Assessing vegetation change temporally and spatially in southeastern Arizona

King, D. M.; Skirvin, S. M.; Collins, Chandra D. Holifield; Moran, M. Susan; Biedenbender, Sharon; Kidwell, Mary R.; Weltz, Mark A.; Díaz-Gutiérrez, A.

doi:10.1029/2006wr005850

Cited by 37 publications

(38 citation statements)

References 33 publications

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“…The composition of ecosystems can be perturbed by a variety of disturbances including fire, drought, and excessive herbivory. Protracted drought has been shown to trigger rapid compositional changes through mortality of historical vegetation [ Allen and Breshears , 1998; Breshears et al , 2005] and can facilitate the spread of opportunistic invaders when the drought ends [ Dukes and Mooney , 2004; King et al , 2008]. Such changes can result in transformations to ecosystem structure and its ecohydrologic functioning that may or may not have lasting effects.…”

Section: Introductionmentioning

confidence: 99%

Carbon dioxide exchange in a semidesert grassland through drought‐induced vegetation change

et al. 2010

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Global warming may intensify the hydrological cycle and lead to increased drought severity and duration, which could alter plant community structure and subsequent ecosystem water and carbon dioxide cycling. We report on the net ecosystem exchange of carbon dioxide (NEE) of a semidesert grassland through a severe drought which drove succession from native bunchgrasses to forbs and to eventual dominance by an exotic bunchgrass. We monitored NEE and energy fluxes using eddy covariance coupled with meteorological and soil moisture variables for 6 years at a grassland site in southeastern Arizona, USA. Seasonal NEE typically showed a springtime carbon uptake after winter‐spring periods of average rainfall followed by much stronger sink activity during the summer rainy season. The two severe drought years (2004 and 2005) resulted in a net release of carbon dioxide (25 g C m−2) and widespread mortality of native perennial bunchgrasses. Above average summer rains in 2006 alleviated drought conditions, resulting in a large flush of broad‐leaved forbs and negative total NEE (−55 g C m−2 year−1). Starting in 2007 and continuing through 2009, the ecosystem became increasingly dominated by the exotic grass, Eragrostis lehmanniana, and was a net carbon sink (−47 to −98 g C m−2 year−1) but with distinct annual patterns in NEE. Rainfall mediated by soils was the key driver to water and carbon fluxes. Seasonal respiration and photosynthesis were strongly dependent on precipitation, but photosynthesis was more sensitive to rainfall variation. Respiration normalized by evapotranspiration showed no interannual variation, while normalized gross ecosystem production (i.e., water use efficiency) was low during drought years and then increased as the rains returned and the E. lehmanniana invasion progressed. Thus, when dry summer conditions returned in 2009, the potential for ecosystem carbon accumulation was increased and the ecosystem remained a net sink unlike similar dry years when native grasses dominated ecosystem structure.

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Section: Introductionmentioning

confidence: 99%

Carbon dioxide exchange in a semidesert grassland through drought‐induced vegetation change

et al. 2010

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“…Lehmann lovegrass was first documented at U.S. Department of Agriculture‐Agricultural Research Service (USDA‐ARS) Walnut Gulch Experimental Watershed (WGEW), near Tombstone, AZ, in 1994, when it was recorded at 7 out of 53 permanent transects, and again at 13 transects in 1999 [ King et al , 2008]. In 2005 Lehmann lovegrass cover was less than 1% at all but one location, where it accounted for 8% of cover and 24% of total vegetation [ King et al , 2008].…”

Section: Introductionmentioning

confidence: 99%

Runoff and erosional responses to a drought‐induced shift in a desert grassland community composition

et al. 2010

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[1] This study investigates how drought-induced change in semiarid grassland community affected runoff and sediment yield in a small watershed in southeast Arizona, USA. Three distinct periods in ecosystem composition and associated runoff and sediment yield were identified according to dominant species: native bunchgrass ) or succeeding period under E. lehmanniana (0.06 t ha −1 yr −1 ). In contrast, measurements on small runoff plots on the hillslopes of the same watershed showed a significant increase in sediment discharge that continued after E. lehmanniana replaced native grasses. Together, these findings suggest alteration in plant community increased sediment yield but that hydrological responses to this event differ at watershed and plot scales, highlighting the geomorphological controls at the watershed scale that determine sediment transport efficiency and storage. Resolving these scalar issues will help identify critical landform features needed to preserve watershed integrity under changing climate conditions.

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“…A flux tower was deployed in 1996 to measure mass and energy exchanges [ Emmerich and Verdugo , 2008]. The flux tower footprint is composed of a sparse shrub community, mainly represented by evergreen shrubs, such as creosotebush ( Larrea tridentata ) and tarbush ( Flourensia cernua ), and deciduous shrubs, such as whitethorn acacia ( Acacia constricta ) [ King et al , 2008; Skirvin et al , 2008]. The climate at the site can be classified as semiarid, almost arid desert‐type.…”

Section: Model Confirmationmentioning

confidence: 99%

A mechanistic ecohydrological model to investigate complex interactions in cold and warm water‐controlled environments: 1. Theoretical framework and plot‐scale analysis

Fatichi

Ivanov

Caporali

2012

J Adv Model Earth Syst

104

188

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[1] Numerous studies have explored the role of vegetation in controlling and mediating hydrological states and fluxes at the level of individual processes, which has led to improvements in our understanding of plot-scale dynamics. Relatively less effort has been directed toward spatially-explicit studies of vegetation-hydrology interactions at larger scales of a landscape. Only few continuous, process-oriented ecohydrological models had been proposed with structures of varying complexity. This study contributes to their further evolution and presents a novel ecohydrological model, Tethys-Chloris. The model synthesizes the state-of-the-art knowledge on individual processes and coupling mechanisms drawn from the disciplines of hydrology, plant physiology, and ecology. Specifically, the model reproduces all essential components of the hydrological cycle: it resolves the mass and energy budgets in the atmospheric surface layer at the hourly scale, while representing up to two layers of vegetation; it includes a module of snowpack evolution; it describes the saturated and unsaturated soil water dynamics, processes of runoff generation and flow routing. The component of vegetation dynamics parameterizes life cycle processes of different plant functional types, including photosynthesis, phenology, carbon allocation, and tissue turnover. This study presents a confirmation of the long-term, plot-scale model performance by simulating two types of ecosystems corresponding to different climate conditions. A consistent and highly satisfactory model skill in reproducing the energy and water budgets as well as physiological cycles of plants with minimum calibration overhead is demonstrated. Furthermore, these applications demonstrate that the model permits the identification of data types and observation frequencies crucial for appropriate evaluation of modeled dynamics. More importantly, through a synthesis of a wide array of process representations, the model ensures that climate, soil, vegetation, and topography collectively identify essential modes controlling ecohydrological systems, i.e., that satisfactory performance is a result of appropriate mimicking of internal processes.Citation: Fatichi, S., V. Y. Ivanov, and E. Caporali (2012), A mechanistic ecohydrological model to investigate complex interactions in cold and warm water-controlled environments: 1. Theoretical framework and plot-scale analysis, J. Adv. Model. Earth Syst., 4, M05002,

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Assessing vegetation change temporally and spatially in southeastern Arizona

Cited by 37 publications

References 33 publications

Carbon dioxide exchange in a semidesert grassland through drought‐induced vegetation change

Carbon dioxide exchange in a semidesert grassland through drought‐induced vegetation change

Runoff and erosional responses to a drought‐induced shift in a desert grassland community composition

A mechanistic ecohydrological model to investigate complex interactions in cold and warm water‐controlled environments: 1. Theoretical framework and plot‐scale analysis

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