Western juniper and ponderosa pine ecotonal climate–growth relationships across landscape gradients in southern Oregon

2008 ◽  
Vol 38 (12) ◽  
pp. 3021-3032 ◽  
Author(s):  
Kevin C. Knutson ◽  
David A. Pyke
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Radial Growth ◽  
Winter Precipitation ◽  
Forest Growth ◽  
Annual Growth ◽  
Growth Responses ◽  
Climate Fluctuations ◽  
Western Juniper ◽  
Tree Ring Data

Forecasts of climate change for the Pacific northwestern United States predict warmer temperatures, increased winter precipitation, and drier summers. Prediction of forest growth responses to these climate fluctuations requires identification of climatic variables limiting tree growth, particularly at limits of tree species distributions. We addressed this problem at the pine–woodland ecotone using tree-ring data for western juniper ( Juniperus occidentalis var. occidentalis Hook.) and ponderosa pine ( Pinus ponderosa Dougl. ex Loud.) from southern Oregon. Annual growth chronologies for 1950–2000 were developed for each species at 17 locations. Correlation and linear regression of climate–growth relationships revealed that radial growth in both species is highly dependent on October–June precipitation events that recharge growing season soil water. Mean annual radial growth for the nine driest years suggests that annual growth in both species is more sensitive to drought at lower elevations and sites with steeper slopes and sandy or rocky soils. Future increases in winter precipitation could increase productivity in both species at the pine–woodland ecotone. Growth responses, however, will also likely vary across landscape features, and our findings suggest that heightened sensitivity to future drought periods and increased temperatures in the two species will predominantly occur at lower elevation sites with poor water-holding capacities.

scholarly journals The Survival of Pinus ponderosa Saplings Subjected to Increasing Levels of Fire Behavior and Impacts on Post-Fire Growth

Fire ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 23 ◽  
Author(s):  
Wade D. Steady ◽  
Raquel Partelli Feltrin ◽  
Daniel M. Johnson ◽  
Aaron M. Sparks ◽  
Crystal A. Kolden ◽  
...  
Keyword(s):  
Dose Response ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Fire Hazard ◽  
Fire Behavior ◽  
Forest Growth ◽  
Growth And Yield ◽  
Radiative Energy ◽  
Fire Growth ◽  
Growth Metrics

Improved predictions of tree species mortality and growth metrics following fires are important to assess fire impacts on forest succession, and ultimately forest growth and yield. Recent studies have shown that North American conifers exhibit a ‘toxicological dose-response’ relationship between fire behavior and the resultant mortality or recovery of the trees. Prior studies have not been conclusive due to potential pseudo-replication in the experimental design and time-limited observations. We explored whether dose-response relationships are observed in ponderosa pine (Pinus ponderosa) saplings exposed to surface fires of increasing fire behavior (as quantified by Fire Radiative Energy—FRE). We confirmed equivalent dose-response relationships to the prior studies that were focused on other conifer species. The post-fire growth in the saplings that survived the fires decreased with increasing FRE dosages, while the percentage mortality in the sapling dosage groups increased with the amount of FRE applied. Furthermore, as with lodgepole pine (Pinus contorta), a low FRE dosage could be applied that did not yield mortality in any of the replicates (r = 10). These results suggest that land management agencies could use planned burns to reduce fire hazard while still maintaining a crop of young saplings. Incorporation of these results into earth-system models and growth and yield models could help reduce uncertainties associated with the impacts of fire on timber growth, forest resilience, carbon dynamics, and ecosystem economics.

Effects of fuel morphology on ember generation characteristics at the tree scale

2020 ◽  
Vol 29 (11) ◽  
pp. 1042
Author(s):  
Tyler R. Hudson ◽  
Ryan B. Bray ◽  
David L. Blunck ◽  
Wesley Page ◽  
Bret Butler
Keyword(s):  
Mass Loss ◽  
Pseudotsuga Menziesii ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Douglas Fir ◽  
Biological Factors ◽  
Abies Grandis ◽  
Western Juniper ◽  
Juniperus Occidentalis ◽  
Spot Fires

This work reports characteristics of embers generated by torching trees and seeks to identify the important physical and biological factors involved. The size of embers, number flux and propensity to ignite spot fires (i.e. number flux of ‘hot’ embers) are reported for several tree species under different combinations of number (one, three or five) and moisture content (11–193%). Douglas-fir (Pseudotsuga menziesii), grand fir (Abies grandis), western juniper (Juniperus occidentalis) and ponderosa pine (Pinus ponderosa) trees were evaluated. Embers were collected on an array of fire-resistant fabric panels and trays filled with water. Douglas-fir trees generated the highest average ember flux per kilogram of mass loss during torching, whereas grand fir trees generated the highest ‘hot’ ember flux per kilogram of mass loss. Western juniper produced the largest fraction of ‘hot’ embers, with ~30% of the embers generated being hot enough to leave char marks. In contrast, only 6% of the embers generated by ponderosa pine were hot enough to leave char marks. Results from this study can be used to help understand the propensity of different species of tree to produce embers and the portion of embers that may be hot enough to start a spot fire.

Ten-year responses of ponderosa pine plantations to repeated vegetation and nutrient control along an environmental gradient

1999 ◽  
Vol 29 (7) ◽  
pp. 1027-1038 ◽  
Author(s):  
Robert F Powers ◽  
Phillip E Reynolds
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Plant Competition ◽  
Site Index ◽  
Stem Volume ◽  
Growth Responses ◽  
Xylem Water Potential ◽  
Potential Productivity ◽  
Vegetation Control ◽  
Moisture Availability

Factorial combinations of vegetation, nutrient, and insect control treatments were applied repeatedly to three contrasting California plantations of Pinus ponderosa var. ponderosa Dougl. ex Laws. Ten-year findings show that potential productivity is far greater than previously believed. Stem volume gains were linked directly with increases in crown volume. Insect problems were negligible. Vegetation control increased tree growth profoundly on xeric sites but less so on the most mesic. Where soil was both droughty and infertile, growth responses traced primarily to improved soil moisture availability and secondarily to better nutrition. The most fertile site also was droughty, and trees responded only to improved moisture availability. Water was less limiting on the most productive site. There, both fertilizers and herbicides triggered similar, substantive growth increases. Drought from both plant competition and climate reduced stomatal conductance, xylem water potential, and net assimilation rates. Assimilation rates increased linearly with site index, but treatment differences were not apparent once drought had peaked. Fertilization improved water-use efficiency where water stress was not extreme. Advantages in water availability to pines from vegetation control will dissipate as tree crowns close and transpiration rises.

Radial growth responses of four oak species to climate in eastern and central North America

2015 ◽  
Vol 45 (7) ◽  
pp. 793-804 ◽  
Author(s):  
David C. LeBlanc ◽  
David W. Stahle
Keyword(s):  
North America ◽  
Great Plains ◽  
Radial Growth ◽  
Correlation Coefficients ◽  
Simulation Models ◽  
Growing Season ◽  
Seasonal Temperature ◽  
Growth Responses ◽  
Temperature And Precipitation ◽  
Tree Ring Data

This study characterized associations between climate variables and radial growth of four oak species at sites distributed across central and eastern North America. Tree-ring data were obtained from 24, 29, 33, and 55 sites for Quercus prinus L., Quercus velutina Lam., Quercus macrocarpa Michx., and Quercus stellate Wangenh., respectively. Pearson’s correlation coefficients were computed between radial growth and monthly and seasonal temperature and precipitation. Growth was most strongly and consistently correlated with precipitation and temperature during the early growing season (May to July). Coincident positive correlations with precipitation and negative correlations with temperature indicate that this relationship is mediated by site water balance. The combination of this plausible cause–effect mechanism and extensive spatial replication of these correlations suggest that they reflect cause–effect relationships. Growth of Q. stellata was correlated with precipitation during the dormant season, suggesting that stored soil water is important for growth of this species in the southern Great Plains. Despite substantial spatial variation in temperature and growing-season initiation between sites in Texas and Manitoba, Canada, there was little variation in the phenology of growth–climate associations; growth–climate correlations were strongest during the same May–July period at all sites. Results of this study support the hypothesis that temperate zone ring-porous oak species have similar phenology of growth–climate correlations and can be treated as a biologically meaningful functional group in forest simulation models.

scholarly journals Three-Year Response of Ponderosa Pine Seedlings to Controlled-Release Fertilizer Applied at Planting

2002 ◽  
Vol 17 (3) ◽  
pp. 154-164 ◽  
Author(s):  
Zhaofei Fan ◽  
James A. Moore ◽  
Bahman Shafii ◽  
Harold L. Osborne
Keyword(s):  
Controlled Release ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Slow Release ◽  
Growing Season ◽  
Relative Magnitude ◽  
Fertilizer Treatment ◽  
Growth Responses ◽  
Pine Seedlings ◽  
Height Increase

Abstract Four controlled-release fertilizers (fast release [FR], moderate release [MR], slow release [SR] and slow release with micronutrients extended [ME]) were applied, at rates of 0, 5, 15 and 30 g/seedling, to ponderosa pine seedlings (Pinus ponderosa Doug. ex Laws) immediately after planting. Compared to the controls, the 5 and15 g/seedling of FR or ME fertilizer produced significantly greater caliper growth and the 5 and 15 g/seedling of ME fertilizer and 15 and 30 g of FR fertilizer produced significantly greater height growth after 3 yr. Mortality occurred mainly during the first growing season and varied substantially with fertilizer types and dosage. High dosage (30 g/seedling) generally caused more mortality than other dosage levels. Seventy-eight, 54, 51, and 36% of total nutrients had been released from the FR, MR, SR and ME products, respectively, by late August of the first growing season. Early in the second growing season, the FR product had released 98% of its total nutrients, and the MR, SR, and ME products had released over 90% of their nutrients. The best fertilizer treatment, 15 g of the ME product, produced a 21% diameter increase and a 30% height increase 3 yr after treatment. The relative magnitude of the growth responses is similar to those observed from other adjacent placement, controlled-release, seedling fertilization studies in the Northwest. West. J. Appl. For. 17(3):154–164.

scholarly journals Climate Effect on Ponderosa Pine Radial Growth Varies with Tree Density and Shrub Removal

Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 477 ◽  
Author(s):  
Kaelyn Finley ◽  
Jianwei Zhang
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Radial Growth ◽  
Explanatory Power ◽  
Early Summer ◽  
Climatic Conditions ◽  
Mountain Range ◽  
Climate Effect ◽  
Moisture Availability

With increasing temperatures and projected changes in moisture availability for the Mediterranean climate of northern California, empirical evidence of the long-term responses of forests to climate are important for managing these ecosystems. We can assess forest treatment strategies to improve climate resilience by examining past responses to climate for both managed and unmanaged plantations. Using an experimental, long-term density and shrub removal study of ponderosa pine (Pinus ponderosa Lawson & C. Lawson) on a poor-quality site with low water-holding capacity and high runoff of the North Coastal mountain range in California, we examined the relationships between radial growth and climate for these trees over a common interval of 1977–2011. Resistance indices, defined here as the ratio between current year radial growth and the performance of the four previous years, were correlated to climatic variables during the same years. We found that all treatments’ radial growth benefited from seasonal spring moisture availability during the current growing year. Conversely, high spring and early summer temperatures had detrimental effects on growth. High-density treatments with manzanita understories were sensitive to summer droughts while lower densities and treatments with full shrub removal were not. The explanatory power of the climate regression models was generally more consistent for the same shrub treatments across the four different densities. The resistance indices for the lower density and complete shrub removal treatment groups were less dependent on previous years’ climatic conditions. We conclude that, for ponderosa pine plantations with significant manzanita encroachment, understory removal and heavy thinning treatments increase subsequent growth for remaining trees and decrease sensitivity to climate.

scholarly journals Dendroclimatic Assessment of Ponderosa Pine Radial Growth along Elevational Transects in Western Montana, U.S.A.

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1094 ◽  
Author(s):  
Evan E. Montpellier ◽  
Peter T. Soulé ◽  
Paul A. Knapp ◽  
Justin T. Maxwell
Keyword(s):  
United States ◽  
Ponderosa Pine ◽  
Radial Growth ◽  
The United States ◽  
Climatic Conditions ◽  
Western Montana ◽  
Drought Severity ◽  
Growth Responses ◽  
Differential Growth ◽  
Climate Conditions

Ponderosa pine (PP) is the most common and widely distributed pine species in the western United States, spanning from southern Canada to the United States–Mexico border. PP can be found growing between sea level and 3000 meters elevation making them an ideal species to assess the effects of changing climatic conditions at a variety of elevations. Here we compare PP standardized and raw growth responses to climate conditions along an elevational transect spanning 1000 meters in western Montana, U.S.A., a region that experienced a 20th century warming trend and is expected to incur much warmer (3.1–4.5 °C) and slightly drier summers (~0.3 cm decrease per month) by the end on the 21st century. Specifically, we assess if there are climate/growth differences based on relative (i.e., site-specific) and absolute (i.e., combined sites) elevation between groups of trees growing in different elevational classes. We find that values of the Palmer drought severity index (PDSI) in July are most strongly related to radial growth and that within-site elevation differences are a poor predictor of the response of PP to either wet or dry climatic conditions (i.e., years with above or below average July PDSI values). These results suggest that any generalization that stands of PP occurring at their elevational margins are most vulnerable to changing climatic may not be operative at these sites in western Montana. Our results show that when using standardized ring widths, PP growing at the lowest and highest elevations within western Montana exhibit differential growth during extreme climatological conditions with lower-elevation trees outperforming higher-elevation trees during dry years and vice versa during wet years.

scholarly journals Growth sensitivity to climate varies with soil moisture regime in spruce–fir forests in central British Columbia

Trees ◽  
2021 ◽  
Author(s):  
Hardy Griesbauer ◽  
S. Craig DeLong ◽  
Bruce Rogers ◽  
Vanessa Foord
Keyword(s):  
British Columbia ◽  
Soil Moisture ◽  
Picea Glauca ◽  
Forest Growth ◽  
Moisture Regime ◽  
Growth Responses ◽  
Soil Moisture Regime ◽  
Moisture Regimes ◽  
Tree Ring Data ◽  
Summer Temperatures

Abstract Key message Growth sensitivity to climate varies with soil moisture regime in spruce–fir forests in central British Columbia. Stands growing at their dry edaphic limits displayed especially strong and unique climatic sensitivities. Abstract Soil moisture regime is an important influence of productivity, process, and structure in forested ecosystems. In western North America, projected warming trends may result in decreasing available soil moisture; however, the potential effects on forest growth remain unclear. This study aimed to determine the influence of stand-level soil moisture regime on the climatic sensitivity of mature hybrid white spruce (Picea glauca (Moensch) Voss x Picea engelmannii Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) forests in central British Columbia, Canada. We collected and analyzed tree-ring data from 51 stands spanning a range of soil moisture regimes. Dendroecological analyses of climate–growth relationships indicated that warm summer temperatures and drought limit growth for both species across all soil moisture regimes; however, responses were strongest on the driest sites. Spruce populations across the gradient of soil moisture regimes displayed unique climate-growth relationships; growth in populations on wetter sites was more correlated with summer climate from the year prior to growth. Radial growth responses to prior summer temperatures strengthened over the past ca. 80 years in both species and across most sites, suggesting that climate–growth relationships are shifting in this region. This study presents evidence of the importance of considering site-level ecological factors such as soil moisture regime when studying forest growth responses to climate.

Effects of fuel characteristics on ember generation characteristics at branch-scales

2019 ◽  
Vol 28 (12) ◽  
pp. 941 ◽  
Author(s):  
Tyler R. Hudson ◽  
David L. Blunck
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Small Diameter ◽  
Quercus Alba ◽  
White Oak ◽  
Western Juniper ◽  
Crossflow Velocity ◽  
Fuel Characteristics ◽  
Time Required ◽  
Significant Factors

Spot fires caused by lofted embers (i.e. firebrands) can be a significant factor in the spread of wildfires. Embers can be especially dangerous near the wildland–urban interface (WUI) because of the potential for the fire to be spread near or on structures. This work sought to identify how ember generation changes for different fuel characteristics and environmental conditions. Samples were burned in a heated wind tunnel and the time required for the ember(s) to form was measured using a DSLR camera. A factorial analysis of variance was used to determine the sensitivity of the time to generation to species, diameter, moisture content, fuel condition (i.e. dowel v. natural sample), crossflow temperature and crossflow velocity. Four fuel species were evaluated: Douglas fir (Pseudotsuga menziesii), western juniper (Juniperus occidentalis), ponderosa pine (Pinus ponderosa) and white oak (Quercus alba). The diameter of the samples had the greatest effect on the time to generation and the fuel species had the second greatest effect. The small diameter samples were relatively insensitive to changes in other parameters. Natural samples required significantly longer time than dowels to generate an ember. These conclusions suggest that fuel morphology is one of the most significant factors influencing ember generation.

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