Natural tree regeneration in agricultural landscapes: The implications of intensification

Abstract

A B S T R A C TConcern about food security is prompting a push to intensify agriculture globally. However, agricultural intensification can inhibit regeneration of vegetation in natural ecosystems. This may jeopardise the persistence of trees in agricultural landscapes and the ecosystem services these treed landscapes offer. Here, we study one of the world's most altered ecosystems -temperate eucalypt woodlands -to explore patterns in natural regeneration of trees, and factors influencing regeneration occurrence, across 300 000 km 2 of south-eastern Australia between 2008 and 2014. During this period, we found the proportion of remnants supporting natural regeneration was stable, and that regeneration occurrence was negatively associated with variables coincident with agricultural intensification: continuous livestock grazing by sheep and cattle, increased exotic plant cover, increased natural soil fertility, and lower elevation. These results indicate that intensive agriculture is incompatible with natural regeneration in our study area. Left unaddressed, low levels of regeneration may result in the widespread loss of trees and the ecosystem services they provide in agricultural landscapes. Thus, strategic implementation of land-sparing and land-sharing strategies is required across broad spatial scales to satisfy production and conservation needs. Based on our results, we recommend that land sharing be prioritised where: (1) livestock grazing can be removed or employed intermittently, (2) exotic plants do not dominate the ground layer, and (3) natural soil fertility is low. For locations that are continuously grazed or dominated by exotic plants, a land-sparing strategy may be more appropriate.Here, farmland should be managed to maximise production, and the next generation of trees should be 'moved' to areas where natural regeneration can be supported.

Remnant vegetation, plantings and fences are beneficial for reptiles in agricultural landscapes

“…2a). Methods for achieving these recommendations include: 1) reducing grazing pressure and fertiliser use (Fischer et al 2009;Sato et al 2016), particularly in areas with remnant vegetation or important resources such as rocks (Michael et al 2015), and 2) embracing active restoration techniques including planting (Rey Benayas, Bullock & Newton 2008) or addition of rock where previously removed (McDougall et al 2016). Agricultural intensification that reduces tree, litter and forb cover of paddocks should be minimised.…”

“…Promote and recruit key habitat features such as trees, leaf litter and shrubs. Reducing grazing intensity and fertiliser application increases native vegetation recruitment (Fischer et al 2009;Sato et al 2016). Active methods of vegetation restoration include planting and rock addition (Rey Benayas, Bullock & Newton 2008;McDougall et al 2016).…”

“…Rotational grazing may result in a different level of habitat amenity of paddocks compared to a continuous grazing regime, as grazing can influence tree recruitment (Fischer et al 2009;Sato et al 2016) There will be greater reptile richness and abundance in rotationally grazed sites than continuously grazed sites.…”

Do migratory and resident birds differ in their responses to interacting effects of climate, weather and vegetation?

“…Predictions are shown from the full model, in which three terms were statistically significant, namely the interactions of migratory status with vegetation type, 12-month temperature and long-term temperature this study, we sought to quantify their collective effects on different functional groups of birds (corresponding to their movement status). This approach is valuable given that multiple interacting factors can underpin species declines (Caughley & Gunn, 1996;Ceballos, Ehrlich, & Dirzo, 2017;Sato et al, 2016), and understanding these interactions is important for facilitating recoveries (Crouzeilles et al, 2016;Garnett et al, 2017;Scheele, Foster, Banks, & Lindenmayer, 2017). Indeed, many Australian birds are considered to be at increased risk of extinction as a result of climate change (Nimmo et al, 2016;Urban, 2015) and habitat loss (Garnett, Szabo, & Dutson, 2011).…”

Human activities in a tropical Mexican desert: Impact of rainfed agriculture and firewood extraction on vegetation and soil

“…The impact of agriculture on temperate deserts has been extensively evaluated in the United States and Australia (Cramer & Hobbs, ; Morris, Monaco, & Sheley, ; Standish, Cramer, Hobbs, & Kobryn, ). In these regions, agriculture reduces the richness and cover of plant species (Lesschen et al, ; Plieninger, Hui, Gaertner, & Huntsinger, ; Sato et al, ) as well as the humidity, organic matter content, and availability of nitrogen, carbon, and phosphorus in soil. However, studies on the impact of human activities such as rainfed agriculture and firewood extraction in tropical deserts are scarce because only five studies were found in the ecological literature of the last 28 years (Ayoub, ; Braimoh, ; Chidumayo, ; El Tahir, Ahmed, Ardö, Gaafar, & Salih, ; Mahiri & Howorth, ).…”