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Responses to Simulated Nitrogen Deposition of Different Ages of Eucalyptus Dunnii Young Growth

Author: LvGuangLin
Tutor: WuChengZuo
School: Fujian Agriculture and Forestry University
Course: Ecology
Keywords: Simulated nitrogen deposition E.dunnii young forest Tree growth Soil nutrient Forest nutrient Litter decomposition
CLC: Q948
Type: Master's thesis
Year: 2009
Downloads: 105
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Abstract

In the past few decades, fossil fuel combustion, fertilizer use and livestock production and intensive management of emissions to the atmosphere by human activities such a large number of nitrides, resulting nitrides to accumulate in the atmosphere, terrestrial and aquatic ecosystems settlement, particularly is the beginning of the 20th century, 70 years, acid deposition has become industrialized countries in Europe and America is one of the important environmental issues; nitrogen deposition on forest ecosystems most important impact is to accelerate the trees and undergrowth soil and litter nutrient leaching, thus changing the System biogeochemical cycles; With the rapid economic development, China has become the Southern Europe's third largest after acid deposition zone, nitrogen deposition on forest ecosystems have been more and more people's attention. Currently about atmospheric nitrogen deposition on broad-leaved forest and woodland soils and litter decomposition and the feedback has little impact report. E.dunnii (EuCahetus dunnii Maiden) as the Fujian region's main economic trees, clarify nitrogen deposition and Dunn eucalyptus plantations between the feedback and negative feedback mechanisms, not only for our country and subtropical regions further nitrogen deposition research foundation, but also for E.dunnii provide a theoretical basis for sustainable forest management. In this study, four levels of field nitrogen treatments: N0 (0kg · hm ^{-2 · a ^{-1 ), N1 (40kg · hm ^{-2 < / sup> · a ^{-1 ), N2 (80kg · hm ^{-2 · a ^{-1 ), N3 (120kg · hm ^{-2 · a ^{-1 ), each treatment was repeated three times to study nitrogen deposition on different age E.dunnii young forest tree growth, soil nutrients, nutrients and litter decomposition in forest effects. The main results are as follows: a simulated nitrogen deposition on different age E.dunnii growth of young forest wood in the whole course of the experiment, each treatment level E.dunnii young forest DBH and tree height quarter growth rate showed an overall trend: first reduce After the rise. After a year of experiments and found that high levels of nitrogen deposition inhibiting DBH growth, and low concentrations of nitrogen deposition promoted the DBH and 2-N2 treatment DBH growth greatest extent (45.55%), the nitrogen treatments to promote the growth of the tree height, and the 2-N1 handling high-growth tree greatest extent (43.83%), two simulated nitrogen deposition on different age E.dunnii young forest soil nutrient nitrogen treatments with the same period the forest soil nitrogen levels were as follows: the upper gt; middle gt; lower; same layer of soil nitrogen deposition at the same level as the total nitrogen content and treatment time has increased; earlier forest soil nitrogen content increases with increasing concentration. Nitrogen same period, the upper layer of soil organic carbon content was significantly higher than the middle and lower soil organic carbon: nitrogen treatment levels with soil organic carbon content in the same layer as the treatment time is reduced; earlier in the same layer of soil organic carbon As the nitrogen content decreases with increasing concentration. Between treatments during the trial period soil C / N has a larger change, and changes in the range between 12.04-77.43. The same level of treatment in the same layer of soil nitrogen C / N with the treatment time is reduced; earlier in the same layer of soil C / N as the nitrogen concentration decreases with an increase; same period with the nitrogen treatment, except in July 2007 sampling The 2-N3 treatment, in October 2007 the 2-N2, 2008 April 2-N3 treatment and January 2008 sampling 3-N0 tackled the other are as follows: the upper layer of soil C / N than the middle and subsoil. Nitrogen same period, the upper layer of soil phosphorus content was significantly higher than the middle and lower soil; same time in the same layer of soil samples with nitrogen phosphorus content decreases with increasing concentration: two forests in the first three quarters of the experiment with nitrogen concentration process in the same layer of soil phosphorus content as treatment time is reduced, but the last two quarters of phosphorus content is relatively stable; years old stands in the whole course of the experiment, the soil phosphorus content is relatively stable. The same sampling time in the same layer as the concentration of soil K content decreased with the increase; except July 2008 sampling three forests, the other with the same sampling time processing nitrogen concentration of the upper soil K content was significantly higher than the middle and subsoil; nitrogen deposition on soil potassium leaching promote the role of the middle and lower concentration of nitrogen in the same soil treatment under the influence of treatment time with the phosphorus content increased, but not significantly. Three simulated nitrogen deposition on different age E.dunnii young forest stumpage forest nutrient content after a year of experiments, nitrogen deposition promotes E.dunnii young forest leaf nitrogen content increased, and 2-N3 treatment increased the maximum level (89.22%). Nitrogen deposition also promotes leaf phosphorus content increased, and the 2-N1 treatment increased the greatest extent (262.22). Nitrogen deposition to promote a three-year forest leaf potassium content increased, and the N2 treatment increased the greatest extent (78.82%); while the two forests will play an inhibitory effect, and the N3 treatment to reduce the maximum level (19.32%). Nitrogen deposition inhibiting two forest leaf carbon content increased, and the N3 treatment increased minimally (-14.17%); N0, N2 and N3 are to promote a three-leaf forest carbon content increased, and N0 treatment increased the greatest extent (5.18 %). Nitrogen deposition caused E.dunnii young forest leaf calcium and magnesium content decreases and reduces the greatest extent treatments were :2-N3 (54.25%) and 2-N1 (49.1%). After a year of experiments, all three nitrogen treatments promote forest branches nitrogen content increased, and N0 treatment increased the greatest extent (96.85%): two-year deal with forest only N3 played a catalytic role. Nitrogen deposition promotes branch phosphorus content increased, and the degree of improvement in maximum 2-N2 (260.91%). Only 3-N1 branch dealing with the promotion of the potassium content increased, other treatments are played inhibition, and 2-N2 treatment to reduce the maximum level (49.44%). 2-N3 and 3-N1 processing branches to promote the increase of carbon content, other treatments have played an inhibitory effect, and the inhibitory effect of 2-N0 most obvious treatment. The average of the treated water to promote the reduction of calcium branches, and 3-N0 reduces the greatest extent (63.14%). The average of the treated water to promote the reduction of magnesium branches, and the 2-N3 treatment to reduce the maximum level (50.65%). 4 simulated nitrogen deposition on different age E.dunnii young forest leaf litter decomposition of nitrogen deposition are inhibited litter decomposition. Two years old stands in May and June 2008 the most significant inhibitory effect, and the maximum inhibition N3, respectively, relative to control weight loss rate decreased 2.96% and 3.12%; while the three-month old stands at 2,5 two most obvious inhibition, other Time inhibitory effect was not significant. N1 treatment on the inhibitory effect of two-year old stand as N2, N3 treatment; years old stand variation inconsistent. In the first three months of the experiment, N2 on two forest litter decomposition in the inhibitory effect of large; three forest in January 2008 when the maximum inhibitory effect. N3 treatment on two years old stand outside the first 4 months in addition to inhibitory effects were greater than N1, N2 treatment, three-year old stand start from June 2008 also showed the same pattern. Litter decomposition occurs mainly in the first 6 months, the maximum weight loss rate reached 41.23%, post-weight loss rate of litter each treatment did not change significantly. After a year of experiments, nitrogen deposition leaf litter inhibits the release of nitrogen, and the degree of inhibition of the maximum 2-N2 (32.17%). Litter decomposition of N elements release mode: quick release - Slow enrichment - slowly released - a small amount of enrichment. The performance of direct release of potassium and nitrogen deposition promotes the release of potassium. Phosphorus release mode: quick release - a small amount of enrichment - a small amount of release - a small amount of enriched, low concentrations of nitrogen treatment inhibited the two forests phosphorus release, and the high concentration of nitrogen treatment promoted the release of phosphorus; and nitrogen deposition on three forest is played a catalytic role. Litter nitrogen deposition promotes carbon degradation, but the difference was not significant between treatments. Nitrogen deposition inhibiting two forest leaf litter loss of calcium and low levels of nitrogen processing inhibitory effect largest relative to control residual rate decreased by 6.43%, by analysis of variance among treatments were significantly different; N1 treatment inhibited three students E.dunnii young forest leaf litter in the loss of calcium, while N2 and N3 then played a catalytic role, and N2 greatest effect, relative to control residual rate increased by 5.84%, by analysis of variance among treatments was not significant. Nitrogen deposition inhibiting two forest leaf litter loss of magnesium, and the inhibitory effect as the concentration increases, by analysis of variance among treatments were significantly different; while N3 treatment for three years has played a catalytic role in forest , N1 and N2 are played inhibition, and the effect of the maximum N2, relative to control residual rate decreased by 4.55% by analysis of variance among treatments was not significant.}}}}}}}}

Responses to Simulated Nitrogen Deposition of Different Ages of Eucalyptus Dunnii Young Growth

Abstract

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