Long-term effects of repeated N fertilization and straw application in a jack pine forest. 2. Changes in the ericaceous ground vegetation

1995 ◽  
Vol 25 (12) ◽  
pp. 1984-1990 ◽  
Author(s):  
C.E. Prescott ◽  
J.W. Kumi ◽  
G.F. Weetman

The cover of the ericaceous shrub Kalmiaangustifolia L. in a jack pine (Pinusbanksiana Lamb.) forest was reduced after repeated fertilization with N or N–P–K, or a single application of straw. Kalmia reductions were greatest in plots that received the highest total N loading (1344 kg N•ha−1), but were also apparent in plots that received 672 kg N•ha−1. The reductions could not be attributed to shading, since tree volume response was small in the plots that received the highest N loading. There was an overall reduction in the amount of ground vegetation in the fertilized plots, so the decline could not be attributed to increased competition from invading species. There was a general negative relationship between the abundance of Kalmia and N availability in the forest floor, in fertilized and straw-amended plots. The reductions in Kalmia cover were still apparent 14 years after the last fertilization and 24 years after the straw application, as was higher N availability. Treatments such as repeated N fertilization or organic amendments that increase N availability in the forest floor may be an option for control of Kalmia in conifer plantations.

1995 ◽  
Vol 25 (12) ◽  
pp. 1991-1996 ◽  
Author(s):  
C.E. Prescott ◽  
B.E. Kishchuk ◽  
G.F. Weetman

A long-term increase in N availability was evident in higher rates of net N mineralization and lower C/N ratios in jack pine (Pinusbanksiana Lamb.) forest floors that received 672 kg N•ha−1 in six applications or a single application of straw. There was no evidence of increased N availability in plots that received P and K in addition to N. Litter N concentrations were higher in N-fertilized and straw-treated plots, but rates of C mineralization and litter decomposition were not increased. Additions of N in repeated small applications or in conjunction with readily decomposable C in straw likely resulted in high retention of N in the ecosystem. The long-term increase in N availability was attributed to increased recycling of N, retention of added N in the ecosystem, and reductions in the ericaceous ground vegetation.


1972 ◽  
Vol 104 (2) ◽  
pp. 263-270 ◽  
Author(s):  
Peter W. Price

AbstractParasitoid populations were sampled before, and for 4 years following, an aerial application of the insecticide phosphamidon to control a sawfly outbreak. Adult parasitoid mortality was high because of spraying, but a reservoir of parasitoids in host cocoons remained to repopulate the treated areas. In moister sites the number of species decreased and their relative abundance changed, but moderate numbers of parasitoids remained 4 years after spraying. In a dry site with little ground vegetation, none of the species present before spraying remained by the fourth year.


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.


2012 ◽  
Vol 42 (5) ◽  
pp. 868-878 ◽  
Author(s):  
Khaled Hamdan ◽  
Margaret Schmidt

It is predicted that bigleaf maple ( Acer macrophyllum Pursh) will almost double in frequency in British Columbia by 2085 due to climate change. We address whether its frequency increase could influence chemical properties of throughfall, stemflow, and forest floor due to species-specific effects. Eight plots with a single bigleaf maple tree in the centre of conifers were paired with eight Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plots without bigleaf maple. Compared with conifer plots, bigleaf maple throughfall and stemflow had higher pH and K concentration. The under-canopy and near-trunk forest floor associated with bigleaf maple showed higher pH, total exchangeable bases, cation-exchange capacity, and concentrations of exchangeable Ca and Mg. In addition, the near-trunk forest floor had higher base saturation and concentrations and contents of NO3-N and contents of total N and S. Throughfall and stemflow beneath bigleaf maple appear to contribute to higher pH and N availability in the forest floor. The results suggest that there is a soil microsite around bigleaf maple stems that is influenced by stemflow. These enriched microsites proximal to bigleaf maple trunks would allow bigleaf maple to have legacy effects on soil fertility and promote conifer productivity later in succession following bigleaf maple mortality.


2002 ◽  
Vol 32 (5) ◽  
pp. 892-902 ◽  
Author(s):  
T I Little ◽  
D J Pluth ◽  
I G.W Corns ◽  
D W Gilmore

After wildfire in the boreal forest, storage of organic carbon (C) begins with the accumulation of forest floor material. Soil properties of Gray Luvisols were studied to determine the differences in development along three toposequences. Our central hypothesis is that slope position does not influence the amount of accumulated organic C and total nitrogen (N) in the forest floor. Organic C and the C/N ratio in the forest floor and in A and B horizons increased from the crest to the toe of the slope. The forest floor contributed 2.0 ± 0.4 kg C·m–2 (mean ± SE) at the crest to 3.5 ± 0.5 kg C·m–2 at the toe. Throughout the solum, the C/N ratio was lower at the top of the slope compared with the toe (p < 0.05), and there were no differences among slope positions for in situ net N mineralization rates. Leaf area index, used as a proxy for net primary productivity, was greater (p < 0.05) at the toe compared with the crest position, and it was negatively correlated with forest floor total N concentration (r = –0.35, p = 0.027). These results, from mixedwood stands approximately 90 years after the last major fire disturbance, indicate that slope position does influence forest floor organic C by horizon volume (p = 0.02), but not total N concentration (p = 0.07). Despite the apparently lower N availability at the toe position, it exhibited the greatest potential productivity.


1974 ◽  
Vol 4 (4) ◽  
pp. 470-476 ◽  
Author(s):  
Neil W. Foster

The annual amounts of N, P, K, Ca, and Mg in litter-fall, throughfall, and stemflow were measured in a 30-year-old jack pine (Pinusbanksiana Lamb.) stand on a coarse glacial outwash soil in northern Ontario. Litter from ground vegetation and from the pine overstory was estimated. The nutrient content of precipitation was measured and the quantity of nutrients in leaf wash determined.Tree litter was the most important source of N, P, Ca, and Mg for the forest floor (51–69% of the total depending on the element), whereas throughfall supplied most K (54% of the total). Ground vegetation litter contributed significant amounts of nutrients (7–23% of the total depending on the element) but stemflow added little (1–8% of the total). Potassium in throughfall was derived mainly from leaf wash whereas N, P, Ca, and Mg in throughfall were derived primarily from precipitation entering the ecosystem. This jack pine forest floor received an annual total of 30 kg/ha of N, 22 kg/ha of Ca, 19 kg/ha of K, 3 kg/ha of Mg, and 2 kg/ha of P from the processes studied. Most of the nutrients in these totals were returning to the forest floor from the vegetation.


1987 ◽  
Vol 17 (12) ◽  
pp. 1557-1564 ◽  
Author(s):  
R. D. Kabzems ◽  
K. Klinka

Previous attempts to characterize soil nutrient regimes of forest ecosystems have been qualitative evaluations utilizing vegetation and (or) topographic features, morphological soil properties, and mineralogy of soil parent materials. The objective of this study was to describe and provide initial data for quantitative classification of soil nutrient regimes in some Douglas-fir ecosystems on southern Vancouver Island. A multivariate classification using forest floor plus mineral soil mineralizable N and exchangeable Mg quantities was proposed for the four nutrient regimes (poor, medium, rich, and very rich) recognized in this study. Significant differences in mineralizable and total N existed between the four identified soil nutrient regimes. The previous N fertilization of two study sites did not seem to change soil N status sufficiently to alter the classification. The differences in nutrient availability were more distinct when forest floor and mineral soil properties, expressed on an areal basis, were summed. There were no significant differences in exchangeable Ca and Mg for the poor and medium soil nutrient regimes. The humus form of the forest floor was an important characteristic for identifying soil nutrient regimes in the field; however, the nutrient quantities of the forest floor reflected differences in bulk density and depth and did not effectively distinguish between regimes.


HortScience ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 146-153
Author(s):  
Amy L. Shober ◽  
Andrew K. Koeser ◽  
Drew C. McLean ◽  
Gitta Hasing ◽  
Kimberly K. Moore

Several Florida cities and counties ban fertilization during the summer rainy season (fertilizer blackout). Little research is available to support or contradict the underlying justifications for these policies. We used large-volume lysimeters to address the impacts of several fertilization regimes on plant growth and aesthetics of sweet viburnum (Viburnum odoratissimum Ker Gawl.) and nitrogen (N) leaching from landscape beds during shrub establishment and maintenance. Three levels of N fertilization (98, 195, and 293 kg·ha−1), two levels of application method (per plant and broadcast), two levels of fertilization timing (regular and blackout), and an unfertilized control (0 kg·ha−1 N) were applied to lysimeters in a completely randomized design with three replicates (3 × 2 × 2 factorial plus untreated control). Increasing fertilization rate increased plant growth and improved plant quality, but also increased N leaching from lysimeters. Including a summer fertilization blackout period reduced nitrate + nitrite (NO3 + NO2-N) loading from lysimeters during sweet viburnum establishment [0 to 28 weeks after planting (WAP)] compared with year-round fertilization at the same total N rate without adversely impacting plant growth or aesthetics. However, NO3 + NO2-N loads from lysimeters were higher when fertilizers were applied on the summer blackout application schedule during the shrub maintenance period. Targeted (per plant) fertilization beneath the dripline of sweet viburnum at an annual N rate of 195 kg·ha−1 can maintain plant health while limiting N leaching losses on a year-round or blackout fertilization schedule.


Author(s):  
Mervin St. Luce ◽  
Noura Ziadi ◽  
Martin H. Chantigny ◽  
Justin Braun

Tillage and nitrogen (N) fertilization can influence soil organic matter (SOM) dynamics, but their interactive effects remain contradictory. A long-term (25 yr) corn (Zea mays L.)-soybean (Glycine max L. Merr.) rotation was used to investigate the effect of tillage [moldboard plow (MP) and no-till (NT)] and N rates (0, 80 and 160 kg N ha-1) on soil organic carbon (SOC), total N (STN), respiration, and SOM fractions [particulate organic matter (POMC, POMN), mineral-associated organic matter (MAOMC, MAOMN), and microbial biomass (MBC, MBN)]. Results indicate that NT had 27% higher SOC and 24% higher STN than MP in the 0-20 cm depth. Furthermore, SOC and STN stocks (0-20 cm) were 22% and 20% higher, respectively, under NT than MP. There was significant stratification under NT, with a rather uniform distribution under MP. The SOM fractions and soil respiration were 28-275% and 20-83% higher at the 0-5 and 5-10 cm depths, respectively, under NT than MP. Interestingly, N fertilizer rate or its interaction with tillage had no impact, except for respiration (tillage × N rate and N rate × depth). Hence, while N addition was required for adequate grain production and increased cumulative plant C and N inputs, our findings indicate that the vertical distribution of SOC, STN and SOM fractions were affected by tillage, thereby influencing resource accessibility and subsequent dynamics of SOM fractions. Taken together, our results support the adoption of NT and judicious use of N fertilizers for enhancing topsoil SOM storage and fertility under humid temperate conditions.


2002 ◽  
Vol 32 (1) ◽  
pp. 120-128 ◽  
Author(s):  
R Jandl ◽  
F Starlinger ◽  
M Englisch ◽  
E Herzberger ◽  
E Johann

We evaluated the soil chemistry, plant species composition, and forest growth rate on a site where a site amelioration project had been realized 30 years earlier. The initial goal of the project was the improvement of a site that had been degraded by litter raking. We wanted to know which amelioration method produced a sustainable result and how different treatments might be rated by today's standards. Treatments included fertilization, underplanting with N-fixing plants, and a combination of both. The amelioration was combined with stand conversion by means of natural regeneration and spruce underplanting. In all treatments, a spruce-dominated stand replaced the secondary pine stand. The biomass of the formerly recalcitrant forest floor (143 Mg·ha–1) was reduced by 30 to 50% in treated plots, thereby reducing the total soil pool of C, N, and exchangeable cations. The mineral soil of treated plots was enriched with N, Ca, and Mg. An increase in pH was restricted to the forest floor. The C pool of treated soils was much smaller than that of the control plots. However, the loss from the soil was at least partly offset by increased growth rates of the aboveground tree biomass. In treated plots, the stem volume was more than twice that of control plots (38.3 m3). Soil chemical data and the composition of the ground vegetation suggest that even the control plots have changed compared with pre-treatment conditions. Comparison of different blocks of the experiment suggests that the exclusion of roe deer (Capreolus capreolus) by fencing was the most significant treatment required for successful stand conversion. Prior to fencing, deer browsing inhibited the establishment of a new stand.


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