Assessing water use by Prosopis invasions and Vachellia karroo trees: Implications for groundwater recovery following alien plant removal in an arid catchment in South Africa

Dzikiti, Sebinasi; Ntshidi, Zanele; Maitre, David C. Le; Bugan, Richard Dh; Mazvimavi, Dominic; Schachtschneider, Klaudia; Jovanović, Nebojša; Pienaar, Harrison

doi:10.1016/j.foreco.2017.05.009

Cited by 29 publications

(22 citation statements)

References 23 publications

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“…Moreover, high-density Prosopis cover impedes accessibility to water points for people and livestock, and limits livestock mobility to grazing areas [50]. Further, Prosopis is known to consume substantial amounts of groundwater [82][83][84][85], but the effect of Prosopis invasion on the groundwater level in Baringo County is currently unknown.…”

Section: Lulc Changes In the Study Areamentioning

confidence: 99%

Spatial Evolution of Prosopis Invasion and its Effects on LULC and Livelihoods in Baringo, Kenya

Mbaabu

Schaffner

et al. 2019

Remote Sensing

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Woody alien plant species have been deliberately introduced globally in many arid and semi-arid regions, as they can provide services and goods to the rural poor. However, some of these alien trees and shrubs have become invasive over time, with important impacts on biodiversity, ecosystem services, and human well-being. Prosopis was introduced in Baringo County, Kenya, in the 1980s, but since then, it has spread rapidly from the original plantations to new areas. To assess land-use and land-cover (LULC) changes and dynamics in Baringo, we used a combination of dry and wet season Landsat satellite data acquired over a seven-year time interval between 1988–2016, and performed a supervised Random Forest classification. For each time interval, we calculated the extent of Prosopis invasion, rates of spread, gains and losses of specific LULC classes, and the relative importance of Prosopis invasion on LULC changes. The overall accuracy and kappa coefficients of the LULC classifications ranged between 98.1–98.5% and 0.93–0.96, respectively. We found that Prosopis coverage increased from 882 ha in 1988 to 18,792 ha in 2016. The highest negative changes in LULC classes were found for grasslands (−6252 ha; −86%), irrigated cropland (−849 ha; −57%), Vachellia tortilis-dominated vegetation (−3602 ha; −42%), and rainfed cropland (−1432 ha; −37%). Prosopis invasion alone directly accounted for over 30% of these negative changes, suggesting that Prosopis invasion is a key driver of the observed LULC changes in Baringo County. Although the management of Prosopis by utilization has been promoted in Baringo for 10–15 years, the spread of Prosopis has not stopped or slowed down. This suggests that Prosopis management in Baringo and other invaded areas in East Africa needs to be based on a more integrated approach.

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Section: Lulc Changes In the Study Areamentioning

confidence: 99%

Spatial Evolution of Prosopis Invasion and its Effects on LULC and Livelihoods in Baringo, Kenya

Mbaabu

Schaffner

et al. 2019

Remote Sensing

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“…The conducting sapwood area was determined by injecting a weak solution of methylene blue dye into the stems to determine the extent of the active xylem vessels. Whole-tree transpiration was derived as the sum of the sap flows in four concentric rings in the sapwood with flow in each ring calculated as the product of the sap velocity at each probe depth and the sapwood area represented by that probe as described by Dzikiti et al (2017b). Sap flux density was derived as the ratio of the daily sap flow rate of an individual tree to the conducting sapwood area.…”

Section: Microclimate Sap Flow and Eddy Covariance Measurementsmentioning

confidence: 99%

Estimating the water requirements of high yielding and young apple orchards in the winter rainfall areas of South Africa using a dual source evapotranspiration model

Dzikiti

Volschenk

Midgley

et al. 2018

Agricultural Water Management

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Exceptionally high yielding (>100 t ha-1) apple orchards (Malus domestica Borkh.) are becoming common in South Africa and elsewhere in the world. However, no accurate quantitative information currently exists on the water requirements of these orchards. Information is also sparse on the water use of young apple orchards. This paucity of data may cause inaccurate irrigation scheduling and water allocation decisions, leading to inefficient use of often limited water resources. The aim of this study was therefore to investigate the dynamics of water use in eight apple orchards in South Africa planted to Golden Delicious and the red cultivars i.e. Cripps' Pink, Cripps' Red and Rosy Glow in order to understand how canopy cover and crop load influence orchard water use. Four of the orchards were young (3-4 years after planting) and non-bearing, while the other four were mature high yielding orchards. Transpiration was monitored using sap flow sensors while orchard evapotranspiration (ET) was measured during selected periods using eddy covariance systems. Scaling up of ET to seasonal water use was done using a modified Shuttleworth and Wallace model that incorporated variable canopy and soil surface resistances. This model provided reasonable estimates in both mature and young orchards. The average yield in the two mature 'Cripps' Pink' was ~110 t ha-1 compared to ~ 88 t ha-1 in the 'Golden Delicious' orchards. However, average transpiration (Oct-Jun) was ~ 638 mm for the 'Cripps' Pink' and ~778 mm in the 'Golden Delicious' orchards. The peak leaf area index was ~2.6 and ~ 3.3 for the mature 'Cripps' Pink and 'Golden Delicious' orchards. So, canopy cover rather than crop load was the main driver of orchard water use. Transpiration by the young orchards ranged from 130 to 270 mm. The predicted seasonal total ET varied from ~ 900 to 1100 mm in the mature orchards and it was ~500 mm in the young orchards. Orchard floor evaporation accounted for ~18 to 36% of ET in mature orchards depending on canopy cover and this increased to more than 60% in young orchards.

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“…The impact of specific invasive alien tree species on streamflow has been assessed in field studies, some of which covered extended periods (Table 15.1). These include Acacia mearnsii (Dye and Jarmain 2004;Clulow et al 2011;Everson et al 2014), Eucalyptus camaldulensis (River Red Gum) (Dzikiti et al 2016), Pinus radiata (Monterey Pine) (Dzikiti et al 2013b), Prosopis species (Dzikiti et al 2013a(Dzikiti et al , 2017 and Populus canescens (Grey poplars) (Ntshidi et al 2018). In recent years some studies have also focused on the impacts of the invasive alien plants on groundwater [e.g.…”

Section: Species and Stand-level Studiesmentioning

confidence: 99%

“…Measurements of A. mearnsii growing alongside an afro-temperate forest in the Eastern Cape found that its water-use was about twice that of the native forest species (Scott-Shaw and Everson 2018). A comparison of the water use of Prosopis species with the coexisting and structurally similar native Vachellia karroo (Sweet Thorn) in an arid riparian environment in the Northern Cape found that water use of comparably-sized trees was similar, but the greater density, and more extensive invasions, of Prosopis resulted in much greater impacts on groundwater per unit area (Dzikiti et al 2017).…”

Section: Species and Stand-level Studiesmentioning

confidence: 99%

Impacts of Plant Invasions on Terrestrial Water Flows in South Africa

Maitre

Blignaut

Clulow

et al. 2020

Biological Invasions in South Africa

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Considerable advances have been made since the first estimates of the impacts of invasive alien plants on water resources in the early 1990s. A large body of evidence shows that invasive alien plants can increase transpiration and evaporation losses and thus reduce river flows and mean annual runoff. Riparian invasions, and those in areas where groundwater is accessible, have 1.2-2 times the impact of invasions in dryland areas. The magnitude of the impacts is directly related to differences between the invading species and the dominant native species in size, rooting depth and leaf phenology. Information on the impacts has been successfully used to compare the water use of invasive plants and different land cover classes, to quantify the water resource benefits of control measures, and to prioritise areas for control operations. Nationally, the impacts of invasive alien plants on surface water runoff are estimated at 1.44-2.44 billion m 3 per year. The most affected primary catchments (>5% reduction in mean annual runoff) are located in the Western and Eastern Cape, and KwaZulu-Natal. If no remedial action is taken, reductions in surface water runoff could increase to 2.59-3.15 billion m 3 per year, about 50%

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Assessing water use by Prosopis invasions and Vachellia karroo trees: Implications for groundwater recovery following alien plant removal in an arid catchment in South Africa

Cited by 29 publications

References 23 publications

Spatial Evolution of Prosopis Invasion and its Effects on LULC and Livelihoods in Baringo, Kenya

Spatial Evolution of Prosopis Invasion and its Effects on LULC and Livelihoods in Baringo, Kenya

Estimating the water requirements of high yielding and young apple orchards in the winter rainfall areas of South Africa using a dual source evapotranspiration model

Impacts of Plant Invasions on Terrestrial Water Flows in South Africa

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