Long-term recovery in the soil profile of 15N from Douglas-fir needles decomposing in the forest floor

1995 ◽  
Vol 25 (5) ◽  
pp. 833-837 ◽  
Author(s):  
CM. Preston ◽  
D.J. Mead
Keyword(s):  
Soil Profile ◽  
Forest Floor ◽  
Mineral Soil ◽  
Sampling Period ◽  
Douglas Fir ◽  
First Year ◽  
N Recovery ◽  
Inorganic N ◽  
Almost All

To follow the movement and transformations of litter-fall N in a forest ecosystem, Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) foliage labelled with 15N was mixed into the forest floor and left to decompose in steel cylinders of 15 cm diameter X 60 cm length. There were four treatments: 15N-labelled foliage only, foliage plus 200 kg N•ha−1 as urea or NH4NO3, and unamended control. The addition of fertilizer N had no significant effects on 15N recovery or distribution in the soil profile. The overall recovery of 15N to 60 cm depth was 53.7%, 24.9%, and 19.9% after 1, 3, and 7.5 years, respectively. After the first year almost all of the recovered 15N was in the L layer. At 3 years, a higher proportion was found in the FH layer, and by 7.5 years, approximately one-third of the 15N was found in mineral soil horizons. There was very little recovery of 15N in inorganic form (1% or less) after 1 year; in subsequent years inorganic N was found at background levels. Recoveries in soil after 1 and 3 years were similar to those reported for 15N added as inorganic fertilizer in the absence of plant uptake. However, very low losses in the next sampling period (3 to 7.5 years) indicated stabilization of 15N in increasingly recalcitrant forms.

scholarly journals Natural Recovery and Liming Effects in Acidified Forest Soils in SW-Germany

Soil Systems ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 38
Author(s):  
Lelde Jansone ◽  
Klaus von Wilpert ◽  
Peter Hartmann
Keyword(s):  
Forest Soils ◽  
Soil Profile ◽  
Forest Floor ◽  
Mineral Soil ◽  
Base Saturation ◽  
Lime Treatment ◽  
Natural Recovery ◽  
Lime Application ◽  
Study Sites

In the state of Baden-Wuerttemberg, Southwest-Germany, a large-scale forest liming trial was government-funded in 1983 and a lime treatment was carried out in autumn 1983 until early winter 1984. Repeated liming was applied in 2003. The limed sites and adjacent control plots were surveyed repeatedly: in 2003 before the second lime application and again in 2010 and 2015. Research of this scope presents a rare opportunity to evaluate firstly the long-term development of acidified soils with their potential for natural recovery on established control plots, and secondly the long-term effects of repeated lime application—at a collective of study sites of various growth regions and soil properties. A natural recovery in soil pH was observed since 2003, on average limited to an increase of 0.2–0.4 pH units in the forest floor and 0.1–0.3 pH units in the mineral soil until 2015. The majority of the organic layers still show very strong or extreme acidity with a pH value 3.9 on average and in the mineral soil with pH values between 3.8 and 4.6 on average. The exchangeable cations calcium and magnesium slightly increased also, although the base saturation remained <20% by 2015. The exchangeable acid cation concentrations indicated no significant changes and thus no recovery. The lime treatment greatly accelerated the rise in pH by 1.2–1.3 units and base saturation by 40–70% in the organic layer, as well as 0.3–1.2 pH units and base saturation by 7–50% in mineral soil. These effects were decreasing (yet still significant) with depth in the measured soil profile as well as with time since last treatment. Changes in soil cation exchange capacity after liming were significant in 0–5 cm mineral soil, below that they were negligible as the significant increase in base cations were accompanied by decreasing acid cations aluminum and iron (III) especially in the upper soil profile. Additionally, a decrease of forest floor and an enrichment of organic carbon and nitrogen in the mineral topsoil tended to follow liming at some sites. Overall the liming effects had a high variability among the study sites, and were more pronounced in the more acidic and coarser textured sites. Liming of acidified forest soils significantly adds to natural recovery and therefore helps to establish greater buffering capacities and stabilize forest nutrition for the future.

Four centuries of soil carbon and nitrogen change after stand-replacing fire in a forest landscape in the western Cascade Range of Oregon

2008 ◽  
Vol 38 (9) ◽  
pp. 2455-2464 ◽  
Author(s):  
T. W. Giesen ◽  
S. S. Perakis ◽  
K. Cromack
Keyword(s):  
Pacific Northwest ◽  
Forest Floor ◽  
Mineral Soil ◽  
Douglas Fir ◽  
Cascade Range ◽  
Carbon And Nitrogen ◽  
The Pacific ◽  
C And N ◽  
Mineral Soils

Episodic stand-replacing wildfire is a significant disturbance in mesic and moist Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) forests of the Pacific Northwest. We studied 24 forest stands with known fire histories in the western Cascade Range in Oregon to evaluate long-term impacts of stand-replacing wildfire on carbon (C) and nitrogen (N) pools and dynamics within the forest floor (FF, Oe and Oa horizons) and the mineral soil (0–10 cm). Twelve of our stands burned approximately 150 years ago (“young”), and the other 12 burned approximately 550 years ago (“old”). Forest floor mean C and N pools were significantly greater in old stands than young stands (N pools: 1823 ± 132 kg·ha–1vs. 1450 ± 98 kg·ha–1; C pools: 62 980 ± 5403 kg·ha–1vs. 49 032 ± 2965 kg·ha–1, mean ± SE) as a result of significant differences in FF mass. Forest floor C and N concentrations and C/N ratios did not differ by time since fire, yet potential N mineralization rates were significantly higher in FF of old sites. Old and young mineral soils did not differ significantly in pools, concentrations, C/N ratios, or cycling rates. Our results suggest that C and N are sequestered in FF of Pacific Northwest Douglas-fir forests over long (∼400 year) intervals, but that shorter fire return intervals may prevent that accumulation.

scholarly journals Dynamic of nitrogen and dissolved organic carbon in an alpine forested catchment: atmospheric deposition and soil solution trends

2019 ◽  
Vol 34 ◽  
pp. 41-66 ◽  
Author(s):  
Raffaella Balestrini ◽  
Carlo Andrea Delconte ◽  
Andrea Buffagni ◽  
Alessio Fumagalli ◽  
Michele Freppaz ◽  
...  
Keyword(s):  
Soil Solution ◽  
Forest Ecosystem ◽  
Forest Floor ◽  
Mineral Soil ◽  
Chemical Species ◽  
Organic N ◽  
Seasonal Temperature ◽  
Inorganic N ◽  
Forest Floor Leachates ◽  
Throughfall Deposition

A number of studies have reported decreasing trends of acidifying and N deposition inputs to forest areas throughout Europe and the USA in recent decades. There is a need to assess the responses of the ecosystem to declining atmospheric pollution by monitoring the variations of chemical species in the various compartments of the forest ecosystem on a long temporal scale. In this study, we report on patterns and trends in throughfall deposition concentrations of inorganic N, dissolved organic N (DON) and C (DOC) over a 20-year (1995–2015) period in the LTER site -Val Masino (1190 m a.s.l.), a spruce forest, in the Central Italian Alps. The same chemical species were studied in the litter floor leachates and mineral soil solution, at three different depths (15, 40 and 70 cm), over a 10-year period (2005–2015). Inorganic N concentration was drastically reduced as throughfall and litter floor leachates percolated through the topsoil, where the measured mean values (2 µeq L-1) were much lower than the critical limits established for coniferous stands (14 µeq L-1). The seasonal temperature dependence of throughfall DOC and DON concentration suggests that the microbial community living on the needles was the main source of dissolved organic matter. Most of DOC and DON infiltrating from the litter floor were retained in the mineral soil. The rainfall amount was the only climatic factor exerting a control on DOC and N compounds in throughfall and forest floor leachates over a decadal period. Concentration of SO4 and NO3 declined by 50% and 26% respectively in throughfall deposition. Trends of NO3 and SO4 in forest floor leachates and mineral soil solution mirrored declining depositions. No trends in both DON and DOC concentration and in DOC/DON ratio in soil solutions were observed. These outcomes suggest that the declining NO3 and SO4 atmospheric inputs did not influence the dynamic of DON and DOC in the Val Masino forest. The results of this study are particularly relevant, as they are based on a comprehensive survey of all the main compartments of the forest ecosystem. Moreover, this kind of long-term research has rarely been carried out in the Alpine region.

scholarly journals Thinning and Burning Effects on Long-Term Litter Accumulation and Function in Young Ponderosa Pine Forests

2020 ◽  
Vol 66 (6) ◽  
pp. 761-769
Author(s):  
Matt Busse ◽  
Ross Gerrard
Keyword(s):  
Ponderosa Pine ◽  
Forest Floor ◽  
Prescribed Burning ◽  
Mineral Soil ◽  
Pine Forests ◽  
Organic Layer ◽  
Litter Accumulation ◽  
Ponderosa Pine Forests ◽  
Essential Components

Abstract We measured forest-floor accumulation in ponderosa pine forests of central Oregon and asked whether selected ecological functions of the organic layer were altered by thinning and repeated burning. Experimental treatments included three thinning methods applied in 1989 (stem only, whole tree, no thin—control) in factorial combination with prescribed burning (spring 1991 and repeated in 2002; no burn—control). Forest-floor depth and mass were measured every 4–6 years from 1991 to 2015. Without fire, there was little temporal change in depth or mass for thinned (270 trees ha−1) and control (560–615 trees ha−1) treatments, indicating balanced litterfall and decay rates across these stand densities. Each burn consumed 50–70 percent of the forest floor, yet unlike thinning, postfire accumulation rates were fairly rapid, with forest-floor depth matching preburn levels within 15–20 years. Few differences in forest-floor function (litter decay, carbon storage, physical barrier restricting plant emergence, erosion protection) resulted from thinning or burning after 25 years. An exception was the loss of approximately 300 kg N ha−1 because of repeated burning, or approximately 13 percent of the total site N. This study documents long-term forest-floor development and suggests that common silvicultural practices pose few risks to organic layer functions in these forests. Study Implications: Mechanical thinning and prescribed fire are among the most widespread management practices used to restore forests in the western US to healthy, firewise conditions. We evaluated their effects on the long-term development of litter and duff layers, which serve dual roles as essential components of soil health and as fuel for potential wildfire. Our study showed that thinning and burning provided effective fuel reduction and resulted in no adverse effects to soil quality in dry ponderosa pine forests of central Oregon. Repeated burning reduced the site carbon and nitrogen pools approximately 9–13 percent, which is small compared to C located in tree biomass and N in mineral soil. Litter accumulation after burning was rapid, and we recommend burning on at least a 15–20-year cycle to limit its build-up.

Biomass and nutrient content of Douglas-fir logs and other detrital pools in an old-growth forest, Oregon, U.S.A.

1992 ◽  
Vol 22 (10) ◽  
pp. 1536-1546 ◽  
Author(s):  
Joseph E. Means ◽  
Paul C. MacMillan ◽  
Kermit Cromack Jr.
Keyword(s):  
Forest Floor ◽  
Soluble Fraction ◽  
Close Association ◽  
C:N Ratio ◽  
Mineral Soil ◽  
Nutrient Content ◽  
Douglas Fir ◽  
Area Index ◽  
Old Growth Forest ◽  
N Release

Logs, forest floor, and mineral soil were sampled and measured, and snags were measured, in a 450-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand on the H.J. Andrews Experimental Forest, Oregon. Logs, some still identifiable after 300 years on the forest floor, contained large amounts of organic matter (222 Mg/ha), C (100 Mg/ha), water (559–10 700 L/log), N (183 kg/ha), and Ca (141 kg/ha), and smaller amounts of P (5.5 kg/ha), K (22 kg/ha), Mg (14 kg/ha), and Na (3.7 kg/ha). Logs and snags covered about 17% of the forest floor and had an all-sided area index of 0.69 m2/m2. Through mineralization, C, N, and K were lost through time; Ca and Mg increased; and P and Na increased then decreased, showing no net change. Also through mineralization, cellulose and hot acid detergent soluble fraction decreased more rapidly than lignin. Lignin was apparently not lost until the later stages of decay, when N was also lost in significant amounts. This parallels the shift from initial dominance by white rots that degraded cellulose and lignin to later dominance by brown rots that preferentially degraded cellulose. Lignin and cellulose were eventually lost at more similar rates in later decay stages. This may have been due in part to a close association between the remaining cellulose and lignin in later decay stages. Lignin was a better predictor of the onset of N release than was the C:N ratio.

Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range

2011 ◽  
Vol 41 (1) ◽  
pp. 195-210 ◽  
Author(s):  
Alison Cross ◽  
Steven S. Perakis
Keyword(s):  
Tree Species ◽  
Forest Floor ◽  
Mineral Soil ◽  
Soil Nutrient ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Coast Range ◽  
Old Growth ◽  
Oregon Coast Range ◽  
Old Growth Forests

Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species – soil relationships in ecosystems that have developed without significant human disturbance. We characterized foliage, forest floor, and mineral soil nutrients associated with four canopy tree species (Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and bigleaf maple (Acer macrophyllum Pursh)) in eight old-growth forests of the Oregon Coast Range. The greatest forest floor accumulations of C, N, P, Ca, Mg, and K occurred under Douglas-fir, primarily due to greater forest floor mass. In mineral soil, western hemlock exhibited significantly lower Ca concentration and sum of cations (Ca + Mg + K) than bigleaf maple, with intermediate values for Douglas-fir and western redcedar. Bigleaf maple explained most species-based differences in foliar nutrients, displaying high concentrations of N, P, Ca, Mg, and K. Foliar P and N:P variations largely reflected soil P variation across sites. The four tree species that we examined exhibited a number of individualistic effects on soil nutrient levels that contribute to biogeochemical heterogeneity in these ecosystems. Where fire suppression and long-term succession favor dominance by highly shade-tolerant western hemlock, our results suggest a potential for declines in both soil Ca availability and soil biogeochemical heterogeneity in old-growth forests.

Unemployment and the Older Worker in the Netherlands: Re-entry into the Labour Force or Resignation

1996 ◽  
Vol 16 (5) ◽  
pp. 561-578 ◽  
Author(s):  
Kène Henkens ◽  
Maarten Sprengers ◽  
Frits Tazelaar
Keyword(s):  
Older Workers ◽  
Older Persons ◽  
Labour Force ◽  
Point Of View ◽  
First Year ◽  
Panel Survey ◽  
One Year ◽  
Almost All ◽  
Formal Application

AbstractIn this article we present the results of a panel survey in which 242 men aged 40 to 55 were followed for approximately seven years after they became involuntarily unemployed. The study focused on reintegration probabilities of the older workers and on the question of their reaction to a situation of prolonged unemployment. The study shows that if policy is not changed, the probability of the reintegration of older, long-term unemployed persons into the labour force will remain extremely low. Re-entry via a ‘normally’ functioning labour market (formal application procedures and official job intermediaries) takes place almost exclusively during the first year after dismissal. If a new job is not found, a resigned feeling occurs among almost all of this older unemployed group. Most of the older people adjust to the new circumstances sooner or later. If one wishes to protect older persons from the trap of long-term unemployment (and in many cases total exclusion), more rapid interventions must be made, and reorientation and retraining efforts must be started sooner, before it is ‘too late’. From the employer’s point of view, there is not much interest in those who are still unemployed after one year.

Effects of bigleaf maple on soils in Douglas-fir forests

1990 ◽  
Vol 20 (3) ◽  
pp. 259-266 ◽  
Author(s):  
Jeremy S. Fried ◽  
James R. Boyle ◽  
John C. Tappeiner II ◽  
Kermit Cromack Jr.
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Nutrient Content ◽  
Douglas Fir ◽  
Organic Carbon Content ◽  
Coast Range ◽  
Litter Fall ◽  
Turnover Rates ◽  
Calcium Magnesium ◽  
Forest Floors

Soil chemical and physical properties, forest floor weights, nutrient content and turnover rates, and litter fall weights and nutrient content under bigleaf maple (Acermacrophyllum Pursh) and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) were compared on five sites on the eastern margin of the Oregon Coast Range. Litter fall weight and nutrient content were significantly greater under maple on every site for every macronutrient and for most micronutrients. Forest floor biomass and nutrient content were extremely variable, much more so than litter fall, and there were no consistent differences between the two species. However, turnover rates for forest floor biomass and nutrients were significantly faster under maple for every nutrient at every site. Bulk density of mineral soil was also highly variable with significant differences at only two sites. Soil under maple was consistently higher in nitrogen, and less consistently, in potassium. There were no consistent trends in amounts of calcium, magnesium, or phosphorus. Soil organic carbon content under maple was significantly greater than under Douglas-fir on four of five sites. These differences may result from the more rapid turnover of forest floors under maple trees.

scholarly journals Seedling roots and forest floor: Misplaced and neglected aspects of British Columbia's reforestation effort?

1995 ◽  
Vol 71 (1) ◽  
pp. 59-65 ◽  
Author(s):  
A. C. Balisky ◽  
P. Salonius ◽  
C. Walli ◽  
D. Brinkman
Keyword(s):  
Root Morphology ◽  
Forest Floor ◽  
Mineral Soil ◽  
Tree Planting ◽  
Vertical Orientation ◽  
Organic Mineral ◽  
Rooting Medium ◽  
Seedling Roots ◽  
Root Location

Concepts of planted seedling root morphology and root location are discussed in the context of reforestation in British Columbia. Comparison of root form and location between natural and planted seedlings reveals profound differences. Unnatural root morphology and delayed development of nursery-produced rooting systems, coupled with current planting techniques that emphasize vertical orientation of roots in mineral soil horizons, may exacerbate harsh microenvironmental site conditions. Inappropriate root systems may inhibit optimal seedling function and compromise long-term stand stability. The forest floor is seen as an appropriate rooting medium to which planted seedlings should be allowed ready access. A change in the biological geometry (direction and depth of root development) of the planted root system may enhance survival, establishment, and growth. The promotion of more natural, lateral, surface rooting at the organic/mineral soil interface is proposed. Site-specific root morphologies and planting strategies may be required. Key words: regeneration silviculture, tree-planting, target seedling stocktype, root egress, root morphology, root location, forest floor, soil temperature, soil moisture, frost heaving, soil nutrients, mycorrhizae, site preparation, alternative stocktypes

Sign in / Sign up

Export Citation Format

Share Document