Effects of Long-Term Trampling on the Above-Ground Forest Vegetation and Soil Seed Bank at the Base of Limestone Cliffs

Exposed limestone cliffs in central Europe harbor a highly divers flora with many rare and endangered species. During the past few decades, there has been increasing recreational use of these cliffs, which has caused local environmental disturbances. Successful restoration strategies hinge on identifying critical limitations. We examined the composition of aboveground forest vegetation and density and species composition of seeds in the soil seed bank at the base of four limestone cliffs in mixed deciduous forests that are intensively disturbed by human trampling and at four undisturbed cliffs in the Jura Mountains in northwestern Switzerland. We found that long-term human trampling reduced total aboveground vegetation cover at the base of cliffs and caused a significant shift in the plant-species composition. Compared with undisturbed cliffs, total seed density was lower in disturbed cliffs. Human trampling also altered the species composition of seeds in the soil seed bank. Seeds of unintentionally introduced, stress-tolerant, and ruderal species dominated the soil seed bank at the base of disturbed cliffs. Our findings indicate that a restoration of degraded cliff bases from the existing soil seed bank would result in a substantial change of the original unique plant composition. Active seed transfer, or seed flux from adjacent undisturbed forest areas, is essential for restoration success.     

Comparison of the Vegetation and Seed Bank on Hedge Banks of Different Ages in Brittany,France

The composition of the herbaceous cover and the seed bank of old and recent hedge banks in Brittany were studied and compared. Concentration method was used for seed bank samples. Grimes plant strategies were used to explain observed patterns. The analysis of the seed bank of these hedge banks showed that the species richness and diversity differed in relation to the date of construction of the hedge banks. The seed banks of recent hedge banks were richer and more diversified than those of old hedge banks. Differences in the floristic composition of the established plant cover between the recent and old hedge banks were determined by multivariate analyses. The species exclusively found in the seed bank and in the herb cover of recent hedge banks were mainly grassland species, whereas the species that only occurred on old hedge banks tended to be woodland species. The floristic composition of the two compartments (established vegetation and seed bank) was very different. A multivariate analysis revealed that the difference between the composition of the seed banks of recent and old hedge banks was less than that between the composition of the established vegetation and seed bank of hedge banks of the same age. Both seed bank and vegetation of recent hedge banks were dominated by ruderal species, whereas old hedge vegetation was dominated by stress-tolerant woodland species, indicating that mechanically constructed hedge banks may impose limitations on colonization by late woodland species.     

Grazing effects on sustainable semiarid rangeiands in Patagonia: The state and dynamics of the soil seed bank

The composition of the germinable seed bank was studied in four vegetation states of the Festuca pallescens grasslands in semiarid Patagonia during four years. The aim of this study was to test whether above-ground vegetation states resulting from grazing exclusion or different combinations of grazing and topography are reflected in different states of the germinable seed bank. The size of the total and dicot germinable seed bank was positively related to the total cover in each state. Dicots dominated all germinable seed bank states. Carex patagonica increased its cover as well as its germinable seed bank under grazing disturbance. Grazing did not reduce the germinable seed bank of perennial grasses in uplands where the grazing pressure is lower as compared with slopes. In slopes the germinable seed bank of perennial grasses was significantly reduced by grazing. A reduction of the length of the grazing period in late spring increases the germinable seed bank of perennial grasses both in upland and slope. These results are interpreted in the frame of a model of management techniques where grazing exclusion during late spring and late summer increases the seed bank of the perennial grasses and promotes their establishment in uplands. The artificial addition of seeds of perennial grasses and the manipulation of the soil surface in order to increase "safe sites" appear as management alternatives that deserve further evaluation to improve plant reestablishment in slopes.     

Ecological Impacts of Revegetation and Management Practices of Ski Slopes in Northern Finland

Outdoor recreation and nature-based tourism represent an increasingly intensive form of land use that has considerable impacts on native ecosystems. The aim of this paper is to investigate how revegetation and management of ski runs influence soil nutrients, vegetation characteristics, and the possible invasion of nonnative plant species used in revegetation into native ecosystems. A soil and vegetation survey at ski runs and nearby forests, and a factorial experiment simulating ski run construction and management (factors: soil removal, fertilization, and seed sowing) were conducted at Ruka ski resort, in northern Finland, during 2003–2008. According to the survey, management practices had caused considerable changes in the vegetation structure and increased soil nutrient concentrations, pH, and conductivity on the ski runs relative to nearby forests. Seed mixture species sown during the revegetation of ski runs had not spread to adjacent forests. The experimental study showed that the germination of seed mixture species was favored by treatments simulating the management of ski runs, but none of them could eventually establish in the study forest. As nutrient leaching causes both environmental deterioration and changes in vegetation structure, it may eventually pose a greater environmental risk than the spread of seed mixture species alone. Machine grading and fertilization, which have the most drastic effects on soils and vegetation, should, therefore, be minimized when constructing and managing ski runs.     

Effects of Disturbance Associated With Seismic Exploration for Oil and Gas Reserves in Coastal Marshes

Anthropogenic disturbances in wetland ecosystems can alter the composition and structure of plant assemblages and affect system functions. Extensive oil and gas extraction has occurred in wetland habitats along the northern Gulf of Mexico coast since the early 1900s. Activities involved with three-dimensional (3D) seismic exploration for these resources cause various disturbances to vegetation and soils. We documented the impact of a 3D seismic survey in coastal marshes in Louisiana, USA, along transects established before exploration began. Two semi-impounded marshes dominated by Spartina patens were in the area surveyed. Vegetation, soil, and water physicochemical data were collected before the survey, about 6 weeks following its completion, and every 3 months thereafter for 2 years. Soil cores for seed bank emergence experiments were also collected. Maximum vegetation height at impact sites was reduced in both marshes 6 weeks following the survey. In one marsh, total vegetation cover was also reduced, and dead vegetation cover increased, at impact sites 6 weeks after the survey. These effects, however, did not persist 3 months later. No effects on soil or water properties were identified. The total number of seeds that germinated during greenhouse studies increased at impact sites 5 months following the survey in both marshes. Although some seed bank effects persisted 1 year, these effects were not reflected in standing vegetation. The marshes studied were therefore resilient to the impacts resulting from 3D seismic exploration because vegetation responses were short term in that they could not be identified a few months following survey completion.     

Germinable Soil Seed Banks and the Restoration Potential of Abandoned Cropland on the Chinese Hilly-Gullied Loess Plateau

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.     

Effects of Short- and Long-Term Disturbance Resulting from Military Maneuvers on Vegetation and Soils in a Mixed Prairie Area

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.     

Impacts of Experimentally Applied Mountain Biking and Hiking on Vegetation and Soil of a Deciduous Forest

Many recent trail degradation problems have been attributed to mountain biking because of its alleged capacity to do more damage than other activities, particularly hiking. This study compared the effects of experimentally applied mountain biking and hiking on the understory vegetation and soil of a deciduous forest. Five different intensities of biking and hiking (i.e., 0, 25, 75, 200 and 500 passes) were applied to 4-m-long × 1-m-wide lanes in Boyne Valley Provincial Park, Ontario, Canada. Measurements of plant stem density, species richness, and soil exposure were made before treatment, two weeks after treatment, and again one year after treatment. Biking and hiking generally had similar effects on vegetation and soil. Two weeks after treatment, stem density and species richness were reduced by up to 100% of pretreatment values. In addition, the amount of soil exposed increased by up to 54%. One year later, these treatment effects were no longer detectable. These results indicate that at a similar intensity of activity, the short-term impacts of mountain biking and hiking may not differ greatly in the undisturbed area of a deciduous forest habitat. The immediate impacts of both activities can be severe but rapid recovery should be expected when the activities are not allowed to continue. Implications of these results for trail recreation are discussed.     

Effects of recreational use on forested sites

Impact of recreational activities on soil and vegetation was evaluated in eight forested camping and picnic areas in southern Rhode Island. Forest vegetation consists of mixed-oak and white pine stands. Soils are of granitic glacial till or outwash origin and textures range from loamy sand to find sandy loam. Recreational use resulted in significant compaction of soils as indexed by soil penetration resistance and bulk density. Evidence indicates that compaction influences bulk densities to a depth of about 12.7 cm. Rates of water infiltration are less on recreation areas. Soil water accretion and depletion during the growing season are less rapid on recreation sites than on control sites. Differences are attributed to reduced infiltration, percolation, and rooting activity. Much of the ground surface on recreation areas is devoid of vegetation. The surface consists primarily of bare mineral soil, rock, or litter. The plants most commonly present are grasses. Native ground cover vegetation including tree seedlings, ericaceous shrubs and herbs has been eliminated or greatly reduced by trampling. Damage to tree trunks is common in recreation areas. White pine radial growth and scarlet oak height growth were significantly less on recreation sites. Scarlet oak appears intolerant to heavy recreation use.     

Characteristics of bird communities on surface mine lands in Pennsylvania

A variety of species was observed as either visitors, permanent, or summer residents on surface mines with different ecological adaptations. Passerine species were the most prevalent of the 25 families represented. Bird communities as well as individual species were correlated with the structure and species of vegetation on the mines. The composition of the bird communities changed in response to successional vegetation stages from grassland to forest communities.     

Impact of Fencing on the Recovery of the Ground Flora on Heavily Eroded Slopes of a Deciduous Forest

This paper seeks to outline early stages in the recovery of forest ground flora on eroded slopes impacted by recreation activities and to suggest how these data might be applied in the formulation of management policies for forest recreation areas. Based on a fencing experiment in the Sonian Forest near Brussels, we investigated whether, over a 6-year period, the vegetation was able to recover after having been destroyed by recreation use. Short-term trends in overall species composition were already observable during this 6-year study. Species recovery on eroded hills was related to slope, aspect, and soil type. During the considered time scale, the proportion of hemicryptophytes and the number of ancient forest species increased significantly. A downward trend was detected for Ellenbergs nitrogen and temperature indexes and for the proportion of therophytes and pioneer plants of disturbed places. Changes in species frequencies suggest six recovery strategies: early, late, expanding, disappearing, transient, and fluctuating species. Aside from seedling reproduction from overstory influences, Luzula sylvatica appeared to be the most resilient of the species identified in the study since this species has the highest global frequency in our sampling plots and has increased its cover during the study period. Study results indicate that (1) protection from recreation has initiated the recovery of species in the herb layer, but (2) it may take a long time before vegetation previously present in the ground flora may recover in both density and species composition.     

The Interactive Effects of Fire and Diversity on Short-Term Responses of Ecosystem Processes in Experimental Mediterranean Grasslands

We conducted a field experiment using constructed communities to test whether species richness contributed to the maintenance of ecosystem processes under fire disturbance. We studied the effects of diversity components (i.e., species richness and species composition) upon productivity, structural traits of vegetation, decomposition rates, and soil nutrients between burnt and unburnt experimental Mediterranean grassland communities. Our results demonstrated that fire and species richness had interactive effects on aboveground biomass production and canopy structure components. Fire increased biomass production of the highest-richness communities. The effects of fire on aboveground biomass production at different levels of species richness were derived from changes in both vertical and horizontal canopy structure of the communities. The most species-rich communities appeared to be more resistant to fire in relation to species-poor ones, due to both compositional and richness effects. Interactive effects of fire and species richness were not important for belowground processes. Decomposition rates increased with species richness, related in part to increased levels of canopy structure traits. Fire increased soil nutrients and long-term decomposition rate. Our results provide evidence that composition within richness levels had often larger effects on the stability of aboveground ecosystem processes in the face of fire disturbance than species richness per se.     

Soil, Vegetation, and Seed Bank of a Sonoran Desert Ecosystem Along an Exotic Plant (Pennisetum ciliare) Treatment Gradient

Ecological conditions following removal of exotic plants are a key part of comprehensive environmental management strategies to combat exotic plant invasions. We examined ecological conditions following removal of the management-priority buffelgrass (Pennisetum ciliare) in Saguaro National Park of the North American Sonoran Desert. We assessed soil, vegetation, and soil seed banks on seven buffelgrass site types: five different frequencies of buffelgrass herbicide plus hand removal treatments (ranging from 5 years of annual treatment to a single year of treatment), untreated sites, and non-invaded sites, with three replicates for each of the seven site types. The 22 measured soil properties (e.g., pH) differed little among sites. Regarding vegetation, buffelgrass cover was low (≤1 % median cover), or absent, across all treated sites but was high (10–70 %) in untreated sites. Native vegetation cover, diversity, and composition were indistinguishable across site types. Species composition was dominated by native species (>93 % relative cover) across all sites except untreated buffelgrass sites. Most (38 species, 93 %) of the 41 species detected in soil seed banks were native, and native seed density did not differ significantly across sites. Results suggest that: (1) buffelgrass cover was minimal across treated sites; (2) aside from high buffelgrass cover in untreated sites, ecological conditions were largely indistinguishable across sites; (3) soil seed banks harbored ≥12 species that were frequent in the aboveground vegetation; and (4) native species dominated post-treatment vegetation composition, and removing buffelgrass did not result in replacement by other exotic species.     

CHANNEL RESPONSE FROM SHRUB DOMINATED RIPARIAN COMMUNITIES AND ASSOCIATED EFFECTS ON SALMONTD HABITAT1

ABSTRACT: We surveyed first‐to third‐order streams (channel widths from 1.4 to 10 m) in the southeastern slopes of the Cascade Range of Washington and found two distinct endpoints of riparian vegetation. Where the forest overstory is dominated by park‐like Ponderosa pine (Pinus ponderosa), channels are commonly bordered with a dense scrub‐shrub vegetation community. Where fire suppression and/or lack of active riparian zone management have resulted in dense encroachment of fir forests that create closed forest canopies over the channel, scrub‐shrub vegetation communities are virtually absent near the channel. Other factors being equal, distinct differences in channel morphology exist in streams flowing thru each riparian community. The scrub‐shrub channels have more box‐like cross‐sections, lower width‐to‐depth ratios, more pools, more undercut banks, more common sand‐dominated substrates, and similar amounts of woody debris (despite lower tree density). Temperature comparisons of forest and scrub‐shrub sections of two streams indicate that summer water temperatures are slightly lower in the scrub‐shrub streams. We surmise that these morphology and temperature effects are driven by differences in root density and canopy conditions that alter dynamic channel processes between each riparian community. We suspect that the scrub‐shrub community was more common in the landscape prior to the 20th century and may have been the dominant native riparian community for these stream types. We therefore suggest that managing these streams for dense riparian conifer does not mimic natural conditions, nor does it provide superior in‐stream habitat.     

Forest restoration potentials of coal-mined lands in the eastern United States

The Appalachian region in the eastern United Sates is home to the Earth's most extensive temperate deciduous forests, but coal mining has caused forest loss and fragmentation. More than 6000 km in Appalachia have been mined for coal since 1980 under the Surface Mining Control and Reclamation Act (SMCRA). We assessed Appalachian areas mined under SMCRA for forest restoration potentials. Our objectives were to characterize soils and vegetation, to compare soil properties with those of pre-SMCRA mined lands that were reforested successfully, and to determine the effects of site age on measured properties. Soils were sampled and dominant vegetation characterized at up to 10 points on each of 25 post-SMCRA mines. Herbaceous species were dominant on 56%, native trees on 24%, and invasive exotics on 16% of assessed areas. Mean values for soil pH (5.8), electrical conductivity (0.07 dS m(-1)), base saturation (89%), and coarse fragment content (50% by mass) were not significantly different from measured levels on the pre-SMCRA forested sites, but silt+clay soil fraction (61%) was higher, bicarbonate-extractable P (4 mg kg(-1)) was lower, and bulk density (1.20 g cm(-1)) was more variable and often unfavorable. Pedogenic N and bicarbonate-extractable P in surface soils increased with site age and with the presence of weathered rocks among coarse fragments. Our results indicate a potential for many of these soils to support productive forest vegetation if replanted and if cultural practices, including temporary control of existing vegetation, soil density mitigation, and fertilization, are applied to mitigate limitations and aid forest tree reestablishment and growth.     

IMPACTS OF RECREATION ON RIPARIAN SOILS AND VEGETATION1

ABSTRACT: The seemingly magnetic attraction of water resources for recreation has direct implications for proximate land resources which are needed to provide access and support facilities. This paper reviews and synthesizes the literature dealing with the impacts of recreation use on riparian soils and vegetation. Part one of the paper sets forth the major negative impacts of recreation use on soils and vegetation. A seven-step soil impact cycle is identified, beginning with the scuffing away of leaf litter and other organic material and working through the soil erosion and sedimentation process. Four major kinds of impacts of recreation use on vegetation are then outlined, and the‘Vicious circle” relationship between impacts on soil and vegetation is demonstrated through a Soil/Vegetation Impact Diagram. Part two identifies several spatial and temporal patterns of environmental impact caused by recreation use. The node and linkage pattern of recreation use, campground and trail expansion, ground cover response and succession, rates of soil compaction, and resource response to various intensities of recreation use are important aspects. The final part of the paper deals with measuring environmental impacts caused by recreation use. Management implications of the research findings are considered throughout the paper.     

Assessment of Vegetation Establishment on Tailings Dam at an Iron Ore Mining Site of Suburban Beijing, China, 7 Years After Reclamation with Contrasting Site Treatment Methods

Strip-mining operations greatly disturb soil, vegetation and landscape elements, causing many ecological and environmental problems. Establishment of vegetation is a critical step in achieving the goal of ecosystem restoration in mining areas. At the Shouyun Iron Ore Mine in suburban Beijing, China, we investigated selective vegetation and soil traits on a tailings dam 7 years after site treatments with three contrasting approaches: (1) soil covering (designated as SC), (2) application of a straw mat, known as “vegetation carpet”, which contains prescribed plant seed mix and water retaining agent (designated as VC), on top of sand piles, and (3) combination of soil covering and application of vegetation carpet (designated as SC+VC). We found that after 7 years of reclamation, the SC+VC site had twice the number of plant species and greater biomass than the SC and VC sites, and that the VC site had a comparable plant abundance with the SC+VC site but much less biodiversity and plant coverage. The VC site did not differ with the SC site in the vegetation traits, albeit low soil fertility. It is suggested that application of vegetation carpet can be an alternative to introduction of topsoil for treatment of tailings dam with fine-structured substrate of ore sands. However, combination of topsoil treatment and application of vegetation carpet greatly increases vegetation coverage and plant biodiversity, and is therefore a much better approach for assisting vegetation establishment on the tailings dam of strip-mining operations. While application of vegetation carpet helps to stabilize the loose surface of fine-structured mine wastes and to introduce seed bank, introduction of fertile soil is necessary for supplying nutrients to plant growth in the efforts of ecosystem restoration of mining areas.     

Water‐Yield Reduction After Afforestation and Related Processes in the Semiarid Liupan Mountains,Northwest China1

Abstract: The increase of coverage of forest/vegetation is imperative to improve the environment in dry‐land areas of China, especially for protecting soil against serious erosion and sandstorms. However, inherent severe water shortages, drought stresses, and increasing water use competition greatly restrict the reforestation. Notably, the water‐yield reduction after afforestation generates intense debate about the correct approach to afforestation and forest management in dry‐land areas. However, most studies on water‐yield reduction of forests have been at catchment scales, and there are few studies of the response of total evapotranspiration (ET) and its partitioning to vegetation structure change. This motivates us to learn the linkage between hydrological processes and vegetation structure in slope ecosystems. Therefore, an ecohydrological study was carried out by measuring the individual items of water balance on sloping plots covered by different vegetation types in the semiarid Liupan Mountains of northwest China. The ratio of precipitation consumed as ET was about 60% for grassland, 93% for shrubs, and >95% for forestland. Thus, the water yield was very low, site‐specific, and sensitive to vegetation change. Conversion of grassland to forest decreased the annual water yield from slope by 50‐100 mm. In certain periods, the plantations at lower slopes even consumed the runon from upper slopes. Reducing the density of forests and shrubs by thinning was not an efficient approach to minimize water use. Leaf area index was a better indicator than plant density to relate ET to vegetation structure and to evaluate the soil water carrying capacity for vegetation (i.e., the maximum amount of vegetation that can be supported by the available soil water for an extended time). Selecting proper vegetation types and plant species, based on site soil water condition, may be more effective than the forest density regulation to minimize water‐yield reduction by vegetation coverage increase and notably by reforestation. Finally, the focuses in future research to improve the forest‐water relations in dry‐land areas are recommended as follows: vegetation growth dynamics driven by environment especially water conditions, coupling of ecological and hydrological processes, further development of distributed ecohydrological models, quantitative relation of eco‐water quota of ecosystems with vegetation structures, multi‐scaled evaluation of soil water carrying capacity for vegetation, and the development of widely applicable decision support tools.     

Altered ecohydrologic response drives native shrub loss under conditions of elevated nitrogen deposition

Many regions of southern California's coastal sage scrub (CSS) are rapidly declining as exotic annual plants replace native shrubs. During this conversion, the subsurface hydrology of the semiarid hillslopes that support CSS may be altered. This could chronically suppress the ability of native shrubland to revegetate the landscape since ecosystem processes of nutrient availability and of seedling establishment rely on spatial patterns of available soil water. In this work, soil water and nutrient N regimes were compared over a 2-yr period between a southern California site where CSS has declined (approximately 5% shrub cover) with high additions of anthropogenic N, and one where CSS remains dominant (over 50% shrub cover) with predominantly background atmospheric additions of N. These two sites have similar climate, bedrock lithology, soils, and topography, and had the same vegetation type (Riversidean CSS) 30 years ago. We found that the depth and rate of rainwater percolation into wildland hillslope soils in response to early-season storm events has been greatly reduced after loss of CSS shrubs and vegetation type conversion to invasive grassland. With decreased rainwater redistribution to soil depths of 100 to 150 cm, the predominant zone of soil water has become the upper 25 cm. This shift exacerbates vegetation type conversion by (i) concentrating smog-produced nitrogenous (N) chemicals in the uppermost soil, where they become readily available, along with high soil water, to shallow-rooted exotic grasses early in the growing season and (ii) depriving adult and juvenile shrubs of deeper regolith water.     

Carbon and nitrogen losses by surface runoff following changes in vegetation

Rainfall simulation experiments were conducted on annual grassland and coastal sage scrub hillslopes to determine the quantities of C and N removed by surface runoff in sediment and solution. Undisturbed coastal sage scrub soils have very high infiltration capacities (> 140 mm h(-1)), preventing the generation of surface runoff. Trampling disturbance to the sage scrub plots dramatically reduced infiltration capacities, increasing the potential for surface runoff and associated nutrient loss. Infiltration capacities in the grassland plots (30-50 mm h(-1)) were lower than in the sage scrub plots. Loss rates of dissolved C and N in surface runoff from grasslands were 0.5 and 0.025 mg m(-2) s(-1) respectively, with organic N accounting for more than 50% of the dissolved N. Total dissolved losses with simulated rainfall were higher than losses in simulations with just surface runoff, demonstrating the importance of raindrop impact in transferring solutes into the flow. Experimental data were incorporated into a numerical model of runoff and sediment transport to estimate hillslope-scale sediment-bound nutrient losses from grasslands. According to the model results, sediment-bound nutrient losses are sensitive to the density of vegetation cover and rainfall intensity. The model estimates annual losses in surface runoff of 0.2 and 0.02 g m(-2) for sediment-hound C and N, respectively. The results of this study suggest that conversion of coastal sage scrub to annual grasslands increases hillslope nutrient losses and may affect stream water quality in the region.