Nutrient management in a Pinusradiata plantation after thinning: the effect of thinning and residues on nutrient distribution, mineral nitrogen fluxes, and extractable phosphorus

1995 ◽  
Vol 25 (8) ◽  
pp. 1278-1291 ◽  
Author(s):  
J. Clive Carlyle

The effects of thinning and residues on nutrient distribution, N fluxes, and extractable P were studied for 3 years after the first thinning of a 10-year-old Pinusradiata D. Don plantation. Treatments were (i) unthinned, (ii) thinned to 52% of basal area with all residues removed (zero residue; ZR), (iii) thinned with all residues retained and spread uniformly (normal residue; NR), and (iv) thinned with all residues retained plus the addition of those removed from the ZR treatment, approximately doubling the amount of residue in treatment NR (high residue; HR). The total nutrient contents of trees (above ground), residues, forest floor, and the top 0.30 m of mineral soil were 1206 kg N•ha−1, 126 kg P•ha−1, 828 kg K•ha−1, and 1272 kg Ca•ha−1 after thinning. Residues contained 11, 10, 10, and 7% of site N, P, K, and Ca, respectively. Thinning without residue retention (unthinned cf. ZR) elevated mean monthly maximum soil temperatures at a depth of 50 mm by up to 5.3 °C in summer and 1 °C in winter. Thinning had no effect on forest floor or mineral soil (0–0.30 m) moisture content. In the unthinned treatment an average of 25 kg N•ha−1•year−1 was mineralized, all of which was taken up by the trees, and there was no leaching. Thinning caused a 10% increase in rates of N mineralization and uptake and a small transient increase in soil mineral N concentrations, but had no effect on leaching. Maintenance of prethinning levels of N uptake by the remaining trees (after a 48% reduction in basal area) suggests that uptake per tree was approximately doubled. Maintenance of N uptake after thinning was consistent with maintenance of basal area growth (m2•ha−1) and an increase in foliar N concentrations. Thinning had no effect on extractable P in the forest floor or mineral soil. The retention of residues (NR and HR) decreased mean monthly maximum and elevated mean monthly minimum soil temperatures relative to the ZR treatment, and the effect increased with the amount of residue. Forest floor moisture content increased with the amount of residue, but residue retention had no effect on mineral soil moisture. Rates of mineralization were higher in the presence of residue and annual averages were 28, 33, and 42 kg N•ha−1•year−1 for ZR, NR, and HR treatments, respectively. Despite increased N mineralization in the presence of residue there was no leaching and all the additional N was taken up by the trees. Basal area increment increased in the presence of residue (P = 0.235) and was 10.7 (ZR), 11.1 (NR), and 11.8 (HR) m2•ha−1 over 4 years of measurement.

2013 ◽  
Vol 10 (6) ◽  
pp. 3691-3703 ◽  
Author(s):  
D. Zhou ◽  
S. Q. Zhao ◽  
S. Liu ◽  
J. Oeding

Abstract. Partial cutting, which removes some individual trees from a forest, is one of the major and widespread forest management practices that can significantly alter both forest structure and carbon (C) storage. Using 748 observations from 81 studies published between 1973 and 2011, we synthesized the impacts of partial cutting on three variables associated with forest structure (mean annual growth of diameter at breast height (DBH), stand basal area, and volume) and four variables related to various C stock components (aboveground biomass C (AGBC), understory C, forest floor C, and mineral soil C). Results show that the growth of DBH increased by 111.9% after partial cutting, compared to the uncut control, with a 95% bootstrapped confidence interval ranging from 92.2 to 135.9%, while stand basal area and volume decreased immediately by 34.2% ([−37.4%, −31.2%]) and 28.4% ([−32.0%, −25.1%]), respectively. On average, partial cutting reduced AGBC by 43.4% ([−47.7%, −39.3%]), increased understory C storage by 391.5% ([220.0%, 603.8%]), but did not show significant effects on C stocks on forest floor and in mineral soil. All the effects, if significant (i.e., on DBH growth, stand basal area, volume, and AGBC), intensified linearly with cutting intensity and decreased linearly over time. Overall, cutting intensity had more strong impacts than the length of recovery time on the responses of those variables to partial cutting. Besides the significant influence of cutting intensity and recovery time, other factors such as climate zone and forest type also affected forest responses to partial cutting. For example, a large fraction of the changes in DBH growth remains unexplained, suggesting the factors not included in the analysis may play a major role. The data assembled in this synthesis were not sufficient to determine how long it would take for a complete recovery after cutting because long-term experiments were scarce. Future efforts should be tailored to increase the duration of the experiments and balance geographic locations of field studies.


1986 ◽  
Vol 16 (6) ◽  
pp. 1320-1326 ◽  
Author(s):  
K. Van Cleve ◽  
O. W. Heal ◽  
D. Roberts

Using a bioassay approach, this paper considers the nitrogen-supplying power of forest floors from examples of the major forest types in interior Alaska. Yield and net N uptake by paper birch seedlings grown in standardized mixtures of quartz sand and forest floor organic matter, and separate incubation estimates of N mineralization and nitrification for the forest floors, were employed to evaluate potential N supply. Black spruce and floodplain white spruce forest floors supplied only one-fifth the amount of N taken up by seedlings growing in other forest floors. Incubation estimates showed these forest floors yielded 4 and 15 times less extractable N, respectively, than the more fertile birch forest floors. In comparison with earlier estimates of P supply from these same forest floors, the upland types showed greater deficiency of N whereas floodplain types showed greater deficiency of P in control of seedling yield. The latter condition is attributed to the highly calcareous nature of the floodplain mineral soil, the consequent potential for P fixation, and hence greater potential deficiency of the element compared with N in mineralizing forest floors. Nitrogen concentration of the forest floors was the best predictor of bioassay response.


1984 ◽  
Vol 14 (2) ◽  
pp. 155-162 ◽  
Author(s):  
M. A. Radwan ◽  
D. S. DeBell ◽  
S. R. Webster ◽  
S. P. Gessel

Effects of different sources of fertilizer N on selected chemical characteristics of soils and foliage, and on growth of western hemlock (Tsugaheterophylla (Raf.) Sarg.) were compared at three different sites in western Washington. Treatments were the following: untreated control (O), ammonium nitrate (AN), ammonium sulfate (AS), calcium nitrate (CN), urea (U), and urea – ammonium sulfate (US). Fertilizers were applied in the spring (April–May) at 224 kg N/ha. Forest floor and mineral soil, to a depth of 5 cm, and foliage were sampled periodically for 2 years. Height and diameter of selected trees were measured periodically for 4 years. Results are reported mostly for two sites, one in the Cascade Range and one in the coastal zone in western Washington. The pH of forest floor and mineral soil varied by treatment, and the two urea fertilizers caused substantial initial rise. Effects on soil and foliar nutrients varied by fertilizer, sampling date, and location. In general, all fertilizers increased NH4 N, N03 N, and total N in the forest floor and mineral soil, and total N in the foliage. Also, with some exceptions, especially with foliar P in the Cascade site, fertilization reduced foliar content of important nutrients. At the Cascade site, 4-year growth responses in height, basal area, and volume averaged over all fertilizers were 30, 34, and 32%, respectively. AN, AS, CN, and urea resulted in height growth significantly (P < 0.20) higher than that of the control. Significant basal area growth and volume-growth responses were produced by AN, CN, and US. No significant height-growth response to any fertilizer occurred in the coastal stand; basal area growth and volume-growth responses averaged 27 and 21%, respectively, and best response occurred with urea. These results suggest that the low and inconsistent response of hemlock to N fertilization cannot be improved by applying some N fertilizer other than urea. Factors limiting response to N fertilization may be associated with availability of native N and other nutrients or other characteristics of hemlock sites and stands.


1988 ◽  
Vol 68 (2) ◽  
pp. 337-344 ◽  
Author(s):  
C. A. CAMPBELL ◽  
R. P. ZENTNER ◽  
F. SELLES

Data from an 18-yr crop rotation study carried out on a Brown loam soil at Swift Current, Saskatchewan, were used to estimate equations that relate spring wheat straw yields, and N and P content of grain and straw to moisture use (MU). Moisture use was defined as soil moisture content in 0- to 120-cm depth at seeding, less soil moisture content at harvest, plus growing season precipitation. Grain yields were also related to straw yields and to N content of the straw. Potential net N mineralization (Nmin) in summerfallow (periods during the growing season with negative Nmin omitted) was related (r = 0.74**) to precipitation received during the spring to fall period. An attempt to relate apparent net Nmin (determined by N balance) in cropped systems to growing season precipitation or to MU was not successful. Highly significant linear regressions were obtained for straw yields, grain N and P contents vs. MU, and for grain yield vs. straw yield (r = 0.66** – 0.83**), but the other relationships were less reliable (r = 0.41** – 0.55**) though still significant. We discussed how these relationships might be used to estimate fertilizer N requirements, for examining N immobilization-mineralization, and for estimating residue sufficiency for erosion control on summerfallowed land. Key words: Straw:grain ratio, N uptake, P uptake, crop residues, N mineralization


2006 ◽  
Vol 82 (6) ◽  
pp. 844-859 ◽  
Author(s):  
Brian D Titus ◽  
Cindy E Prescott ◽  
Doug G Maynard ◽  
Alan K Mitchell ◽  
Robert L Bradley ◽  
...  

The MASS (Montane Alternative Silvicultural Systems) trial was established in the coastal mountains of British Columbia to compare clearcut, patch cut, green tree and shelterwood systems. A number of studies were carried out at the MASS trial to determine the extent to which these variable levels of stand retention retained old-growth attributes of N cycling and associated ecological processes. Harvesting led to increases in N mineralization in the forest floor (2×) and mineral soil (10×), and fluxes of N through the upper 25 cm of mineral soil (2× to 3×). However, fluxes of N were not large (< 0.35 kg ha-1 per growing season). Nitrogen mineralized was predominantly ammonium and not nitrate in the forest floor (> 95% in all but clearcut, > 75% in clearcut) and upper mineral soil horizon (42–86%). The nitrate component came from heterotrophic decomposition of organic matter, not conversion of ammonium to nitrate by autotrophs, and nitrate increases resulted from decreased gross nitrate consumption with harvesting, rather than increased nitrate production. The increases in soil N availability resulting from harvesting were reflected in only slight increases in seedling foliar N concentrations for two to four years after logging (peak of ~ 2% for western hemlock and ~ 1.6% for amabilis fir) before decreasing to below deficiency thresholds for both species. Overall, estimated losses of N from the rooting zone after harvesting (1 kg ha-1 yr-1) were minimal in comparison to estimated N inputs (4 kg ha-1 yr-1), N exports in logs at harvesting (250 kg ha-1) and soil reserves (11 400 kg ha-1). Although unlikely to affect future site productivity, losses of N could be reduced somewhat through the use of shelterwood harvesting. Key words: alternative silvicultural systems, variable retention harvesting, nitrogen cycling, litterfall, decomposition, nitrification, N mineralization, microbial ecology, leaching, foliar N, Abies amabilis, Tsuga heterophylla, Thuja plicata


1987 ◽  
Vol 17 (11) ◽  
pp. 1434-1441 ◽  
Author(s):  
D. A. Perry ◽  
C. Choquette ◽  
P. Schroeder

Nitrogen and carbon in the surface 12 cm of mineral soil, N in leaf litterfall, anaerobic N mineralization rates in the soil and forest floor, and root and N accretion to sand traps placed in surface soil layers were compared in forests with hardwoods either completely or partially removed during a conifer thinning 3 years before. An adjacent unthinned conifer–hardwood stand was also included. Conifer stocking did not differ between thinned stands with and without hardwoods. Stands without hardwoods averaged 520 kg/ha more N in mineral soil (p < 0.001), 20% more N mineralized from soil during 7-day incubations (p < 0.001), and lower soil C:N ratio (p = 0.02) than stands with hardwoods. These variables did not differ between thinned and unthinned mixed stands. Soil N did not correlate with the number of hardwoods removed. Weight of forest floor and rate of N mineralization from the forest floor did not differ between mixed and pure stands. However, stands with hardwoods returned about 10 kg•ha−1•year−1 more N in leaf litter (due to higher N concentration in conifer litter as well as the presence of high-N hardwood litter); stands without hardwoods accreted about 10 kg•ha−1•year−1 more N in sand traps. Soil N mineralization in mixed stands correlated positively with N mineralization in the forest floor but not with N accretion to sand traps, while the opposite was true in pure conifer stands. Although pretreatment variability among stands cannot be ruled out, the replicated treatments within a relatively uniform area make it appear likely that differences were related to the presence or absence of hardwoods. This was not a simple additive effect, however, but a community-level phenomenon, that is, conifers cycled N differently when mixed with hardwoods than when in pure stands.


2013 ◽  
Vol 10 (1) ◽  
pp. 787-813 ◽  
Author(s):  
D. Zhou ◽  
S. Q. Zhao ◽  
S. Liu ◽  
J. Oeding

Abstract. Partial cutting, which removes some individual trees from a forest, is one of the major and widespread forest management practices that can significantly alter both forest structure and carbon (C) storage. Using 746 observations from 82 publications, we synthesized the impacts of partial cutting on three variables associated with forest structure (i.e. mean annual growth of diameter at breast height (DBH), basal area (BA), and volume) and four variables related to various C stock components (i.e. aboveground biomass C (AGBC), understory C, forest floor C, and mineral soil C). Results shows that the growth of DBH elevated by 112% after partial cutting, compared to the uncut control, while stand BA and volume reduced immediately by 34% and 29%, respectively. On average, partial cutting reduced AGBC by 43%, increased understory C storage by 392%, but did not show significant effects on C storages on forest floor and in mineral soil. All the effects on DBH growth, stand BA, volume, and AGBC intensified linearly with cutting intensity (CI) and decreased linearly with the number of recovery years (RY). In addition to the strong impacts of CI and RY, other factors such as climate zone and forest type also affected forest responses to partial cutting. The data assembled in this synthesis were not sufficient to determine how long it would take for a complete recovery after cutting because long-term experiments were rare. Future efforts should be tailored to increase the duration of the experiments and balance geographic locations of field studies.


1990 ◽  
Vol 70 (1) ◽  
pp. 73-81 ◽  
Author(s):  
J. W. FYLES ◽  
I. H. FYLES ◽  
M. C. FELLER

Nitrogen mineralization in five forest floors of differing morphological characteristics was compared using a greenhouse plant bioassay and laboratory aerobic and anaerobic incubations. Forest floors dominated by F materials mineralized more N and had higher k values than those dominated by H. Plant N uptake in the bioassay was highly correlated with N mineralized during the laboratory incubations across all forest floors but was 50–80% lower than predictions based on first-order kinetic parameters derived from the aerobic incubation. The relationship between bioassay plant uptake and predicted N mineralization differed among forest floors, indicating that the effect of plants on dynamics of the mineralizable N pool differs among organic matter types. Differences in N mineralization characteristics between forest floor materials suggest that forest floor morphology may provide a basis for assessing site quality. Key words: Nitrogen, anaerobic mineralization, aerobic mineralization, bioassay, forest floor


2001 ◽  
Vol 1 ◽  
pp. 505-513 ◽  
Author(s):  
Frank S. Gilliam ◽  
Frank C.C. Somerville ◽  
Frank N.L. Lyttle ◽  
Frank M.B. Adams

Nitrogen (N) saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF), West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4) and WS4 (untreated control). Samples of forest floor material (O1 horizon) and mineral soil (to a 5-cm depth) were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively) of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C), lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3-to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30°C), followed by 1 NKCl extraction and analysis for NH4+and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30°C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of N-treated/high N), whereas untreated/low N exhibited no net nitrification. However, soils exhibiting no net nitrification tested positive for presence of nitrifying bacteria, causing us to reject our initial hypothesis. We hypothesize that nitrifier populations in such soil are being inhibited by a combination of low Ca to Al ratios in mineral soil and allelopathic interactions with mycorrhizae of ericaceous species in the herbaceous layer.


2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Rodolfo Andrés Martiarena ◽  
Jorge Luis Frangi ◽  
Martín Alcides Pinazo ◽  
Alejandra Von Wallis ◽  
Roberto Antonio Fernández

The aim of this study was to evaluate the effect of thinning intensity and different harvest types on ecosystem P conservation in 20-year-oldPinus taedaplantation ecosystems at Misiones province, Argentina. The plantation was established in 1985, thinned at three intensities—0, 33, and 66% of basal area of control plots removed by thinning—and harvested in 2005. The nutrient content at harvest was determined for tree, shrub, and herb layers, the forest floor and upper mineral soil. Two harvest types were simulated: stem only and whole tree. Total P content was 56.8, 46.8, and 38.6 kg· ha−1for 0, 33, and 66% thinning, respectively. Total P exported by harvest was different among treatments, the highest at 0% thinning treatment. Phosphorus stability index values indicated that the P most conservative management option is 66% thinning, harvest of stem only and retention of forest floor, understory, and harvest residues.


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