Seasonal variation in surface fuel moisture between unthinned and thinned mixed conifer forest, northern California, USA

2012 ◽  
Vol 21 (4) ◽  
pp. 428 ◽  
Author(s):  
Becky L. Estes ◽  
Eric E. Knapp ◽  
Carl N. Skinner ◽  
Fabian C. C. Uzoh
Keyword(s):  
Canopy Cover ◽  
Stand Density ◽  
Fire Risk ◽  
Fuel Moisture ◽  
Northern California ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest ◽  
Crown Fires ◽  
Stand Thinning

Reducing stand density is often used as a tool for mitigating the risk of high-intensity crown fires. However, concern has been expressed that opening stands might lead to greater drying of surface fuels, contributing to increased fire risk. The objective of this study was to determine whether woody fuel moisture differed between unthinned and thinned mixed-conifer stands. Sections of logs representing the 1000- and 10 000-h fuel sizes were placed at 72 stations within treatment units in the fall (autumn) of 2007. Following snow-melt in 2008, 10-h fuel sticks were added and all fuels were weighed every 1–2 weeks from May until October. Moisture of the 1000- and 10 000-h fuels peaked at the end of May, and then decreased steadily through the season. Moisture of the 10- and 1000-h fuels did not differ between unthinned and thinned stands at any measurement time. The 10 000-h fuel moisture was significantly less in thinned than unthinned stands only in early to mid-May. Overall, even when fuel moisture varied between treatments, differences were small. The long nearly precipitation-free summers in northern California appear to have a much larger effect on fuel moisture than the amount of canopy cover. Fuel moisture differences resulting from stand thinning would therefore not be expected to substantially influence fire behaviour and effects during times of highest fire danger in this environment.

scholarly journals Thinning, tree-growth, and resistance to multi-year drought in a mixed-conifer forest of northern California

2018 ◽  
Vol 422 ◽  
pp. 190-198 ◽  
Author(s):  
Michael J. Vernon ◽  
Rosemary L. Sherriff ◽  
Phillip van Mantgem ◽  
Jeffrey M. Kane
Keyword(s):  
Tree Growth ◽  
Northern California ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest

Coarse woody debris and canopy cover in an old-growth Jeffrey pine-mixed conifer forest from the Sierra San Pedro Martir, Mexico

2007 ◽  
Vol 240 (1-3) ◽  
pp. 87-95 ◽  
Author(s):  
Scott L. Stephens ◽  
Danny L. Fry ◽  
Ernesto Franco-Vizcaíno ◽  
Brandon M. Collins ◽  
Jason M. Moghaddas
Keyword(s):  
Coarse Woody Debris ◽  
Woody Debris ◽  
Canopy Cover ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Old Growth ◽  
Jeffrey Pine ◽  
San Pedro ◽  
Mixed Conifer Forest ◽  
Sierra San Pedro Martir

scholarly journals Long-term demographic trends in a fire-suppressed mixed-conifer forest

2016 ◽  
Vol 46 (5) ◽  
pp. 745-752 ◽  
Author(s):  
Carrie R. Levine ◽  
Flora Krivak-Tetley ◽  
Natalie S. van Doorn ◽  
Jolie-Anne S. Ansley ◽  
John J. Battles
Keyword(s):  
Sierra Nevada ◽  
Fire Regime ◽  
Fire Suppression ◽  
Basal Area ◽  
Stand Density ◽  
Community Level ◽  
Homogeneous State ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest

In the western United States, forests are experiencing novel environmental conditions related to a changing climate and a suppression of the historical fire regime. Mixed-conifer forests, considered resilient to disturbance due to their heterogeneity in structure and composition, appear to be shifting to a more homogeneous state, but the timescale of these shifts is not well understood. Our objective was to assess the effects of climate and fire suppression on stand dynamics and demographic rates of an old-growth mixed-conifer forest in the Sierra Nevada. We used a Bayesian hierarchical analysis to quantify species and community rates of recruitment, growth, and mortality. Despite a warming climate, we found that stand density, basal area, and carbon have increased over 56 years. Fir recruitment and growth significantly exceeded the community-level median rates, whereas pine recruitment and growth was significantly lower than the community-level median rates. Shifts in species composition from a well-mixed stand to a more dense fir-dominated stand appear to be driven by low growth and recruitment rates of pines relative to firs. In forests such as these with consistent and relatively low mortality rates, we recommend that restoration and management activities be focused on promoting pine recruitment and growth.

Anthropogenic and natural disturbance and patterns of mortality in a mixed conifer forest in California

1994 ◽  
Vol 24 (6) ◽  
pp. 1149-1159 ◽  
Author(s):  
Melissa Savage
Keyword(s):  
Forest Ecosystems ◽  
Stand Structure ◽  
Fire Suppression ◽  
Stand Density ◽  
Natural Disturbance ◽  
Anthropogenic Influences ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest

Anthropogenic and natural disturbances have been implicated in recent mortality episodes in montane forests. While the role of natural disturbance in patterning forest ecosystems has been widely explored in recent decades, the agency of human influence is less well understood. In this paper, stand structure analysis is used to characterize patterns of mortality in a montane mixed conifer forest in southern California subject to multiple influences, both anthropogenic and natural, including fire suppression, air pollution, drought, competition, and insect infestation. While it is difficult to separate the contribution of any one of these factors to tree death, because there have been cumulative and synchronous disturbances, successional trends can be identified. Anthropogenic influences appear to abet the effects of natural disturbance in enhancing the shift from early successional pines to species that tolerate stresses such as drought, fire suppression, or competition that result from increased stand density, or a combination of such stresses.

Spatial variability in microclimate in a mixed-conifer forest before and after thinning and burning treatments

2010 ◽  
Vol 259 (5) ◽  
pp. 904-915 ◽  
Author(s):  
Siyan Ma ◽  
Amy Concilio ◽  
Brian Oakley ◽  
Malcolm North ◽  
Jiquan Chen
Keyword(s):  
Spatial Variability ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest ◽  
Before And After

Development of the mixed conifer forest in northern New Mexico and its relationship to Holocene environmental change

2008 ◽  
Vol 69 (2) ◽  
pp. 263-275 ◽  
Author(s):  
R. Scott Anderson ◽  
Renata B. Jass ◽  
Jaime L. Toney ◽  
Craig D. Allen ◽  
Luz M. Cisneros-Dozal ◽  
...  
Keyword(s):  
New Mexico ◽  
Pinus Ponderosa ◽  
Late Glacial ◽  
Conifer Forest ◽  
Lake Levels ◽  
Mixed Conifer ◽  
The Holocene ◽  
Groundwater Levels ◽  
Mixed Conifer Forest ◽  
Jemez Mountains

Chihuahueños Bog (2925 m) in the Jemez Mountains of northern New Mexico contains one of the few records of late-glacial and postglacial development of the mixed conifer forest in southwestern North America. The Chihuahueños Bog record extends to over 15,000 cal yr BP. AnArtemisiasteppe, then an openPiceawoodland grew around a small pond until ca. 11,700 cal yr BP whenPinus ponderosabecame established. C/N ratios,δ13C andδ15N values indicate both terrestrial and aquatic organic matter was incorporated into the sediment. Higher percentages of aquatic algae and elevated C/N ratios indicate higher lake levels at the opening of the Holocene, but a wetland developed subsequently as climate warmed. From ca. 8500 to 6400 cal yr BP the pond desiccated in what must have been the driest period of the Holocene there. C/N ratios declined to their lowest Holocene levels, indicating intense decomposition in the sediment. Wetter conditions returned after 6400 cal yr BP, with conversion of the site to a sedge bog as groundwater levels rose. Higher charcoal influx rates after 6400 cal yr BP probably result from greater biomass production rates. Only minor shifts in the overstory species occurred during the Holocene, suggesting that mixed conifer forest dominated throughout the record.

scholarly journals Changes in Nitrogen-Fixing and Ammonia-Oxidizing Bacterial Communities in Soil of a Mixed Conifer Forest after Wildfire

2005 ◽  
Vol 71 (5) ◽  
pp. 2713-2722 ◽  
Author(s):  
Chris M. Yeager ◽  
Diana E. Northup ◽  
Christy C. Grow ◽  
Susan M. Barns ◽  
Cheryl R. Kuske
Keyword(s):  
Bacterial Communities ◽  
Fragment Length Polymorphism ◽  
Rflp Analysis ◽  
Ammonia Oxidizing Bacteria ◽  
Nitrogen Fixing ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest ◽  
In Fire ◽  
Sequence Types

ABSTRACT This study was undertaken to examine the effects of forest fire on two important groups of N-cycling bacteria in soil, the nitrogen-fixing and ammonia-oxidizing bacteria. Sequence and terminal restriction fragment length polymorphism (T-RFLP) analysis of nifH and amoA PCR amplicons was performed on DNA samples from unburned, moderately burned, and severely burned soils of a mixed conifer forest. PCR results indicated that the soil biomass and proportion of nitrogen-fixing and ammonia-oxidizing species was less in soil from the fire-impacted sites than from the unburned sites. The number of dominant nifH sequence types was greater in fire-impacted soils, and nifH sequences that were most closely related to those from the spore-forming taxa Clostridium and Paenibacillus were more abundant in the burned soils. In T-RFLP patterns of the ammonia-oxidizing community, terminal restriction fragments (TRFs) representing amoA cluster 1, 2, or 4 Nitrosospira spp. were dominant (80 to 90%) in unburned soils, while TRFs representing amoA cluster 3A Nitrosospira spp. dominated (65 to 95%) in fire-impacted soils. The dominance of amoA cluster 3A Nitrosospira spp. sequence types was positively correlated with soil pH (5.6 to 7.5) and NH3-N levels (0.002 to 0.976 ppm), both of which were higher in burned soils. The decreased microbial biomass and shift in nitrogen-fixing and ammonia-oxidizing communities were still evident in fire-impacted soils collected 14 months after the fire.

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