Scales of heterogeneity in prairie and forest

Kleb, Heather R.; Wilson, Scott D.

doi:10.1139/b99-004

Cited by 15 publications

(2 citation statements)

References 26 publications

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“…In grassland ecosystems, microtopographic habitat heterogeneity is found on the scale of clonal grass tufts (Schlesinger et al 1996, Rietkerk et al 2000. In general, microtopographic variation scales with the size of the vegetation in systems dominated by macrophytes (Huenneke & Sharitz 1986, Kleb 1999.…”

Section: Introductionmentioning

confidence: 99%

Microtopographic variability in plant distribution and biogeochemistry in a brackish-marsh system

Stribling

Glahn²,

Chen³

et al. 2006

Mar. Ecol. Prog. Ser.

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Microtopography is often observed and studied in plant communities where environmental conditions limit distribution, for example in desert and peatland ecosystems. Brackish marshes, relatively poorly studied despite their importance in many coastal areas, frequently display similar fine-scale variability. In these systems, limits to plant distribution derive from the combination of flooding and salinity fluctuations. We examined the relationship between spatial variability of vegetation and biogeochemical features of sediment in a brackish tidal ecosystem in 2 adjacent Spartina spp. marshes of differing hydrology and vegetation distribution. The first, a low-elevation, interior marsh, was frequently flooded and poorly drained, and it exhibited distinct hummock/hollow topography. The plant distribution was reflected in patchy sediment biogeochemical features at the same scale. The second marsh, on a well-drained, elevated streamside bank, contained homogeneous vegetation cover and relatively uniform sediment chemistry. The formation of the hummock/hollow topography in the interior marsh appeared to be controlled by the plants, as they maximized growth in a high-stress, variable environment. The plants favorably modified discrete patches of these environments to such a degree that the hummock sediment biogeochemistry was very similar to that of the higher-elevation homogeneous marsh. The microtopography of this interior brackish marsh strongly resembles that of other stress-impacted ecosystems.KEY WORDS: Hummock/ hollow topography · Ecosystem engineering · Spatial variability · Patchiness · Marsh sediment · Microsite heterogeneity Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 320: [121][122][123][124][125][126][127][128][129] 2006 Such systems include peatlands (Malmer & Wallen 1999, Branfireun 2004, forested wetlands (Huenneke & Sharitz 1986), and even subtidal seagrass beds (Hebert & Morse 2003). For each of these, sediment biogeochemical variability has been shown to coincide with vegetational patterns. As with terrestrial systems, the scale of the spatial variability may also reflect that of the dominant plant species (e.g. Huenneke & Sharitz 1986).Tidal marshes exhibit both mesoscale (10 to 1000 m 2 ) and microtopographic variability. These dynamic systems display well-defined spatial variability related to age (Tyler & Zieman 1999) and to geomorphological features such as distance from tidal creeks and elevation (Bertness & Ellison 1987, Gardner et al. 1988). This mesoscale topography may develop along hydrological or salinity gradients, which largely determine soil chemical conditions. Variability at finer spatial scales in marshes is also common, often resulting from disturbance (Fischer et al. 2000). Fire, grazing, wrack deposition, treefall, and flooding may all generate discrete patches in wetlands (e.g. Bertness & Ellison 1987, White & Howes 1994, Berg et al. 1997, Stoeckel & Miller-Goodman 2001, McLaren & Jefferies 2004. On longer time sc...

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Section: Introductionmentioning

confidence: 99%

Microtopographic variability in plant distribution and biogeochemistry in a brackish-marsh system

Stribling

Glahn²,

Chen³

et al. 2006

Mar. Ecol. Prog. Ser.

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“…After emergence from the soil, canopy distribution and density create gradients of blue-light intensity. Blue light falls sharply with canopy closure in agricultural and natural vegetation Kleb and Wilson 1999;Kobayashi and Kamitani 2000). Under canopy conditions where light has both diffuse and directional components, blue-light and red-light mediated plastic responses are thought to optimize growth by guiding stems and leaves of young plants into patches of high light intensity (Ackerly and Bazzaz 1995;Ballare et al 1995;Muth and Bazzaz 2002).…”

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confidence: 99%

An Experimental Test of the Adaptive Evolution of Phototropins: Blue-Light Photoreceptors Controlling Phototropism in Arabidopsis Thaliana

2004

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Abstract. Phototropins are blue-light photoreceptor molecules mediating the capacity for phototropism or bending toward or away from directional light. Like the red-light sensing phytochromes that control shade avoidance, phototropins modulate developmental plasticity in plant architecture. Yet, unlike phytochromes, the adaptive significance of phototropins has been largely a topic of conjecture. In Arabidopsis thaliana, phototropism of seedling and plant stems is under the control of two paralogous genes, PHOT1 and PHOT2, that encode different phototropins with partially redundant light response qualities. The PHOT1 gene product interacts with the NPH3 gene product to cause phototropic bending over a broad range of light intensity, from very weak light in the soil to stronger light in the aerial environment. The PHOT2 gene product modulates shoot bending in response to light of higher intensity only. We compared the fitness of wild-type, phot1, phot2, and nph3 genotypes over a range of light conditions in the field. Seeds were sown in the field on the soil surface and left bare or covered with either gravel or bark mulch chips. Plantings were made under full sun and dense canopy cover. Rates of seedling emergence, survival to flowering, and total seed set were measured. All mutant genotypes had significantly reduced lifetime fitness compared to wild-type. Consistent with their different fluence rate sensitivities, phot1 and phot2 signaling pathways affected fitness at discrete life-cycle stages. Fitness costs of phot1 and nph3 were expressed mainly during seedling emergence from the soil whereas that of phot2 was expressed solely after emergence. Surprisingly, the only significant genotype-by-environment interaction for fitness occurred during emergence: genotypes blind to dim blue light (phot1 and nph3) had poor emergence in the open, but not in the shade. Possibly, the loss of negative phototropism in seedling roots of mutant genotypes reduced establishment success in open (dry soil) conditions. Results show that phototropin-modulated pathways are adaptive and that their evolution has involved functional specialization. However, mechanism(s) of selection on these pathways remain a mystery.

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Species effects on resource supply rates: do they influence competitive interactions?

et al. 2004

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Scales of heterogeneity in prairie and forest

Cited by 15 publications

References 26 publications

Microtopographic variability in plant distribution and biogeochemistry in a brackish-marsh system

Microtopographic variability in plant distribution and biogeochemistry in a brackish-marsh system

An Experimental Test of the Adaptive Evolution of Phototropins: Blue-Light Photoreceptors Controlling Phototropism in Arabidopsis Thaliana

Species effects on resource supply rates: do they influence competitive interactions?

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