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

Marchesini, Victoria A.; Giménez, Raúl; Nosetto, Marcelo D.; Jobbágy, Estéban G.

doi:10.1002/eco.1822

Cited by 29 publications

(26 citation statements)

References 36 publications

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“…In addition, larger values of total Q are found for two LSMs, which might implicitly be indicative of groundwater recharge (groundwater is only simulated in CLSM). This is in agreement with studies that have been carried out on a local scale by Giménez et al (2016), Marchesini et al (2017), Magliano et al (2017) and Nosetto et al (2012). They all reported wetter soils on agriculture land compared to forest across different regions of the Chaco.…”

Section: Effects Of Soil and Vegetation Parameters On Soil Moisturesupporting

confidence: 92%

Simulating the Dry Chaco Hydrology under Deforestation Pressure

Maertens¹,

Lannoy²,

Apers³

et al. 2020

Preprint

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Abstract. Various regions in the world experience land cover and land use changes. One such a region is the Dry Chaco ecoregion in South America, characterized by deforestation and forest degradation since the 1980s. In this study, we simulated the water balance over the Dry Chaco and assessed the impact of land cover changes thereon, using three different state-of-the-art land surface models (LSMs) within the NASA Land Information System (LIS) with updated parameters. The default LIS parameters were revised with (i) improved soil parameters, (ii) satellite-based dynamic vegetation parameters instead of default climatological vegetation parameters, and (iii) yearly land cover information instead of static land cover. A relative comparison in terms of water budget components and ‘efficiency space’ for various baseline and revised experiments showed that large regional and long-term differences relate to different LSM structures, whereas smaller local differences resulted from updated soil, vegetation and land cover parameters. Furthermore, different LSM structures redistributed water differently in response to these parameter updates. A time series comparison of the simulations to independent satellite-based estimates of evapotranspiration and brightness temperature showed that no LSM setup significantly outperformed another for the entire region, and that not all LSM simulations improved with updated parameter values. However, the revised soil parameters generally reduced the simulated surface soil moisture bias relative to pixel-scale in situ observations, and the simulated Tb bias relative to regional Soil Moisture Ocean Salinity (SMOS) observations.

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Section: Effects Of Soil and Vegetation Parameters On Soil Moisturesupporting

confidence: 92%

Simulating the Dry Chaco Hydrology under Deforestation Pressure

Maertens¹,

Lannoy²,

Apers³

et al. 2020

Preprint

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show abstract

“…This pattern, already documented in other woody systems, even more humid than the one studied here (Adane & Gates, 2015;Li, Si, & Li, 2018;Marchesini et al, 2016), warns us about the possible hydrological consequences of this land-use transformation at the regional and landscape levels.…”

Section: Discussionsupporting

confidence: 63%

“…may be the key vegetation attribute to explain the disruption of deep drainage, because their deep roots can absorb soil water that escaped the roots of herbaceous/shrubby vegetation.This pattern, already documented in other woody systems, even more humid than the one studied here(Adane & Gates, 2015;Li, Si, & Li, 2018;Marchesini et al, 2016), warns us about the possible hydrological consequences of this land-use transformation at the regional and landscape levels.At the watershed scale, the seasonal water yield dynamic showed a good match with simulated deep drainage fluxes (Figure 6). The flow data of Chubut river, between El Maitén and Nacimiento stations (Period 1993-2004, Source: Argentinean Water Resources Office), which collect water from a large part of El Maitén plain, showed a similar seasonal dynamic to that of deep drainage fluxes, though smoother and with a 1-month delay.…”

supporting

confidence: 61%

Hydrological impacts of afforestation in the semiarid Patagonia: A modelling approach

Milkovic¹,

Paruelo

Nosetto

2019

Ecohydrology

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Afforestation has been widely encouraged with different goals, including as a strategy to tackle global warming. However, the side-effects of this land-use transformation have been in many cases underestimated. Particularly, the hydrological impacts may become relevant in (semi)arid regions where water is a key element. In this work, we evaluated the hydrological effects triggered by afforestation with ponderosa pine in the semiarid Argentine Patagonia that is currently a focus of afforestation programs. For this purpose, we used complementary approaches that included hydrological modelling (DINAQUA model), satellite image analysis, and soil wetness data. All analyses provided convergent results into hydrological effects of afforestation. The modelling results showed that afforestation significantly increased transpiration in relation to native grass-shrub steppe. In the steppe in degraded condition, transpiration accounted for only 10% (40 mm year −1 ) of total water flux, whereas in adult pine plantations, it accounted for up to 73% (277 mm year −1 ). Deep drainage was also severely affected by afforestation as it decreased from 182 mm year −1 in the steppe to zero in adult plantations, according to model simulations. Estimates from Landsat images also showed that evapotranspiration was higher in plantations compared with the steppe. Soil wetness data also revealed significantly drier soils in plantations. Our results indicate that pine plantations in the semiarid Patagonia evaporate all rainfall inputs, resulting in zero deep drainage and groundwater recharge. If the afforested area in the region increases, downstream meadow ecosystems, which are hotspots of primary productivity, may be negatively impacted.

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“…Over the last decades, soil salinization has grown at an unprecedented rate, becoming a global environmental issue (Datta & Jong, 2002;Schofield & Kirkby, 2003;Wicke et al, 2011;FAO, 2015), with substantial repercussions on both natural (Thomas & Middleton, 1993;Lombardini, 2006;Zhou et al, 2017) and managed ecosystems (Oldeman et al, 1990;Rohades et al, 1992;Jobb agy & Jackson, 2004;Marchesini et al, 2017). Out of the 1.5 billion ha in use for crop production world-wide, human-induced (secondary) salinity is now impacting some 0.3 billion ha and already represents a threat to the food security of arid regions, where irrigation is employed routinely (Ghassemi et al, 1995;Pitman & L€ auchli, 2002).…”

Section: Introductionmentioning

confidence: 99%

Xylem–phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress

2019

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Summary Salinity is known to affect plant productivity by limiting leaf‐level carbon exchange, root water uptake, and carbohydrates transport in the phloem. However, the mechanisms through which plants respond to salt exposure by adjusting leaf gas exchange and xylem–phloem flow are still mostly unexplored. A physically based model coupling xylem, leaf, and phloem flows is here developed to explain different osmoregulation patterns across species. Hydraulic coupling is controlled by leaf water potential, ψl, and determined under four different maximization hypotheses: water uptake (1), carbon assimilation (2), sucrose transport (3), or (4) profit function – i.e. carbon gain minus hydraulic risk. All four hypotheses assume that finite transpiration occurs, providing a further constraint on ψl. With increasing salinity, the model captures different transpiration patterns observed in halophytes (nonmonotonic) and glycophytes (monotonically decreasing) by reproducing the species‐specific strength of xylem–leaf–phloem coupling. Salt tolerance thus emerges as plant's capability of differentiating between salt‐ and drought‐induced hydraulic risk, and to regulate internal flows and osmolytes accordingly. Results are shown to be consistent across optimization schemes (1–3) for both halophytes and glycophytes. In halophytes, however, profit‐maximization (4) predicts systematically higher ψl than (1–3), pointing to the need of an updated definition of hydraulic cost for halophytes under saline conditions.

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

Cited by 29 publications

References 36 publications

Simulating the Dry Chaco Hydrology under Deforestation Pressure

Simulating the Dry Chaco Hydrology under Deforestation Pressure

Hydrological impacts of afforestation in the semiarid Patagonia: A modelling approach

Xylem–phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress

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