Breeding movements and reproductive activities of porcupine in the Great Basin Desert

I assessed movements of North American porcupines ( Erethizon dorsatum ) in the Great Basin of northwestern Nevada in relation to reproductive activities during the late summer and fall periods of 1991 and 1992. Porcupines exhibit a mate-defense polygynous mating system and I hypothesized that (1) competitively dominant males would have larger home ranges than both subordinate males and adult females, and (2) variation in home range size among adult male porcupines would be positively correlated with reproductive success. Results indicated that dominant male porcupines ranged over larger areas (average 95% minimum convex polygon home range = 20.7 ha) than subordinate males (average 95% MCP home range = 2.9 ha) and adult females (average 95% MCP home range = 8.2 ha). Analyses of movements in relation to body size and energetic requirements revealed that home ranges of dominant male porcupines were larger than predicted based on body size (approximately 10.2 ha). Breeding period home ranges of dominant male porcupines encompassed portions of the home ranges of 3 to 10 adult females, and indices of reproductive success based on observations of mate-guarding behaviors suggested a strong positive relationship between home range sizes of male porcupines and mating success. Together these data suggested that larger home ranges among dominant males were related to increased mating opportunities and not increased metabolic requirements associated with larger male body sizes. In the study area, however, female porcupines congregated around small, patchily distributed riparian areas, and dominant males with relatively small home ranges encompassing riparian areas may have gained mating access to multiple females. Finally, analyses of overlap among core home ranges (60% MCP) of adult male and adult female porcupines suggested that both sexes maintained relatively exclusive core home range areas, with males exhibiting significantly less range overlap with other males ( ￣x = 9.4%) than females with other females ( ￣x = 27.1%). It is possible that the small, patchily distributed riparian areas in this desertlike area were such a limited resource that females were unable to maintain exclusive use of their home range areas.     

Some spatial and behavioral features of the thirteen-lined ground squirrel

Some relationships between home range, agonistic behavior, and reproductive patterns in thirteen-lined ground squirrels were investigated in Laramie Plains, Wyoming (August 1966–April 1969). Population size and densities fluctuated seasonally and annually. Adult male (N = 7) home ranges averaged 0.24 ha and were smaller than those of the female (N = 9), which averaged 0.35 ha. Agonistic interactions were more frequent during the natal period (late May–June) than during the breeding-gestation period (mid April–May). Most squirrels (86 percent) shared capture sites and had overlapping home ranges. However, a certain degree of spacing existed because of agonistic behavior.     

Growth and development of the western harvest mouse, Reithrodontomys megalotis megalotis

Growth rates, gestation period, litter size, reproductive age, sex ratios, and development were studied on 198 litters of Reithrodontomys megalotis megalotis (Baird). Growth was characterized by several standard skull and body measurements and was partitioned into four phases of 1 – 3, 4 – 12, 13 – 22, and 23 – 70 days. Growth was best described by measurements of tail length, ear length, and dried eye - lens weight. Reproductive activity began as early as 38 days for females and 59 days for males. The gestation period was 22 days, and the mean litter size was 3.83 (range 1 – 7). Sex ratio was 53.49 percent males to 46.51 percent females. Reproductive efficiency was 53.53 percent. The development of R. m. megalotis was very similar to that of R. m. dychei. Early breeding, postpartum estrous, year - round breeding, high reproductive efficiency, and a short gestation period contribute to a high reproductive potential in R. m. megalotis.       

Deer mouse ( Peromyscus maniculatus ) home-range size and fidelity in sage-steppe habitat

Within a species, home-range size can vary due to factors such as sex, mass, age, and breeding condition of individuals as well as habitat type, food availability, population density, and season. The objectives of this study were to estimate home ranges of deer mice ( Peromyscus maniculatus ) in sage-steppe habitat and to test the hypothesis that several factors (sex, mass, reproductive status, and seasonality) affect home-range size. We also tested the hypothesis that deer mice exhibit home-range fidelity over time. Passive integrated transponder (PIT) technology was used to estimate home ranges in June and September 2006. Home-range estimates varied from 360 m 2 to 5868 m 2 (65 individuals, 753 observations). Home-range size increased by approximately 60% from June to September. Besides seasonality, none of the other predictors of home range were informative in explaining the variation in home range. Deer mice recaptured in September (3 months after initial capture) had high fidelity in home-range use (42.1% [SE = 8.4%] overlap with 74.1% [SE = 8.7%] area conserved; n = 9). All animals for which home range was estimated in both seasons retained some fraction of their June home range in September. Results support the use of combined location data collected over long periods, such as weeks or months, to estimate home range for deer mice. The results have implications for deer mouse–pathogen ecology, particularly with respect to modeling transmission of Sin Nombre virus—a pathogen that is directly transmitted by deer mice.     

Population ecology and reproduction of the Mexican mud turtle ( Kinosternon integrum ) in Tonatico Estado De México

Ecological data directly from the field are important in understanding the life history strategies of kinosternid species in the tropics. Herein we summarize the basic population ecology and life history of Kinosternon integrum in the municipality of Tonatico (southeastern Estado de México, México). From October 2003 to November 2004, we marked a total of 204 turtles and recaptured 118 of them. Mean population size using the Jolly-Seber model was 197 (95% CI 128–416) individuals, with a sex ratio of 1:1.7, biased to females. Males were larger than females in carapace length and plastron length. The reproductive season starts in late June and finishes in late October. The smallest female with oviductal eggs was 122 mm in carapace length. Mean clutch size was 4 eggs ( s = 1.77, range 1–8) and was significantly and positively related to body size. Mean egg length was 30.43 mm ( s = 2.24, range 23.92–35.96), mean width was 16.35 mm ( s = 1.01, range 12.99–18.30), and mean weight was 5.14 g ( s = 0.60, range 3.41–6.57). Mean egg length was significantly and inversely related to clutch size. Relative clutch mass (reproductive effort) was 0.043 ( s = 0.017, range 0.017–0.071), which is the smallest value reported for the genus Kinosternon. Additionally, there was no evidence of a pelvic restriction on egg size in this population. This is the first study that documents basic population ecology and reproductive characteristics for a single population of the most widespread freshwater turtle in Mexico.     

Movements and home ranges of San Joaquin kit foxes ( Vulpes macrotis mutica ) relative to oil-field development

We examined the effect of oil-field development on movements and patterns of spatial use of San Joaquin kit foxes ( Vulpes macrotis mutica ) on the Naval Petroleum Reserves in California (NPRC) in the San Joaquin Valley. To do this, we compared movements and home ranges of kit foxes from June 1984 to September 1985 in areas developed for petroleum production (30% of native habitat lost to production facilities) and areas with little development (3%). Distances traveled nightly by kit foxes did not differ between levels of petroleum development or between sexes ( P > 0.2). Mean length of nightly movements during breeding (14.6 km) was longer than during pup-rearing (10.7 km) and pup-dispersal (9.4 km) periods ( P = 0.01). Mean size of home ranges was 4.6 ± 0.4 ( s￣x ) km 2 ( n = 21) and did not differ between levels of petroleum development and sexes ( P > 0.2). Overlap of home ranges of foxes from the same social group (78 ± 4.3%) was greater than that of same-sex foxes (35 ± 7.8%) and males and females of different social groups (32 ± 8.0%, P P > 0.4). Despite extensive overlap of home ranges, kit foxes on NPRC maintained relatively exclusive core areas, particularly adjacent foxes of the same sex. Future studies should examine which levels of habitat conversion impact spatial use of kit foxes.     

Demographic characteristics of American marten populations in Jackson Hole, Wyoming

Some American marten population characteristics (numbers, density, body weights, sex and age ratios, natality, mortality-survivorship, immigration-emigration, home ranges) were studied at four sites in the southern part of the Greater Yellowstone Ecosystem, Teton County, Wyoming, in 1975-1979. Ninety-eight different martens were examined. Males (n = 25) weighed 1,111 g (± 110 SD, range 875-1,235), whereas females (n = 17) averaged 743 g (± 83 SD, range 600-900). Live-trapping showed sex ratios of 1.5M:1.0F, whereas carcasses showed 3.0M:1.0F. Of 27males that were aged, 12 (44%) were less than 1 year old and 2 were 9-10 years old. Of 10 females, 6 were less than 1 year old and 1 was 12-13 years old. The mean length of time a male was present on the major study area was 144 days (± 266 SD, range 1-1,364), and for females it was 145 days (± 45 SD, range 1-560). Home ranges for six males averaged 3.2 km 2 (± 20 SD, range 0.7-5.8) on the main study area. Some management implications are given.     

Reproductive cycle of the lizard Sceloporus mucronatus with comments on intraspecific geographic variation

Sceloporus mucronatus is a viviparous lizard that inhabits high altitudes in central México. Lizards from Tecocomulco, Hidalgo, México, were collected monthly at 2500 m throughout one year. Macro- and microscopic evidence of gonads showed that both sexes reproduce synchronously during the fall. In males, after a short testicular quiescence in December, the recrudescence begins in winter (January) and continues through spring and summer (July), with maximum activity occurring from late summer to early fall (August–September). Regression takes place simultaneously with copulation during the fall (October–November). In females, vitellogenesis occurs during summer and fall (August–November), with ovulation in the fall (November–December). Gravid females were found throughout the winter, and parturition occurs during spring (May). Litter size was correlated with female snout–vent length. Female reproductive phenology of viviparous Sceloporus species seems to be highly conservative at different altitudes, but male reproductive phenology shifts between spring–summer (in populations higher than 2500 m) and summer–fall (in populations 2500 m or lower), as in the present study. The longer period of testicular recrudescence (January–July) in the studied population from Tecocomulco suggests plasticity in testicular activity.     

Home range and seasonal movements of Columbian Sharp-tailed Grouse associated with Conservation Reserve Program and mine reclamation

During 1999 and 2000 we trapped and radio-marked 156 Columbian Sharp-tailed Grouse ( Tympanuchus phasianellus columbianus ) on leks in Conservation Reserve Program (CRP, n = 73) and mine reclamation (MR, n = 83) lands in northwestern Colorado. Median spring--fall home range sizes using the 95% fixed kernal and minimum convex polygon estimators for 54 grouse were 86 ha and 61 ha, respectively. Median fixed kernal home range size did not differ between males (79 ha) and females (87 ha). Home ranges of grouse associated with CRP (112 ha) were larger than those of grouse in MR (75 ha). Directional orientation of movements from leks of capture to wintering areas was nonrandom, and there was a positive elevation gain (median = 102 m) associated with these movements. Movements did not differ between grouse captured in CRP and MR for any season but did differ between genders for the spring--fall period. Males exhibited stronger fidelity and less variation in their movements than females; 96% of males compared with only 77% of females remained within 2.0 km of their lek of capture from spring through fall. Ninety percent of females nested within 2.5 km of their lek of capture. During winter all grouse were found farther (median = 21.5 km) from lek sites than in any other season. Males remained on the breeding range longer in the fall and returned earlier in the spring than females even though they wintered similar distances away (median males = 21.5 km, median females = 21.4 km). Our findings support the 2.0-km radius used in the Habitat Suitability Index model for Columbian Sharptailed Grouse to assess nest and brood-rearing cover around leks, but not the 6.5-km radius used to evaluate winter cover.     

Aspects of the biology of the flathead chub ( Hybopsis gracilis ) in Montana

Mature flathead chubs ( Hybopsis gracilis ) were present in mid - July and mid - August collections from the Musselshell River, Montana. The estimated numbers of mature eggs present in eight females were 360–753 per female. The smallest mature female and male collected were 113 and 123 mm in total length, respectively. The male to female sex ratio in collections was about 1:1. Only small differences were detected among the length – weight relationships of males and females and samples taken from various seasons and localities in Montana. Observations on size groups, fish associates, and habitat characteristics of flathead chubs are presented.         

Studies on the biology and ecology of the northern scorpion, Paruroctonus boreus (Girard)

An investigation to elucidate some facets of the biology and ecology of Paruroctonus boreus (Girard), in southeast Idaho, was conducted from 21 March to 13 October 1972. Three hundred and eighty - five observations were made on 202 scorpions captured in covered pitfalls and by ultraviolet light. The greatest activity occurred at 2130 hours. Surface activity was not observed when ambient temperature was below 10 C, and, as ambient temperature increased, an increase in surface activity was noted. Male scorpions frequently moved as much as 30 m between observations, while females seldom moved more than five m. Sex ratios varied considerably depending on time of year and method of sampling. Of 142 scoipions observed by blacklight, 92 were males, and 50 were females (1.84 males/female). Limited data suggest a mean litter size of 34 ± 11.     

Denning chronology of black bears in eastern Rocky Mountain National Park, Colorado

Understanding factors influencing the timing of den entrance and emergence of black bears ( Ursus americanus ) provides insight for bear management. We determined den entrance and emergence dates for bears in Rocky Mountain National Park (RMNP) and related these dates to vegetative productivity, weather, habitat, and demographic factors to assess the influence of these factors on denning chronology. Date of den entrance was most strongly influenced by age class, precipitation, and proportion of human-use areas in annual home ranges. Den entrance was typically later for adult bears during wetter years and when annual home ranges contained a greater proportion of human-use areas. Sex and presence of human-use areas were most strongly related to den emergence. Male bears typically emerged from dens before females, and bears emerged from dens earlier when human-use areas composed a greater proportion of annual home ranges. Collectively, our results suggest that denning behavior of black bears in RMNP was strongly influenced by presence of human-use areas, likely because of foods associated with such areas. Managers of black bears in RMNP can use precipitation to predict relative dates of den entrance, thereby allowing for more efficient strategies to combat potentially negative human–black bear encounters.     

Mineral lick use by GPS radio-collared mountain goats in southeastern British Columbia

In most populations of mountain goats ( Oreamnos americanus ), mineral lick use is an essential part of the ecology of the species. In many areas, the distribution and use of licks in the landscape is poorly known, rendering planning for resource development difficult. We examined lick use by 28 GPS radio-collared mountain goats in 2 study areas in southeastern British Columbia during 2004–2005. Viewing collar-location movements on digital orthophotos, we assumed goat use of 6 previously known and 10 suspected mineral licks. Field visits verified that 9 of the 10 suspected sites were mineral licks. Thirteen of the 15 licks used by collared goats were within forests with commercial harvesting potential. All but 3 of the licks were ≤600 m from the closest logging block, and 5 licks were <100 m away. Number of annual visits to licks by individual goats ranged from 0 to 9. Goats often moved considerable distances (up to 17.3 km) to visit licks. Most visits by males occurred between early May and late June (median 9 June), and most visits by females occurred between early June and mid-July (median 21 June). Mean time spent at licks on each visit was 1.5 days for females and 1.6 days for males. Most of the licks were characterized by numerous cavities dug under trees (which we term “lick trees”). Using GPS collars, we were able to collect data on lower-elevation mineral licks not previously known to researchers.     

Distribution, movements, and habitat use of razorback sucker ( Xyrauchen texanus ) in a lower Colorado River reservoir, Arizona-Nevada

Distribution, movements, and habitat use of 10 wild adult razorback suckers ( Xyrauchen texanus ) were examined in Lake Mohave, Arizona-Nevada, from November 1994 through July 1997. Movement rates (0.00-17.35 km d -1 ) and ranges ( x = 39 km) were similar to those for riverine populations. All study fish returned to spawning sites used in previous years, but they also visited other spawning areas. Spawning females were significantly ( P = 0.031) more active than males (480 vs. 87 m d -1 ) and moved substantial distances between spawning sites during peak reproduction (1-28 February). Fish became most active (m d -1 , km month -1 ) after spawning and moved to areas known to support higher algal production. Fish were typically within 50 m ( P 30.0 m). Adults were detected throughout the available thermal gradient (12°-30°C), but during summer typically had body temperatures between 18° and 22°C. Vertical movements within the water column showed no correlation with depth or time of day, but seasonal shifts suggest fish may regulate body temperature by seeking specific temperatures during reservoir stratification.     

Composition of forest stands used by White-headed Woodpeckers for nesting in Washington

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.     

High rates of photosynthesis in the desert shrub Chrysothamnus nauseosus ssp. albicaulis

  Basic aspects of photosynthesis were investigated in white rubber rabbitbrush ( Chrysothamnus nauseosus (Pallas) Britt. ssp. albicaulis ), a common C 3 deciduous shrub native to arid regions of the western U.S. Under favorable field conditions, net photosynthesis (P n ) ranged from 36 to 73 mgCO 2 · dm – 2 · hr – 1 , which is relatively high for a woody species. The leaves from the actively growing flowering shoots exhibited higher P n than those on the vegetative shoots. P n also varied according to the age of the leaves and the location of the plants. P n did not light saturate even at quantum flux densities (QFD) equivalent to full sunlight. The light compensation point was relatively high (ca 100 μ mol · m – 2 · S – 1 ), perhaps due to the presence of a tomentose vestiture on the leaf surface. At high QFD's, the stomatal conductance was high (ca 520 mmol · m – 2 · s – 1 ) for a woody species. RUBP - carboxylase content of the leaves ranged from 20 to 22 mg per gram F.W., which is similar to that found in most C 3 crop species. These results suggest that rabbitbrush is able to maintain high rates of P n , at least under nonstressed conditions.           

Home range and activity patterns of black-tailed jackrabbits

Home range use and activity patterns of black-tailed jackrabbits ( Lepus californicus ) in northern Utah were studied using telemetry. Home range sizes ranged from 2 to 3 km 2 and did not differ between sexes or among seasons. Jackrabbits were inactive during daylight, became active at dusk, and remained active throughout the night. Animals often traversed their home ranges in a few hours. During the breeding season, males were more active than females. Jackrabbits were most active during well-lit nights, and high winds decreased jackrabbit activity.     

Life history of the Lahontan cutthroat trout, Salmo clarki henshawi, in Pyramid Lake, Nevada

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The Pyramid Lake Lahontan cutthroat trout ( Salmo clarki henshawi ) population was sampled on a monthly basis from November 1975 through December 1977. A subsample of 676 trout, stratified by fish size and lake habitat, provided biological data. The entire population is presently derived from hatchery production, stocked at lengths of approximately 75 to 300 mm. Peak annulus formation occurs in March and April, followed by the period of maximum growth. Scale patterns illustrate a variable growing season. Maximum growth in length is in the first three years of life; after that males begin to grow faster than females. Males attained a greater age in our sample; i.e., the oldest male was seven years old compared to six years for females. The Pyramid Lake Lahontan cutthroat trout exhibit nearly isometric growth. The legal sport fishery removed 380 mm); other decimating factors are poorly understood. No evidence of the following diseases or pathogens was found in the Pyramid Lake population, presuming a carrier incidence of 2 percent at the 95 percent confidence level: infectious pancreatic necrosis, infectious hematopoietic necrosis, viral hemorrhagic septicema, bacterial kidney disease, enteric redmouth, furunculosis, whirling disease, blood fluke; however, 7 of 235 (≈3 percent) adults sampled at the Marble Bluff fishway were positive for furunculosis. Small trout feed primarily on zooplankton and benthic invertebrates; cutthroat trout >300 mm are piscivorous, feeding almost exclusively on tui chub ( Gila bicolor ). The spawning migration of Pyramid Lake cutthroat trout to the Marble Bluff egg taking facility in spring 1976 and 1977 peaked in April and May. Females mature at three or four years (352–484 mm), and males mature at two or three years (299–445 mm). Mean diameter of mature eggs is 4.51 mm; both ovum size and fecundity are a function of fish size. Fecundity ranges from 1241 to 7963 eggs, with a mean of 3815. Lahontan cutthroat trout comprise     

Monitoring Idaho fescue grasslands in the Big Horn Mountains, Wyoming, with a modified Robel pole

The reliability of monitoring visual obstruction and estimating standing herbage with a modified Robel pole was examined for high-elevation meadows in sedimentary soils on the Bighorn National Forest, Wyoming. Our objectives were to (1) test a modified pole graduated with 1.27-cm (0.5-inch) bands for estimating standing herbage based on linear regression of visual obstruction readings (VORs) on standing herbage, (2) validate the derived regression, (3) provide sample size estimates, and (4) develop guidelines for monitoring mountain grasslands. Each transect had 20 visual obstruction stations spaced 10 meters apart with 4 visual obstruction readings at each station. At 4 stations, vegetation within a 0.25-m 2 area was clipped at ground level. VORs and clipped standing herbage were averaged by transect for analysis. Visual obstruction reliably predicted average standing herbage (dry weights) for mountain meadows ( r 2 = 0.81, s x¯ = 382 kg ⋅ ha –1 ). Standing herbage ranged from 387 kg ⋅ ha –1 to 3930 kg ⋅ ha –1 , with a mean of 1742 kg ⋅ ha –1 . A validation data set of 13 transects sampled across the range of variation in standing crop showed that 85% of transects fell within the 90% prediction limits. We recommend a minimum of 4 transects for monitoring key areas or small areas up to 259 ha (640 acres) when managers need to consider differences in VOR bands and address multiple objectives. Cluster analyses (ISODATA) applied to the pole readings resulted in 4 visual obstruction categories: short, short-intermediate, tall-intermediate, and tall. This tool provides a simple, reliable, and cost-effective (time-saving) alternative to clipping vegetation and obtaining dry weights for monitoring. Mention of a proprietary product does not constitute a guarantee or warranty of the product by USDA or the authors and does not imply its approval to the exclusion of other products that also may be suitable.     

Mycorrhization of ponderosa pine in a second-growth Sierra Nevada forest

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.