised Impacts at this scale are critical, since biodiversity conservation has rapidly shifted in recent decades to embrace landscape-scale conservation planning which aims to support biodiversity alongside agricultural and other human land uses The fundamental tenet of landscape-scale conservation is that biodiversity can still persist in these landscapes if the relative composition of different land uses is carefully managed and if connectivity among elements in fragmented landscapes supports dispersal and other movement by a range of species (Crooks and Sanjayan 2006; Hilty et al 2006; Smith et al 2013)

Objectives

Methods

Results

Conclusion