Thickness Of Organic Horizons Research Articles

Grey alder at the regeneration stage: Long-term effects on soil nitrogen and carbon pools and Norway spruce growth

Increasing soil N availability is an effective way to enhance soil organic carbon (SOC) sequestration and biomass production in N-limited ecosystems such as boreal Norway spruce forests. Alder has a root nodule symbiosis with Frankia, an N2-fixing bacterium, and can thus add considerable amounts of N to soil mainly through its N-rich leaf litter. The objective of this study was to determine whether the presence of grey alder at the regeneration stage had any long-term effects on soil C and N cycling and stocks and spruce growth. The study sites were two relatively fertile 40-year-old Norway spruce stands (Luhdansuo and Porkkola) in Southern Finland. At both study sites, half the spruce stand had an admixture of grey alders for approximately 10–15 years after regeneration (alder treatment), but no alder had been present in the other half (control treatment). Alders were cut from the alder treatment 25 (Luhdansuo) or 30 (Porkkola) years before the measurements. At Porkkola, alder treatment received ash fertilisation 13 years ago. We observed no significant differences in the plant-available N fluxes, measured with a microdialysis technique, or SOC stocks between treatments. The total N stock (organic horizon + 0–30 cm mineral soil) and organic horizon thickness were larger, while the microbial biomass C:N and C mineralisation rate were lower in the alder versus the control treatment at Luhdansuo. The annual ring widths of spruces were larger in the alder versus the control treatment for up to six years after alder removal at both sites, but no differences were observed in the current tree diameters or diameter increments. In conclusion, most of the current soil or tree properties did not differ significantly between treatments, possibly because the effect of alder had faded out over the 25–30 years since its removal, and because the sites were initially relatively fertile.

Past Disturbance–Present Diversity: How the Coexistence of Four Different Forest Communities within One Patch of a Homogeneous Geological Substrate Is Possible

Understanding the relationship between disturbance and forest community dynamics is a key factor in sustainable forest management and conservation planning. The study aimed to determine the main factors driving unusual differentiation of forest vegetation into four communities, all coexisting on the same geological substrate. The fieldwork, conducted on the fluvioglacial sand area in Central Poland, consisted of vegetation sampling, together with soil identification and sampling, up to depths of 150 cm. Additional soil parameters were measured in the laboratory. A Geographical Information System was applied to assess variables related to topography and forest continuity. Vegetation was classified and forest communities identified. Canonical Correspondence Analysis indicated significant effects of organic horizon thickness, forest continuity, soil disturbance and soil organic matter content on vegetation composition. We found that the coexistence of four forest communities, including two Natura 2000 habitats, a Cladonia-Scots pine forest and an acidophilous oak forest (codes–91T0 and 9190 respectively), resulted from former agricultural use of the land followed by secondary succession. The lowest soil-disturbance level was observed within late-successional acidophilous oak forest patches. Nearly complete soil erosion was found within the early-successional Cladonia-Scots pine forest. We propose that both protected habitat types may belong to the same successional sere, and discuss the possibility of replacement of the early- and late-successional forest habitat types in the context of sustainable forest management and conservation.

Molecular trade-offs in soil organic carbon composition at continental scale

The molecular composition of soil organic carbon remains contentious. Microbial-, plant- and fire-derived compounds may each contribute, but whether they vary predictably among ecosystems remains unclear. Here we present carbon functional groups and molecules from a diverse spectrum of North American surface mineral soils, collected primarily from the National Ecological Observatory Network and quantified by nuclear magnetic resonance spectroscopy and a molecular mixing model. We find that soils vary widely in relative contributions of carbohydrate, lipid, protein, lignin and char-like carbon, but each compound class has similar overall abundance. Ninety percent of the variance in carbon composition can be explained by three principal component axes representing a trade-off between lignin and protein, a trade-off between carbohydrate and char, and lipids. Reactive aluminium, crystalline iron oxides and pH plus overlying organic horizon thickness—predictors that are all related to climate—best explain variation along each respective axis. Together, our data point to continental-scale trade-offs in soil carbon molecular composition that are linked to environmental and geochemical variables known to predict carbon mass concentrations. Controversies regarding the genesis of soil carbon and its potential responses to global change can be partially reconciled by considering diverse ecosystem properties that drive complementary persistence mechanisms.

Which generative reproduction characteristics determine successful establishment of the subalpine shrub Pinus mugo?

AbstractQuestionsShrub expansion in arctic, alpine and subalpine areas has been occurring recently due to warming, land abandonment and increasing nitrogen deposition. However, shrub expansion is strongly affected by largely unknown site‐specific regeneration patterns. We evaluated the importance of seed production, suitable microsite availability and seedling survival for seedling establishment of the subalpine conifer shrub Pinus mugo.LocationHrubý Jeseník Mts., Czech Republic (50° N, 17° E).MethodsWe collected data on: (a) seed quantity and quality; (b) seedling microsite preferences; and (c) seedling survival during initial ontogenetic stages. From 2006 to 2016 we assessed cone production annually and tested seed viability every second year. Microsite preferences were analyzed for 650 seedlings at six sites. The following microsite characteristics were recorded for 1‐m2 around each seedling: percentage of bare surface; surrounding plant species cover; surface shape; and organic horizon thickness. Additionally, distance and direction to the nearest adult pine were recorded. Finally, we tested survival of 200 newly established seedlings in relation to microsite type.ResultsSeed source and viability were not critical factors for seedling establishment. Far more important was the presence of suitable bare‐surface microhabitats with thin or no organic layer near mature pine stands. Vegetation communities dominated by Avenella flexuosa and Nardus stricta facilitated seedling establishment; communities dominated by Vaccinium myrtillus showed strong competitive effects on seedlings. Vegetation's effect on seedling establishment was closely related to disturbance regime, which influences vegetation type. Seedling mortality was highest in the first year of life irrespective of microsite vegetation type. Highest mortality was associated with open mineral‐soil microsites, while microsites with dense herbaceous vegetation showed the lowest.ConclusionsPotential Pinus mugo expansion will occur in close proximity to existing mature stands, and its intensity will be strongly modified by site‐specific density of suitable microsites and/or dominant species of host communities.

Effect of environmental factors on the composition of terrestrial bryophyte and lichen species in Scots pine forests on fixed sand dunes

Aim of the study: To investigate terrestrial bryophyte and lichen species richness and environmental factors affecting the composition of species. Area of the study: Four Boreal zone fixed dunes were selected in the coastal area of the Baltic Sea in southwest Estonia. Material and methods: Non-metric multidimensional scaling was performed to analyse distribution patterns and environmental factors like canopy cover, photosynthetically active radiation, soil organic horizon thickness and decomposition rates, soil volumetric water content, soil pH and electrical conductivity and soil nutrients correlated with bryophyte and lichen species composition. Main results: Thirty bryophytes and 22 lichens were found on 232 sample plots, the most frequent species were Pleurozium schreberi (Willd. ex Brid.) Mitt., Hylocomium splendens (Hedw.) Schimp., Dicranum polysetum Sw. ex anon., Cladonia arbuscula (Wallr.) Flot. and Cladonia furcata (Huds.) Schrad. The lichen species richness was highest on the slopes of the dunes and decreased towards the bottoms and tops; bryophyte species richness was higher on the bottoms and decreased towards the tops of the dunes. Research highlights: The composition of bryophytes and lichens is significantly influenced by the aspect and the location on the dune, light conditions, soil pH, soil salinity (measured as electrical conductivity) and volumetric water content, thickness of moderately decomposed organic horizon and vascular plant species cover. Keywords Inland dunes; terrestrial bryophyte and lichen communities; environmental factors; topography.

Specific features of the development of soils of hydromorphic ecosystems in the northern taiga of Western Siberia under conditions of cryogenesis

Differently directed and heterochronous cryogenic processes have contributed to the contrasting soil cover patterns and spatial heterogeneity of the properties of soils in hydromorphic ecosystems of the discontinuous permafrost zone of the northern taiga in Western Siberia. Frost heave and permafrost thawing within ecosystems of highmoor bogs have led to the development of specific cryogenic landforms, such as flat-topped and large peat mounds. A set of cryogenic soils is developed in these ecosystems; it includes different variants of cryozems, gleyzems (Cryosols), and peat soils (Histosols). The distribution of these soil types is controlled by the local topography and thawing depth, other factors being insignificant. Alternation of peat horizons of different types and ages, whirl-like patterns of horizon boundaries, considerable variations in the thickness of soil horizons, and inversions of soil horizons under the impact of frost cracking, frost heave, and cryoturbation are typical of the considered soils. Thawing depth is the most significant factor affecting the thickness of organic horizons, the soil pH, and the degree of decomposition of peat. As a result of the upward movement of bog ecosystems under the impact of frost heave, peat soils are subjected to considerable transformation: peat horizons undergo mineralization, and the thickness of organic horizons decreases; in some cases, eluvial–illuvial differentiation of the mineral horizons takes place, and peat podzols are developed. However, the opposite process of the return of the soils to the bog stage of pedogenesis with peat accumulation may take place in any time in the case of activation of thermokarst processes.

Spatial variation of soil magnetic susceptibility in relation to different emission sources in southern Poland

The study in the area surrounding the Rybnik urban agglomeration (southern Poland) was conducted to determine the influence of various emission sources on the occurrence of local magnetic anomalies observed in the forest topsoils. For this reason field measurement of volume-specific magnetic susceptibility (κ) was conducted in forest topsoil on the area of study. The measurements were performed twice: directly on the surface and after removal of forest litter to see the influence of the litter on the magnetic signal measured on the soil surface. The maps of surface distribution of κ value revealed that magnetic anomalies were observed 2.0km around the residential areas dominated by low emission sources, 2.1km around the coke plant, 2.8km around the old steelworks, 1.4km around the coal-mining waste heaps, and 4.0km around the combined heat and power plant and coal mines. On the 43% of the study area, the topsoil magnetic susceptibility was between 50 and 100×10−5 SI units; on the 5.2% of the area, κ value was between 100 and 200×10−5 SI units; and on the 1.2% of the research area, the κ value was over 200×10−5 SI units. Also the vertical distribution of technogenic magnetic particles (TMPs) along the topsoil profile was analysed using topsoil 30cm cores. Two κ value maxima were observed in the soil profile. The upper one (κaverage=333.9×10−5 SI units) was found in either the Oa or Ah subhorizons at the depth of 3cm to 8cm dependently of thickness of organic horizon. The lower one (κaverage=53.4×10−5 SI units) was observed in the B or C horizon at the depth of 19cm to 23cm. The upper maxima was of anthropogenic origin with large content of the magnetic fraction (magnetic spherules), whereas the lower maxima containing isometric crystals of iron oxides was of pedogenic or geogenic origin. The soil magnetometry seems to be a useful tool in identification of anthropogenic “hot spots” caused by industrial and urban dust deposition from different emission sources.

Impacts of surface soil organic content on the soil thermal dynamics of alpine meadows in permafrost regions: data from field observations

The relationship between soil organic matter and soil temperature plays an important role in our understanding of the effect of climate change on the hydrological and carbon cycles in permafrost regions. Several studies have documented that the organic horizon thickness has profound buffering effects on soil temperature for both tundra and boreal forest ecosystems. In the present study, the alpine meadow ecosystem in the middle and low-latitude permafrost region of the Qinghai–Tibet Plateau (QTP) was selected to examine the impacts of surface soil organic matter on the thermal properties of deep soil. Based on the data obtained from more than 23 observation sites, the relationship between soil organic content and soil temperature dynamics in different seasons was determined. The findings indicate a strong positive exponential (in thawing period) and linear (in freezing period) relationship between surface soil organic content (SOC) and soil temperature dynamics in deep soil layers. The higher SOC at the surface soil layer is associated with a lower rate of soil temperature variation and a later onset time for the thaw–freeze transformation. In permafrost regions of the QTP, the greater lapse rate of soil temperature per 100m of increased elevation resulted in more significant modification of the SOC and soil thermal relationship in alpine meadows than that in tundra and boreal ecosystems. The coupled soil organic matter, soil thermal and water relationships play an important role in the resilience of permafrost during climate changes.

Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change

Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at -0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink strength of boreal forests. It is also important for large-scale biogeochemical and earth system models to include organic soil dynamics in applications to assess regional C dynamics of boreal forests responding to warming and changes in fire regime.

Effect of local species composition on topsoil properties in mixed stands with silver fir (Abies alba Mill.)

This study was carried out in three stands with fir and spruce (Picea abies L. Karst.), pine (Pinus sylvestris L.) and beech (Fagus sylvatica L.). The objectives were to characterize the spatial pattern of topsoil variation; to determine the contribution of local stand density and local species composition to small-scale variation in topsoil morphology, pH and gravimetric water content during mild midsummer drought; and to compare the effect of spruce, pine and beech vs fir. Although local stand density was related to soil properties, only in the case of single soil characteristics could this variable explain more than 10 per cent of their variation. Compared with fir, increasing density of pine exerted a stronger effect on an increase in organic horizon thickness and a comparable effect on a decrease in pH, but a weaker effect on decrease in topsoil moisture. Irrespective of the soil characteristics, the effect of spruce was approximately twice as strong as that of fir. Beech, however, had a much weaker effect on a decrease in topsoil moisture than did fir and the influence of this species on topsoil pH was the opposite.

Inter-crown versus under-crown area: contribution of local configuration of trees to variation in topsoil morphology, pH and moisture in Abies alba Mill. forests

This investigation of three Abies alba stands differing in stem density (338–715 per ha) and vertical structure (one-storeyed or multi-layered) explored the relations between distance from neighbouring tree stems and local canopy openness and selected topsoil properties. The null hypothesis was that in relatively densely stocked forests of close–random stem distribution topsoil morphology, pH and moisture do not differ in inter-crown and under-crown patches. In three plots 1.1 ha in area, soil samples were taken in a square grid 5.0 × 5.0 m and analysed using semivariogram estimation and spatial autocorrelation. The local configuration of trees around the sampled locations was characterised using hemispheral photography and a local stand density index based on tree locations and diameters. The largest portion of the total variation in the soil variables analysed (68–100%) was attributable to small-scale variation in scales <5 m. In all stands, irrespective of density and vertical structure, local stand density/canopy openness correlated positively/negatively with ectohumus layer thickness but negatively/positively with upper soil pH and moisture. Variation in the local configuration of trees explained up to 17% of the total variation in organic horizon thickness, up to 22–29% in topsoil pH (depending on the horizon) and up to 19–27% in topsoil moisture. The results indicate that even in stands of random tree patterning, stem neighbourhood and small-scale variation in canopy density may contribute significantly to topsoil heterogeneity and potentially affect the functioning and structure of forest floor vegetation.

Soil variability through spatial scales in a permanently disturbed natural spruce-fir-beech forest

Soil variability was assessed in a 74.2-ha area within the Žofinský prales natural forest. Parameters evaluated for 1765 soil profiles inside 353 graticule plots were as follows: (1) thickness of organic horizons, (2) thickness and form of mineral horizons, (3) humus form (HF), (4) soil taxonomic unit (STU) and (5) anomalies. In addition, soil reaction (pHKCl) and oxidizable carbon content (Cox) were measured in the laboratory for 734 samples from the upper mineral (A) and lower mineral (B) horizons. The most frequently occurring humus form was mor followed by moder, hydromor and peaty T-horizon. Entic Podzols, Dystric Cambisols, Haplic Cambisols, Albic Podzols, Histic (or Haplic) Gleysols, Endogleyic Stagnosols, Fibric or Hemic or Sapric Histosols and Stagnic Gleysols were all present at the site despite its homogeneous geological bedrock. Overall coefficient of variance (CV) was lower in terrestrial soils compared with (semi-)hydromorphic soils. Overall variance decreased in both soil groups with increasing depth, as did CV differences between the fine (up to 10 m) and the locality scales. The lowest CV values occurred for Cox and pHKCl. The CV values differed between STUs as well. Compared to lower horizons, variograms of upper horizons showed greater autocorrelation at the intermediate spatial scale (10–320 m)—ranging from 50 to 150 m. Semivariance values, however, reached 70–80% of sill already at a distance of 10 m. The most significant factor of variability at all studied spatial scales is presumably the soil disturbance regime, followed by terrain micro-topography and the effect of tree species.

Responses of soil carbon, nitrogen and cations to the frequency and seasonality of prescribed burning in a Cape Cod oak-pine forest

Fire is an important component of the historic disturbance regime of oak and pine forests that occupy sandy soils of the coastal outwash plain of the northeastern US. Today prescribed fire is used for fuel reduction and for restoration and maintenance of habitat for rare plant and animal, animal species. We evaluated the effects of the frequency and seasonality of prescribed burning on the soils of a Cape Cod, Massachusetts's coastal oak-pine forest. We compared soil bulk density, pH and acidity, total extractable cations and total soil carbon (C) and nitrogen (N) in unburned plots and in plots burned over a 12-year period, along a gradient of frequency (every 1–4 years), in either spring (March/April) or summer (July/August). Summer burning decreased soil organic horizon thickness more than spring burning, but only summer burning every 1–2 years reduced organic horizons compared with controls. Burning increased soil bulk density of the organic horizon only in the annual summer burns and did not affect bulk density of mineral soil. Burn frequency had no effect on pH in organic soil, but burning every year in summer increased pH of organic soil from 4.01 to 4.95 and of mineral soil from 4.20 to 4.79. Burning had no significant effect on organic or mineral soil percent C, percent N, C:N, soil exchangeable Ca 2+, Mg 2+, K + or total soil C or N. Overall effects of burning on soil chemistry were minor. Our results suggest that annual summer burns may be required to reduce soil organic matter thickness to produce conditions that would regularly allow seed germination for oak and for grassland species that are conservation targets. Managers may have to look to other measures, such as combinations of fire with mechanical treatments (e.g., soil scarification) to further promote grasses and forbs in forests where establishment of these plants is a high priority.

Hydrogeological influences on forest community type along forest–peatland complexes in coastal British Columbia

The prospect of harvesting forest–peatland systems in the coastal western hemlock forest region of British Columbia has created the need for an understanding of the interrelationship between topography, groundwater flow, and site productivity. Detailed topographic mapping including the use of ground-penetrating radar coupled with point measurements of specific yield, bulk density, saturated hydraulic conductivity, and groundwater level were used to determine the characteristics of groundwater flow along forest–peatland complexes. A topographic index was then used to characterize the spatial distribution of groundwater flow and site conditions (as represented by water table depth and organic horizon thickness) influencing forest community type. Forest community type mean index decreased from open peatland to upland forest. Areas with high slope indices had thicker organic horizons (0.7–1.8 m), water tables closer to the surface (0–0.2 m), and higher soil moisture contents (46–92%). These conditions affect successional dynamics and favour the invasion of hydrophytic species such as Sphagnum mosses. Areas with low slope index values were associated with shallower organic horizons (&lt;0.4 m), deeper water table (0.3 to &gt;1.6 m), and drier soil moisture (35–76%), favouring more prolific timber growth.

Long-term changes in the nutrient pools of forest soil organic horizons between 1949/50 and 1987, Alltcailleach Forest, Scotland

Abstract Fifteen soil profiles from the Alltcailleach Forest, northeast Scotland were first sampled in 1949/50 and resampled in 1987. The original soils were stored and each of the sites accurately relocated. Previous studies showed that soil chemical changes over the 37/38-a period are characterized by decreases in pH, base saturation and CEC and increases in extractable Al and S04. Median decreases in pH of the upper O horizon and the lowermost B/C horizon were 0.28 and 0.26 pH units, respectively. Samples collected from the upper organic horizons of these soils were analysed for total Ca, Mg, Na, K, P and N. Long-term changes in total element contents were characterized by decreases in Ca, Mg, P and N and increases in Na; there were no changes in K concentrations. Between 1949/50 and 1987 increases in the thickness of the forest soil organic horizon resulted in an increase in the total amounts of nutrients stored in the forest floor. The increases in organic horizon thickness therefore largely override the decreases observed in nutrient concentrations. Accumulation rates have been estimated for each of the elements, and changes in nutrient concentration and storage are discussed in terms of effects on forest nutrient cycling.

Long-term changes in the Cu, Pb, and Zn content of forest soil organic horizons from North-East Scotland

Forest soil organic horizons from old and young plantations in the Alltcailleach Forest, N.E. Scotland were first sampled in 1949/50 and resampled in 1987. Copper, Pb and Zn in the soils were determined simultaneously on the original (stored) and the resampled soils. Overall mean Cu and Pb concentrations increased from 12.7 to 15.3 and 49.5 to 60.8 mg kg−1 between 1949/50 and 1987. Zinc concentrations decreased from 76.4 to 60.7 mg kg−1. Amounts of all 3 heavy metals increased because of increases in the thickness of organic horizons. Mean accumulation rates for Cu, Pb and Zn were 39.1, 186 and 114 g ha−1 yr−1, respectively. The rate of accumulation of Pb was significantly related to the rate of accumulation of organic matter. Copper and Zn concentrations were directly correlated with pH and inversely correlated with C/N ratio, whereas Pb was inversely correlated with pH and directly correlated with % C and C/N ratio. The more acidic soil organic horizons therefore contained higher concentrations of Pb and lower concentrations of Cu and Zn.

Soils under beech forest in an experimental catchment area near Nelson, New Zealand

Abstract Soils of four contiguous small forested experimental catchments, covering 40 ha in hill country formed in Moutere Gravel in NW South Island, New Zealand, were studied. The indigenous vegetation of the area was Nothofagus forest; the rainfall averages 1,550 mm per annum; the topography is a dissected pattern of narrow ridges and small valleys; and the parent materials are Late Pleistocene to Holocene slope deposits derived from reworking of underlying early Quaternary weathered gravels. One hundred and thirty-one profiles were described on cross-catchment traverses on a variety of sites in differing parts of the catchments. Additional profiles were described from tracks that were formed at the time of logging. The soils are characterised in terms of their physical properties by summarising all the profile data. Their particle size, chemical and clay mineralogical characteristics are also summarised from analyses of representative profiles. Variation in soil development, as expressed by horizon differentiation, was correlated with thickness of organic horizons and soil pH. The soils with the thickest 0 horizons and lowest pH values are podzols. Variation is attributed to differential biological decomposition which in turn is related to site differences. The three soil series identified are classified as podzols, podzolised yellow-brown earths and yellow-brown earths. Their distribution is complex, often passing from one to another in less than a metre. The yellow-brown earths occur widely over all landforms within the catchment, while the podzol and podzolised soils occur more commonly on ridges, spurs and upper slopes. Parent material variation and slope angle have no direct influence on the soil pattern. Soil disturbance by tree overturn is a major factor influencing soil development in the beech forest, and accounts for the high proportion of yellow-brown earths.

Prescribed Burning White Spruce Slash in Interior Alaska

Abstract Broadcast burning following harvesting on flood-plain sites in Alaska substantially decreased residual organic material and increased exposed mineral soil. Two forest types were studied: white spruce/alder/feathermoss and white spruce/alder/lingenberry/feathermoss. The latter site contained permafrost. Fuel was reduced 67% and 81%, respectively; organic horizon thickness was decreased 43% to 2.9 in (7.4 cm) and 55% to 2.5 in (6.4 cm), respectively; and mineral soil exposure was 13% and 8%, respectively. Burning created good conditions for planting on both types. In addition, mechanical site preparation to increase mineral soil exposure appears to be necessary to achieve adequate, well-distributed regeneration from seed. North. J. Appl. For. 3:16-18, Mar. 1986.

Predictability of Recreational Impact on Soils

AbstractBiophysical measurements were taken on 96 paired campsites and controls in the Boundary Waters Canoe Area Wilderness of north‐eastern Minnesota. Multiple regression analysis was used to identify and evaluate factors affecting changes in bulk density, organic horizon thickness, and exposed soil associated with campsite use. The best predictors of change in bulk density were campsite age, mineral soil organic content, organic horizon thickness, and offsite bulk density. Offsite organic horizon thickness and level of use were the best predictors of change in campsite organic horizon thickness. Level of use and campsite age were the best predictors of amount of exposed soil. Bulk density and exposed soil continued to increase with campsite age, even though all sites included in the study were &gt; 5 yr in age. Other studies have not found this relationship. This information can be used to assist managers in selecting recreation site locations and appropriate site management techniques.