The San Dimas experimental forest: 50 years of research

Dunn, Paul H.; Barro, Susan C.; Wells, Wade G.; Poth, Merrily; Wohlgemuth, Peter M.; Colver, Charles G.

doi:10.2737/psw-gtr-104

Cited by 46 publications

(43 citation statements)

References 55 publications

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“…The lysimeter installation is located within the San Dimas Experimental Forest, a U.S. Forest (Dunn et al, 1988). The lysimeters consist of large (5.3 by 5.3 m horizontally and 2.1 m deep) earthen-walled pits that were ®lled in 1937 with ®ne sandy loam (58% sand, 31% silt, 11% clay) derived on site from the weathering of diorite (Colman and Hamilton, 1947).…”

Section: Site Descriptionmentioning

confidence: 99%

Vegetation control on soil organic matter dynamics

Quideau

Chadwick

Trumbore

et al. 2001

Organic Geochemistry

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Soil organic matter (SOM) formation is one of the least understood steps of the global carbon cycle. An example is uncertainty around the role of plant communities in regulating SOM formation and turnover. Here we took advantage of the highly controlled conditions at the San Dimas lysimeter installation to quantify the in¯uence of oak and pine vegetation on SOM dynamics. SOM turnover rates, estimated using total C and 14 C content of litter and physically separable soil fractions, were faster under oak than under pine. In contrast to the rapid turnover for the oak litter (<2 years), the delay in litter incorporation into the mineral soil under pine was a controlling factor of SOM¯uxes. # 2001 Published by Elsevier Science Ltd.

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Section: Site Descriptionmentioning

confidence: 99%

Vegetation control on soil organic matter dynamics

Quideau

Chadwick

Trumbore

et al. 2001

Organic Geochemistry

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“…Krammes (1969) reported that the soil and bedrock are similar hydrologically, with |70% of the porosity being noncapillary. The Mediterranean climate provides cool, wet winters and hot, dry summers with an annual temperature range of about 24 to 388C (Dunn et al, 1988). Most precipitation occurs as rain.…”

Section: Environmental Settingmentioning

confidence: 99%

“…Most precipitation occurs as rain. Historically, annual precipitation varied from 258 to 1595 mm, with a mean of 678 mm (Dunn et al, 1988). Native vegetation is chaparral.…”

Section: Environmental Settingmentioning

confidence: 99%

“…After the 1960 fire that burned .96% of the SDEF, large areas were rehabilitated using a combination of manual vegetation removal, herbicide application, and hand seeding (Dunn et al, 1988). One such rehabilitation method involved highdensity seeding of perennial grasses in watersheds that were also stabilized by planting barley (Hordeum vulgare L.) along contours in 0.6-m intervals, hereafter called the HDPB treatment (Corbett and Green, 1965;Rice et al, 1965).…”

Section: Vegetation Conversionmentioning

confidence: 99%

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Pedogenesis–Terrain Links in Zero‐Order Watersheds after Chaparral to Grass Vegetation Conversion

Williamson¹,

Gessler²,

Shouse

et al. 2006

Soil Science Soc of Amer J

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Four decades after conversion from chaparral to grass, zero-order watersheds were compared to identify differences in topography and its relation to soil characteristics. Three watersheds of each vegetation type were topographically mapped and sampled at random points for depth to weathered bedrock and soil water content. Stepwise regression was used to explain spatial variability in terms of terrain variables. In chaparral watersheds, convex slopes result in widespread infiltration and significantly higher storage of water on the slopes. Topography of watersheds converted to grass is more concave, resulting in higher upslope contributing areas. This favors water convergence in the subsurface and results in significantly lower soil water content in grass watersheds. In chaparral watersheds, upslope average slope gradient best explains variability in depth to weathered bedrock. In contrast, slope gradient best explains depth to weathered bedrock in grass watersheds, suggesting that the uniform plant distribution localizes erosional processes. Soil water content is explained by depth to weathered bedrock and slope aspect in both vegetation types; however, a positive relation with profile curvature is the third indicator in chaparral watersheds, compared with an inverse relation with upslope average slope gradient in grass watersheds. The result is that grass watersheds drain water downslope, creating similar processes and forms in watersheds of various sizes. For both depth to weathered bedrock and soil water content, prediction using the regression models is only successful in grass watersheds. Thus terrain variables may be ineffective predictors of soil characteristics in shrublands where a dense canopy hides a nonuniform erosional environment.

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“…The region is typi¢ed by a warm Mediterraneantype climate (mean annual temperature 14.4 8C) and, on average receives 678 mm precipitation per annum (Dunn et al 1988). The soils within the basin are composed of sandy loams or sandy clay loams that are derived from a weathered granite or granodiorite (United States Department of Agriculture 1971), tend to be slightly acidic (pH 5.8^6.0) and contain signi¢cant reserves of phosphorous (mean 30 mg g 71 , HCO 3 -extractable) and potassium (200 mg g 71 ).…”

Section: (A) Site Description and Sampling Proceduresmentioning

confidence: 99%

Reconstruction of the historical changes in mycorrhizal fungal communities under anthropogenic nitrogen deposition

Egerton‐Warburton¹,

Graham²,

Allen³

et al. 2001

Proc. R. Soc. Lond. B

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Archived soil samples (1937^1999) and historic air quality data from the Los Angeles Basin were used for reconstructing the record of change between atmospheric NO x loads, soil d 15 N values and the diversity of arbuscular mycorrhizae (AM), which are ubiquitous plant^fungus mutualists that control plant community productivity. A tripling of atmospheric NO x loads between 1937 and the 1970s was paralleled by soil nitrogen enrichment (d 15 N 3.18). From 1975 onwards, atmospheric NO x declined, but soils became nitrogen saturated (d 15 N 74 and NO 3 -nitrogen 171mg kg 71 ). The shifts in the AM community followed 28 years of atmospheric nitrogen enrichment and coincided with the onset of soil nitrogen saturation. Such changes were manifest in the loss of AM productivity, species richness (one species per year), three genera (Acaulospora, Scutellospora and Gigaspora) in the spore community and Gigaspora within the roots. Nitrogen enrichment also enhanced the proliferation of potentially less mutualistic species of Glomus. Autoregressive models implied that such patterns will persist and be driven by soil nitrogen cycling patterns. Chronic nitrogen enrichment from air pollution thus alters the diversity and mutualistic functioning of AM communities, which, in turn, may in£uence the plant community.

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The San Dimas experimental forest: 50 years of research

Abstract: USDA Forest Service Gen. Tech. Rep. PSW-104. 1988 'Unless otherwise noted, available and unpublisheddata areon file in the SDEF archives at the Forest Fire Laboratory,4955 CanyonCrest Drive, Riverside, California 92507.

Cited by 46 publications

References 55 publications

Vegetation control on soil organic matter dynamics

Vegetation control on soil organic matter dynamics

Pedogenesis–Terrain Links in Zero‐Order Watersheds after Chaparral to Grass Vegetation Conversion

Reconstruction of the historical changes in mycorrhizal fungal communities under anthropogenic nitrogen deposition

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