Competition in the Semidesert Grass‐shrub Type as Influneced by Root Systems, Growth Habits, and Soil Moisture Extraction

Cable, Dwight R.

doi:10.2307/1934659

Cited by 68 publications

(48 citation statements)

References 2 publications

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“…We found significant numbers of both coarse and fine roots up to 2 m beneath dune surface and to at least 1 m depth in soils between dunes. Jenkins et al (1988) identified mesquite roots in Jornada dunes at depths of up to 6 m. In comparison, desert grasses generally concentrate roots in the upper 15 cm of soil (Cable 1969). We found only fine root biomass in our grassland profiles, most of which was concentrated between 0 and 40 cm depth.…”

Section: Discussionmentioning

confidence: 54%

“…These transformations, in turn, may alter the composition and turnover of constituent SOM pools. An increase in mesquite dominance has been shown to alter belowground production, from fine root biomass distributed in surface horizons to deeper coarse root biomass concentrated beneath shrub canopies (Cable 1969;Heitschmidt et al 1988;Brown and Archer 1990). While total root weight increases in soils beneath mesquite, relative to grasses (McPherson et al 1993), the proportion of fine root biomass (<2 mm) apparently declines (Virginia et al 1992).…”

Section: Introductionmentioning

confidence: 99%

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Carbon isotopes reveal soil organic matter dynamics following arid land shrub expansion

1997

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Over the past century, overgrazing and drought in New Mexico's Jornada Basin has promoted the replacement of native black grama (Bouteloua eriopoda Torr.) grass communities by shrubs, primarily mesquite (Prosopis glandulosa Torr.). We investigated the effects of shrub expansion on the distribution, origin, turnover, and quality of light (LFC) and heavy (HFC) soil organic matter (SOM) fractions using δC natural abundance to partition SOM into C (grass) and C (shrub) sources. Soil organic matter beneath grasses and mesquite was isotopically distinct from associated plant litter, providing evidence of both recent shrub expansion and Holocene plant community changes. Our δC analyses indicated that SOM derived from mesquite was greatest beneath shrub canopies, but extended at least 3 m beyond canopy margins, similar to the distribution of fine roots. Specific C activities of LFC indicated that root litter is an important source of SOM at depth. Comparison of turnover rates for surface LFC pools in grass (7 or 40 years) and mesquite (11 or 28 years) soils and for HFC pools by soil depth (∼150-280 years), suggest that mesquite may enhance soil C storage relative to grasses. We conclude that the replacement of semiarid grasslands by woody shrubs will effect changes in root biomass, litter production, and SOM cycling that influence nutrient availability and long-term soil C sequestration at the ecosystem level.

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Section: Discussionmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Carbon isotopes reveal soil organic matter dynamics following arid land shrub expansion

1997

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“…Water at depth is recharged on some grasslands largely by rainfall during the dormant season of grasses (e.g., Cable 1969). In these ecosystems, changes in grass transpiration probably will not greatly affect growth of deeply-rooting shrubs.…”

Section: Potential Consequences Of Lower Evapotranspiration To the Spmentioning

confidence: 99%

Viewpoint: Atmospheric CO 2 , Soil Water, and Shrub/Grass Ratios on Rangelands

Polley¹,

Mayeux²,

Johnson³

et al. 1997

Journal of Range Management

156

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The abundance of woody plants on grasslands and savannas often is controlled by the availability of water and its location in soil. Water availability to plants is limited by precipitation, but the distribution of soil water and period over which it is available in these ecosystems are intluenced by the transpiration rates of grasses. We discuss implications of recent and projected increases iu atmospheric CO2 concentration for transpiration, soil water availability, and the balance of grasses and shrubs. Au increase in CO2 concentration often reduces potential transpiration/leaf area by reducing stomata1 conductance. On grasslands where effects of stomata1 closure on transpiration are not negated by an increase iu leaf temperature and leaf area, rising CO2 concentration should slow the depletion of soil water by grasses and potentially favor shrubs and other species that might otherwise succumb to water stress. Predicted effects of CO, are supported by results from COZ-enrichment studies in the field and are compatible with recent models of interactions between resource levels and vegetation pattern and structure.

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“…The depth of the soil profile above a water-and root-restrictive layer (e.g., bedrock, caliche, claypan) defines the volume of soil in which water can be held and from which roots can extract retained water (Cable 1969). However, fractures in the restrictive layer can allow water penetration to greater depths and provide plant roots with access to deep soil moisture (Noy-Meir 1973).…”

Section: Introductionmentioning

confidence: 99%

On the brink of change: plant responses to climate on the Colorado Plateau

et al. 2011

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Abstract. The intensification of aridity due to anthropogenic climate change in the southwestern U.S. is likely to have a large impact on the growth and survival of plant species that may already be vulnerable to water stress. To make accurate predictions of plant responses to climate change, it is essential to determine the long-term dynamics of plant species associated with past climate conditions. Here we show how the plant species and functional types across a wide range of environmental conditions in Colorado Plateau national parks have changed with climate variability over the last twenty years. During this time, regional mean annual temperature increased by 0.188C per year from 1989-1995, 0.068C per year from 1995-2003, declined by 0.148C from [2003][2004][2005][2006][2007][2008], and there was high interannual variability in precipitation. Non-metric multidimensional scaling of plant species at long-term monitoring sites indicated five distinct plant communities. In many of the communities, canopy cover of perennial plants was sensitive to mean annual temperature occurring in the previous year, whereas canopy cover of annual plants responded to cool season precipitation. In the perennial grasslands, there was an overall decline of C 3 perennial grasses, no change of C 4 perennial grasses, and an increase of shrubs with increasing temperature. In the shrublands, shrubs generally showed no change or slightly increased with increasing temperature. However, certain shrub species declined where soil and physical characteristics of a site limited water availability. In the higher elevation woodlands, Juniperus osteosperma and shrub canopy cover increased with increasing temperature, while Pinus edulis at the highest elevation sites was unresponsive to interannual temperature variability. These results from well-protected national parks highlight the importance of temperature to plant responses in a water-limited region and suggest that projected increases in aridity are likely to promote grass loss and shrub expansion on the Colorado Plateau.

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Competition in the Semidesert Grass‐shrub Type as Influneced by Root Systems, Growth Habits, and Soil Moisture Extraction

Cited by 68 publications

References 2 publications

Carbon isotopes reveal soil organic matter dynamics following arid land shrub expansion

Carbon isotopes reveal soil organic matter dynamics following arid land shrub expansion

Viewpoint: Atmospheric CO 2 , Soil Water, and Shrub/Grass Ratios on Rangelands

On the brink of change: plant responses to climate on the Colorado Plateau

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