A comparison of the capacities of granitic and andesitic soils, with and without nutritional augmentation, to promote above- and below-ground development of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings was conducted. Shoot dimensions and dry weight along with root system length and weight within both the coarse and fine fractions were all significantly enhanced in granitic soils compared to an andesitic one, and seedlings grown in the former had far more short roots and ectomycorrhizae as well. For both shoots and roots, the magnitude of these growth enhancements was somewhat more pronounced in a less weathered granitic soil than in a more weathered one such that at the conclusion of the study, total shoot biomass of seedlings grown in the andesitic soil averaged 38% of that produced in the less weathered granitic one and 47% of that in the more heavily weathered granitic soil, while such comparisons regarding that of the roots revealed values of 28% and 34%, respectively. Fertilization at the onset of the study with either N or P or N+P had little capacity to compensate for the growth deficiencies in either above- or below-ground seedling tissues attributable to the andesitic soil, and its influences in the granitic soils were muted and largely ephemeral. Shoot growth was well correlated with root system length and weight and at least moderately so with short root and mycorrhizal counts, although such counts were commensurate with stronger regression models primarily when limited to the fine rather the coarse root size fraction.

Comparison of the burned and unburned portions of a Jeffrey pine stand in the eastern Sierra Nevada that was partially destroyed by a wildfire approximately a half century earlier served as the basis of an investigation intended to provide insight into the direction and pace of unaided recovery from such events in this and similar forest cover types. With Jeffrey pine the predominant species regardless of treatment, lodgepole pine was a secondary component of the overstory in both stand portions but a minor representation of white fir in the unburned portion was absent from the burned acreage. Commensurate with the large difference in age, tree dimensions, basal area, and biomass in the overstory of the burned stand portion were greatly exceeded by those of the overstory in the unburned portion. Tree seedlings and saplings were much more abundant in the burned acreage, with those of Jeffrey pine largely accounting for the disparity. Predominant among shrubs in the understory of the burned stand portion was snowbrush ceanothus with that in the unburned portion consisting of prostrate ceanothus, while among herbaceous species a small quantity of Sandberg bluegrass in the former contrasted against none in the latter. Fine and total fuel loading along with fuel bed depth on the burned substrate were greatly exceeded by those on the unburned substrate, while proportionally, less fine fuels but more of the coarsest ones were found on the former compared to the latter.

Long-term influences of mechanized thinning using a cut-to-length approach combined with on-site slash mastication along with those of prescription under burning on downed and dead fuel accumulations were evaluated in an uneven-aged eastern Sierra Nevada mixed conifer stand. Based on an initial inventory conducted soon after treatment implementation, accumulations in an unburned portion of the stand subunit subjected to thinning were elevated with respect to both 1+10 hr time lag and total fuel loads. In contrast, the near immediate effect of the under burn on these fuels was marked diminishment in their abundance. Nearly a decade later, however, effects of the mechanized and fire treatments had largely dissipated. In the interim between inventories, the thinned but unburned treatment combination exhibited the greatest reduction in 1+10 hr and total fuels while the unthinned and unburned combination also exhibited a large reduction in the former. Furthermore, diminished reductions in 1+10 hr fuels were apparent within the burned portions of the thinned and unthinned stand subunits, and the unthinned but burned combination was the only one to incur an increase in total fuels. These findings offer land managers insight regarding the persistence of fuel bed alterations induced by these increasingly common management practices in Sierran mixed conifer and similar forest cover types.

Forest thinnings accomplished through cut-to-length and whole-tree harvesting followed by a prescribed underburn were assessed for their influences on mineral nutrition in eastern Sierran Jeffrey pine (Pinus jeffreyi Grev. & Balf.). As derived from foliar elemental concentrations determined at six samplings distributed over three growing seasons, molar Ca/Al, Mg/Al, K/Al, Ca/Mn, Mg/Mn, and K/Mn were generally higher in the unthinned treatment and lower in burned stand portions. Conducted under drought conditions, the driest phase of the study resulted in lower Ca/Al, Mg/Al, and K/Al and higher Ca/Mn and Ca/Zn when averaged across treatments. Foliar K/Mn, K/Zn, and K/Cu were generally lower in the early portion of the growing season compared to the late portion. At mid growing season, Mg/Al, K/Al, Mg/Mn, K/Mn, K/Fe, K/Zn, and K/Cu were higher in young needles while Ca/Al, Ca/Fe, Mg/Fe, Ca/Zn, Ca/Cu, and Mg/Cu were so in older ones. At mid study, soil Ca/Fe was higher in the unthinned treatment generally and especially in its unburned portion while K/Cu was higher overall in burned stand portions, most especially in the unthinned treatment. These findings provide insight into the interrelationships of base cations and metallic elements in forest nutrition as influenced by restoration practices.

Thinning implemented with a cut-to-length harvesting system coupled with on-site slash mastication and redistribution and followed by prescribed under burning were assessed for their impacts on the shrub understory and natural regeneration in an uneven-aged Sierra Nevada mixed conifer stand. Initial suppression of the cover and weight of huckleberry oak, the most prevalent ground cover species, by the combined thinning and mastication operations and those of prostrate ceanothus by the under burn were followed by a pronounced resurgence in abundance for both species in burned stand portions, particularly where thinning had preceded the fire. White fir was most prevalent initially among species represented in the seedling size class of natural regeneration and became predominant thereafter while this species dominated the sapling class throughout the study. White fir seedling establishment was enhanced where the mechanized operations were excluded, and especially so where fire was as well, and such was also the case for incense-cedar initially but its seedling abundance declined precipitously as the study progressed. White fir saplings were most numerous in the unthinned stand subunit but the under burn proved lethal to many of them therein. Jeffrey and sugar pine were little represented among seedlings and absent altogether among saplings.

Thinning implemented with a cut-to-length system accompanied by on-site slash mastication and dispersal and followed by prescribed underburning were evaluated for their influences on individual tree and stand level growth in eastern Sierran mixed conifer. California white fir (Abies concolor var. lowiana [Gord.] Lemm.) dominated stand composition with Jeffrey pine (Pinus jeffreyi Grev. & Balf.) and sugar pine (Pinus lambertiana Dougl.) moderately represented while incense-cedar (Libocedrus decurrens Torr.) and California red fir (Abies magnifica A. Murr.) were exceedingly minor constituents. One decade after treatment, trees in the thinned stand subunit exhibited large height and DBH gains irrespective of fire treatment, responses attributable to the thinning protocol and to enhanced growth of residual stems, while minimal dimensional changes prevailed in the unthinned subunit. Diminished board feet and cubic volumes prevailed in the thinned subunit, and especially in its burned portion, through the end of the study, however, reflecting a reduction in stocking exacerbated by further loss caused by the underburn. Steep reductions in white fir volumes were responsible for the overall losses in the thinned and burned treatment combination. Jeffrey pine responded favorably to thinning but not to underburning, while sugar pine volume responses were unaffected by either treatment.

Multiple forest health variables were examined in an eastern Sierra Nevada mixed conifer stand, principal among them bark beetle demography. As indicated by pitch tube counts, California white fir (Abies concolor var. lowiana [Gord.] Lemm.), the predominant species, was colonized prodigiously compared to Jeffrey pine (Pinus jeffreyi Grev. and Balf.) and sugar pine (Pinus lambertiana Dougl.). Across host species, pitch tube abundance was positively related to white fir prevalence and negatively related to tree species diversity. Bark beetles preferentially attacked trees of small to medium DBH in white fir and sugar pine. Attack intensity in small Jeffrey pine was positively correlated with stand basal area and biomass and that in sugar pine of medium size was positively correlated with basal area also. Minor mistletoe infestations were detected in white fir along with incense-cedar (Libocedrus decurrens Torr.) and California red fir (Abies magnifica A. Murr.), with bark beetle colonization in the smallest and largest white fir positively related to the percentage of this fir thus infested. Mortality in white fir and Jeffrey pine irrespective of size was positively correlated with the pitch tube count in the largest white fir regarding the former and with total tree count regarding the latter.

Forest thinnings implemented with cut-to-length and whole-tree harvesting systems followed by prescribed underburning were evaluated for their effects on red turpentine beetle (Dendroctonus valens LeConte) colonization in pure, uneven-aged Jeffrey pine (Pinus jeffreyi Grev. & Balf.). Based on pitch tube abundance expressed as bole surface area-based counts, this beetle was significantly more prevalent where thinnings were implemented regardless of harvesting approach than in the unthinned treatment, but the population increases were confined to the burned stand portions. Substantial evidence indicated that fire-induced crown and bole damage culminating in compromised defense mechanisms elevated turpentine beetle colonization, and some evidence suggested a proclivity of this beetle to attack stems exhibiting general characteristics of low vigor, specifically smaller trees with weak crowns. Tree mortality was likely induced by the turpentine beetle infestation but was probably not its sole cause. The responses presented herein to these thinning and burning practices, which are being increasingly relied upon in forest restoration efforts in the western USA, provide natural resource managers insight into potentially compromised forest health outcomes over the intermediate term when implemented in Jeffrey pine and similar dry site forest types.

Forest thinnings implemented through cut-to-length and whole-tree harvesting followed by underburning were evaluated for their effects on long-term downed and dead fuels accumulations in pure, uneven-aged Jeffrey pine (Pinus jeffreyi Grev. & Balf.) accompanied by isolated California white fir (Abies concolor var. lowiana [Gord.] Lemm.). Based on an initial inventory consisting of dry weight and fuel bed depth measurements conducted posttreatment, accumulations in the cut-to-length treatment were elevated according to most measures. Burned stand portions exhibited smaller quantities of fuels initially in individual timelag categories and in total as well as reduced fuel bed depths compared to their unburned counterparts except for the 1,000-hr fuels in the whole-tree treatment where postburn mortality of small stems nullified this effect. A linkage between initial mortality resulting from prescribed fire and final 1,000-hr fuels, as measured 8 yr later, was established but was probably attributable to combined thinning and burning effects. Over the course of the study, either greater accruals or diminished reductions in loading were apparent within burned stand portions compared to unburned portions, most notably in the whole-tree treatment. Results presented here provide insight into potentially compromised fuels reduction outcomes when implemented in uneven-aged stands on dry forest sites.

An investigation of wildfire effects on mineral nutrition of Jeffrey pine (Pinus jeffreyi Grev. & Balf.) along with species comparisons of the nutrition of unburned specimens of this pine to those of unburned California white fir (Abies concolor var. lowiana [Gord.] Lemm.) were conducted in an eastern Sierran mixed conifer stand. Foliar Fe and Mn concentrations were frequently higher and Al was consistently so in burned than in the unburned pine as assessed in six sampling periods distributed over more than two postfire growing seasons while base cation/metallic element molar ratios consisting of Ca/Al, K/Al, K/Mn, Ca/Fe, Mg/Fe, K/Fe, and Ca/Zn were often lower in the former. Foliar N, P, Fe, Zn, and Cu were frequently higher in unburned pine than unburned fir while the reverse proved true concerning K, Ca, Mn, B, and Al; and likewise several molar ratios involving Al and Mn were higher in the former while several involving Fe, Zn, and Cu were higher in the latter. At midstudy, mineral soil in the burned stand portion had lower K but higher S, Mn, and Zn than that in the unburned portion, and the former had several molar ratios that were lower as well.

An investigation of wildfire effects on water relations of Jeffrey pine (Pinus jeffreyi Grev. & Balf.) along with species comparisons of the water relations of unburned specimens of this pine to those of unburned white fir (Abies concolor var. lowiana [Gord.] Lemm.) were conducted in a mixed conifer stand located in the Lake Tahoe Basin. Xylem water potentials were significantly lower in burned than in the unburned Jeffrey pine as measured in predawn, midday, and evening periods distributed over more than two postfire growing seasons, while soil water potentials were lower in burned than in unburned stand portions during the drier parts of the growing season, but the reverse proved true during the wetter part. Diurnal fluctuation in bole diameter, a measure of stored water recharge capacity, was largely unaffected by wildfire, however. Xylem water potentials were consistently lower in unburned white fir than in unburned Jeffrey pine and DBH fluctuation was often lower in the fir than in the pine as well, but soil water potentials associated with unburned subject trees did not differ significantly between the two species. Demonstrated here are ecophysiological alterations that occur in Sierra Nevada mixed conifer due to wildfire and shifting species composition.

Forest thinnings implemented with cut-to-length and whole-tree harvesting systems followed by underburning were evaluated for their effects on bark beetle prevalence in pure, uneven-aged Jeffrey pine (Pinus jeffreyi Grev. & Balf.) interspersed with isolated California white fir (Abies concolor var. lowiana [Gord.] Lemm.). Based on pitch tube counts in a stand with a moderate bark beetle population in its pine component, the Jeffrey pine beetle (Dendroctonus jeffreyi Hopkins) generally preferred larger trees before treatment implementation, but after exhibiting mixed pretreatment tendencies concerning stand density demonstrated a posttreatment proclivity toward higher density. Cut-to-length thinning followed by underburning increased the pine beetle population while whole-tree thinning unaccompanied by burning reduced it. Tree mortality was induced by the bark beetle infestation but was not its sole cause. Pitch tube abundance on white fir far exceeded that on Jeffrey pine, and the greatest influence on the fir engraver (Scolytus ventralis LeConte) population was the prevalence of its host tree. The responses presented herein to these thinning and burning practices, which are being increasingly utilized in forest restoration efforts in the western USA, provide natural resource managers insight into potential forest health outcomes when implemented in Jeffrey pine and similar dry site forest types.

Thinning and prescribed fire are common management tools used to eliminate thick fuel loads that could otherwise facilitate and encourage a more severe catastrophic wildfire. The objective of this study was to quantify the lasting effects of prescribed fire on forest floor and soil nutrients approximately 9 yr after a burn occurred near Truckee, CA. The study site includes a prescribed fire following various harvest and understory removal treatments: whole‐tree thinning, cut‐to‐length thinning, and no thinning. Data were collected before, immediately after, and 9 yr later following a prescribed burn. All forest floor and soil samples were analyzed for nutrients (O horizon: total N; mineral soil: total N, total C, mineral N). Fuel reductions were evident 9 yr after the fire in the burned plots. No significant changes in total C or total N in surface (0–20‐cm) mineral soils occurred during the 9‐yr period. Mineral N concentrations in surface soils were greater in unburned than in burned cut‐to‐length thinning treatments after 9 yr. These differences were attributed to N inputs from decomposing slash and to the reduction in the biomass of N 2 fixers by burning.

Wildfire effects on understory shrubs and herbs, regeneration of the seedling and sapling size classes, and downed and dead fuels were assessed in a mixed conifer stand located in the Lake Tahoe Basin in which California white fir (Abies concolor var. lowiana [Gord.] Lemm.) was most abundant but with Jeffrey pine (Pinus jeffreyi Grev. & Balf.) also prevalent. In burned and unburned stand portions, prefire measurements served as a basis of comparison for the postfire measurements pertinent to each study component. Fire severely suppressed the understory vegetation, which was dominated by shrubs such as bush chinquapin (Chrysolepis sempervirens [Kellogg] Hjelmqvist) and antelope bitterbrush (Purshia tridentata [Pursh] DC.), while a tepid postfire recovery of most of the preexisting species in the burned stand portion was augmented by new ones, including shrubs such as snowbrush (Ceanothus velutinus Douglas ex Hook.) and whitethorn (Ceanothus cordulatus Kellogg) ceanothus and herbs such as Holboell's rockcress (Arabis holboellii Hornem.). Tree seedling abundance was also substantially reduced in the burned portion, but the postfire population was dominated by Jeffrey pine whereas white fir had been most prevalent originally. Sapling regeneration was eliminated from the burned stand portion regardless of species. Downed and dead fuel loading was severely diminished by the fire, especially regarding fine fuels, permitting subsequent sheet erosion to imperil new seedling regeneration. These results contribute to an understanding of the direction and pace of postwildfire succession on sites occupied by Sierra Nevada mixed conifer and similar forest cover types, which is critical in decisions concerning the need for, and extent of, postfire site rehabilitation measures.

Selected fertilizer formulations were assessed for their capacity to enhance growth and nutrition of Jeffrey pine (Pinus jeffreyi Grev. & Balf.) seedlings on an acidic and possibly toxic Sierran surface mine when applied three years after planting. In a study encompassing five growing seasons conducted on a semiarid, montane surface mine site on the eastern slope of the Sierra Nevada, seedling survival, dimensions, and volume measurements were coupled with foliar and soil analyses for macronutrients, micronutrients, and potentially phytotoxic metallic elements. Administered by broadcasting at four rates each, the formulations consisted of an organic amendment derived from municipal biosolids; a controlled release fertilizer containing urea, ammoniacal, and nitrate N sources; and two conventional fertilizers with one featuring urea as the predominant N form while the other delivered ammoniacal and nitrate forms. None of the formulations induced seedling mortality regardless of application rate, but the controlled release fertilizer and the conventional urea-based formulation were the most stimulatory overall, with intermediate rates of both proving most advantageous among those tested. Foliar analysis revealed that enhanced N and P nutrition, which was otherwise severely impacted by soil infertility, possibly along with that of K, probably accounted for most of the growth stimulation by the amendments, but an accessory role may have been attributable to reduced concentrations of potentially phytotoxic metallic elements, principally Mn but possibly including Fe, Cu, and Al, for which soil levels were all exceedingly elevated. With careful selection of formulation and application rate, post-planting broadcast fertilization can enhance growth and nutrition of Jeffrey pine on degraded substrates. These results provide a more complete understanding of the benefits that judicious fertilization can impart to young forest stands on surface mines and other harsh sites.

The authors would like to add a co-author “Brittany G. Johnson” as sixth author in the published paper [1], doi: 10.3390/f3020398, website: http://www.mdpi.com/1999-4907/3/2/398. After publication, we discovered that we left our one deserving graduate student author from the published paper, Brittany G. Johnson, who helped in collecting data for this paper. The authors apologize for any convenience this may have caused.

Forest thinnings implemented with cut-to-length and whole-tree harvesting systems followed by underburning were evaluated for their effects on individual tree and stand level growth responses in pure, uneven-aged Jeffrey pine (Pinus jeffreyi Grev. & Balf.) accompanied by isolated California white fir (Abies concolor var. lowiana [Gord.] Lemm.). Based on both dimension and volume measures, trees of the unburned whole-tree treatment combination exhibited the greatest individual growth responses. At the stand level, a diminished volume growth response in the whole-tree treatment was especially pronounced in the burned portion, mostly attributable to exaggerated stocking losses, while a superior response in the unburned cut-to-length combination likely reflected not only the absence of detrimental fire impacts but also benefits of on-site slash retention. For stand level biomass, diminished growth in the whole-tree treatment was again evident, with that in the burned portion again most pronounced, while biomass accrual in the unburned cut-to-length treatment combination was generally comparable to that in the unthinned control. Increasingly utilized in forest restoration efforts in the western USA, the responses presented herein to these thinning and burning practices provide natural resource managers insight into potential compromised outcomes when implemented in Jeffrey pine and similar dry site forest types.

Wildfire has been shown to increase the short-term (1-3 yr) mobilization of mineral N and P in forest ecosystems of the Sierra Nevada Mountains and Lake Tahoe Basin. The ensuing effects on tributary and lake water quality are uncertain. The purpose of this investigation was to assess the impacts on runoff water quality over an intermediate time frame of 5 yr (2002-2007) after a wildfire event. Our design included fixed plots randomly placed within burned and unburned areas. Because each plot was sampled repeatedly during the study, we treated plots as repeated random effects in the analysis. We used a mixed model approach to analyze nutrient runoff concentrations and load for NH-N, NON and P in phosphate form (designated as ortho P or PO-P) where treatment (unburned vs. burned), time (pre-wildfire, post-wildfire year 1, year 2, etc.), and their interaction were fixed effects. Concentrations and loads of mineral N and P were higher in runoff from the burned areas immediately after wildfire. Because high water years may also contribute to higher runoff nutrient concentrations and loading, a wildfire followed by a high water year within the first season after a wildfire would likely have a much greater impact on runoff (and hence tributary) water quality than a wildfire followed by a low runoff water year.

The effects of thinning followed by residue mastication (THIN), prescribed fire (BURN), and thinning plus residue mastication plus burning (T+B) on nutrient budgets and resin-based (plant root simulator [PRS] probe) measurements of soil nutrient availability in a mixed-conifer forest were measured. Because of site differences, removals of carbon (C) and nutrients by harvesting were greater in the T+B than in the THIN (Mg) treatment. Harvesting caused greater exports of C, phosphorus, potassium (K), calcium (Ca), and magnesium than burning, harvesting and burning caused approximately equal exports of nitrogen (N), and burning caused greater exports of sulfur than harvesting. Burning caused greater volatilization losses of C and N from the T+B than from the BURN treatment because the addition of chips from mastication in the T+B treatment caused greater combustion of the native forest floor. The most significant effect of the chips on soil nutrients was the addition of K to the forest floor pools, which was also reflected in resin-based measurements of soil nutrients. Burning caused increases in soil NO−3−N, mineral N, Ca2+, and SO2−4 as measured by PRS probes, which persisted for 2 years after the burn. The more intense burning in the T+B treatment also caused elevated orthophosphate levels 2 years after the burn. Burning effects on K+ and Mg2+ were not significant. Overall, the most ecologically significant effect of treatment was the export of N from the combination of harvesting and burning in the T+B treatment, which totaled 932 kg ha−1 and 13