Patterns of Growth and Soil-water Utilization in some Exotic Annuals and Native Perennial Bunchgrasses of California

Holmes, Tyson H.; Rice, Kevin J.

doi:10.1006/anbo.1996.0117

Cited by 165 publications

(133 citation statements)

References 31 publications

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“…RICE sumably, a higher degree of physiological stress. Depletion patterns in weeded plots at the Agronomy Farm showed that target plants had some proportion of root biomass extending into the lower soil levels and thus had continuous access to soil moisture throughout the relatively longer growing season (see also Holmes and Rice [1996]). Thus, the degree of water stress experienced by N. pulchra in the two experiments was related to total soil water availability which, in turn, was related to soil depth.…”

Section: Belowground Resource Availabilitymentioning

confidence: 99%

“…Resource requirements and patterns of resource use by annual grasses are clearly different from perennial grasses. Decreased root to shoot ratios of annuals relative to perennial species result in rapid canopy development and soil moisture depletion in upper soil layers (Jackson and Roy 1986, Gordon et al 1989, Holmes and Rice 1996. With high relative densities and high relative growth rates, annual grasses can change the resource availability in the grassland both spatially and temporally.…”

Section: Belowground Resource Availabilitymentioning

confidence: 99%

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Effects of Competition on Resource Availability and Growth of a California Bunchgrass

Dyer

Rice

1999

Ecology

116

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Abstract. In California, little is known about the sensitivity of native bunchgrasses to competition or to changes in resource availability. We investigated the effect of nonnative annual vegetation on resource availability and growth of a native bunchgrass, Nassella pulchra, in a pair of factorial field experiments that incorporated effects of both interspecific and intraspecific competition as well as variation in soil depth. Plots of differing target densities and neighborhoods were used to assess changes in aboveground (light) and belowground (water) resource availability over multiple seasons in two sites with differing soil depth. N. pulchra grown without interspecific competitors grew larger and produced more culms at all planting densities compared to plants in plots with interspecific competitors. Intraspecific competition significantly influenced growth only in the absence of interspecific competition. Reproductive effort, as measured by flowering culm production, was more sensitive than vegetative growth to both forms of competition. Light availability and variability at the soil surface was greatly reduced by the nonnative annual neighborhood. As expected, soil moisture was rapidly depleted by annuals to 30 cm in all plots. In deepsoil plots, soil moisture was reduced at 60-150 cm depths only when annual vegetation was removed, and depletion was correlated with N. pulchra basal area. This result suggests that the interspecific neighborhood reduced root growth in N. pulchra and its subsequent ability to use deep moisture. Within California's inland grasslands, nonnative annual vegetation has changed seasonal patterns of resource availability. We conclude that (1) increased competition for light during the spring, when growth of annuals is most rapid, suppresses growth and reproduction of N. pulchra; (2) by suppressing bunchgrass growth, annual grasses reduce access to belowground resources by competitive interference; and (3) the loss of perennial grasses in California grasslands and the general dominance by nonnative annual species results in the relative underutilization of deep soil resources. These conclusions suggest that the dominance of California grasslands by nonnative annual vegetation has shifted the primary limiting resource from soil moisture to light and the timing of resource limitation from summer to winter and spring.

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Section: Belowground Resource Availabilitymentioning

confidence: 99%

Section: Belowground Resource Availabilitymentioning

confidence: 99%

Effects of Competition on Resource Availability and Growth of a California Bunchgrass

Dyer

Rice

1999

Ecology

116

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“…bunchgrasses) due to increased competition (Dyer and Rice, 1997; Brown and Rice, 2000). Grazing is suggested to favor exotic annual grasses, as they have higher growth rates and seed dispersal rates than perennials (Holmes and Rice, 1996). Annuals can also sustain populations in grazed landscapes by rapidly dispersing and colonizing open patches, while perennial recruitment is severely limited by defoliation and trampling (Holmes and Rice, 1996;Seabloom et al, 2003).…”

Section: The Effect Of Grazing On Plant Communities and Soil Richnessmentioning

confidence: 99%

“…Grazing is suggested to favor exotic annual grasses, as they have higher growth rates and seed dispersal rates than perennials (Holmes and Rice, 1996). Annuals can also sustain populations in grazed landscapes by rapidly dispersing and colonizing open patches, while perennial recruitment is severely limited by defoliation and trampling (Holmes and Rice, 1996;Seabloom et al, 2003). Furthermore, an increased abundance of exotic annuals has been found to lead to the accumulation of large amounts of above-ground dead biomass which can negatively affect perennial germination, recruitment, species richness and relative dominance of native taxa (Bergelson, 1990;Facelli and Pickett, 1991;Tilman and Pacala, 1993;Foster and Gross, 1998).…”

Section: The Effect Of Grazing On Plant Communities and Soil Richnessmentioning

confidence: 99%

Influence of Grazing Intensity on Swamp Plant Communities in the Tropical Montane Wetland Ecosystems, Nilgiris, Southern India

Mohandass¹

2016

Appl Ecol Env Res

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Abstract. Livestock grazing is a major anthropogenic impact influencing both grasslands and wetlands of the world which often results in the alteration of the structure, diversity and functioning of the plant communities. Here, we seek to understand how grazing intensity influences swamp vegetation, with an emphasis on their diversity, structure and function. Six swamps were selected, two each in high, moderate and low intensity grazing sites, from the tropical montane swamps of the Upper Nilgiri Mountains, southern India. We recorded a total of 78 species belonging to 63 genera and 31 families. Our results showed that species richness, abundance and species composition differed significantly across grazing treatments. Moreover, mean vegetation cover and mean height differed significantly across grazing treatments, indicating that grazing significantly affected the vegetation structure and growth of swamp plant communities. Species compositional patterns showed that moderately grazed plant communities were significantly different from low and high grazing sites. In summary, grazing intensity influenced swamp species richness, abundance, and swamp plant communities. Specifically, high grazing pressure reduced vegetation cover causing changes in swamp community structure leading to the gradual conversion of the swamp habitat into grasslands.

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“…Some NNGs transform otherwise intact ecosystems by altering the cycling and composition of soil nutrients (Ehrenfeld 2003), soil water regimes (Holmes and Rice 1996), geomorphology and sedimentation (Eamer et al 2013), and even fire regimes (Ehrenfeld 2010;Adie et al 2011;MacDougall et al 2013). Others quickly colonise and dominate disturbed systems (Firn et al 2010;D'Antonio et al 2011), and when coupled with anthropogenic drivers that increase their dispersal and fitness (e.g., MacDougall and Turkington 2005;MacDougall et al 2014), have become major degraders of agricultural production systems.…”

Section: Introductionmentioning

confidence: 99%

Why non-native grasses pose a critical emerging threat to biodiversity conservation, habitat connectivity and agricultural production in multifunctional rural landscapes

et al. 2017

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Context Landscape-scale conservation planning is key to the protection of biodiversity globally. Central to this approach is the development of multifunctional rural landscapes (MRLs) that maintain the viability of natural ecosystems and promote animal and plant dispersal alongside agricultural land uses. Objectives We investigate evidence that non-native grasses (NNGs) in rangelands and other low-intensity agricultural systems pose a critical threat to landscape conservation initiatives in MRLs both in Australia and globally.Methods We first establish a simple socio-ecological model that classifies different rural landscape elements within typical MRLs based on their joint conservation and agro-economic value. We then quantify the impacts of eight Australian NNGs (Andropogon gayanus, Cenchrus ciliaris, Eragrostis curvula, Hyparrhenia hirta, Nassella neesiana, Nassella trichotoma, Phalaris aquatica and Urochloa mutica) on different landscape elements and then classify and describe the socio-ecological transformations that result at the MRL scale. Results Our data indicate that two broad classes of NNGs exist. The first reduces both conservation and agro-economic value ('co-degrading' species) of invaded landscapes, while the second improves agroeconomic value at the expense of conservation value ('trade-off' species). Crucially, however, both classes cause hardening of the landscape matrix, agricultural intensification, reduced habitat connectivity, and the loss of multi-value land use types that are vital for landscape conservation. Conclusions NNGs drive socio-ecological transformations that pose a growing threat to landscape-scale connectivity and conservation initiatives in Australia and globally. There is an urgent need for further research into the impacts of NNGs on habitat connectivity and biodiversity within multifunctional landscapes, and the socio-ecological goals that can be achieved when landscape transformation and degradation by these species is unavoidable.Electronic supplementary material The online version of this article

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Patterns of Growth and Soil-water Utilization in some Exotic Annuals and Native Perennial Bunchgrasses of California

Cited by 165 publications

References 31 publications

Effects of Competition on Resource Availability and Growth of a California Bunchgrass

Effects of Competition on Resource Availability and Growth of a California Bunchgrass

Influence of Grazing Intensity on Swamp Plant Communities in the Tropical Montane Wetland Ecosystems, Nilgiris, Southern India

Why non-native grasses pose a critical emerging threat to biodiversity conservation, habitat connectivity and agricultural production in multifunctional rural landscapes

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