Soil Surface Disturbance Research Articles

Factors limiting rosette recruitment in scarlet gilia, Ipomopsis aggregata : seed and disturbance limitation

We performed a factorial combination of seed additions, surface soil disturbance, and protection from potential seed predation in experimental plots to elucidate the relative importance of each factor in the recruitment of scarlet gilia seedlings. We detected a significant interaction between seed addition and surface soil disturbance on seedling recruitment over 2 years of establishment. Plots that received both supplemental seed addition and disturbance established 10.5 times as many rosettes as control plots. We did not detect main or interactive effects of caging on seedling establishment. We explored the importance of density-dependent recruitment by investigating the number of rosettes per experimental plot through time. In addition, we used planned contrasts to compare the absolute and percent changes in control and treatment plot rosette densities between the study years. We found significant downward concave curvature to the seedling recruitment curve, suggesting negative density-dependent recruitment across the experimental range of rosette densities. We found a significant difference between the control plots and the seed addition-disturbance plots in terms of absolute changes in plot density from 1997 to 1998. Greater net mortality occurred in plots that received both seed addition and disturbance. However, we found no differences among treatments in the percent change in rosette density across the study years. Our study demonstrates that seedling recruitment in natural plant populations may be limited by the interaction of seed and microsite availability, and that seedling recruitment in scarlet gilia may be negatively density dependent. Our results suggest that the fecundity effects of particular plant-animal interactions (e.g., pollination, herbivory) may affect scarlet gilia population dynamics, particularly under conditions of high soil disturbance.

Effects of surface disturbance and light level on seedling emergence in a Japanese secondary deciduous forest

Abstract. The effects of soil surface disturbance and light level on seedling emergence were examined by creating experimental conditions differing in soil surface treatment and light level in a temperate deciduous broadleaved secondary forest in central Japan. The results of MANOVA showed that soil surface disturbance exerted a favourable influence upon the seedling emergence of many species. Effect of soil disturbance on total density and number of emerged species was greater than that of a high light level. The interaction between soil surface disturbance and light level revealed significant positive effects for seedling emergence, especially for small‐seeded species. The relationship between the percentage of emerged seedlings and seed weight was significantly negative in the soil‐surface disturbed and high light level condition, suggesting that minute‐seeded species largely depend on both factors for seedling emergence. Both soil surface disturbance and high light level had a positive effect on the number of emerged species, suggesting that these factors contributed to species richness at the stage of seedling emergence.

No-till Vegetable Production—Its Time is Now

Advantages of no-till (NT) production systems are acknowledged throughout the world. During the 1990s, production of NT vegetable crops has increased for both direct seeded and transplanted crops. Increased interest in reduced-tillage systems among research workers and vegetable growers is attributed to: 1) development and commercialization of NT transplanters and seeders, 2) advancements in the technology and practice of producing and managing high-residue cover crop mulches, and 3) improvements and acceptance of integrated weed management techniques. Results from research experiments and grower's fields over the years has shown that success with NT transplanted crops is highly dependent on achieving key production objectives, including: 1) production of dense, uniformly distributed cover crops; 2) skillful management of cover crops before transplanting, leaving a heavy, uniformly distributed killed mulch cover over the soil surface; 3) establishment of transplants into cover crops with minimum disturbance of surface residues and surface soil; and 4) adoption of year-round weed control strategies.

Effects of soil surface disturbance on vegetation recovery following a scrub fire on Mt. Tenjo, Kozu-shima Island, Japan.

Effects of soil surface disturbance on vegetation recovery following a scrub fire on Mt. Tenjo, Kozu-shima Island, Japan.

Sources of plants colonizing experimentally disturbed patches in an acidic grassland, in eastern England

1 The sources of propagules for regeneration in an acidic grassland were identified from analysis of differences in colonization between plots subject to surface (0–5 cm) soil disturbance and plots where surface soil had been replaced by ‘seed‐free’ soil from deeper soil horizons (30–35 cm), and between plots with and without the removal of rabbit pellets. 2 After 1 year, 10 species had a significantly higher cover on plots where the seed bank had been left intact. These included Agrostis capillaris (the dominant species prior to disturbance), Myosotis arvensis and Veronica arvensis. 3 Five species, including Sagina apetala, Senecio jacobaea and Veronica arvensis, showed significantly higher cover on plots where rabbit pellets were left in situ. 4 From calculations it appeared that rabbit‐dispersed seeds accounted for 15% of the developing higher plant cover, other means of dispersal from outside the plot accounted for 40%, and regeneration from the seed bank accounted for 45%. 5 Similar calculations suggested that three higher plant species, Geranium molle, Myosotis arvensis and Senecio jacobaea, appeared to depend most on non‐rabbit dispersed seed for colonization of bare ground. 6 High concentrations of Urtica dioica in pellets contrasted with its poor establishment in the experiment. However, the other common species in the pellets, Sagina apetala, Senecio jacobaea and Veronica arvensis, all established in greater numbers on the plots where the pellets were not removed. 7 Seed bank content correlated well with the pattern of regeneration for Agrostis capillaris, Holcus lanatus, Myosotis arvensis and Veronica arvensis. However, removal of the seed bank did not have a significant effect on the regeneration of either of the most common species in the seed bank, Rumex acetosella and Sagina apetala. 8 No species appeared to be reliant on only one mechanism for regeneration from seed in disturbed areas in this community.

Sedimentary characteristics of drifting sediments above an eroding loessal sandy loam soil as affected by mechanical disturbance

Our understanding of the physical mechanisms of wind erosion and dust emission stimulated by disturbance of surface soils is not adequate, even though it is a problem leading to desertification in the arid zone. Simulations of the influence of surface soil disturbance ratios on wind erosion and sedimentary characteristics of an eroded loessal sandy loam soil were conducted in an indoor wind tunnel. The results showed that the grain-size composition of the drifting soil was finer than, though similar to, the original soil, as the surface disturbance ratio increased. Wind erosion on the loessal sandy loam soil was selective. The eroded sediments were poorly sorted and became poorer with increases in the disturbance ratio and wind speed. The relative proportion of suspension population increased with increasing disturbance ratio. Several parameters such as the pattern of the frequency distribution curves, skewness and kurtosis reflected the dependence of the sedimentary characteristics of the drifting sediments on the eroding source soil. Soil erosion and dust emission by wind in drylands can be reduced by reducing unnecessary mechanical disturbance during erosion seasons.

Ground-penetrating Radar Techniques and Three-dimensional Computer Mapping in the American Southwest

New techniques of ground-penetrating radar (GPR) acquisition and computer processing were tested at archaeological sites in the American Southwest and found to be highly effective in producing images of buried archaeological features. These new methods, especially amplitude slice-maps, were combined with more standard data processing and interpretation techniques and tested at sites with little or no surface expression. In southern Arizona, numerous pit structures buried in terrace alluvium were discovered and mapped. In the Four Corners region, a Chaco period great kiva and other pit structures and features were mapped by GPR and later confirmed through excavation. At some sites, GPR surveys did not successfully identify buried archaeological features. These failed surveys highlight both geological and methodological problems including soil conditions, surface disturbance, and equipment calibration that may be avoided or ameliorated in future GPR surveys.

Seedling emergence of Betula maximowicziana following human disturbance and the role of buried viable seeds

We observed seed rain and seedling emergence of a pioneer tree species, Betula maximowicziana Regel., for 5 years at various sites differing in canopy and soil surface conditions, and clarified that a buried seed bank contributed to the recruitment of B. maximowicziana seedlings. More seedlings emerged at sites where the soil surface had been disturbed than at sites where the soil surface had not been disturbed. Within each soil surface condition, the densities of the emerged seedlings were generally proportional to the densities of the seeds dispersed the previous year. However, the seedling densities were disproportionately higher than the dispersed seed densities at the sites where the soil surface had been disturbed in the previous year. Soil samples taken during different seasons indicated that B. maximowicziana maintained a persistent seed bank in the soil below 1 cm deep, while it formed a more transient seed bank in the top 1 cm of the soil. The seed rain in the previous year was the primary contributor to the establishment of B. maximowicziana seedlings in a year after a mast seed year. On the other hand, the soil seed bank had a compensational role in a year after a poor seed year. Canopy cover did not affect seedling emergence. Therefore, the previously reported lack of a persistent seedling bank of B. maximowicziana under a canopy will be partially attributed to a relatively rare soil surface disturbance in a stable stand.

Community Structure and Regulatory Mechanism of Pest Populations in Rice Paddies Cultivated Under Intensive, Traditionally Organic and Lower Input Organic Farming in Japan

ABSTRACT Three different rice production systems in the Chugoku district of southwestern Japan were compared to characterize differences in the arthropod community structures and insect pest regulatory mechanisms. In older traditionally organic rice paddy fields, Nilaparvata lugens was uncommon and was controlled by the sedentary nematode parasite, Agamermis unka. In contrast, in intensively farmed rice paddies, N. lugens was very abundant and A. unka was absent. There were no differences between the intensive paddies and younger traditional paddies. In addition, differences of abundance in spider and collembola populations were not clear in these paddies. In lower-input organic farming systems with no-tillage and winter legume mulch, Sogatella furcifera was much less abundant, and the most important predators, sedentary lycosids, were much more abundant than in the traditionally managed paddy. Densities of N. lugens were similar, but A. unka was not present in the lower-input organic systems. These sedentary natural enemies were more abundant in paddy fields farmed with less soil surface disturbance.

5540288 Primary tillage unit with reduced disturbance of surface soil and residue : Dietrich William J Congerville, IL, United States assigned to DMI Inc

5540288 Primary tillage unit with reduced disturbance of surface soil and residue : Dietrich William J Congerville, IL, United States assigned to DMI Inc

Soil surface disturbances in cold deserts: effects on nitrogenase activity in cyanobacterial-lichen soil crusts

Soil surface disturbances in cold deserts: effects on nitrogenase activity in cyanobacterial-lichen soil crusts

A comparison of relative abundance and biomass of ground-dwelling arthropods under different forest management practices

Habitat structural characteristics and relative abundance and biomass of ground-dwelling arthropods were compared among four replicated stand treatments: intense burning and salvage logging; clearcutting follwed by roller-chopping (100% soil surface disturbance); clearcutting followed by bracke seeding (30% soil surface disturbance); and naturally regenerated mature, forested sand pine scrub. Arthropods were classified by taxa and by mean maximum width. Monthly trends in abundance and biomass of arthropods captured are described. Mature forest differed from the three disturbance treatments in most habitat structural features, but disturbance treatments were similar. Total numbers and dry weight did not differ among treatments but more individuals and biomass of arthropods less than 5 mm mean maximum width occurred in burned sites. These were significantly more arthropods 10 mm or less in mean maximum width than over 10 mm, but arthropods 5–10 mm had the highest biomass. The relative abundance of some taxa differed among treatments, and taxa differed in monthly capture rates. Total numbers and biomass of captured arthropods were greatest from late May through November.

Soil surface disturbances in cold deserts: effects on nitrogenase activity in cyanobacterial-lichen soil crusts

CyanobacteriaMichen soil crusts can be a domi- nant source of nitrogen for cold-desert ecosystems. Effects of surface disturbance from footprints, bike and vehicle tracks on the nitrogenase activity in these crusts was inves- tigated. Surface disturbances reduced nitrogenase activity by 30-100%. Crusts dominated by the cyanobacterium Microcoleus vaginatus on sandy soils were the most sus- ceptible to disruption; crusts on gypsiferous soils were the least susceptible. Crusts where the soil lichen Collema te- nax was present showed less immediate effects; however, nitrogenase activity still declined over time. Levels of ni- trogenase activity reduction were affected by the degree of soil disruption and whether sites were dominated by cya- nobacteria with or without heterocysts. Consequently, anthropogenic surface disturbances may have serious im- plications for nitrogen budgets in these ecosystems.

Effects of bannertail kangaroo rat mounds on small-scale plant community structure.

The effects of bannertail kangaroo rat (Dipodomys spectabilis) mounds and associated soil-surface disturbance on plant species composition and diversity in the Chihuahuan Desert were examined with multivariate analysis. Kangaroo rat mounds created disturbance gaps and contributed to local species diversity by creating microhabitats that supported unique plant communities. These microhabitats supported populations of species that were relatively rare in surrounding areas. The diversity observed at the whole habitat level resulted from (1) local spatial heterogeneity, because the mounds offered microenvironments with distinctive nutrient, water, and light conditions; and (2) local patterning of disturbance, because the digging and traffic of the kangaroo rats maintained high levels of soil disturbance at and near the mounds. At a finer scale, species diversity was highest in the area immediately adjacent to active and inactive mounds, and was lower on both the highly disturbed soil of the mounds and in the relatively undisturbed area between mounds. Lowest species diversity occurred on inactive mounds. Annual plant biomass was much greater on mounds than in inter-mound areas. The results support the predictions that intermediate levels of disturbance and small-scale environmental heterogeneity contribute to supporting high species diversity.

Environmental damage from tracked vehicle operation

Soil surface forces resulting from traffic tracked vehicles can cause environmental damage by decreasing plant development and increasing erosion. This paper investigates the soil surface disturbance from tracked vehicle operation. Sharp turns (lower turning radius) from M113 operation produce increased disturbed widths and more severe vegetation damage. The pad-load ratio for the M113 track shoe was determined at various loads. The soil rut produced from tracked vehicle operation was determined at various driving models (straight, smooth turn, sharp turn). The width and depth of track rut and height of soil piled increased when the tracked vehicle negotiated a sharp turn. The results of this study indicate for the soil conditions tested, the width of disturbance is dependent on the operating characteristics of the vehicle. A vehicle conducting sharp turns will disturb a larger width of soil than a vehicle travelling straight or conducting smooth turns.

The effect of initial soil water content and vegetative cover on surface soil disturbance by tracked vehicles

A field trial was conducted to examine the effect of initial soil water content and vegetative cover on soil disturbance caused by tracked military vehicles. Disturbance was measured as depth of rut produced. Soil disturbance increased as the number of passes and turns increased, but especially after turning manoeuvres. Greater disturbance occurred on reduced vegetation plots and with increasing initial soil water content. Simple regression analysis was undertaken to determine which factor had the greatest influence on disturbance.

Vegetation pattern and microtopography on a landslide scar of Mt Kiyosumi, central Japan

AbstractVegetation pattern and microtopography were examined on a mountain slope with a rotational type landslide scar on Mt Kiyosumi, central Japan. Similarities of distribution patterns among 55 woody species were calculated using Cole's species association coefficient, and based on them, seven vegetation units were classified using cluster analysis and principal coordinates analysis. The seven vegetation units coincide with seven microtopographical facets at 101 to 102 m2 order. Furthermore, these vegetation units were grouped into three higher categories by reciprocal averaging and principal coordinates analysis. They were ridge slopes, surrounding slopes and landslide slopes. The three categories were arranged in the above‐mentioned order based on similarity in floristic composition. In the ridge slopes, late‐successional trees and deciduous trees had high relative basal areas. In the surrounding slopes, Euptelea polyandra and other deciduous trees had high relative basal areas. In the landslide slopes, E. polyandra and deciduous shrubs had high relative basal areas. The density and the age distributions of E. polyandra, a typical pioneer tree which invades disturbed sites, suggested that the severity of soil surface disturbances increase in this order. The disturbance regime explains the vegetation pattern on the study site, where the rotational type landslide had occurred.

Species structure of artificial grasslands with Zoysia japonica STEUD in Pyongyang, North Korea

AbstractIn Far East (mainly in Japan), considerable attention has been devoted to weeds of many types of seminatural and artificial vegetation. It allows us to compare the weed flora of artifical grasslands (seeded and planted) dominated by Zoysia japonica in Pyongyang (the capital of North Korea) with other similar communities.Some of the dominant or common species of the artificial monocoenoses with Z. japonica (Tables 1a, 1b, 2; Fig. 4) may be considered dangerous for field crops and seeded meadows. There are, especially, Kummerowia striata and Viola mandshurica. Of the rare species there are Oxalis corniculata, Equisetum arvense and Setaria viridis.Many weed species of the studied artificial grasslands also occur in intensive pastures with Zoysia japonica in Japan (Table 3). This similarity of both vegetation types is ascribed to a similar way of disturbance of vegetation and soil surface (grazing and trampling by livestock on the one hand and cutting and weeding on the other) and by the occurrence of the same dominant.Artificial grasslands in Pyongyang were classified as Zoysia japonica community. Four groups of phytosociological relevés were distinguished by using the ordination technique DCA and its comparison with BRAUN‐BLANQUET (Tables 1a, 1b, 2; Fig. 3).

Zero-tillage furrow opener effects on seed environment and wheat emergence

Optimum emergence is necessary to attain maximum crop yields, particularly in reduced and zero-tillage systems. However, zero-tillage seeder performance under zero-tillage conditions is not always adequate, and thus may limit potential yield benefits from this soil and water conserving practice. A study was conducted to measure the range of influence of zero-tillage openers on some soil physical properties of the soil-seed environment. Furrow opener design has direct consequences on soil surface disturbance, furrow compaction levels, and post-seeding soil water requirements in the seed row. While soil temperature and wheat cultivar differed between two distinct field trials, furrow opener designs conducive to adequate compaction of seed furrow with press wheels consistently resulted in better wheat emergence, when soil water potentials were not limiting. This study demonstrates that seeding tool design has a quantifiable influence on seed furrow properties, and that this information can be used to develop precise guidelines for future designs of furrow openers and press wheels.

NO-TILL SEEDERS EFFECTS ON SEED ZONE PROPERTIES AND WHEAT EMERGENCE

ABSTRACT Four no-till seeders were evaluated to determine their effects on soil-seed environment properties, soil water and temperature regimes in seed rows, and subsequent spring wheat emergence in the Pacific Northwest. All treatment variability in wheat emergence could not be explained by differences in seeding depth alone. A seeder equipped with hoe openers (HZ-hoe) protruding below seed placement depth resulted in deep seed placement, extensive disturbance of soil surface, loose seed row environment, and high rate of water loss from seed rows. These factors contributed to slower and lower emergence compared to a seeder with double disc opener (USDA II) which opens seed furrows with minimum soil tillage. Fertilizer placement features with three of these seeders generally increased furrow surface roughness and drying rate of the seed rows compared to the USDA 11 seeder. In contrast, hoe openers of the HZ-hoe seeder, modified for fertilizer placement below the seed, improved seed zone soil water regimes for a short period after seeding by bringing up moist soil from beneath seeding depth.