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1.
Many “natural” areas are exposed to military or recreational off-road vehicles. The interactive effects of different types
of vehicular disturbance on vegetation have rarely been examined, and it has been proposed that some vegetation types are
less susceptible to vehicular disturbance than others. At Fort Riley, Kansas, we experimentally tested how different plant
community types changed after disturbance from an M1A1 Abrams tank driven at different speeds and turning angles during different
seasons. The greatest vegetation change was observed because of driving in the spring in wet soils and the interaction of
turning while driving fast (vegetation change was measured with Bray-Curtis dissimilarity). We found that less vegetation
change occurred in communities with high amounts of native prairie vegetation than in communities with high amounts of introduced
C3 grasses, which is the first experimental evidence we are aware of that suggests plant communities dominated by introduced
C3 grasses changed more because of vehicular disturbance than communities dominated by native prairie grasses. We also found
that vegetation changed linearly with vehicular disturbance intensity, suggesting that at least initially there was no catastrophic
shift in vegetation beyond a certain disturbance intensity threshold. Overall, the intensity of vehicular disturbance appeared
to play the greatest role in vegetation change, but the plant community type also played a strong role and this should be
considered in land use planning. The reasons for greater vegetation change in introduced C3 grass dominated areas deserve further study. 相似文献
2.
Scott R. Abella 《Environmental management》2010,46(3):391-403
Globally the area in forest plantations is rising by 2% annually, increasing the importance of plantations for production
of human goods and services and for ecological functions such as carbon storage and biodiversity conservation. Specifically
in the Great Lakes states and provinces of Midwestern North America, thousands of hectares of pine plantations were established
in the early and mid-1900s to revegetate abandoned agricultural fields that had replaced mixed-species forests and oak–prairie
ecosystems. Plantation establishment also was intended to bolster the timber base. Management priorities have shifted, with
many resource managers currently seeking to manage existing plantations for promoting mixed-species ecosystems. The purpose
of this study was to assess plant succession and the reestablishment of oak savanna and prairie species after thinning 14
plantations of Pinus resinosa and strobus in northwestern Ohio, USA. Thinning reduced tree basal area by an average of 75%. Plant communities were sampled on 0.05-ha
plots one and 3 years after thinning and compared to 10 unthinned control plantations. By 3 years after thinning, thinned
plots contained 2–3 times more species and 14 times more plant cover than control plots. The species composition of colonizing
plants was most strongly correlated with residual pine basal area and soil variables related to drainage (e.g., sand concentration,
available water capacity). Although plant composition was dominated by widespread colonizers such as Erechtites hieraciifolia, the coefficient of conservatism (indicative of species of more intact, undisturbed communities) significantly increased
on thinned plots from year 1 to 3. This finding, coupled with the presence of four rare, state-listed Ohio species whose eight
plot occurrences all were on thinned plots, suggests that plant composition is moving towards species typifying more high-quality
savanna and prairie habitats. 相似文献
3.
Bison and cattle grazing management,bare ground coverage,and links to suspended sediment concentrations in grassland streams
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Bartosz P. Grudzinski Melinda D. Daniels Kyle Anibas David Spencer 《Journal of the American Water Resources Association》2016,52(1):16-30
This study quantified the impact of bison and cattle grazing management practices on bare ground coverage at the watershed, riparian, and forested riparian scales within the Flint Hills ecoregion in Kansas. We tested for correlations between bare ground coverage and fluvial suspended sediment concentrations during base‐flow and storm‐flow events. We used remotely sensed imagery combined with field surveys to classify ground cover and quantify the presence of bare ground. Base‐flow water samples were collected bi‐monthly during rain‐free periods and 24 h following precipitation events. Storm‐flow water samples were collected on the rising limb of the hydrograph, using single‐stage automatic samplers. Ungrazed treatments contained the lowest coverage of bare ground at the watershed, riparian, and forested riparian scales. Bison treatments contained the highest coverage of bare ground at the watershed scale, while high‐density cattle treatments contained the highest coverage of bare ground at the riparian and forested riparian scales. In bison and cattle‐grazed treatments, a majority of bare ground was located near fence lines, watershed boundaries, and third‐ and fourth‐order stream segments. Inorganic sediment concentrations at base flow were best predicted by riparian bare ground coverage, while storm‐flow sediment concentrations were best predicted by watershed scale bare ground coverage. 相似文献
4.
Stephen E. Watts 《Environmental management》1998,22(4):611-616
Artemisia tridentata Nutt.) habitat within the Idaho Army National Guard Orchard Training Area in southwestern Idaho. The purpose of this study
was to determine the short-term (1–2 years) influence of tank tracks on vegetation and microphytic crusts in shrubsteppe habitat.
The two types of tank tracks studied were divots (area where one track has been stopped or slowed to make a sharp turn) and
straight-line tracks. Divots generally had a stronger influence on vegetation and microphytic crusts than did straight-line
tracks. Tank tracks increased cover of bare ground, litter, and exotic annuals, and reduced cover of vegetation, perennial
native grasses, sagebrush, and microphytic crusts. Increased bare ground and reduced cover of vegetation and microphytic crusts
caused by tank tracks increase the potential for soil erosion and may reduce ecosystem productivity. Reduced sagebrush cover
caused by tank tracks may reduce habitat quality for rodents. Tank tracks may also facilitate the invasion of exotic annuals
into sagebrush habitat, increasing the potential for wildfire and subsequent habitat degradation. Thus, creation of divots
and movement through sagebrush habitat by tanks should be minimized. 相似文献
5.
A study was carried out in Nova Scotia, Canada, to experimentally assess the effect of snowmobiles on old field and marsh vegetation. Snowmobile treatments ranging from a single pass to 25 passes (five passes on five separate days) were administered. The first pass by a snowmobile caused the greatest increase in snow compaction-roughly 75% of that observed after five sequential passes. Snowmobile treatment resulted in highly significant increases in snow retention in spring. Frequency was more important than intensity in this regard.Standing crop and species composition were measured the following summer. Standing crop in the field showed a significant reduction with increasing snowmobile use; frequency of treatment (p < 0.01) was more important than intensity (p = 0.125).Stellaria graminea, Aster cordifolius, Ranunculus repens, andEquisetum arvense all showed significant (p < 0.05) differences in percent cover resulting from the treatment. Marginally significant changes were observed inAgrostis tenuis andPhleum pratense Marsh vegetation showed no significant effects of snowmobile treatment. This may have been because of solid ice cover during the winter.The literature is critically reviewed. It is concluded that snowmobile use can have a highly significant effect upon natural vegetation. Management suggestions are made. 相似文献
6.
Gerhardus Petrus Nortjé Wouter van Hoven Michiel C. Laker 《Environmental management》2012,50(6):1164-1176
Studies on the effects of off-road driving on soils were conducted in the Makuleke Contractual Park of the Kruger National Park. The studies were conducted on three different soils with different textures and soil compactibilities. Traffic pressure was applied with a game drive vehicle loaded with 11 sand bags, each weighing 70?kg. This gave a total vehicle mass of 3,795?kg, simulating a vehicle fully laden with tourists. The study included: (i) comparing of the effects of four different tyre pressures; (ii) comparing the effects of 1–3 vehicle passes over the same tyre tracks; (iii) comparison of traffic effects under dry and wet soil moisture conditions, on soil compaction, respectively. After each pass penetration resistances were measured (a) on the tyre tracks, (b) between the tyre tracks and (c) at different distances outside the tyre tracks. As expected, vehicular traffic caused soil compaction below the wheel tracks. Lower tyre pressures caused less compaction than higher tyre pressures. Fewer vehicle passes also caused less compaction than more passes on the same tracks, but most compaction occurred during the first pass. Thus, driving on the same tracks more than once is less damaging than driving once on different tracks. Controlled traffic should be considered when developing management strategies for off-road driving in wildlife protected areas. 相似文献
7.
Ning Wang Ju-Ying Jiao Yan-Feng Jia Wen-Juan Bai Zhen-Guo Zhang 《Environmental management》2010,46(3):367-377
Poor vegetation cover is generally considered to be a major factor causing soil erosion on the Loess Plateau in China. It
has been argued that tree planting restoration is ineffective, and natural re-vegetation is an alternative ecological solution
for restoring abandoned cropland and controlling soil erosion. The aims of this study were to investigate the characteristics
of soil seed banks and to assess the natural restoration potential of abandoned cropland in the hilly-gullied Loess Plateau.
The soil seed bank was identified by the germination method with the soil samples, which were collected at four sampling times
(April, August, and October 2005 and August 2006) from 12 plots abandoned 3–30 years prior to sampling. The seed bank densities
of all of the samples in the 0–10 cm soil layer varied from 1,067 ± 225 to 14,967 ± 1,606 seeds m−2. Fifty-one species (24 annual and 27 perennial species) belonging to 18 families were identified, and 39% of these species
belonged to the families Compositae and Gramineae. The pioneer species Artemisia scoparia dominated the seed bank, with an average seed density of 3,722 seeds m−2, and accounted for 74.4% of the seeds in the bank. The local dominant species (such as Lespedeza davurica, Artemisia gmelinii, Bothriochloa ischaemun and Stipa bungeana) of the later succession stages also existed at densities varying from 17 to 1, 383 seeds m−2. The combination of soil seed bank characteristics, reproductive traits of the species, the specific landscape conditions
indicates that the potential to restoring the abandoned croplands in the hilly-gullied Loess Plateau via natural re-vegetation
could be substantial. 相似文献
8.
Loss of grassland species resulting from activities such as off-road vehicle use increases the need for models that predict
effects of anthropogenic disturbance. The relationship of disturbance by military training to plant species richness and composition
on two soils (Foard and Lawton) in a mixed prairie area was investigated. Track cover (cover of vehicle disturbance to the
soil) and soil organic carbon were selected as measures of short- and long-term disturbance, respectively. Soil and vegetation
data, collected in 1-m2 quadrats, were analyzed at three spatial scales (60, 10, and 1 m2). Plant species richness peaked at intermediate levels of soil organic carbon at the 10-m2 and 1-m2 spatial scales on both the Lawton and Foard soils, and at intermediate levels of track cover at all three spatial scales
on the Foard soil. Species composition differed across the disturbance gradient on the Foard soil but not on the Lawton soil.
Disturbance increased total plant species richness on the Foard soil. The authors conclude that disturbance up to intermediate
levels can be used to maintain biodiversity by enriching the plant species pool. 相似文献
9.
Brian Miller Christen Wemmer Dean Biggins Richard Reading 《Environmental management》1990,14(6):763-769
Prairie dogs (Cynomys spp.) have been poisoned throughout this century because of grazing competition with livestock. Recent evidence showed these
early claims were exaggerated, but animal control was already entrenched in government policy. As a result, ongoing government
subsidized poisoning has reduced prairie dogs to about 2% of their former distribution. The reduction of prairie dogs diminished
species diversity in the arid grasslands of North America, including the potential extinction of the black-footed ferret (Mustela nigripes). Cost-benefit analysis revealed that poisoning costs more than any grazing benefits accrued. This analysis did not consider
the long-term costs of reversing ecosystem degradation, the intangible value of biological diversity as a public benefit,
or the depletion of biotic resources as a loss of actual or potential wealth. The government presently finances the poisoning
policy and the preservation of endangered species like the black-footed ferret, two apparently conflicting programs. We, therefore,
propose an integrated management plan that considers both interests. We propose that federal monies allocated to the poisoning
program be converted into a rebate for ranchers who manage livestock while preserving the prairie dog community. This would
redirect funds and personnel already allocated to prairie dog eradication to an incentive for ranchers who manage for livestock
and wildlife. Livestock interests and grassland biotic diversity would both benefit. 相似文献
10.
Brian G. Katz A. Alejandro Sepulveda Richard J. Verdi 《Journal of the American Water Resources Association》2009,45(3):607-627
Abstract: A nitrogen (N) mass‐balance budget was developed to assess the sources of N affecting increasing ground‐water nitrate concentrations in the 960‐km2 karstic Ichetucknee Springs basin. This budget included direct measurements of N species in rainfall, ground water, and spring waters, along with estimates of N loading from fertilizers, septic tanks, animal wastes, and the land application of treated municipal wastewater and residual solids. Based on a range of N leaching estimates, N loads to ground water ranged from 262,000 to 1.3 million kg/year; and were similar to N export from the basin in spring waters (266,000 kg/year) when 80‐90% N losses were assumed. Fertilizers applied to cropland, lawns, and pine stands contributed about 51% of the estimated total annual N load to ground water in the basin. Other sources contributed the following percentages of total N load to ground water: animal wastes, 27%; septic tanks, 12%; atmospheric deposition, 8%; and the land application of treated wastewater and biosolids, 2%. Due to below normal rainfall (97.3 cm) during the 12‐month rainfall collection period, N inputs from rainfall likely were about 30% lower than estimates for normal annual rainfall (136 cm). Low N‐isotope values for six spring waters (δ15N‐NO3 = 3.3 to 6.3‰) and elevated potassium concentrations in ground water and spring waters were consistent with the large N contribution from fertilizers. Given ground‐water residence times on the order of decades for spring waters, possible sinks for excess N inputs to the basin include N storage in the unsaturated zone and parts of the aquifer with relatively sluggish ground‐water movement and denitrification. A geographical‐based model of spatial loading from fertilizers indicated that areas most vulnerable to nitrate contamination were located in closed depressions containing sinkholes and other dissolution features in the southern half of the basin. 相似文献
11.
Charles W. Slaughter Charles H. Racine Donald A. Walker Larry A. Johnson Gunars Abele 《Environmental management》1990,14(1):63-72
Use of off-road vehicles (ORVs) in permafrost-affected terrain of Alaska has increased sharply over the past two decades.
Until the early 1960s, most ORV use was by industry or government, which employed heavy vehicles such as industrial tractors
and tracked carriers. Smaller, commercial ORVs became available in the 1960s, with the variety and number in use rapidly increasing.
Wheeled and tracked ORVs, many used exclusively for recreation or subsistence harvesting by individuals, are now ubiquitous
in Alaska. This increased use has led to concern over the cumulative effects of such vehicles on vegetation, soils, and environmental
variables including off-site values.
Factors affecting impact and subsequent restoration include specific environmental setting; vegetation; presence and ice content
of permafrost; microtopography; vehicle design, weight, and ground pressure; traffic frequency; season of traffic; and individual
operator practices. Approaches for mitigating adverse effects of ORVs include regulation and zoning, terrain analysis and
sensitivity mapping, route selection, surface protection, and operator training.
We regret the untimely death of Gunars Abele on August 27, 1989; he was a valued colleague and good friend. 相似文献
12.
The condition of the semi-arid Borana rangeland in southern Ethiopia was assessed by studying different land-use systems (communal land, a government ranch and a traditional grazing reserve enclosure) and along a distance gradient (near, middle and far) from water sources. The assessment incorporated the soil, herbaceous and woody plant layers. Two methods were employed to evaluate the grass layer, viz. ecological condition index (ECI) and weighted palatability composition (WPC). The ECI on the government ranch was 21.7% and 26% greater than that of the traditional reserve and the communal land, respectively. The WPC on the government ranch was 83.3% and 48.6% greater than that of the communal area and the traditional reserve, respectively. Both ECI and WPC values were similar for all distance sites from water. Tree equivalent (TE) density, of all encroaching woody plants combined, was higher on the communal land (504 TE ha(-1)) than the government ranch (373 TE ha(-)1) and traditional grazing reserve (118 TE ha(-1)), but with no marked variations in the distance sites from water. Height class distribution of encroaching woody plants in the study areas showed the largest abundance (range: >50-100%) at the height class >0-2m. Tree equivalents per hectare of encroaching woody plants were negatively correlated (r = -0.60) with ECI and WPC and positively correlated (r=0.87) with percentage bare ground. The correlation (r = 0.50) between percentage bare ground and soil compaction was positive and low. Although the government ranch had a greater composition of highly palatable grass species than the other land uses, the rangeland was not in good condition due to severe bush encroachment. The communal land was generally in poor condition. In the traditional grazing reserve, bush encroachment was not a problem, but the productivity of the grass layer was poor when assessed on the basis of ecological and palatability merits. The negative interaction of TE density of all encroaching woody plants combined with ECI or WPC and the positive interaction with bare ground, may suggest that the abundance of these species is more critical in aggravating deterioration in grassland productivity. Therefore, the priority of any bush control program must be towards minimizing the abundance of these woody plants. 相似文献
13.
This study evaluated the effectiveness of two application rates of a coral-derived surfacing material for both traffic and
nontraffic road conditions using simulated rainfall (110–120 mm h−1 for 30–90 min) on 0.75-m (wide) × 5.0-m (long) plots of similar slope (roughly 0.1 m m−1). The coral is a locally available material that has been applied to unpaved roads surfaces on Schoffield Barracks, Oahu,
Hawaii (USA), where this experiment was conducted. The simulations show that compared with a bare control plot, the coral-based
surface application rates of 80 and 160 kg m−2 (equivalent to only 10- and 20-mm thicknesses) reduced road sediment production by 75% and 95%, respectively, for nontraffic
conditions. However, after two passes of the research vehicle during wet conditions, sediment production rates for the two
coral treatments were not significantly different from those on the bare road plots. The overall effectiveness of the coral-derived
surfacing material is unsatisfactory, primarily because the on-road surface thickness associated with the application rates
tested was too small. These rates were selected to bracket those applied to training roads in the study area. Furthermore,
the composition of the coral-based material does not facilitate the development of a sealed, erosion-resistant surface. When
applied at the low rates tested, the coral material breaks down under normal traffic conditions, thereby losing its ability
to counter shearing forces exerted by overland flow on long hillslopes where erosion measures are most needed. These simulations,
combined with observations on roads in the study area, indicate that this material is not an appropriate road surfacing material
for the site—at least for the low application rates examined. These results are preliminary; extended testing of higher applications
rates at the hillslope scale under natural climate and traffic conditions is needed to better judge the effectiveness of this
material over time. 相似文献
14.
This paper describes the programs and policies regarding prairie dog control in the northern Great Plains states of Montana, South Dakota, and Wyoming. The poisoning programs of federal and state agencies are described, along with the statutes and legal mandates that shape agency management of prairie dogs. Current policies on National Grasslands and other federal lands typically limit prairie dogs to small percentages of available potential habitat, to the detriment of prairie dogs and associated species. State programs to assist landowners in prairie dog control differ greatly, employing cost-share incentives (Wyoming) and regulatory fines (South Dakota) to encourage the poisoning of prairie dogs. Prairie dog control is not actively funded or practiced by state or county agencies in Montana. We document federal and state involvement in more than 1 million acres of prairie dog poisoning in the study area during 1978–1992. In combination with undocumented poisoning by private landowners, plague, and shooting, prairie dogs may be experiencing net regional declines, contributing to the disintegration of the prairie dog ecosystem. We recommend that Animal Damage Control operations concerning prairie dogs be terminated, on the basis that they duplicate state programs and are at cross purposes with federal wildlife management programs that seek to perpetuate and/or recover wildlife species that depend on the prairie dog ecosystem. We further recommend that federal range improvement funds be offered as subsidies for the integration of prairie dogs in range management, as opposed to funding prairie dog eradication programs. 相似文献
15.
昆仑山木孜塔格峰北坡藏羚繁殖地的自然植被 总被引:2,自引:0,他引:2
通过对阿尔金山国家级自然保护区内藏羚产羔繁殖期的野外考察,研究了昆仑山木孜塔峰北坡藏羚繁殖地的自然植被及其分布,从繁殖地的自然生态特征按摩了藏羚与其繁殖期栖息生之间的关系。结果表明,藏羚对产羔繁殖地的选择不是基于植被条件,而是选择更加安全的区域作为其产羔繁殖地。 相似文献
16.
Many revegetated landfills have poor cover including bare areas where plants do not grow. This study, on the Bisasar Road Landfill site in South Africa, assessed grass species preferences to microhabitat conditions in a mosaic of patches of well-established grassed areas and bare, nonvegetated areas. Factors, including soil CO2, CH4, O2, nutrients, and other general soil conditions, were measured in relation to species distribution and grass biomass in the field. Cynodon dactylon was the dominant grass in the established grass areas but was less abundant in the areas bordering the bare areas where Paspalum paspalodes and Sporobolus africanus were common. A number of soil factors measured were significantly correlated with grass biomass and these included Mg, Ca, Zn, Mn, K, temperature, moisture, and CO2. However, a laboratory bioassay using the growth of C. dactylon with soils removed from the landfill indicated that there were no differences in the soils from the bare areas and those that supported high plant biomass. Thus, no nutrient deficiency or chemical toxicity was inherent in the soil in the laboratory. The results of the field investigation and bioassay indicated that soil CO2 as a result of landfill gas infiltration into the root zone was probably the main factor causing bare areas on the landfill where no grass species could colonize and grow and that C. dactylon was more sensitive to elevated soil CO2 than other grass species such as P. paspalodes and S. africanus. 相似文献
17.
2005年5,8,10月份对黄河三角洲无棣岔尖、东营市五号桩、小清河口米草分布区与土著植物芦苇分布区的昆虫作了调查,并辅以2003年同期调查资料,结果表明:米草分布区共鉴定出昆虫9种,芦苇分布区鉴定出49种,是米草分布区昆虫种数的5.4倍,米草分布区昆虫种数明显少于芦苇分布区,且优势类群存在很大差异,米草入侵对昆虫的结构、组成与多样性产生了影响。 相似文献
18.
本文报道了1988年8月至1990年5月对釜溪河4个断面调查采集的藻类植物。初步鉴定的藻类植物有176种(含变种),分属于8门,72属。基本弄清了该区段藻类种类组成及数量变化。用污水指示生物,Shannon-weaver指数及Margalef指数评价了水体污染,其结果与理化评价结果基本一致,表明釜溪河除长土断面受到轻污染外,其余断面受到严重污染,发生了不同程度的富营养化。 相似文献
19.
Response of Organic and Inorganic Carbon and Nitrogen to Long-Term Grazing of the Shortgrass Steppe 总被引:3,自引:0,他引:3
We investigated the influence of long-term (56 years) grazing on organic and inorganic carbon (C) and nitrogen (N) contents of the plant–soil system (to 90 cm depth) in shortgrass steppe of northeastern Colorado. Grazing treatments included continuous season-long (May–October) grazing by yearling heifers at heavy (60–75% utilization) and light (20–35% utilization) stocking rates, and nongrazed exclosures. The heavy stocking rate resulted in a plant community that was dominated (75% of biomass production) by the C4 grass blue grama (Bouteloua gracilis), whereas excluding livestock grazing increased the production of C3 grasses and prickly pear cactus (Opuntia polycantha). Soil organic C (SOC) and organic N were not significantly different between the light grazing and nongrazed treatments, whereas the heavy grazing treatment was 7.5 Mg ha–1 higher in SOC than the nongrazed treatment. Lower ratios of net mineralized N to total organic N in both grazed compared to nongrazed treatments suggest that long-term grazing decreased the readily mineralizable fraction of soil organic matter. Heavy grazing affected soil inorganic C (SIC) more than the SOC. The heavy grazing treatment was 23.8 Mg ha–1 higher in total soil C (0–90 cm) than the nongrazed treatment, with 68% (16.3 Mg ha–1) attributable to higher SIC, and 32% (7.5 Mg ha–1) to higher SOC. These results emphasize the importance in semiarid and arid ecosystems of including inorganic C in assessments of the mass and distribution of plant–soil C and in evaluations of the impacts of grazing management on C sequestration. 相似文献
20.
William R. Bidlake 《Journal of the American Water Resources Association》2002,38(1):197-211
ABSTRACT: Reliable estimates of evapotranspiration from areas of wildland vegetation are needed for many types of water-resource investigations. However, little is known about surface fluxes from many areally important vegetation types, and relatively few comparisons have been made to examine how well evapotranspiration models can predict evapotranspiration for soil-, climate-, or vegetation-types that differ from those under which the models have been calibrated. In this investigation at a prairie site in west-central Florida, latent heat flux (λE) computed from the energy balance and alternatively by eddy covariance during a 15-month period differed by 4 percent and 7 percent on hourly and daily time scales, respectively. Annual evapotranspiration computed from the energy balance and by eddy covariance were 978 and 944 mm, respectively. An hourly Penman-Monteith (PM) evapotranspiration model with stomatal control predicated on water-vapor-pressure deficit at canopy level, incoming solar radiation intensity, and soil water deficit was developed and calibrated using surface fluxes from eddy covariance. Model-predicted λE agreed closely with λE computed from the energy balance except when moisture from dew or precipitation covered vegetation surfaces. Finally, an hourly PM model developed for an Amazonian pasture predicted λE for the Florida prairie with unexpected reliability. Additional comparisons of PM-type models that have been developed for differing types of short vegetation could aid in assessing interchangeability of such models. 相似文献