Influence of soil thickness on stand characteristics in a Sierra Nevada mixed-conifer forest

Abstract

Soil thickness can be an important factor influencing vegetation, yet few spatiallyexplicit studies have examined soil horizon thickness and vegetation composition in summerdrought forests. We compared seismic and soil penetration measurements of combined A + C and Cr horizon thickness, soil moisture and temperature, and stand variables in a contiguous 4-ha mixed-conifer stand of the Sierra Nevada. Thickness of A + C and Cr horizons were highly variable but were not correlated to each other. Total basal area and canopy cover were positively related with A + C horizon thickness, and shrub cover was positively related with Cr horizon thickness. Basal area of white fir [Abies concolor (Gord and Glend) Lindl.] and incense-cedar [Calocedrus decurrens (Torrey) Florin] were positively correlated with A + C horizon thickness, but there was no relationship between A + C or Cr horizon thickness and basal area of Jeffrey pine (Pinus jeffreyi Grev. and Balf.), sugar pine (P. lambertiana Douglas), or red fir (A. magnifica A. Murray). Both white and red fir seedlings were associated with decreased soil temperature, but only white fir seedlings were positively associated with soil moisture. Soil penetration estimates of soil thickness were similar to seismic estimates for shallow soils (<50 cm depth) but were poorly related on deeper soils. Visual surface conditions and tile probe estimates of soil thickness can be highly misleading because 'shallow' areas may have a thick layer of weathered bedrock that can serve as a potential rooting medium for deep-rooted trees and shrubs. In our study only the refraction seismic method had the potential to measure total soil depth that included A + C and Cr horizon thickness.

Erosion rates as a potential bottom‐up control of forest structural characteristics in the Sierra Nevada Mountains

“…Both the less extensively weathered saprolite and loss of clay from the soil as erosion rates increase (Yoo et al 2011) act to reduce the amount of water retained on the hillslope for ecological use, thus limiting forest productivity. The clear trends expressed in this landscape corroborate previous work elsewhere in the Sierra Nevada by Meyer et al (2007), who noted that at the stand level, stand basal area was positively correlated with the combined thickness of the A and C horizons, which should obey an inverse relationship with erosion rate (Dixon et al 2012).…”

Historical and current landscape‐scale ponderosa pine and mixed conifer forest structure in the Southern Sierra Nevada

“…3) had higher water holding capacity, leading to greater values of AET. While water holding capacity and AET were relatively lower in the rest of the study area, perhaps the trees may be able to access deeper water stores in weathered bedrock (Meyer et al 2007) allowing these areas to sustain more productive forest types.…”

Profundidade do solo e micro-relevo em bananais irrigados: impactos na nutrição mineral e potencial produtivo

“…Em alguns trabalhos é comprovada a influência da profundidade e d o v o lume efetivo do solo no crescimento de espécies vegetais (MEYER et al, 2007;NAGESWARA RAO;JESSY, 2007). Especificamente para bananeira, estudos de crescimento foram feitos levando em consideração a disponibilidade hídrica e não a profundidade do solo, mostrando redução no crescimento das plantas quando há falta de água (FIRTH et al, 2003;MAHOUACHI, 2009 Tabela 2 -Resumo da análise de variância para atributos referentes ao crescimento e produção das bananeiras: altura da planta-mãe (APM), altura da planta filha (APF), diâmetro do pseudocaule da planta mãe (DPPM), massa de folhas secas (MFS), massa de folhas frescas (MFF), umidade (U) e massa dos cachos (MC) (Ca e Mg) e por titulação (Al).…”

“…Estudos destacam a importância da profundidade do solo como condicionante do crescimento de plantas (MEYER et al, 2007), da dinâmica hídrica (WANG et al, 2006), da produtividade de sistemas naturais (ROMANYA; VALLEJO, 2004) e do stand de plantas devido, essencialmente, à sua influência no volume de raízes e no conteúdo de água disponível. Diferenças na profundidade, mesmo que dentro de uma mesma classe de solo, podem influenciar o desenvolvimento das culturas.…”