Bole volume growth in stems of Quercus gambelii

Shrub-form and tree-form Gambel oak ( Quercus gambelii ) stands contain a potentially significant fuelwood resource. Information on their growth characteristics can form a basis for future stand management. Stem analyses showed that height growth of shrub-form stems essentially ceased after age 50, while tree-form stems continued to increase in height until approximately age 100. Both stem forms continued to increase in basal area and volume at a relatively constant rate as the stems increased in age and size. Increases in all size measures were substantially greater in tree-form stems than in shrub-form stems. Mean bole volume for tree-form stems at age 100 was over 16 times that of shrub-form stems. Sprouts from tree-form stands would reach minimum size for fuelwood marketing in approximately 45 years.     

Microhabitat affinities of Gambel oak seedlings

Previous work suggested that Gambel oak seedlings are rare in the northern parts of its range in Utah where summer rainfall is relatively low but should be abundant in southern parts of the range where summer rainfall is usually high. Gambel oak grades from a relatively minor component of a ponderosa pine/mixed conifer assemblage in the south to a virtually monotypic formation in the north, where it exists as long-lived clones.   Quadrat analysis in Arizona and New Mexico, within the oak zone, revealed a seedling density ranging from 120 to 1320 per hectare. We found a significant tendency of seedlings to be located on the NE (cool, shady) side of sheltering objects in the environment. Mature ponderosa pine ranged in density from ca 40 to 500 stems per hectare, whereas mature Gambel oak ranged from ca 10 to 20 genets per hectare with ca 1 to 7 ramets per clone. These results support our previous conclusion that Gambel oak in northern Utah probably became established as a minor component of a mixed pine/oak woodland at a time in mid-Holocene when summer rainfall was much higher than today.     

Compositional similarity within the oakbrush type in central and northern Utah

Indices of similarity were used to evaluate the similarity of oakbrush stands throughout the Uinta National Forest and to compare oak communities in central and northern Utah. Results show that Gambel oak stands in central Utah differ significantly among themselves in respect to quantitative aspects of the vegetation. Those differences can be correlated with elevation, slope exposure, and fire history. Nevertheless, there is currently inadequate justification for recognizing more than one habitat type for the species in the study area. There is a need to develop a model capable of predicting growth rate of oak on specific sites.     

Spatially scaled response of a Lazuli Bunting population to fire

We examined the response of Lazuli Bunting ( Passerina amoena ) to fire in Gambel oak ( Quercus gambelii ) woodland at Camp Williams, Utah, during 1993–1998. Overall, Lazuli Bunting abundance on the study area increased significantly during the 2 years after a stand-replacing wildfire, which covered 800 ha of Gambel oak woodland. This increase suggested that Lazuli Buntings respond positively to fire. However, a comparison of pre- and postfire abundance of Lazuli Bunting for 2 groups of monitoring plots with different fire histories showed that abundance was significantly greater during the post-fire period for both burned and unburned plots. When we examined our data at a spatial scale appropriate to Lazuli Bunting, we found that post-fire increases observed on unburned plots were limited to plots in close proximity to the burned area. A comparison of pre- and post-fire abundance of Lazuli Bunting for 3 groups of monitoring plots located at various distances from the burned area revealed that post-fire abundance was similar only for plots within the fire boundary and for those ≤1000 m from the fire boundary; plots located >1000 m from the fire boundary had fewer individuals per plot post-fire. However, prefire Lazuli Bunting abundance was similar among all 3 categories. This differential, spatially scaled response of Lazuli Bunting to fire at the landscape level may support a hierarchical view of habitat selection.     

A mountain cercocarpus population-revisited

A mountain cercocarpus ( Cercocarpus montanus Raf.) population was analyzed first in 1965 and again in 1975 to gain insight into the growth and reproduction of this species. The basis for comparison was plant height and number of basal stems. Growth (measured by height) was slow during the 10 - year period, with plants on the northeast - facing slope having an average increase of 37 cm and those on the southwest - facing slope maintaining relatively the same average height. There was an overall decrease in average number of base stems for plants positioned on both slopes.        

Survival and sprouting responses of Chihuahua pine after the Rodeo-Chediski fire on the Mogollon Rim, Arizona

Chihuahua pines ( Pinus leiophylla Schiede and Deppe var. chihuahuana Engelmann) were surveyed on 11 study plots on the Mogollon Rim in east central Arizona to compare characteristics of trees that sprouted from the base or root collar after the Rodeo-Chediski fire with those of trees that did not sprout. The differences in trees killed and top-killed by the fire versus those that survived were also assessed. Trees that sprouted were significantly smaller in height and diameter at breast height; they also experienced lower fire intensities than trees that did not sprout. Smaller trees had higher incidences of mortality than larger trees. These results indicate that, even though Chihuahua pine has fire resiliency, sprouting rates after fire are related to size of trees, age of trees, and burn intensity. Since Chihuahua pine is a rare species in the area studied, its ability to recover from and tolerate fire could prove advantageous for sustainability.     

Present effects of past wildfires on leaf litter breakdown in stream ecosystems

We investigated the present effects from a 10-year-old wildfire on leaf litter breakdown rates in 3 headwater streams in central Idaho. These systems experienced a massive debris flow one year after the fire. Based on soil instability and burn patterns, we identified 3 stream conditions: unburned, burned only, and burned/scoured. We placed leaf bags containing willow leaves ( Salix sp.) in each stream type and removed bags at various time intervals until all bags were collected 100 days after their introduction. Leaf material was dried and weighed, and decay rate coefficients were calculated. Macroinvertebrates colonizing the bags were enumerated and identified, and selected taxa were placed into trophic groups. We found that the unburned stream had the fastest leaf litter breakdown rate, the lowest level of incident light reaching the stream, and the largest amount of benthic organic matter. The burned/scoured stream was nearly opposite in all respects. Numbers of 2 detritivore invertebrate taxa, Serratella tibialis and Zapada oregonensis, were highest in the unburned stream but lowest in the burned/scoured stream. A third taxon, Baetis sp., showed the opposite relationship. Presence of predatory invertebrates did not affect detritivore abundance or leaf decay rate in the bags. Our research suggests that recovery response variables of some stream systems may not have returned to prefire levels even a decade after the initial wildfire. In this study, the recovery of our streams appears to be connected to the return of the riparian zone, though fire-induced debris flows may slow or alter final recovery of the stream system.     

Effects of rangefire on soil algal crusts in semiarid shrub-steppe of the Lower Columbia Basin and their subsequent recovery

Effects of rangefire on soil algae in sagebrush steppe in the Lower Columbia Basin were studied. Dynamics of recovery of the soil algal community in the first two years following the fire were also documented. The study site was on the Arid Lands Ecology Reserve managed by Battelle Pacific Northwest Laboratory. Fire decreased the numbers of algae by more than an order of magnitude. Species composition in burned plots was similar to that in unburned plots, although some cyanophyte algae, particularly Nostoc commune , were decimated by the fire. Algal recovery took place in the winter months of the second year. Ninety taxa of algae were identified during the course of the study, over half of which were chlorophytes. Seasonal changes in the algal flora were also noted.     

Nest-site selection by Sage Thrashers in southeastern Idaho

Nest sites selected by Sage Thrashers ( Oreoscoptes montanus ) in southeastern Idaho were characterized and compared with available habitat. Microhabitats within 5 m of nests had taller and more aggregated shrubs and less bare ground than the study area in general. Big sagebrush ( Artemisia tridentata wyomingensis ) plants used for nesting were taller than average ,available shrubs, had greater foliage density, were more often living, and more frequently had branches and foliage within 30 cm of the ground. Nest placement was specific with respect to relative nest height and distance from the top and perimeter of the support shrub. Sage Thrashers disproportionately used easterly exposures and underused westerly exposures for their nests.     

A new lycaenid butterfly exclusively associated with the subalpine sclerophyllous oak forests in Taiwan (Lepidoptera,Lycaenidae, Theclinae)

Subalpine sclerophyllous oak forest grows at high elevation in Taiwan, distantly separated from similar forest communities found in western China, Tibet and India. An investigation on bud‐breaking phenology of oaks and associated phytophagous insects in this community revealed an undescribed species of Teratozephyrus lycaenid. This and other oak‐associated insects suggest that the presence of this oak community in Taiwan resulted from a more widely distributed community. The newly discovered Teratozephyrus turned out to be most closely related to T. nuwaii, described from western China, and is described below as T. elatus sp. nov. Two other species of Teratozephyrus also inhabit Taiwan, but both are associated with broad‐leaved oak forests. Of them, T. arisanus is widespread both in China and Taiwan, is morphologically distinct from the other Teratozephyrus species and is exclusively associated with broad‐leaved oaks. The other, T. yugaii, probably gained its broad‐leaved oak association secondarily as no similar species is found in the broad‐leaved oak communities on continental Asia, and it favours cool, higher‐elevation environments even though its host plant ranges into far lower elevations.     

Modeling aboveground biomass of Tamarix ramosissima in the Arkansas River Basin of southeastern Colorado, USA

Predictive models of aboveground biomass of nonnative Tamarix ramosissima of various sizes were developed using destructive sampling techniques on 50 individuals and four 100- m 2 plots. Each sample was measured for average height (m) of stems and canopy area (m 2 ) prior to cutting, drying, and weighing. Five competing regression models ( P T. ramosissima using average height and/or canopy area measurements and were evaluated using Akaike's Information Criterion corrected for small sample size (AIC c ). Our best model (AIC c = –148.69, ΔAIC c = 0) successfully predicted T. ramosissima aboveground biomass (R 2 = 0.97) and used average height and canopy area as predictors. Our 2nd-best model, using the same predictors, was also successful in predicting aboveground biomass (R 2 = 0.97, AIC c = –131.71, ΔAIC c = 16.98). A 3rd model demonstrated high correlation between only aboveground biomass and canopy area (R 2 = 0.95), while 2 additional models found high correlations between aboveground biomass and average height measurements only (R 2 = 0.90 and 0.70, respectively). These models illustrate how simple field measurements, such as height and canopy area, can be used in allometric relationships to accurately predict aboveground biomass of T. ramosissima . Although a correction factor may be necessary for predictions at larger scales, the models presented will prove useful for many research and management initiatives.     

Bottom-up factors influencing riparian willow recovery in Yellowstone National Park

After the elimination of wolves ( Canis lupis L.) in the 1920s, woody riparian plant communities on the northern range of Yellowstone National Park (YNP) declined an estimated 50%. After the reintroduction of wolves in 1995–1996, riparian willows ( Salix spp.) on YNP’s northern range showed significant growth for the first time since the 1920s. However, the pace of willow recovery has not been uniform. Some communities have exceeded 400 cm, while others are still at pre-1995 levels of <80 cm mean height. We took intensive, repeated measurements of abiotic factors, including soil and water-table characteristics, to determine whether these factors might be contributing to the varying pace of willow recovery. Willows at all of our study sites were “short” (<250 cm max. height) prior to 1995 and have recovered to varying degrees since. We contrasted “tall” (>250 cm max. height) willow sites where willows had escaped elk ( Cervus elaphus L.) browsing with “short” willow sites that could still be browsed. Unlike studies that manipulated willow height with fences and artificial dams, we examined sites that had natural growth differences in height since the reintroduction of wolves. Tall willow sites had greater water availability, more-rapid net soil nitrogen mineralization, greater snow depth, lower soil respiration rates, and cooler summer soil temperatures than nearby short willow sites. Most of these differences were measured both in herbaceous areas adjacent to the willow patches and in the willow patches themselves, suggesting that they were not effects of varying willow height recovery but were instead preexisting site differences that may have contributed to increased plant productivity. Our results agree with earlier studies in experimental plots which suggest that the varying pace of willow recovery has been influenced by abiotic limiting factors that interact with top-down reductions in willow browsing by elk.     

Factors affecting selection of winter food and roosting resources by porcupines in Utah

Ecological and phytochemical factors potentially affecting winter dietary discrimination by porcupines ( Erethizon dorsatum ) in the mountain brush zone of Utah were studied. Porcupines utilized gambel oak ( Quercus gambelii ) as their primary winter food and roosting resource. Big-tooth maple ( Acer grandidentatum ) was the most common tree species in the study area but was rarely utilized by porcupines. Conifer species were used as a food and roosting resource significantly less often than they occurred in the study area, despite thermal advantages provided by their relatively dense canopies. Oak feed trees were successfully separated from conifer feed trees by discriminant analysis 100% of the time. Oak trees were correctly classified as feed and nonfeed trees 71% of the time. Gambel oak contained higher amounts of crude protein, fiber, and tannins, but was lower in either extract fractions and fatty acid content than conifers. A layer of adipose tissue used as an energy reserve by porcupines may have relaxed energy intake demands sufficiently to permit them to concentrate on a diet of oak tissue, which is high in protein, rather than a high-fat conifer diet. A diet relatively high in protein may have facilitated digestion of food material high in fiber. Temperature did not affect selection of tree species for roosting. Rock and snow caves were utilized infrequently and the study population ranged widely. Three of 15 study animals were eaten by predators.     

Rediscovery of the southern California endemic American Keeled Slug Anadenulus cockerelli (Hemphill, 1890) after a 68-year hiatus

ABSTRACT

We report the first records of the southern California endemic American Keeled Slug Anadenulus cockerelli (Hemphill, 1890) in 68 years. Due to the restricted range of this species and lack of recent detection, it has received a NatureServe conservation status of Critically Imperilled or Imperilled. This species has always been difficult to detect, and will likely continue to be. This may be the result of genuine rarity, or may be the result of being cryptic and occurring in a microhabitat only ephemerally accessible to humans. We created a Species Distribution Model for A. cockerelli, which strongly predicts its occurrence where it is known, as well as some locations where it is currently unknown, such as in the northern Peninsular Ranges and in the San Bernardino Mountains in California. Threats to the continued existence of this species in southern California include human encroachment and resulting habitat loss, the climate changing to be hotter and drier, increased fire frequency, oak death due to beetle infestation, and other introduced species. Anadenulus cockerelli should continue to be surveyed and monitored into the future in order to better understand its distribution and level of conservation concern.     

Lesser prairie-chicken nest site selection and vegetation characteristics in tebuthiuron-treated and untreated sand shinnery oak in Texas

Radiotelemetry was used to evaluate lesser prairie-chicken ( Tympanuchus pallidicinctus ) nesting response to herbicidal conversion of sand shinnery oak ( Quercus havardii ) rangeland to grassland. Hens selected nest sites in residual grasses within lightly grazed sand shinnery oak habitat with > 75% vertical screening in the first 0.33 m and 50% overhead cover.     

Anatomy of rockcress pseudoflowers caused by Puccinia consimilis

Arabis pulchra plants infected by the crucifer rust fungus ( Puccinia consimilis ) develop pseduoflowers. These pseudoflowers are characterized by stems with short internodes and numerous closely spaced, bright yellow leaves coated with a sweet sugary substance. Pseudoflowers do not resemble normal A. pulchra flowers. Pseudoflowers, leaves, and stems of A. pulchra plants infected with P. consimilis and true flowers, stems, and leaves of uninfected A. pulchra plants were fixed, embedded, sectioned, and stained using standard microtechniques. Epidermal, ground, and vascular tissues of true leaves, true petals and pseudopetals were examined and compared for anatomic differences. Examination of anatomic characteristics revealed that pseudopetals are modified leaves.     

Sprouting and seedling establishment in plains silver sagebrush ( Artemisia cana Pursh. ssp. cana )

The importance and nature of vegetative reproduction was compared with seedling establishment in plains silver sagebrush ( Artemisia cana Pursh. ssp. cana ). Sixty-three percent of plants excavated originated from rhizomes. Sites that experienced habitat disturbance did not have a significantly different number of plants originating from vegetative reproduction than did undisturbed sites. Parent rhizomes were significantly older than taproots, which were significantly older than aboveground stems. Rhizome systems were spread 3.3 times that of plant height. Seventy-nine percent of rhizomatous daughter plants were 100 cm or less from parent plants. Up to 52 sprouts were found on one rhizome. Seedling establishment was greatest during wet growing seasons, and vegetative reproduction was greatest during dry years.     

Fire history of Paunsaugunt Plateau in southern Utah

A fire history of the Pausaugunt Plateau in southern Utah was developed using dendrochronological methods. Fire frequencies of individual ponderosa pine trees from three sites on the plateau varied from 19.5 to 47 years. Composite fire intervals for the three sites ranged from 15.2 to 18.4 years. The last recorded fires in these study areas occurred in 1892, 1902, and 1911, corresponding to the initiation of fire suppression policies in the West. The absence of fire since 1911 may be contributing to a recently documented decrease in ponderosa pine regeneration within the high-elevation, mixed-coniferous forests of the Paunsaugunt Plateau.     

The biology of some Phyllonorycter species (Lepidoptera: Gracillariidae) mining leaves of oak and beech

Summary

The oak leaf miners P. quercifoliella and P. harrisella were encountered at first generation densities of 40 and 48 mines per 1000 leaves in 1968 and 1969 and second generation densities of 179 and 211 mines per 1000 leaves. The 1969 densities for the two generations of P. maestingella on beech were 54 and 118 mines per 1000 leaves. The mines on oak were found to be aggregated on certain trees but the reason for this was not discovered. There was also aggregation on certain leaves within a tree.

The moths had two generations of adults per year at Dunham, the first generation mines appearing on the leaves in June and the second generation mines in August. P. maestingella seemed to be slightly in advance of the oak species.

The sampling data provided estimates of the mortality through 1969. Larval interference and mine damage caused negligible mortality. Death due to unknown factors figured prominently in the early instars but in the later instars, especially during the second generation, parasitism was important. Leaf browning was an added source of mortality in the second generation as was overwintering.

Fifteen species of hymenopterous parasites were bred from Phyllonorycter on oak and eight from P. maestingella on beech. Among these were some new host records. T. ecus was the most common first generation parasite of oak mines and C. nephereus. E. latreillei, S. sericeicornis, C. diallus and C. vittatus figured prominently in the second generation parasite complex. E. cilla was the commonest parasite of both generations of P. maestingella.