Equations for potential annual direct incident radiation and heat load

McCune, Bruce; Keon, Dylan

doi:10.1111/j.1654-1103.2002.tb02087.x

Cited by 852 publications

(258 citation statements)

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“…Larger‐leaved species were observed more often in the mesic scrub group, and smaller‐leaved species were observed more often in the xeric scrub group. Additionally, elevation, slope, and aspect patterns in the data support the interpretation of water availability being a significant process (Cornwell & Ackerly, 2009; Franklin, 1998; Keeley & Keeley, 1988; Moody & Meentemeyer, 2001; Poole & Miller, 1981; Westman, 1981), as well as heat load (McCune & Keon, 2002), and thus potential evapotranspiration (PET) among sites at a fine scale. As a whole, in ordinations, mesic scrub plots were in opposition to plots in the xeric scrub group (Figure 5a,b).…”

Section: Discussionsupporting

confidence: 64%

“…We measured the distance to coast of each plot. We estimated mean annual precipitation, maximum temperature of the warmest month, and minimum temperature of the coldest month at each site, at a resolution of 1 km 2 (WorldClim gridded climate dataset, Hijmans, Cameron, Parra, Jones, & Jarvis, 2005); mean annual wind speed at a resolution of 200 m 2 (NREL, 2003); and heat load at the plot coordinates (McCune & Keon, 2002). Cloud frequency was acquired from a composite of MODIS satellite images between July and October from 2000 to 2006, giving the mean frequency of days with cloud cover at 10:00 a.m. (Fischer, Still, & Williams, 2009).…”

Section: Methodsmentioning

confidence: 99%

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Local patterns of diversity in California northern coastal scrub

Wrubel

Parker

2018

Ecology and Evolution

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Within global biodiversity hotspots such as the California Floristic Province, local patterns of diversity must be better understood to prioritize conservation for the greatest number of species. This study investigates patterns of vascular plant diversity in relation to coast–inland environmental gradients in the shrublands of Central California known as northern coastal scrub. We sampled coastal shrublands of the San Francisco Bay Area at coastal and inland locations, modeled fine‐scale climatic variables, and developed an index for local exposure to maritime salts. We compared diversity, composition, and structure of the coastal and inland plots using indirect gradient analysis and estimated species accumulation using rarefaction curves. Coastal plots were significantly higher in alpha, beta, and gamma diversity than inland plots. Plant diversity (effective species number) in coastal plots was 2.1 times greater than inland plots, and beta diversity was 1.9 times greater. Estimated richness by rarefaction was 2.05 times greater in coastal sites than inland sites. Salt deposition and water availability were the abiotic process most strongly correlated with increased maritime plant diversity and compositional differences. Stands of northern coastal scrub on the immediate coast with higher maritime influence exhibit markedly higher plant diversity than most interior stands, paralleling previous work in other vegetation types in this region. These studies suggest that the California coastline deserves special consideration for botanical conservation. Fine‐scale climatic models of cloud frequency, water availability, and the salt deposition index presented here can be used to define priority areas for plant conservation in California and other coastal regions worldwide.

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Section: Discussionsupporting

confidence: 64%

Section: Methodsmentioning

confidence: 99%

Local patterns of diversity in California northern coastal scrub

Wrubel

Parker

2018

Ecology and Evolution

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“…As a group, stands covered all topographic aspects, with two or three stands facing each of the following directions: north, northeast, east, south, southwest, west, and northwest; southeasterly facing stands were not sampled because the few available did not fulfill our size criteria. Aspect was subsequently converted to heat load index, according to McCune and Keon (2002), as solar radiation plays a key role in determining strength and depth of edge effects. All stands were located on hillsides with slopes averaging 17.2°(standard deviation = 5.4°); oak forests are generally absent from ridgetops or valleys within this region.…”

Section: Field Methodsmentioning

confidence: 99%

The association of two invasive shrubs, common buckthorn (Rhamnus cathartica) and Tartarian honeysuckle (Lonicera tatarica), with oak communities in the midwestern United States

2011

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Oak forests throughout North America are declining due to changes in disturbance regimes that have led to increased competition from other tree and shrub species. We evaluated associations between oak regeneration, the occurrence of two common invasive shrubs (common buckthorn (Rhamnus cathartica L.) and Tartarian honeysuckle (Lonicera tatarica L.)), and forest edges in oak forests in a portion of the midwestern United States where bur (Quercus macrocarpa Michx.), red (Quercus rubra L.), and white oak (Quercus alba L.) were historically dominant. We found poor recruitment of oaks in comparison to other, more shade-tolerant tree species. Results further revealed a strong stand-scale association between bur oak, open canopy conditions, high soil nutrient levels, and the presence of common buckthorn and Tartarian honeysuckle; these same site characteristics were disassociated with red and white oak. Within red and white oak stands, however, the presence of the invasive shrubs was more pronounced near forest edges. While oak recruitment is hampered throughout stands, our research suggests that predominant constraints may vary based on soil and light gradients found along forest edges. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/nrem_pubs/148The association of two invasive shrubs, common buckthorn (Rhamnus cathartica) and Tartarian honeysuckle (Lonicera tatarica), with oak communities in the midwestern United States Lisa A. Schulte, Erik C. Mottl, and Brian J. Palik Abstract: Oak forests throughout North America are declining due to changes in disturbance regimes that have led to increased competition from other tree and shrub species. We evaluated associations between oak regeneration, the occurrence of two common invasive shrubs (common buckthorn (Rhamnus cathartica L.) and Tartarian honeysuckle (Lonicera tatarica L.)), and forest edges in oak forests in a portion of the midwestern United States where bur (Quercus macrocarpa Michx.), red (Quercus rubra L.), and white oak (Quercus alba L.) were historically dominant. We found poor recruitment of oaks in comparison to other, more shade-tolerant tree species. Results further revealed a strong stand-scale association between bur oak, open canopy conditions, high soil nutrient levels, and the presence of common buckthorn and Tartarian honeysuckle; these same site characteristics were disassociated with red and white oak. Within red and white oak stands, however, the presence of the invasive shrubs was more pronounced near forest edges. While oak recruitment is hampered throughout stands, our research suggests that predominant constraints may vary based on soil and light gradients found along forest edges.Résumé : Les forêts de chêne dépérissent, partout en Amérique du Nord, à cause de changements dans les régimes de perturbation qui ont e...

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“…Climate predictors (mean annual temperature, BIO1; maximum temperature of the warmest month, BIO5; minimum temperature of the coldest month, BIO6; yearly temperature range, BIO7; average temperature of the wettest quarter, BIO8; average temperature of the driest quarter, BIO9; average temperature of the warmest quarter, BIO10; average temperature of the coldest quarter, BIO11; yearly precipitation sum, BIO12; precipitation sum of the wettest month, BIO13; precipitation sum of the driest month, BIO14; precipitation sum of the wettest quarter, BIO16; precipitation sum of the driest quarter, BIO17; precipitation sum of the warmest quarter, BIO18; precipitation sum of the coldest quarter, BIO19), with a spatial resolution of 1 km, were obtained from the WorldClim dataset (Hijmans et al, 2005) and resampled at a 30 m resolution by linear interpolation. We used a digital elevation model (DEM) with a resolution of 10 m to calculate elevation and slope and calculated a linearization of aspect as cos(aspect − 225 • ) as a proxy for evapotranspiration (Franklin and Tolonen, 2000), and heat load index (McCune and Keon, 2002) as a proxy of solar radiation.…”

Section: Discussionmentioning

confidence: 99%

Modeling anthropogenic and natural fire ignitions in an inner-alpine valley

Vacchiano

Foderi

Berretti

et al. 2018

Nat. Hazards Earth Syst. Sci.

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Abstract. Modeling and assessing the factors that drive forest fire ignitions is critical for fire prevention and sustainable ecosystem management. In southern Europe, the anthropogenic component of wildland fire ignitions is especially relevant. In the Alps, however, the role of fire as a component of disturbance regimes in forest and grassland ecosystems is poorly known. The aim of this work is to model the probability of fire ignition for an Alpine region in Italy using a regional wildfire archive (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009) and MaxEnt modeling. We analyzed separately (i) winter forest fires, (ii) winter fires on grasslands and fallow land, and (iii) summer fires. Predictors were related to morphology, climate, and land use; distance from infrastructures, number of farms, and number of grazing animals were used as proxies for the anthropogenic component. Collinearity among predictors was reduced by a principal component analysis. Regarding ignitions, 30 % occurred in agricultural areas and 24 % in forests. Ignitions peaked in the late winter-early spring. Negligence from agrosilvicultural activities was the main cause of ignition (64 %); lightning accounted for 9 % of causes across the study time frame, but increased from 6 to 10 % between the first and second period of analysis. Models for all groups of fire had a high goodness of fit (AUC 0.90-0.95). Temperature was proportional to the probability of ignition, and precipitation was inversely proportional. Proximity from infrastructures had an effect only on winter fires, while the density of grazing animals had a remarkably different effect on summer (positive correlation) and winter (negative) fires. Implications are discussed regarding climate change, fire regime changes, and silvicultural prevention. Such a spatially explicit approach allows us to carry out spatially targeted fire management strategies and may assist in developing better fire management plans.

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Equations for potential annual direct incident radiation and heat load

Cited by 852 publications

References 3 publications

Local patterns of diversity in California northern coastal scrub

Local patterns of diversity in California northern coastal scrub

The association of two invasive shrubs, common buckthorn (Rhamnus cathartica) and Tartarian honeysuckle (Lonicera tatarica), with oak communities in the midwestern United States

Modeling anthropogenic and natural fire ignitions in an inner-alpine valley

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