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1.
Beavers (Castor canadensis) disappeared from drainages north of Yellowstone National Park in the mid-1900s because of trapping, a potential tularemia outbreak, and willow (Salix spp.) stand degradation by ungulates. Beavers were reintroduced in 1986 after a 40–yr absence with inventories of active-beaver structures completed each fall after reintroduction for 24 consecutive yr. We used this inventory to evaluate the expansion of beaver populations in a riparian environment recovering from past overuse by ungulates. Specifically, we investigated the density of active-beaver colonies and dams, the change in willow cover, and habitats associated with beaver expansion since reintroduction. Successful establishment and expansion of beavers indicate that sufficient resources were available to the population despite the suboptimal condition of riparian vegetation. Carrying capacity on third-order streams was reached approximately 14 yr after reintroduction (2000) with an average annual density of 1.33 (95th percentile = 1.23 ? 1.44 active colonies/stream km) between 2000 and 2010. The average annual density of beaver dams during this time was 2.37 (2.04 ? 2.71 active dams/stream km). Despite the beaver population being at carrying capacity in meadows since 2000, willow cover increased by 16% between 1981 and 2011. We speculate that beaver activities, together with reduced ungulate browsing from predation and habitat loss, combined to increase willow cover. Willow cover and height were positively associated with colony longevity, but numerous other influencing variables included secondary channels, sinuosity, stream depth, and sandbar width. Our results provide evidence that beaver reintroduction can be successful in riparian areas where willow stand condition is less than optimal and that beavers might ultimately improve willow condition. We suggest that reducing ungulate use of overgrazed riparian environments will facilitate the reestablishment of beaver populations. We also provide managers with habitats that should be identified in an environment targeted for reintroduction.  相似文献   

2.
Horse flies can mechanically transmit Besnoitia besnoiti, the agent of bovine besnoitiosis. Although previously limited to enzootic areas, especially the French Pyrenees Mountains, bovine besnoitiosis is now considered a re-emerging disease in western Europe. To improve understanding of the role of horse flies as mechanical vectors, this study investigated their blood-feeding ecology in the eastern French Pyrenees, in two high-altitude summer pastures whose main domestic ungulates were cattle, and in a wildlife park with native fauna. Species-specific PCR assays were conducted to identify the sources of blood meals: wild boar, horse, cattle (or bison), sheep (or mouflon), goat, red deer, roe deer and izard (or Pyrenean chamois). In La Mouline pasture, tabanids (N = 20) fed on red deer (70%) and cattle (30%). In Mantet pasture, tabanids (N = 24) fed on cattle (52%), red deer (20%), wild boar (16%), horse (8%) and sheep (4%). In the wildlife park, Tabanus bromius (N = 32), the most abundant species collected, fed on red deer (85%), bison (9%) and wild boar (6%). Despite relatively high densities in both the pastures and in the wildlife park, small wild ungulates (izard, mouflon and roe deer) were not detected as a source of blood meals. Only two mixed blood meals were identified in two specimens of T. bromius: cattle/horse for the specimen collected in the pastures, and bison/wild boar for the specimen collected in the wildlife park. Our findings showed that tabanids display a level of opportunistic feeding behaviour, in addition to a preference for red deer, the latter being particularly true for Philipomyia aprica, the most abundant species collected in the pastures.  相似文献   

3.
Management practices are often needed to ensure that riparian areas are not heavily grazed by livestock. A study was conducted in Montana during midsummer to evaluate the efficacy of low-stress herding and supplement placement to manage cattle grazing in riparian areas. Three treatments were evaluated in three pastures over a 3-yr period in a Latin-square design (n = 9). Each year, naïve 2-yr-old cows with calves were randomly assigned to the three treatments: 1) free-roaming control, 2) herding from perennial streams to upland target areas, and 3) herding to upland sites with low-moisture block supplements. Stubble heights along the focal stream were higher (P = 0.07) in pastures when cattle were herded (mean ± SE, 23 ± 2 cm) than in controls (15 ± 3 cm). Global positioning system telemetry data showed that herding reduced the time cows spent near (< 100 m) perennial streams (P = 0.01) and increased the use of higher elevations (P = 0.07) compared with controls. Evening visual observations provided some evidence that free-roaming cows (44% ± 19%) were in riparian areas more frequently (P = 0.11) than herded cows (23% ± 6%). Fecal abundance along the focal stream was less (P = 0.07) with herding (61.9 ±  kg · ha−1) than in controls (113.2 ±  kg · ha−1). Forage utilization within 600 m of supplement sites was greater (P = 0.06) when cows were herded to low-moisture blocks (18% ± 6%) compared with controls and herding alone (8% ± 2%). Moving cattle to uplands at midday using low-stress herding is an effective tool to reduce use of riparian areas. Herding cattle to low-moisture blocks can increase grazing of nearby upland forage but may not provide additional reduction in cattle use of riparian areas compared with herding alone.  相似文献   

4.
Aspen is a foundation species that provides vital habitat for hundreds of plant and animal species. However, changing ungulate herbivory regimes may be altering recruitment success and resilience of aspen forests. The objective of this observational study was to quantify the impacts of ungulate herbivory on aspen recruitment potential. We sampled 36 aspen dominant stands on the Fishlake National Forest in Utah for browse of apical meristems, suckering density (< 180 cm in height), and recruitment density (≥ 180 cm). Our analysis indicated that for each 10% of apical meristems browsed, annual vertical and radial growth rates and recruitment density were reduced by 1.2 cm, 0.02 mm, and 17 ha? 1, respectively. In contrast, aspen suckering density increased by 1 230 suckers ha? 1, with each 10% browse of apical meristems. This suggests that ungulates contribute to aspen suckers persisting in the understory for longer periods and may alter recruitment success of aspen stands. Aspen that were under high ungulate browse pressure were associated with lower growth rates and persisted for twice as long in the understory. For example, a 5-yr-old sucker was predicted to be 115 cm without browse of apical meristems and 60 cm with 100% browse of apical meristems. Further, aspens of the same height with 100% browse of apical meristems were nearly 4 yr older on average than aspens with no evidence of browse of apical meristems. Approximately 34% of aspen suckers had persisted in the understory < 100 cm for ≥ 6 yr, and 7% of suckers had persisted in the understory for ≥ 10 yr. Our results suggest that high rates of meristem removal are correlated with increased aspen suckering yet reduced aspen growth and recruitment.  相似文献   

5.
Western juniper (Juniperus occidentalis Hook.) has expanded into sagebrush steppe plant communities the past 130 ? 150 yr in the northern Great Basin. The increase in juniper reduces herbage and browse for livestock and big game. Information on herbaceous yield response to juniper control with fire is limited. We measured herbaceous standing crop and yield by life form in two mountain big sagebrush communities (MTN1, MTN2) and a Wyoming/basin big sagebrush (WYOBAS) community for 6 yrs following prescribed fire treatments to control western juniper. MTN1 and WYOBAS communities were early-successional (phase 1) and MTN2 communities were midsuccessional (phase 2) woodlands before treatment. Prescribed fires killed all juniper and sagebrush in the burn units. Total herbaceous and perennial bunchgrass yields increased 2 to 2.5-fold in burn treatments compared with unburned controls. Total perennial forb yield did not differ between burns and controls in all three plant communities. However, tall perennial forb yield was 1.6- and 2.5-fold greater in the WYOBAS and MTN2 burned sites than controls. Mat-forming perennial forb yields declined by 80 ? 90% after burning compared with controls. Cheatgrass yield increased in burned WYOBAS and MTN2 communities and at the end of the study represented 10% and 22% of total yield, respectively. Annual forbs increased with burning and were mainly composed of native species in MTN1 and MTN2 communities and non-natives in WYOBAS communities. Forage availability for livestock and wild ungulates more than doubled after burning. The additional forage provided on burned areas affords managers greater flexibility to rest and treat additional sagebrush steppe where juniper is expanding, as well as rest or defer critical seasonal habitat for wildlife.  相似文献   

6.
Invasive woody plant expansion is a primary threat driving fragmentation and loss of sagebrush (Artemisia spp.) and prairie habitats across the central and western United States. Expansion of native woody plants, including conifer (primarily Juniperus spp.) and mesquite (Prosopis spp.), over the past century is primarily attributable to wildfire suppression, historic periods of intensive livestock grazing, and changes in climate. To guide successful conservation programs aimed at reducing top-down stressors, we mapped invasive woody plants at regional scales to evaluate landscape level impacts, target restoration actions, and monitor restoration outcomes. Our overarching goal was to produce seamless regional products across sociopolitical boundaries with resolution fine enough to depict the spatial extent and degree of woody plant invasion relevant to greater sage-grouse (Centrocercus urophasianus) and lesser prairie-chicken (Tympanuchus pallidicinctus) conservation efforts. We mapped tree canopy cover at 1-m spatial resolution across an 11-state region (508 265 km2). Greater than 90% of occupied lesser prairie-chicken habitat was largely treeless for conifers (< 1% canopy cover), whereas > 67% was treeless for mesquite. Conifers in the higher canopy cover classes (16 ? 50% and > 50% canopy cover) were scarce (< 2% and 1% canopy cover), as was mesquite (< 5% and 1% canopy cover). Occupied habitat by sage-grouse was more variable but also had a relatively large proportion of treeless areas (x? = 71, SE = 5%). Low to moderate levels of conifer cover (1 ? 20%) were fewer (x? = 23, SE = 5%) as were areas in the highest cover class (> 50%; x? = 6, SE = 2%). Mapping indicated that a high proportion of invading woody plants are at a low to intermediate level. Canopy cover maps for conifer and mesquite resulting from this study provide the first and most geographically complete, high-resolution assessment of woody plant cover as a top-down threat to western sage-steppe and prairie ecosystems.  相似文献   

7.
Trichinellosis is one of the most important zoonotic diseases in Romania. Even though the disease is a serious public health concern, only a limited number of Trichinella isolates have been identified at the species level; in the past, all larvae were assumed to be Trichinella spiralis. The present study was conducted to identify Trichinella spp. circulating among wild and domestic animals in Romania, using PCR-based methods. Trichinella spp. larvae originating from 54 wild and 23 domestic mammals were examined. No Trichinella spp. larvae were detected in muscle samples of 182 birds. T. spiralis and Trichinella britovi were the only two species identified in the 40 isolates that yielded a positive PCR result. Overall, T. britovi was more prevalent (n = 26; 65%) than T. spiralis (n = 14; 35%). T. spiralis was the predominant species found in domestic animals (n = 9; 75%), while T. britovi was more prevalent in wildlife (n = 24; 86%). No mixed infections were found. The highest prevalence of Trichinella infection was detected in wolves (11/35; 31%), in European wild cats (4/28; 14%), and in red foxes (5/71; 7%). The distribution of Trichinella spp. in Romania does not show a species-specific clustering; both of the two species found were present over the entire range of counties studied.  相似文献   

8.
Quaking aspen (Populus tremuloides Michx.) recruitment and overstory stem densities were sampled in 315 clones in 1991 and 2006 on 560 km2 of the Northern Yellowstone Winter Range (NYWR). A primary objective was to observe if aspen status had improved from 1991 to 2006: evidence of a wolf (Canis lupus) caused trophic cascade. Recruitment stems (height > 2 m and diameter at breast height < 5 cm) represent recent growth of aspen sprouts above elk (Cervus elaphus) browsing height, whereas overstory stems (all stems > 2 m) represent the cohort of stems, which will insure the sustainability of the clone. Overstory stem densities declined by 12% (P = 0.04) on the landscape scale when compared with paired t-tests. Overstory stems declined in 58% of individual clones and in 63% of the 24 drainages of the study area. The second objective was to determine which factors influenced changes in aspen density. Winter ungulate browsing (P = 0.0001), conifer establishment (P = 0.0001), and cattle (Bos spp.) grazing (P = 0.016) contributed to the decline in overstory stem densities when analyzed using a mixed effects model of log transformed medians. Eighty percent of the clones were classified as having medium to high browsing levels in 1991, whereas 65% of the clones received a similar rating in 2006, possibly due to the reduced NYWR elk population. Aspen recruitment has increased in some 2–10 km2 areas, but not consistently. Our study found that a trophic cascade of wolves, elk, and aspen, resulting in a landscape-level recovery of aspen, is not occurring at this time.  相似文献   

9.
Management of rangelands for wildlife and livestock entails understanding growth of clonal shrubs such as Chickasaw plum (Prunus angustifolia Marsh.). We studied growth of this species in one county in north-central (Payne) and two counties in northwestern Oklahoma (Ellis, Harper) during 2006 and 2007. We estimated age of stems and roots by growth rings and area of stands with the use of a handheld GPS unit. Based on zero-intercept regression models, stands grew at similar rates (overlapping 95% confidence intervals [CIs]) among counties with a pooled estimate of 31.0 m2 · yr−1 (95% CI = 26.5–35.6 m2 · yr−1; n = 95). This rate showed considerable variability within and among study sites (r = 0.52). Stem diameter increased (zero-intercept models) more rapidly in north-central Oklahoma (5.27 mm · yr−1; 95% CI = 5.01–5.53 mm · yr−1; r = 0.90; n = 53) than in northwestern Oklahoma (3.68 mm · yr−1; 95% CI = 3.55–3.81 mm · yr−1; r = 0.91; n = 102); data were pooled because of similar rates in Ellis and Harper counties. Stem height was a power function of stem age (y = 0.97x0.28; r = 0.56), indicating rate of growth in height (m · yr−1) declined with age according to dy/dx = 0.27x−0.72. Knowledge of the area expansion rate of Chickasaw plum clones aids in management planning to increase or decrease canopy coverage by this shrub.  相似文献   

10.
《Veterinary parasitology》2015,207(1-2):140-143
Cryptosporidium spp. is the most important parasitic diarrheal agent in the world, is among the top four causes of moderate-to-severe diarrheal disease in young children in developing nations, and is problematic as an opportunistic co-infection with HIV. In addition, Cryptosporidium is a persistent challenge for livestock production. Despite its zoonotic potential, few studies have examined the ecology and epidemiology of this pathogen in rural systems characterized by high rates of overlap among humans, domesticated animals, and wildlife. To improve our understanding of the zoonotic potential of Cryptosporidium species in the rural tropics, we screened humans, livestock, peridomestic rodents, and wildlife using PCR-RFLP and sequencing-based approaches to distinguish species of Cryptosporidium in rural southeastern Madagascar. Cryptosporidium of multiple species/genotypes were apparent in this study system. Interestingly, C. suis was the dominant species of Cryptosporidium in the region, infecting humans (n = 1), cattle (n =  18), pigs (n= 3), and rodents (n = 1). The broad species range of C. suis and the lack of common cattle Cryptosporidium species (Cryptosporidium parvum and Cryptosporidium andersoni) in this system are unique. This report represents the fifth confirmed case of C. suis infection in humans, and the first case in Africa. Few rural human and livestock populations have been screened for Cryptosporidium using genus-specific genotyping methods. Consequently, C. suis may be more widespread in human and cattle populations than previously believed.  相似文献   

11.
Appropriate management of livestock in riparian areas can help ensure that these ecosystems are maintained. We evaluated how one indicator of livestock grazing in riparian areas, streambank alteration, was affected by choices related to protocols and personnel used for these assessments. We found that although streambank alteration protocols were generally repeatable among observers, results were affected by factors not directly related to grazing intensity, including 1) training, 2) professional background, 3) location and intensity of measurements, and 4) the protocol used. Training reduced estimates of alteration and observer variability. Rangeland professionals had higher estimates of streambank alteration than seasonal technicians. Rapid assessments of alteration were correlated with more intensive estimates; however, the relationship was not 1∶1. Different protocols resulted in different alterations estimates when alterations at the same locations were estimated. Given the large number of monitoring programs, personnel, and methods used to assess streambank alteration, we suggest more thought be given on how to standardize monitoring efforts so results consistently reflect the true amount of alteration at a site. We also remind managers that no protocol can be implemented without some error. Managers should therefore be careful when taking action based on a single evaluation—especially when the result is near a management standard or threshold. When these concerns are addressed, indicators such as streambank alteration can help ensure management decisions maintain both sustainable allotments and landscapes.  相似文献   

12.
Mechanical cutting and mastication of juniper trees aims to restore grassland habitat by reducing the density of encroaching woody species. However, the associated soil disturbance may also create conduits for invasive species, a risk that must be mitigated by land managers. We characterized herbaceous communities in treated and adjacent untreated areas in a piñon-juniper (Pinus edulis and Juniper monosperma) woodland in northern Arizona 2.5 years after treatment. Untreated plots had 4 × the herbaceous cover (82%) than treated plots (21%). Within treated plots, native species cover (19%) was 10 × higher than invasive species cover (2%). Furthermore, treated plots exhibited greater plant community variability and diversity than untreated plots, driven by an increase in the diversity of native grasses and non-native forbs. No new recruits were Arizona listed noxious weeds, indicating that, at least in the short term, mastication is not producing invasive species hot spots in this piñon-juniper woodland.  相似文献   

13.
Uneven and/or inefficient livestock distribution is often a product of an inadequate number and distribution of watering points. Placement of off-stream water practices (OSWP) in pastures is a key consideration in rangeland management plans and is critical to achieving riparian recovery by improving grazing evenness, while improving livestock performance. Effective OSWP placement also minimizes the impacts of livestock use radiating from OSWP, known as the “piosphere.” The objective of this study was to provide land managers with recommendations for the optimum placement of OSWP. Specifically, we aimed to provide minimum offset distances of OSWP to streams and assess the effective range of OSWP using Normalized Difference Vegetation Index (NDVI) values, an indicator of live standing crop. NDVI values were determined from a time-series of Satellite Pour l'Observation de la Terre (SPOT) 20-m images of western South Dakota mixed-grass prairie. The NDVI values in ephemeral stream channels (in-channel) and uplands were extracted from pre- and post-OSWP images taken in 1989 and 2010, respectively. NDVI values were normalized to a reference imagine and subsequently by ecological site to produce nNDVI. Our results demonstrate a significant (P < 0.05) increase in the nNDVI values of in-channel vegetation within 1 250 m of OSWP following their implementation. The area of piospheres (n = 9) increased with pasture size (R2 = 0.49, P = 0.05) and increased with average distance to OSWP in a pasture (R2 = 0.43, P = 0.07). Piospheric reduction in nNDVI was observed within 200 m of OSWP, occasionally overlapping in-channel areas. The findings of this study suggest placement of OSWP 200 to 1 250 m from streams to achieve optimal results. These results can be used to increase grazing efficiency by effectively placing OSWP and insure that piospheres do not overlap ecologically important in-channel areas.  相似文献   

14.
Microhistological analysis of feces is the most applied noninvasive method for assessing diets of wild ungulates. However, the method is complicated by differential digestibility of forage species. To evaluate the efficacy of this method in quantifying browse components in summer diets of moose (Alces alces L.) on Norwegian rangelands, we compared it to parallel field surveys of browsed vegetation on the same range. Although the same principal diet components were identified in the feces and in the field, there were consistent discrepancies between the two methods in estimated proportional diet contents. Birch (Betula spp.) showed the highest field:fecal ratio: 3.3 ±  compared to 0.9 ±  for Salix spp., 0.8 ±  for aspen (Populus tremula L.), and 0.6 ±  for rowan (Sorbus aucuparia L.). Until in vivo fecal correction factors for differential forage digestibility are available, we caution against broad application of fecal analyses for estimating proportions of browse in moose diet. Although we could not determine the exact amount of discrepancy implicit in each method, previous studies of moose summer diet in the area clearly indicate that fecal analyses gave a less accurate representation of actual moose browse diet than did the field survey. Fecal analyses are nevertheless needed to identify moose diet components other than browse, which are not easily obtained from field surveys.  相似文献   

15.
Serum samples collected from Iberian red deer (Cervus elaphus hispanicus; n = 472), fallow deer (Dama dama; n = 293) and European wild boar (Sus scrofa; n = 174) in Asturias, Northern Spain, from 1999 to 2005 were examined for antibodies against a reference panel of 14 Leptospira spp. serovars. Positive antibody titres at a microscopic agglutination test cut-off of 1:80 were detected against serovars Pomona (1.6%, 5.8%, 5.2%), Bratislava (1.1%, 0.7%, 4.7%), Grippotyphosa (0.7%, 2.4%, 1.7%), Muenchen (2.6%, 0%, 0%), Pyrogenes (0.4%, 2.4%, 1.2%), Panama (1.2%, 1.7%, 0%), Copenhageni (0%, 0.7%, 0.6%), Autumnalis (0.4%, 0%, 0.6%) and Icterohaemorrhagiae (0%, 0%, 0.6%) in Iberian red deer, fallow deer and European wild boar, respectively.  相似文献   

16.
Culicoides species (Diptera: Ceratopogonidae) belonging to the Obsoletus and Pulicaris groups are considered to be the main vectors of bluetongue virus (BTV) in non Mediterranean Europe. Selected terrestrial microhabitats (n = 17) on a farm in northern Spain were sampled repeatedly over a year-long period and characterized for use by Culicoides species for immature development. Concurrent use of CDC light traps showed the presence of 37 species and 66,575 specimens of adult Culicoides. A total of 28 species and 11,396 individuals emerged from laboratory-maintained soil samples. Culicoides obsoletus and Culicoides scoticus (pooled as Obsoletus complex) were particularly abundant (comprising 58.6% and 74.5% of the total collections in light traps and emergence traps respectively). Potential key vectors of animal viruses (such as BTV) were found in two main terrestrial types of microhabitats. In the case of C. obsoletus, different types of manure (old and composted manure, manure mixed with organic matter, and fresh manure) produced most of the specimens. In contrast, larvae of C. scoticus and Culicoides lupicaris were associated with soil substantially comprised of rotting leaf litter that included the parasitic plant Lathraea clandestina. Several species, Culicoides festivipennis, Culicoides punctatus and Culicoides brunnicans, were very common in mud at pond margins. Indeed, pond microhabitats and runoff below barn rooflines supported the greatest species richness. In the pond habitat, 49.4% of Culicoides specimens emerged from mud at the water edge, as opposed to 50 cm above (32.4%) and 1 meter above waterline (18%). Similar species richness, but statistically significant differences in abundance, were observed among the four pond microhabitats. Overall, the majority of the specimens were found in the upper layer (0–3 cm), except in manure, where they preferred deeper layers (>6 cm). Maximum peaks of abundance occurred in both light traps and soil samples in summer months, whereas increased captures in autumn were noticed only in light traps. Both trapping systems failed to collect adult Culicoides midges in the coldest months of December, January and February. The literature on immature habitats of species suspected in BTV transmission in Europe, the Pulicaris group and particularly the Obsoletus group, is briefly reviewed.  相似文献   

17.
Four distinct cat hemoplasma species are recognized worldwide. However, this is the first study to investigate the prevalence, risk factors, and hematological findings of hemoplasmas in cats from Chile. Complete blood count and 16S rRNA real-time PCR for cat hemoplasma species were performed in 384 blood samples from domestic cats in Valdivia, Chile. Among the 384 samples the species-specific prevalence was as follows: ‘Candidatus Mycoplasma haemominutum’ (7.8%), Mycoplasma haemofelis (4.4%), ‘Candidatus Mycoplasma turicensis’ (1%), ‘Ca. M. haemominutum’ + M. haemofelis (0.78%), ‘Ca. M. haemominutum’ + Ca. M. turicensis’ (0.52%), ‘Ca. M. haemominutum’ + Candidatus Mycoplasma haematoparvum’ (0.26%) and ‘Ca. M. haemominutum’ + M. haemofelis + Ca. M. haematoparvum’ (0.26%). Male sex, older age, outdoor access, and FIV status were risk factors for hemoplasmosis. Mycoplasma haemofelis-positive cats had higher mean corpuscular volume and monocyte count. Four hemoplasma species circulate in the cat population of Valdivia. ‘Candidatus M. turicensis’ and ‘Ca. M. haematoparvum’ have been reported for the first time in Chilean cats.  相似文献   

18.
Half of the world's land base is grazed by domesticated livestock. Because of the important functional role of ants in grasslands, it is important to understand the effect of livestock grazing on ant abundance and diversity. The objectives of this study were to examine the effect of cattle grazing and site productivity on the abundance, species richness, and species diversity of ants in Lac du Bois Grasslands Provincial Park, British Columbia, Canada. We hypothesized that the measured ant variables would be lowest in grazed areas and at low site productivity. Pitfall trapping was conducted at four sites: two at each low and high site productivity levels. At each site an ungrazed (fenced exclosure) and grazed transect was sampled during May, July, and August of 2008. Captured ants were preserved in ethanol and identified. Eight genuses of ants were collected: Tapinoma, Camponotus, Formica, Lasius, Aphaenogaster, Myrmica, Solinopsis, and Temnotharox. The mean number of ants per pitfall was higher at high site productivity sites that were grazed (15.10 ±  SE) compared to high productivity sites ungrazed (3.28 ±  SE); grazing at low productivity reduced numbers of ants from 5.07 (± 0.70 SE) to 2.20 (± 0.39 SE) (F = 21.806; P [ 0.001). Tapinoma sessile and A. occidentalis had the greatest numbers in the pitfall traps. Species richness (F = 23.330, P [ 0.001) and diversity (F = 11.764, P = 0.001) followed a similar trend. Because productivity and cattle grazing affect ant diversity and abundance, and ants impact ecosystem functioning, these factors should be considered in management of grasslands.  相似文献   

19.
Trichinella surveillance in wildlife relies on muscle digestion of large samples which are logistically difficult to store and transport in remote and tropical regions as well as labour-intensive to process. Serological methods such as enzyme-linked immunosorbent assays (ELISAs) offer rapid, cost-effective alternatives for surveillance but should be paired with additional tests because of the high false-positive rates encountered in wildlife. We investigated the utility of ELISAs coupled with Western blot (WB) in providing evidence of Trichinella exposure or infection in wild boar. Serum samples were collected from 673 wild boar from a high- and low-risk region for Trichinella introduction within mainland Australia, which is considered Trichinella-free. Sera were examined using both an ‘in-house’ and a commercially available indirect-ELISA that used excretory–secretory (E/S) antigens. Cut-off values for positive results were determined using sera from the low-risk population. All wild boar from the high-risk region (352) and 139/321 (43.3%) of the wild boar from the low-risk region were tested by artificial digestion. Testing by Western blot using E/S antigens, and a Trichinella-specific real-time PCR was also carried out on all ELISA-positive samples. The two ELISAs correctly classified all positive controls as well as one naturally infected wild boar from Gabba Island in the Torres Strait. In both the high- and low-risk populations, the ELISA results showed substantial agreement (k-value = 0.66) that increased to very good (k-value = 0.82) when WB-positive only samples were compared. The results of testing sera collected from the Australian mainland showed the Trichinella seroprevalence was 3.5% (95% C.I. 0.0–8.0) and 2.3% (95% C.I. 0.0–5.6) using the in-house and commercial ELISA coupled with WB respectively. These estimates were significantly higher (P < 0.05) than the artificial digestion estimate of 0.0% (95% C.I. 0.0–1.1). Real-time PCR testing of muscle from seropositive animals did not detect Trichinella DNA in any mainland animals, but did reveal the presence of a second larvae-positive wild boar on Gabba Island, supporting its utility as an alternative, highly sensitive method in muscle examination. The serology results suggest Australian wildlife may have been exposed to Trichinella parasites. However, because of the possibility of non-specific reactions with other parasitic infections, more work using well-defined cohorts of positive and negative samples is required. Even if the specificity of the ELISAs is proven to be low, their ability to correctly classify the small number of true positive sera in this study indicates utility in screening wild boar populations for reactive sera which can be followed up with additional testing.  相似文献   

20.
Aristida purpurea (purple threeawn) is a competitive native perennial grass with monoculturistic tendencies and poor palatability. We examined effects of fire, defoliation, and interspecific/intraspecific planting for 1) threeawn responses in the presence of threeawn, Bouteloua gracilis, or Pascopyrum smithii, and 2) B. gracilis and P. smithii response with threeawn. Biomass, aboveground production, tillers, and axillary buds were analyzed following two fire and four clipping treatments applied to three species–pair combinations in a completely randomized factorial design with nine replications. Fire killed 36% of threeawn. Fire reduced surviving threeawn biomass 61% and reduced production 27%. Threeawn production was greatest when neither plant was clipped and least when competing species were moderately clipped, or when both plants were severely clipped. Tiller counts of burned threeawn were similar among clipping treatments, and less than non-clipped or moderately clipped plants not burned. Fire decreased threeawn axillary buds on average by 25%. Moderately clipped plants had greater production than those from other clipping treatments across species. Average threeawn percentage of pot biomass was greater with B. gracilis (46 ± 3% SE) than P. smithii (38 ± 3% SE). Fire reduced threeawn from 60 ± 3% to 23 ± 3% of pot biomass, indicating good potential for rapid reductions in threeawn dominance and restoration of plant diversity with fire.  相似文献   

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