scholarly journals Evaluating potential trade‐offs among fuel treatment strategies in mixed‐conifer forests of the Sierra Nevada

Ecosphere ◽  
2016 ◽  
Vol 7 (9) ◽  
Author(s):  
Jens T. Stevens ◽  
Brandon M. Collins ◽  
Jonathan W. Long ◽  
Malcolm P. North ◽  
Susan J. Prichard ◽  
...  
2004 ◽  
Vol 34 (6) ◽  
pp. 1332-1342 ◽  
Author(s):  
Rolf Gersonde ◽  
John J Battles ◽  
Kevin L O'Hara

The spatially explicit light model tRAYci was calibrated to conditions in multi-aged Sierra Nevada mixed-conifer forests. To reflect conditions that are important to growth and regeneration of this forest type, we sampled a variety of managed mature stands with multiple canopy layers and cohorts. Calibration of the light model included determining leaf area density for individual species with the use of leaf area – sapwood area prediction equations. Prediction equations differed between species and could be improved using site index. The light model predicted point measurements from hemispherical photographs well over a range of 27%–63% light. Simplifying the crown representation in the tRAYci model to average values for species and canopy strata resulted in little reduction in model performance and makes the model more useful to applications with lower sampling intensity. Vertical light profiles in managed mixed-conifer stands could be divided into homogeneous, sigmiodal, and continuous gradients, depending on stand structure and foliage distribution. Concentration of leaf area in the upper canopy concentrates light resources on dominant trees in continuous canopies. Irregular canopies of multiaged stands, however, provide more light resources to mid-size trees and could support growth of shade-intolerant species. Knowledge of the vertical distribution of light intensity in connection with stand structural information can guide regulation of irregular stand structures to meet forest management objectives.


2021 ◽  
Author(s):  
Adrian J. Das ◽  
Michèle R. Slaton ◽  
Jeffrey Mallory ◽  
Gregory P. Asner ◽  
Roberta E. Martin ◽  
...  

Fire Ecology ◽  
2018 ◽  
Vol 14 (2) ◽  
Author(s):  
Scott L Stephens ◽  
Jens T Stevens ◽  
Brandon M Collins ◽  
Robert A York ◽  
Jamie M Lydersen

2012 ◽  
Vol 274 ◽  
pp. 17-28 ◽  
Author(s):  
H.D. Safford ◽  
J.T. Stevens ◽  
K. Merriam ◽  
M.D. Meyer ◽  
A.M. Latimer

Author(s):  
Mike Premer ◽  
Sophan Chhin ◽  
Jianwei Zhang

Forest growth processes are driven by site productivity and species functional traits, ultimately constrained by cumulative resource demand, and resulting in competitive dynamics across successional forest communities. Historic efforts to quantify competition utilize density metrics or neighborhood crowding indices for yield modeling and reforestation surveys. These methods have expanded to dendroclimatology and restoration applications that commonly assume similar competitive response across species of various functional types. We assessed competitive indices of two focal species (Pinus lambertiana Douglas and Pinus ponderosa Lawson & C. Lawson) in Sierra Nevada mixed conifer forests to estimate stem radial growth under current stand structure. We ranked correlations of basal area increment of the last 10 years (BAI10) separately across 20 competition indices (CIs). Best ranked CIs were used to test the relative influence of competition, tree size, and site variables on BAI10 with linear mixed models. While crown overlap was a common variable in CIs among both species, BAI10 of P. lambertiana was less impacted by intraspecific competition, and P. ponderosa appeared sensitive to all competing stems. Results suggest that local calibration of CIs with crown parameters may aid in interpreting Pinus species growth patterns, and the relative impact of competition on growth is species-specific.


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