Changes in evapotranspiration and phenology as consequences of shrub removal in dry forests of central Argentina

Marchesini, Victoria A.; Fernández, Roberto; Reynolds, James F.; Sobrino, José A.; Bella, Di

doi:10.1002/eco.1583

Cited by 18 publications

(20 citation statements)

References 54 publications

(74 reference statements)

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“…A few studies have evaluated the ecohydrological impact of dry forest clearance and cultivation in South America (Amdan, Aragón, Jobbágy, Volante, & Paruelo, 2013;Jayawickreme, Santoni, Kim, Jobbágy, & Jackson, 2011;Santoni, Jobbágy, & Contreras, 2010), being confined to specific study areas. For example, a study in dry forests of central Argentina indicated that the elimination of perennial woody vegetation with deep root system and longer active phenology shortened the growing season by 3 months and reduced evapotranspiration by 30% (Marchesini, Fernández, Reynolds, Sobrino, & Di Bella, 2015).…”

Section: Land Use Changes In the Dry Forests Of South Americamentioning

confidence: 99%

Ecohydrological transformation in the Dry Chaco and the risk of dryland salinity: Following Australia's footsteps?

et al. 2017

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During the last century, the massive conversion of Australian dry forests to crops and pastures triggered the massive soil and groundwater degradation process known as dryland salinity.Currently, South American Chaco's dry forests are undergoing a similar transformation, leading global deforestation rates. The goal of this study was to review existing ecohydrological information about natural and cultivated systems in the Chaco to assess the dryland salinity risks. We review deep soil water, salt stocks, and groundwater recharge from agriculture or native dry forests stands located in a precipitation range of 450-1100 mm. We complement this with water table level records and geoelectric profiles together with personal observations. We use data from 15 Australian studies for comparison. Strong salt leaching, especially after 20 years of forest clearance, indicates the onset of deep drainage following forest conversion to agriculture in the Dry Chaco. Water stocks were more than double in the cleared stands compared to their dry forest pairs, and recharge rates were up to two order magnitude higher in agricultural areas.Although lower atmospheric salt deposition, younger sediments, and relatively high water-consuming agricultural systems in the Dry Chaco attenuate salinization risks compared to Australia, the very flat topography and related shallow water table levels of the South American region could make groundwater recharge and salt mobilization processes more widespread and difficult to manage. The lack of awareness among the general public, farmers, and decision makers about this issue amplifies the problem, making land management plans for the Argentine dry forest territories essential.

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Section: Land Use Changes In the Dry Forests Of South Americamentioning

confidence: 99%

Ecohydrological transformation in the Dry Chaco and the risk of dryland salinity: Following Australia's footsteps?

et al. 2017

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“…Although rainfed agriculture is not usually profitable in our study site, there is room for improving forage production for extensive cattle raising. Our results, and some experiences from local farmers, highlight the underlying litter effects that would potentially explain the effectiveness of the roller chopping practice based on favouring those key species that produce a large quantity (amount) of litter, such as Prosopis flexuosa trees (Blanco et al, 2005;Marchesini et al, 2015;Steinaker et al, 2016). This study suggests that the conditions generated by the roller-chopping practice (open canopies and large amount of palatable grasses) in combination with the ecohydrological effect of high amounts of litter on surface are the key to improve extensive livestock production in Dry Chaco rangelands.…”

Section: Resultsmentioning

confidence: 65%

“…Under practical conditions, reference evapotranspiration, rainfall inputs, and soil type are not controllable factors, but the amount, distribution, and persistence of litter (or crop residues in agricultural systems) are amenable to be controlled by management practices (Klocke et al, 2009;Steiner, 1989;Van Donk et al, 2010). Our results, and some experiences from local farmers, highlight the underlying litter effects that would potentially explain the effectiveness of the roller chopping practice based on favouring those key species that produce a large quantity (amount) of litter, such as Prosopis flexuosa trees (Blanco et al, 2005;Marchesini et al, 2015;Steinaker et al, 2016). 500-600 mm/year) such as the southern great plains in United States or the northeast plain in China (Ji & Unger, 2001).…”

Section: Figurementioning

confidence: 73%

“…So, n = 54 in forests (18 patches × 3 transects) and n = 27 in pastures (9 patches × 3 transects). More observations were considered necessary in forest than in pasture because of the higher heterogeneity of the former in our study site (Magliano et al, 2016;Magliano et al, 2017;Marchesini, Fernández, & Jobbágy, 2013;Marchesini, Fernández, Reynolds, Sobrino, & Di Bella, 2015).…”

Section: Methodsmentioning

confidence: 99%

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Litter is more effective than forest canopy reducing soil evaporation in Dry Chaco rangelands

et al. 2017

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Soil evaporation is a dominant water flux of flat dry ecosystems, reducing available water for plant transpiration. Vegetation plays a key role at controlling evaporation, especially by altering soil surface micro‐meteorological conditions. Here, we explored the vegetation cover effect on soil evaporation, differentiating the effects of canopy cover (shadow) and of surface cover (litter) in forests and pastures of Dry Chaco rangelands (San Luis, Argentina). We measured daily soil evaporation using irrigated micro‐lysimeters installed at regularly spaced (2 m) patches along transects in native dry forests (n = 54 patches) and pastures (n = 27 patches). In each forest patch, we established a pair of micro‐lysimeters, one with litter (3 cm depth, representing high litter cover conditions of the site) and one with bare soil, but in pastures, only one micro‐lysimeter with bare soil was installed at each patch (representing the typical no litter cover conditions of pastures of the study site). We found that, when soil water was not limiting, litter cover had the strongest effect in reducing evaporation rates, with a 4‐ and 6.4‐fold reduction respect to bare soil micro‐lysimeters in the forest and pasture, respectively. Evaporation decreased sharply with declining incident radiation fraction in bare soil micro‐lysimeters from 5.6 mm/day (full radiation) to 3.5 mm/day (full canopy shadow; R2 = 0.50). Litter‐covered micro‐lysimeters showed lower and more stable evaporation rates, decreasing only from 1.35 to 1.03 mm/day under the same radiation conditions (R2 = 0.10). In accordance with J.T. Ritchie evaporation model, we identified a threshold of ~10.5 mm of cumulative evaporation at which evaporation switched from energy to water limitation in all situations, as revealed by declining evaporation rates and raising surface temperatures. Under typical wet–summer conditions, the pasture, the forest with bare soil, and the forest with litter would need on average a drying cycle of 1.5, 2.5, and 9.5 days, respectively, to reach that threshold. Simulations showed that, considering the distribution of rainfall events at our study site, litter would maintain evaporation in the energy‐limited mode most of the time (68.8% of summer days), potentially favouring transpiration. The ecohydrological key role of soil litter controlling evaporation highlights the importance of an accurate assessment of management practices controlling the evaporation/transpiration partition in dry ecosystems.

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“…It is unclear how long complete recovery will take, but the timing may be similar to recovery from other disturbances. For example, after repeated vehicle damage, L. tridentata experienced no mortality and canopy size recovered within five years (Gibson, Sharifi, & Rundel, 2004), and following roller-chopping, productivity of the related species Larrea divaricata recovered to pretreatment levels in four years (Marchesini, Fernández, Reynolds, Sobrino, & Di Bella, 2015). Resprouting patterns of L. tridentata are also linked to disturbance severity (Bellingham & Sparrow, 2000).…”

Section: Discussionmentioning

confidence: 99%

Minimal mortality and rapid recovery of the dominant shrub Larrea tridentata following an extreme cold event in the northern Chihuahuan Desert

Ladwig

Collins

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et al. 2019

J Vegetation Science

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Questions Woody encroachment into grasslands is a worldwide phenomenon partially influenced by climate change, including extreme weather events. Larrea tridentata is a common shrub throughout the warm deserts of North America that has encroached into grasslands over the past 150 years. Physiological measurements suggest that the northern distribution of L. tridentata is limited by cold temperatures; thus extreme winter events may slow or reverse shrub expansion. We tested this limitation by measuring the response of individual L. tridentata shrubs to an extreme winter cold (−31°C) event to assess shrub mortality and rate of recovery of surviving shrubs. Location Sevilleta National Wildlife Refuge, Socorro County, New Mexico, USA. Methods Canopy dieback and recovery following an extreme cold event were measured for 869 permanently marked individual L. tridentata shrubs in grass–shrub ecotone and shrubland sites. Individual shrubs were monitored for amount of canopy dieback, rate of recovery, and seed set for three growing seasons after the freeze event. Results Shrubs rapidly suffered a nearly complete loss of canopy leaf area across all sites. Although canopy loss was high, mortality was low and 99% of shrubs resprouted during the first growing season after the freeze event. Regrowth rates were similar within ecotone and shrubland sites, even when damage by frost was larger in the latter. After three years of recovery, L. tridentata canopies had regrown on average 23–83% of the original pre‐freeze canopy sizes across the sites. Conclusions We conclude that isolated extreme cold events may temporarily decrease shrubland biomass but they do not slow or reverse shrub expansion. These events are less likely to occur in the future as regional temperatures increase under climate change.

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Changes in evapotranspiration and phenology as consequences of shrub removal in dry forests of central Argentina

Cited by 18 publications

References 54 publications

Ecohydrological transformation in the Dry Chaco and the risk of dryland salinity: Following Australia's footsteps?

Ecohydrological transformation in the Dry Chaco and the risk of dryland salinity: Following Australia's footsteps?

Litter is more effective than forest canopy reducing soil evaporation in Dry Chaco rangelands

Minimal mortality and rapid recovery of the dominant shrub Larrea tridentata following an extreme cold event in the northern Chihuahuan Desert

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