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1.
Following an Ips bark beetle outbreak in 2002, mortality of ponderosa pine ( Pinus ponderosa Douglas ex C. Lawson) was evaluated in 2 study areas infested with southwestern dwarf mistletoe ( Arceuthobium vaginatum [Willd.] Presl subsp. cryptopodum [Engelm.] Hawksw. & Wiens) in the Coconino and Tonto National Forests, Arizona. A pairwise comparison of dwarf mistletoe ratings for live and dead ponderosa pines was conducted to determine whether dead ponderosa pines had higher dwarf mistletoe ratings than pines that were not attacked. In both study areas, dead ponderosa pines had significantly higher dwarf mistletoe ratings, indicating an association between the severity of dwarf mistletoe infection and susceptibility to attack by Ips spp. We suggest that the probability of ponderosa pine mortality is greater in stands severely infested with southwestern dwarf mistletoe in northern Arizona.  相似文献   

2.
Ectomycorrhizal colonization and rooting characteristics were quantified in a mature ponderosa pine ( Pinus ponderosa Dougl. ex Laws.) stand in the western Sierra Nevada. Root length totaled 3835.9 m · m –2 of forest floor surface area, with 96% consisting of the fine-root fraction. Total root dry weight and volume were 2230.4 g · m –2 and 5807.4 cm 3 · m –2 of forest floor area, respectively, with 69% of the former and 75% of the latter accounted for by the coarse fraction. Fine roots were most prevalent in the upper 15 cm of the mineral soil profile, and their abundance declined with increasing depth. Coarse roots were most abundant at a depth of 15–30 cm. Ectomycorrhizal counts totaled 26,814 · m –2 of forest floor area, and an overwhelming preponderance was associated with the fine-root fraction. More than three-quarters of mychorrhizae resided in the upper 15 cm of mineral soil, with an overall trend of declining numbers with increasing depth. Roots and mycorrhizae were exceedingly scarce at a depth of 45–60 cm, and neither was found in the organic soil layer above the mineral profile. A necessary step in understanding the ecophysiological role of mycorrhizae in mature forests is to quantify their abundance in such settings, and the results of this study contribute such information for ponderosa pine.  相似文献   

3.
In this study, I examined the composition of managed ponderosa pine ( Pinus ponderosa ) forests used by nesting White-headed Woodpeckers ( Picoides albolarvatus ) along the eastern slope of the Cascade Range in Washington. I sampled trees and snags using the point-centered quarter method to assess species composition, tree and snag density, and stand basal area in 16 forest stands containing White-headed Woodpecker nests. All stands had a history of timber management and 2 had been burned and salvage-logged. Mean live-tree density (≥10.16 cm dbh) was 182.3 trees · ha –1 (SE = 13.52), mean snag density (≥10.16 cm dbh) was 11.5 snags · ha –1 (SE = 1.92), and mean stand basal area was 17.2 m 2 · ha –1 (SE = 1.58). Ponderosa pine had the highest importance value (mean = 220.9, SE = 17.25) of any tree species in all but 2 stands. Mean dbh of ponderosa pines was 33.0 cm (SE = 0.26) and ranged from 26.1 to 50.2 cm within stands. Mean density of ponderosa pine was greatest in the 20.3–30.5 cm dbh size class and lowest in the 50.8–61.0 cm and >61.0 cm dbh size classes. Tree density was up to 5.3 times greater than densities believed to be typical of ponderosa pine forests prior to fire suppression. Snag densities were within the range estimated for historical dry forests of the eastern Cascades, yet only 50% of all snags sampled had a dbh >25.4 cm. Although White-headed Woodpeckers are considered strongly associated with old-growth ponderosa pine, my results suggest that they may be more adaptable to using forests dominated by smaller diameter trees. En este estudio, examiné la composición de los bosques manejados de pino ponderosa ( Pinus ponderosa ), utilizados para anidamiento por el pájaro carpintero cabeciblanco ( Picoides albolarvatus ), a lo largo de la vertiente oriental de la cordillera Cascade del Estado de Washington. Muestreé árboles vivos y muertos usando el método de cuadrantes al punto central en 16 rodales con nidos del pájaro carpintero cabeciblanco para evaluar la composición de especies, la densidad de árboles vivos y muertos y el área basal del rodal. Todas las áreas tenían una historia de manejo maderable y 2 habían sido quemadas y taladas para recuperar madera. La densidad promedio de árboles vivos (≥10.16 cm DAP) fue 182.3 árboles · ha –1 (DE = 13.52), la densidad promedio de árboles muertos (≥10.16 cm DAP) fue 11.5 árboles muertos · ha –1 (DE = 1.92) y el área basal promedio de los rodales fue 17.2 m 2 · ha –1 (DE = 1.58). El pino ponderosa tuvo el valor de importancia más alto (promedio = 220.9, DE = 17.25) de las especies de árboles en todos, menos 2 rodales. El DAP promedio de los pinos ponderosa fue 33.0 cm (DE = 0.26) y variaba de 26.1 a 50.2 cm dentro de rodales. La densidad promedio del pino ponderosa fue la mayor en la clase de 20.3–30.5 cm DAP y menor de las clases de 50.8–61.0 cm y >61.0 cm DAP. La densidad de árboles fue hasta 5.3 veces mayor que las consideradas típicas para bosques de pino ponderosa antes de la intervención para prevenir incendios. Las densidades de árboles muertos estuvo dentro del rango estimado para los bosques secos históricos del oriente de la cordillera Cascade, no obstante sólo 50% de los árboles muertos muestreados tuvieron un DAP >25.4 cm. Aunque se considera que los pájaros carpinteros cabeciblancos están estrechamente asociados con bosques primarios de pino ponderosa, mis resultados sugieren que podrían ser más adaptados a usar bosques donde predominan árboles de diámetro menor.  相似文献   

4.
An insect survey was conducted on the Idaho National Engineering Laboratory during the summers of 1981–1983. This site is on the Snake River Plains in southeastern Idaho. Presented here is an annotated checklist of the Coleoptera collected. Successful collecting methods, dates of adult occurrence, and relative abundance are given for each species. Relevant biological information is also presented for some species.  相似文献   

5.
This study compared brood production of the spruce beetle ( Dendroctonus rufipennis Kirby [Coleoptera: Curculionidae, Scolytinae]) in downed host material felled during summer and spring seasons on the Wasatch Plateau in south central Utah. Thirty-three matched pairs of Engelmann spruce ( Picea engelmannii Parry ex Engelm.) trees were selected for study in spring 1996. One tree of each pair was cut during August 1996 (summer-felled), and the other tree was cut in early April 1997 (spring-felled), so that trees would be colonized by spruce beetles of the same flight period. Brood adults were collected and counted from bark samples, which were removed from the top, bottom, and sides of all sample trees in October 1998. The number of emergent adults produced in June 1999 was determined from exit holes counted in bark samples removed from these same locations. Mixed-model procedures were used to compare differences in the mean number of adults produced in summer-felled versus spring-felled trees in each year. The results indicated that significantly fewer spruce beetles were produced in summer-felled trees than in spring-felled trees. More brood adults were also present in, or emerged from, unexposed bole aspects (bottom, north, and east) of sample trees than exposed aspects (top, south, and west). These findings suggest that disturbances providing spruce beetles with an abundance of fresh host material in the spring result in the greatest potential for spruce beetle production, particularly beneath unexposed bark aspects. Examples of such disturbances include snow avalanches, blowdown, and snow and ice damage.  相似文献   

6.
《Journal of Natural History》2012,46(23-24):1481-1490
ABSTRACT

During the course of a targeted bark beetle survey of the Hawaiian Islands, insect sampling undertaken in native forest biotopes on Moloka‘i island revealed the presence of one native and three exotic species of xyleborine bark beetles (Coleoptera: Curculionidae: Scolytinae: Xyleborini) hitherto not recorded from the island. We present detailed new island records for these species, which include the second record of Xyleborus pleiades Samuelson, 1981, an endemic Hawaiian species not recorded in over 50 years, and previously known only from two specimens from the island of Maui. The three newly recorded introduced species are widespread pantropical beetles of actual or potential pest status: Xyleborus affinis Eichhoff, 1867, Xyleborinus saxesenii (Ratzeburg, 1837), and Xylosandrus crassiusculus (Motschulsky, 1866). The importance of the records is briefly discussed, and all newly recorded species are illustrated in colour photographs.  相似文献   

7.
Dryocoetes confusus Swaine, the western balsam bark beetle, is an important bark beetle associated with Abies lasiocarpa (Hook.) Nutt. (subalpine fir) in western North America. Little information is available on the life cycle and ecology of this insect in Colorado. In this study in north central Colorado, we examined its flight periodicity, attack patterns, and life cycle in downed trees. Flight season, as indicated by pheromone-trap catches, began in early June. Peak flight was observed during early to mid-July. A second peak in flight was observed in some years, but its occurrence was not consistent. Preferred attack sites on downed trees were the underside or side of the log and through branch stubs. The life cycle for this beetle was completed in 2 years, consistent with earlier observations from British Columbia. Sex ratio was 1:1, but a higher percentage of males fly earlier in the season.  相似文献   

8.
《Journal of Natural History》2012,46(17):2225-2249
Dung beetle guilds of different competitive level coexist at high abundances in the forest–savanna mosaic of Ivory Coast. A total of 25?875 specimens was recorded from 90 samples of fresh buffalo dung exposed for 4-h periods over the day in the Parc National de la Comoé. Redundancy analyses show different patterns of the guild structure determined by time of day, and positive correlations of guild abundance with temperature. The competitively superior telecoprids (rollers) have their abundance peak at midday when the high temperatures presumably enable them to perform their energetically costly rolling behaviour at greater speed. The competitively intermediate paracoprids (tunnellers) and the competitively inferior endocoprids (dwellers) have their peak around dusk when: (1) the superior competitors are not active, and (2) they can easily synchronize their flight activity using light intensity changes. During the two peaks of flight activity of the dung beetles, their abundance at the resource is very high, causing obvious competition. On the other hand, the resource is hardly used between 22:00?h and 10:00?h. This is probably due to physiological constraints (high optimum temperature required for the diurnal species and dependence on light intensity patterns as a flight trigger of the nocturnal species, respectively). Shifting flight activity to these periods of low competition does not occur, resulting in a unequal level of competition over the day, thus periods of considerable competition within dung beetle assemblages alternate with vacant temporal refuges.  相似文献   

9.
The green June beetle (Cotinis nitida) was observed in northern Virginia for a second and third flight season. The study yielded some results that were consistent with earlier findings, namely that mate-locating beetles were vulnerable to attack by avian predators and matings occurred primarily early in the flight season. Novel findings included the following: (1) blue jays (Cyanocitta cristata) were the major predators, not common grackles (Quiscalus quiscala), (2) some jays appeared to selectively prey on female beetles, (3) competition for mates among male beetles could be so intense that some males attempted to copulate with already mated (unreceptive) females, and (4) the sex ratio of the beetle population feeding on wild blackberries remained near equality late in the flight season despite the fact that the sex ratio of the population of beetles at the emergence site became highly female-biased over time.  相似文献   

10.
The flight periodicity of western balsam bark beetle ( Dryocoetes confusus Swaine) in Big Cottonwood Canyon, Utah, was studied during the summer months of 1992, 1993, and 1994. Contents of baited funnel traps were tallied by species up to 3 times weekly. Two main periods of flight activity were observed each year. The first and, generally, largest occurred in early summer soon after flight was initiated for the season. A 2nd period was observed in late summer, generally August. Timing of the 2 periods was influenced by unusually warm or cool weather in each study year. The 1st period had more males than females while the 2nd period had a majority of females. Except during periods of cool or wet weather, western balsam bark beetles were found to be active at least at minimal levels from June through September.  相似文献   

11.
Listed are 96 species of Scolytidae (Coleoptera) from Montana. Eighteen species reported from Montana for the first time are: Scierus pubescens Swaine, Hylastinus obscurus (Marsham), Hylesinus aculeatus Say, Hylesinus californicus (Swaine), Hylesinus criddlei (Swaine), Pseudohylesinus granulatus (LeConte), Dendroctunus punctatus LeConte, Phloeosinus hoferi Blackman, Phloeosinus pini Swaine, Carphoborus pinicolens Wood, Scolytus subscaber LeConte, Ips grandicollis (Eichhoff), Trypodendron betulae Swaine, Trypodendron retusum (LeConte), Trypophloeus populi Hopkins, Procryphalus mucronatus, (LeConte), Pityophthorus alpinensis G. Hopping, and Gnathotrichus denticulatus Blackman.  相似文献   

12.
The herbaceous understory stratum contains most of the plant diversity in ponderosa pine ( Pinus ponderosa P. & C. Lawson var. scopulorum Engelm.) forests of the American Southwest and provides critical food and habitat for many wildlife species. During the last century, this stratum has been affected by livestock grazing and by increased dominance of overstory trees. We sampled a unique grazing exclosure to examine the relative importance of long-term livestock grazing (grazed or ungrazed) and habitat (park or tree) on the understory community. We sampled 3 plots of 192 contiguous quadrats (each quadrat 0.5 m 2 ) in each of the 4 treatment combinations, for a total of 2304 quadrats. Species-area curves were generated by aggregating quadrats into nonoverlapping areas at grain sizes of 0.5 to 576 m 2 . The effects of habitat and grazing on species density were evident at very different scales. Species density was higher in park than tree plots at scales ≤32 m 2 but did not differ between habitats at larger scales. Species density differed minimally between grazed and ungrazed treatments at small grains, but grazed plots contained more species than ungrazed plots at larger grains. Grazing treatments differed at smaller grains (to 4–8 m 2 ) than did habitats (to 32 m 2 ), with respect to density of native species and graminoids. Grazed plots had more exotic species than ungrazed plots at all grain sizes, though few exotics were present. Twenty-two species were identified as indicator species associated with habitats and/or grazing treatments. Evaluations of plant community response to treatments would be improved by accounting for the grain at which data have been collected and analyzed and by identifying indicator species associated with various treatments. These data would enable more-informed conservation and management decisions.  相似文献   

13.
Reported are 105 species of Scolytidae (Coleoptera) from Idaho. About one-third of these are rarely collected, of which 22 species are known from a single locality each. Twelve species reported from Idaho for the first time are: Carphoborus carri Swaine, C. sansoni Swaine, Phloeosinus hoferi Blackman, Conophthorus monophyllae Hopkins, Dryocoetes betulae Hopkins, Ips confuses (LeConte), Pityophthorus absonus Blackman, P. aquilus Blackman , P. blandus Blackman, P. deletus LeConte, P. sculptor Blackman, and Xyleborinus saxeseni (Ratzeburg). Significant extensions of the known distributions in Idaho are reported for seven other scolytids; Alniphagus aspericollis (LeConte), Dendroctonus murrayanae Hopkins, Phloeotribus lecontei Schedl, Procryphalus mucronatus (LeConte), Trypophloeus populi Hopkins, Xyleborus dispar (Fabricius), and X. intrusus Blandford. Xyleborus dispar especially needs study in anticipation that it may become increasingly important in Idaho fruit trees and other woody plants including ornamentals and shade trees.  相似文献   

14.
15.
The deserts of southern California house a diverse and unique insect fauna. Velvet ants (Hymenoptera: Mutillidae) are common in these deserts. Velvet ants are important to ecosystem health, particularly in desert environments, because they are parasitic on the bees and wasps that help maintain overall ecosystem function. The goal of this study was to measure velvet ant diversity across the deserts of southern California. We made preliminary collections from 10 sites in a variety of areas in the western Sonoran Desert (Colorado Desert), the Mojave Desert, and the Great Basin Desert. We measured β-diversity using Sørensen’s similarity index to compare velvet ant richness and relative abundance between different sites. To determine how accurate our similarity estimates were, and to gain an understanding of actual velvet ant diversity, we also compared velvet ant richness of 2 sites (Algodones Sand Dunes and Deep Canyon) using data obtained from the examination of museum specimens borrowed from over 12 museums across the West. Comparisons of velvet ant faunas between sites revealed low similarities (0.167–0.75 species richness only; 0.022–0.67 both abundance and richness). Low similarity values indicate that a rich velvet ant fauna exists in the deserts of southern California.  相似文献   

16.
Phenology and abundance of the floral resources used by bees and other flower-visiting insects were recorded weekly from permanent quadrats for two years on two shortgrass prairie sites in the Laramie Basin, Wyoming. Each site was composed of three distinct plant communities. Results suggest considerable spatiotemporal variability in floral resources. Specifically, most species at both sites showed the following temporal variation: (1) bloom times between one and two weeks earlier in the second year; (2) differences of approximately 1–2 weeks in bloom span between years; (3) substantial differences in abundance of flowers between years. Species blooming during the last half of the census period were significantly more variable in flower abundance between years than those blooming earlier. Spatial variation was shown both by differences between sites and between plant communities within sites in the direction and magnitude of between-year changes in floral abundance. For example, floral production at Boulder Ridge in 1976 was much lower than in 1975, but at The Dirt Farm between-year differences were less pronounced and depended upon season. Similarity measures and cluster analysis suggest differences in the structure of the bloom season at both sites between years, and a relatively rapid turnover of floral composition within years such that bees face a very different flora over the latter part of their flight seasons relative to that encountered initially. Evidence from other reports support the hypothesis of spatiotemporal unpredictability of floral resources.  相似文献   

17.
Small mammals play key ecological roles in grassland ecosystems, yet little is known regarding small mammal communities in large (>50 km 2 ), high-elevation prairies embedded in ponderosa pine ( Pinus ponderosa ) forests in north central Arizona. To provide information on community composition and habitat relationships, we live-trapped small mammals on 6 transects in 2 prairies in 2008. We captured 78 individuals in 5501 trap occasions. Capture rates were low and varied widely among transects. Community composition was simple, with only 3 species of small mammals captured. In order of relative abundance, these species were deer mouse ( Peromyscus maniculatus, n = 44 individuals), Mogollon vole ( Microtus mogollonensis, n = 22), and spotted ground squirrel ( Spermophilus spilosoma, n = 12). Deer mice were captured on all transects and voles on all but one transect. In contrast, spotted ground squirrels were captured on only 2 transects and were relatively common on only one transect. There were no previous records of spotted ground squirrels in these prairies. Deer mice were positively associated with rock cover and vegetation height. Voles were positively associated with shrub cover and combined cover of live and dead vegetation and were negatively associated with bare ground. Spotted ground squirrels were positively associated with forb cover. This study provides baseline data on small mammal communities in these prairies and documents the presence of a previously unknown species. Further studies would be desirable to better understand spatial and temporal variation in these communities, habitat relationships, and effects of land-use practices on small mammals and their habitats. Los mamíferos pequeños desempeñan papeles clave en los ecosistemas de pradera; sin embargo, se conoce poco con respecto a las comunidades de pequeños mamíferos en las grandes (>50 km 2 ) praderas altas, rodeadas por bosques de pino ponderosa ( Pinus ponderosa ) en la parte norte central de Arizona. Para proporcionar información sobre la composición de las comunidades y sus relaciones con el hábitat, colocamos trampas para pequeños mamíferos vivos en 2008 en 6 transectos en 2 praderas. Capturamos 78 individuos en 5501 ocasiones de trampeo. Las tasas de captura fueron generalmente bajas y variaron ampliamente entre transectos. La composición de las comunidades fue simple, con tan solo 3 especies de mamíferos pequeños capturados. Éstas fueron, en orden de abundancia relativa, el ratón ciervo ( Peromyscus maniculatus, n = 44), el metorito Mogollon ( Microtus mogollonensis, n = 22) y la ardilla moteada de tierra ( Spermophilus spilosoma, n = 12). Los ratones ciervo fueron capturados en todos los transectos y los metoritos en todos, menos uno. En contraste, las ardillas moteadas de tierra fueron capturadas sólo en 2 transectos y fueron relativamente comunes en sólo uno. No había registros anteriores de ardillas moteadas de tierra en estas praderas. Los ratones ciervo estuvieron asociados positivamente con la rocosidad y la altura de vegetación. Los metoritos estuvieron asociados positivamente con la cobertura de arbustos y la cobertura combinada de vegetación viva y muerta, y asociados negativamente con el suelo desnudo. Las ardillas moteadas de tierra estuvieron asociadas positivamente con la cobertura de maleza. Este estudio proporciona datos de referencia sobre las comunidades de pequeños mamíferos en estas praderas, y documenta la presencia de una especie previamente desconocida. Sería conveniente llevar a cabo estudios adicionales para entender mejor la variación espacial y temporal en estas comunidades, sus relaciones con el hábitat y los efectos de prácticas del uso del suelo en equeños mamíferos y sus hábitats.  相似文献   

18.
Stomach contents of 650 clouded salamanders ( Aneides ferreus ), collected monthly throughout the year from Curry County, Oregon, were examined. Samples from three age classes were involved: (1) 489 adults, (2) 131 juveniles, and (3) 30 hatchlings. Foods did not vary by sex, but did vary by age and by season. Hatchlings ate small items, particularly mites, springtails, flies, and small beetles. Juveniles fed mainly on flies, isopods (sowbugs), beetles, mites, and centipedes in winter; beetles, ants, and isopods in spring; ants and beetles in summer; and isopods, beetles, and ants in fall. Adults ate isopods and beetles as their major foods in winter, spring, and fall and isopods, ants, beetles, and earwigs in summer. Four species were exceedingly important as foods for these salamanders: an unidentified isopod, the snout beetle ( Trachyphloeus bifoveatus ), the European earwig ( Forficula auricularia ), and an ant ( Lasius alienus ).    相似文献   

19.
《Journal of Natural History》2012,46(35-36):2301-2316
ABSTRACT

Despite the importance of diet in avian ecology, knowledge of bird diet in tropical regions, particularly South-East Asia, is limited. Assessing predator–prey relationships of how energy flows across ecosystems provides insight into niche segregation of sympatric species. We examined induced-regurgitation samples from 15 species of insectivorous birds – 12 babblers and three flycatcher-like species – from the Krau Wildlife Reserve, central Peninsular Malaysia. The main objective of this study was to compare and characterise the diet of similar trophically insectivorous birds so as to examine the occurrence of dietary overlap or segregation. The majority of identified prey items belong to the following arthropod taxa: Coleoptera (53%), Hymenoptera (19%), Blattodea (11%), and Araneae (11%). The diet of all bird species slightly overlapped (p = 0.070) but network analysis yielded a relatively low value (Ro = 0.53), indicating dietary divergence may have occurred among the studied bird species, possibly reflected by the variation in proportion of arthropod groups. A high proportion of Coleoptera and three other arthropod groups (i.e. Hymenoptera, Blattodea and Araneae) in the diet of studied birds could be related to their richness and abundance in aerial leaf-litter, the substrate preferred by most babblers. Dietary differences may further be explained by variations in bill shapes and sizes, likely corresponding to prey size. Unique foraging strategies (utilising different vertical strata, microhabitats, and attack manoeuvres) could also lead to dietary separation among sympatric species. Flycatcher-like species were expected to flycatch different prey items (families or lower taxa) versus the gleaning birds (most babblers). This study successfully discerned more details on the diets of insectivorous birds inhabiting Malaysian forests, providing a foundation for future studies on the ecology and biology of understorey birds.  相似文献   

20.
The interaction between Southwestern dwarf mistletoe, Arceuthobium vaginatum subspecies cryptopodum , infestation and defoliation by the pandora moth, Coloradia pandora pandora , on the Kaibab Plateau in Arizona was evaluated. Heavy defoliation of ponderosa pine, Pinus ponderosa , in 1979 and 1981 resulted in mortality of individual trees in areas of heavy dwarf mistletoe infestation. Postmortem evaluation of ponderosa pines indicated that dead trees had a significantly higher dwarf mistletoe rating than did nearby paired live trees. Of 25 tree pairs evaluated, only two live trees had higher dwarf mistletoe ratings than the paired dead tree. Mean dwarf mistletoe ratings were: live trees 2.9, dead trees 4.6 (6 class dwarf mistletoe rating system). Implications for management of the pandora moth are discussed.     相似文献   

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