| 其他摘要 | The North China larch is main afforestation species of middle mountains above in
north China, one of the important species used in fast-growing plantation, which can
resistant to bad weather and plays an important role in water and soil conversation,
forest region ecosystem formation and maintenance. But in recent years, there are many
problems in North China larch plantation development, such as single tree species, the
structure of community is simple, poor stability, low productivity, frequent harm of
wind throw and snowbreak, the serious problem of disease and insect pests, degradation
of plantation quality. These problems seriously affect the sustainable development of
North China larch and management. Nitrogen and phosphorus are not only the basics
elements for plant growth but also the main limiting factor in plant growth of terrestrial
ecosystem. Nitrogen and phosphorus fertilization can change the North China larch on
soil nutrients absorption and utilization, thus affecting the growth of North China larch
plantation. In this study, we collected the 23-year-old North China larch plantation as
the research object in Qinling, which is conducted by nitrogen and phosphorus
fertilization experiment for four consecutive years, determined the contents of organic
carbon, total nitrogen, total phosphorus, total potassium in fine roots，stems，needles
and the contents of organic carbon, available nitrogen, available phosphorus, available
potassium in soil. Effects of fertilization on contents and ecological stoichiometry of C,
N, P, K in different organs be analyzed and the impact of fertilization on soil nutrient
content in North China larch plantation and their seasonal variations be explored. The
aim of this study is also to explicit the nutrient resorption efficiency of N, P, K and
discuss internal relation of nutrient resorption efficiency and C, N, P, K ecological stoichiometry characteristics, in order to provide theoretical basis of study of nutrient
uptake, utilization and restoration mechanism. The main results were as follows:
(1) Nitrogen and phosphorus fertilization can have a significance influence on the
needles、stems and roots nitrogen, phosphorus and potassium content in the larch, but
has no significant influence on organic carbon content. Both nitrogen treatment and the
combination of N and P treatment increased the carbon organic content of 3.32% and
5.43%. The N2 treatment has improved the nitrogen content of needles and roots and
the most significant effect is N 150 kg·hm-2 + P 75 kg·hm-2 fertilizer rate; the needles
and roots phosphorus content also increased by phosphorus fertilization and the
combination of N and P treatment, all of above showed that there are some degree of N
and P limited of North China larch land. Nitrogen and phosphorus fertilization has no
significant influence on potassium content. The North China larch carbon, nitrogen,
phosphorus and potassium content show obvious seasonal variations, among them
organic carbon have the minimum seasonal variability while total potassium have the
maximum seasonal variability. The needles and roots can be a good characterization of
nutrient deficiency, July and August is the best for diagnosis of nutrient deficiency.
(2) Nitrogen and phosphorus fertilization has a significant influence on soil
organic carbon content. The combination of N and P treatment obviously increased the
soil organic carbon, available nitrogen and phosphorus content, single N and P
fertilization respectively increased the soil available nitrogen and phosphorus content,
all of them indicate that fertilizer can improve the soil nutrient availability. Single P
fertilization also increased the content of available potassium. Both soil organic carbon
and available nutrient have obviously seasonal variability, the maximum is available
nitrogen and the minimum is available phosphorus.
(3) Nitrogen and phosphorus fertilizer significantly influenced the ecological
stoichiometric ratio in North China larch, to judge the nutrient limitation well, single N
fertilization and the combination of N and P treatment significantly improved the C:N、
N:K and N:P in needles and improved the P content of needles. The single P fertilization
and the combination of N and P treatment significantly reduced the C:P while increased
the P:K, and showed that fertilizer could improved the P content in needles. On the
basis of nutrient limitation judgement theory, the growth of the North China larch limited by N.
(4) The stem nutrient can’t represent the nutrient limitation and not obviously
response the fertilization. The fertilization has no significant influence on C:N, N:K and
C:K of stem, but single P fertilization decreased N:P and increased P:K. The ecological
stoichiometrics of roots nutrient can reflect the nutrient absorption and utilization.
Single N fertilization and the combination of N and P treatment significantly improved
the C:N and N:K，Single P fertilization and the combination of N and P treatment
significantly decreased C:P but improved P:K Nitrogen and phosphorus fertilizer
significantly improved the use efficiency of N and P and growth rate of fine roots.
(5) The soil available nutrient has a close correlation with the carbon, nitrogen,
phosphorus and potassium content in needles, stem and roots of North China larch, and
the soil available nutrient content obviously affected the growth of North China larch.
Both the nutrient resorption efficiency of N and P higher than the global average, the
fertilizer also reduced its nutrient resorption efficiency. So it indicated that the soil need
more nitrogen and phosphorus from another perspective.
Keywords: Larix principis-rupprechtii Mayr; Fertilization; Ecological stoichiometrics;
Nutrient |
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