Vegetation and Ecological Characteristics of Mixed-Conifer and Red Fir Forests at the Teakettle Experimental Forest

Abstract

Detailed analysis of mixed-conifer and red fir forests were made from extensive, large vegetation sampling, systematically conducted throughout the Teakettle Experimental Forest. Mixed conifer is characterized by distinct patch conditions of closed-canopy tree clusters, persistent gaps and shrub thickets. This heterogeneous spatial structure provides contrasting microclimate, habitat and resource conditions probably associated with the high diversity of understory plants, fungi, and invertebrates found in ongoing studies in the Teakettle Experiment. In contrast, red fir forests are more homogeneous with continuous high canopy cover, cooler, more consistent microclimate conditions and fewer plant species. In both forests, annual fluctuations in available soil moisture resulting from El Niño influences on snow pack depth may have a significant influence on tree establishment and understory diversity. In depth descriptions of Teakettle's mixed conifer may provide a target of historic old-growth conditions for forest management.

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

“…In many locations, large, dominant ponderosa pine trees have been significantly reduced leaving today's stands dominated by small trees. This has also been documented in other studies in mixed-conifer and ponderosa pine forests in the western US (Swetnam and Baisan 2003, Moore et al 2004, North et al 2009.…”

“…The majority of the variability in structure in frequent-fire forests has been observed at spatial scales smaller than 0.4 ha Churchill 2012, Fry et al 2014), and topographic characteristics that influence forest structure may also be observed at a smaller scale (Lydersen and North 2012). The scale at which the 1911 inventory data were recorded homogenizes this patchiness, which has been shown to include widely spaced individuals, clusters of large trees, dense patches of regeneration, and small openings (North et al 2002, Franklin and Van Pelt 2004, Larson and Churchill 2012, Lydersen et al 2013, Fry et al 2014. This fine-scale patchiness, and the scale at v www.esajournals.org which topography affects forest patterns, are important characteristics that warrant further investigation.…”

“…Comparing forest inventory data from 1911 to the present (Table 6) indicates that current forests have changed greatly, particularly in tree density, canopy cover, density of large trees, dominance of white fir in mixed conifer forests, and the similarity of tree basal area in contemporary ponderosa pine and mixed conifer forests. The vast majority of published studies on historic mixed-conifer forests document lower tree densities and a more open structure comprised of a higher proportion of old and large trees that were more spatially heterogeneous (having gaps and patches of trees) and more uneven-aged compared to current conditions (Fulé et al 2002, Moore et al 2004, Stephens and Gill 2005, North et al 2009, Collins et al 2011.…”

“…These large patches, where most if not all of the trees are dead, can impede conifer tree regeneration (Barton 2002, Goforth and Minnich 2008, Roccaforte et al 2012, Collins and Roller 2013, Crotteau et al 2013, Crotteau et al 2014) and predispose them for repeated high severity fire and potentially, type conversion (Van Wagtendonk et al 2012, Collins andSkinner 2014). As a result, many forest managers today are tasked with mitigating the potential for uncharacteristic severe fire (North et al 2009, Stephens et al 2013.…”

Precipitation drives interannual variation in summer soil respiration in a Mediterranean-climate, mixed-conifer forest

“…Elevation at TEF ranges from 1,880 to 2,485 m (North et al 2002). Site description including species composition, topography, soils and climate has been described previously (North et al 2002).…”