Tree spatial patterns and stand development along the pine-grassland ecotone in the Colorado Front Range

Joy Nystrom Mast; Thomas T Veblen

doi:10.1139/x99-025

Tree spatial patterns and stand development along the pine-grassland ecotone in the Colorado Front Range

Canadian Journal of Forest Research ◽

10.1139/x99-025 ◽

1999 ◽

Vol 29 (5) ◽

pp. 575-584 ◽

Cited By ~ 43

Author(s):

Joy Nystrom Mast ◽

Thomas T Veblen

Keyword(s):

Spatial Autocorrelation ◽

Spatial Patterns ◽

Tree Regeneration ◽

Colorado Front Range ◽

Tree Age ◽

Stand Development ◽

Front Range ◽

Ripley’S K ◽

Ripley's K ◽

Tree Spatial Patterns

Patterns of stand development may be interpreted from spatial analyses, based on variables such as tree age and size, together with past records of climate and disturbance. In the present study, our objective is to examine spatial patterns of tree age and size to determine if they are consistent with the episodic pattern of tree regeneration proposed for ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) and expected changes in tree spatial patterns as cohort patches age. According to our hypothesis, internal patch structure should become less clumped as single cohort patches age due to self-thinning, with few trees attaining dominance in a small patch. In this study, tree spatial patterns in 16 stands of P. ponderosa in the Colorado Front Range are described and related to patterns of stand development. Analytical methods included Ripley's K(t) (a univariate statistic of tree spatial distribution), Ripley's K12(t) (a bivariate statistic of spatial association), and Moran's I (a measure of spatial autocorrelation). Spatial patterns imply establishment of patches of pines followed by self-thinning. Continued stand development results in strong size hierarchies as manifested by stronger spatial autocorrelation of tree age than tree size. Hence, pines exhibit a strong size class hierarchy developed within an even-aged patch.

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A field experiment informs expected patterns of conifer regeneration after disturbance under changing climate conditions

Canadian Journal of Forest Research ◽

10.1139/cjfr-2015-0033 ◽

2015 ◽

Vol 45 (11) ◽

pp. 1607-1616 ◽

Cited By ~ 44

Author(s):

Monica T. Rother ◽

Thomas T. Veblen ◽

Luke G. Furman

Keyword(s):

Field Experiment ◽

Pinus Ponderosa ◽

Ponderosa Pine ◽

Douglas Fir ◽

Tree Regeneration ◽

Colorado Front Range ◽

Front Range ◽

Average Growth ◽

Growth And Survival ◽

Treatment Type

Climate change may inhibit tree regeneration following disturbances such as wildfire, altering post-disturbance vegetation trajectories. We implemented a field experiment to examine the effects of manipulations of temperature and water on ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings planted in a low-elevation, recently disturbed setting of the Colorado Front Range. We implemented four treatments: warmed only (Wm), watered only (Wt), warmed and watered (WmWt), and control (Co). We found that measures of growth and survival varied significantly by treatment type. Average growth and survival was highest in the Wt plots, followed by the Co, WmWt, and Wm plots, respectively. This general trend was observed for both conifer species, although average growth and survival was generally higher in ponderosa pine than in Douglas-fir. Our findings suggest that warming temperatures and associated drought are likely to inhibit post-disturbance regeneration of ponderosa pine and Douglas-fir in low-elevation forests of the Colorado Front Range and that future vegetation composition and structure may differ notably from historic patterns in some areas. Our findings are relevant to other forested ecosystems in which a warming climate may similarly inhibit regeneration by dominant tree species.

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Blowdown and stand development in a Colorado subalpine forest

Canadian Journal of Forest Research ◽

10.1139/x89-186 ◽

1989 ◽

Vol 19 (10) ◽

pp. 1218-1225 ◽

Cited By ~ 58

Author(s):

Thomas T. Veblen ◽

Keith S. Hadley ◽

Marion S. Reid ◽

Alan J. Rebertus

Keyword(s):

18Th Century ◽

Lodgepole Pine ◽

Growth Patterns ◽

Colorado Front Range ◽

Subalpine Forest ◽

Stand Development ◽

Front Range ◽

Southern Rocky Mountains ◽

Engelmann Spruce ◽

Shade Tolerant Species

Stand development of a subalpine forest in the Colorado Front Range following a ca. 15-ha blowdown was examined by analyzing tree population age structures and radial growth patterns. The stand studied was initiated by a fire at the start of the 18th century and was dominated by a dense population of lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) at the time of blowdown in 1973. Before the blowdown, the subcanopy was characterized by abundant subalpine fir (Abieslasiocarpa (Hook.) Nutt.) and scarce Engelmann spruce (Piceaengelmannii (Parry) Engelm.). Comparison with an adjacent control stand, affected only slightly by the blowdown, indicates that new seedling establishment following the blowdown was slight. Instead, the response was dominated by the release of the subcanopy fir and spruce, resulting in acceleration of the successional replacement of lodgepole pine by these shade-tolerant species. Given the >300 years required for an old-growth fir and spruce stand to develop following catastrophic fire, the likelihood of a major canopy disturbance in the form of blowdown and (or) lethal insect attack is high and should be explicitly incorporated into general explanations of stand development of subalpine forests in the southern Rocky Mountains.

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