Chinese fir plantation-the second most important timber species
in China: problems and solutions
1)Liping Liao, 2)Shidong Zhao
1)Professor, Institute of
Applied Ecology, Chinese Academy of Sciences,
Shenyang 110015, China
2)Professor, Institute of
Geographic Science and Natural Resources,
Chinese Academy of Sciences,
Beijing 100101, China
Abstract
Chinese fir is the most important
conifer species for commercial timber with huge distribution area in southern
China, covering 24% of plantation forests and providing 1/4 of total wood
materials in the country. At present, however, the plantation forests have
faced serious problems of soil degradation. We review the main processes
concerning soil degradation in terms of nutrient bio-cycles, soil nutrients, soil
biochemical activity and productivity of the plantations. We also proposed and
discussed the possible countermeasures to solve the problems.
Contents of N, P, and K of
0-60cm soil under pure Chinese fir plantation with the age of 20 declined by
43.4%, 24.3% and 43.2% respectively compared to those of 1 year-old plantation.
Soil microbes populations changed markedly, bacteria decreasing by 19.2%, fungi
and actinomyces increasing 10.4
and 42.7 times respectively. When
Chinese fir plantations were managed in successive rotations, the problems
turned more serious in soil fertility decline and soil microbes change.
Long-term localized investigations on two permanent plots of Chinese fir
plantation showed that the soil content of available N, K and P declined by
40.5%, 47.5% and 42.3% respectively when the plantation turned into second
rotation from the first, and declined by 17.5% , 51.5% and 34.1% when established into the third
rotation from the second . The total amount of soil microbes of third rotation
of Chinese fir plantation was reduced to 45.0% below of that of the first
rotation. The biochemical activities of soil microbes were inhibited obviously
by the management practice of successive rotations, with ammonification
declining by 80.0%, nitrification by 53.9%, and fiber decomposition by 58.3%,
when Chinese fir plantation was repeated on the site for three rotations.
The deteriorated soil
properties were well mirrored in the reduction of the plantation growth. The mean diameter at breast
height (DBH) decreased by 13.3% and 21.7% respectively for the second and third
rotation, and the average tree height by 11.0% and 35.5% . The volumes of three
rotations of Chinese fir plantations were as follows: First, 383.0 m3.hm-2;
Second, 262.5 m3.hm-2; Third, 173.6 m3.hm-2.
Keywords: Chinese fir, plantation, soil fertility,
productivity, soil degradation, ecosystem management
INTRODUCTION
China is one of the countries with
limited forest resources. Although the Chinese government has spent much effort
on reafforestation and plantation projects since 1949, the forest cover has
only reached 16.55% up to now. The situation is getting more serious because
the forest resource has been continuously decreasing. This has been caused by
the pressure of a fast growing population, the development of the economy and
the poor management of resources (1).
Chinese fir (Cunninghamia lanceolata (Lamb) Hook.) is
a fast growing ever-green conifer, and native to China, with extensive
distribution from 220 N and 1020 E to 340N and
1220 E, and is the second most important timber species in China
(2). It produces good quality timber, with straight shape, high resistance of
bending and cracking, and easily processing trait. Its timber is most popular
with local people, widely used in furniture manufacturing and construction
building. It produces 24% of the total timber grown in China each year. The
Chinese have more than 1000 years experience in managing its plantations. The
local people have been using shifting cultivation approach in order to maintain
the soil fertility for a long time. Three rotations, lasting about 70 years,
are grown on a site and then the land is left under natural conditions for
another 70 years. At the end of this period the natural growth is cut and burnt.
The land is then replanted with Chinese fir(3). Because of rapid population
growth and limited land, this system is becoming more and more difficult to
maintain.
The purposes of this article
are (1) to review the problems with replanting Chinese fir plantations for
consecutive rotations in terms of soil nutrient depletion, change in soil
biochemical activity and decline in stand productivity; (2) to discuss the
solutions to those problems from three aspects: reformation of conventional
management system, cultivation of Chinese fir mixture and utilization of
fertilizers.
PROBLEMS
I. Soil fertility decline over the same rotation
Nutrient
content
The species prefers rich soil with
thick depth, which implies that it consumes large amount of nutrients to meet
its fast growth. Over the same rotation of Chinese fir plantation, soil
nutrient contents decreased greatly. When the plantation got its age of 20
years, contents of soil total N, P and K
in the depth of 0- 20 cm
were only 50.8% , 14.1% and 36.6% of those before the establishment of the
plantation( Table 1). The contents in the depths of 20- 40cm and 40-60 cm
declined markedly as well. The
serious decline in nutrient contents could be caused by the imbalance between
uptake and return. The ratios of return to uptake were 0.43, 0.46 and 0.25,
respectively, for N, P and K (Table 2), due to low rate of litter decomposition
(4). It returned much less
nutrients than uptook even when the plantation got over-mature up to sixties
years of age(Table 2). The ratios of return to uptake were still low, and were
0.26, 0.29, 0.16, 0.25 and 0.26 respectively for N, P, K, Ca and Mg (Table 2).
Table. 1. Changes of soil nutrient contents from the
establishment of Chinese fir plantation to the age of 20 years (g.kg-1).
|
Sampling time |
Sampling depth (cm) |
N |
P |
K |
|
Pre-establishment |
0-20 |
1.79 |
0.311 |
10.44 |
|
At the age of 20 |
0.91 |
0.044 |
3.82 |
|
|
Pre-establishment |
20-40 |
1.33 |
0.311 |
9.78 |
|
At the age of 20 |
0.74 |
0.089 |
3.82 |
|
|
Pre-establishment |
40-60 |
1.07 |
0.308 |
8.63 |
|
At the age of 20 |
0.17 |
0.089 |
4.81 |
Table. 2. Nutrient uptake and return in Chinese fir
plantations of different ages (kg.hm-2.a-1).
|
Stand age(yr) |
Items |
N |
P |
K |
Ca |
Mg |
|
|
Uptake |
40.97 |
15.09 |
18.47 |
79.01 |
42.86 |
|
20 |
Return |
17.79 |
7.0 |
4.61 |
25.82 |
14.35 |
|
|
Return/Uptake |
0.43 |
0.46 |
0.25 |
0.33 |
0.34 |
|
60 |
Uptake |
73.85 |
48.94 |
33.48 |
139.27 |
103.35 |
|
Return |
19.17 |
14.06 |
5.43 |
34.82 |
26.83 |
|
|
Return/Uptake |
0.26 |
0.29 |
0.16 |
0.25 |
0.26 |
Soil
microbe population
As the important decomposers of plantation ecosystem, soil microbes play important role in nutrient transformations, and meanwhile are the good indicator of habitat change. The total number of soil microbes decreased, as the plantation grew old. When the plantation became 21 years old from one-year, the total number of soil microbes decreased by 8.4% due to the decrease in the number of soil bacteria (Table 3), but the numbers of fungi and actinomyces increased 532.4% and 4173.5%, respectively. The numbers of soil microbes and three component populations changed in similar pattern, but for total microbes and bacteria the numbers declined in greater magnitude, by 58.1% and 59.9%, respectively, and increased in less extent for fungi and actinomyces, by 20.6% and 111.6%, respectively (Table 3).
Table 3 Variation of soil microbe population under different ages of
Chinese fir plantations (103.g-1 soil)
|
Age(yr) |
Total microbes |
Bacteria |
Fungi |
Actinomyces |
|
19 |
39859 |
39350 |
165 |
344 |
|
39 |
16687 |
15760 |
199 |
728 |
|
1 |
17008 |
16900 |
74 |
34 |
|
21 |
15581 |
13660 |
468 |
1453 |
II. Contents of soil nutrients and biochemical
activities of soil microbes in different rotations
Soil nutrient
We chose three sites where Chinese
fir plantations grew in first, second and third rotations, respectively, and
were not far from each other. The contents of soil humus carbon, N, P and K
were analyzed by taking soil samples from the three sites. As the sampling
depth got deeper, the contents of all the elements declined for all the three
sites (Table 4). There were severe decreases in the contents of all the
elements when the rotation times of Chinese fir plantation increased from one
to three. The average content of
soil humus carbon decreased by 16.2% for the second rotation and by 33.7% for
the third rotation, N, 20.0% and 35.0%, P, 9.0% and 63.5%, and K, 2.8% and
10.3%, respectively (Table 4).
To further confirm the above
results, two permanent plots F1 and F2, in one of which the first rotation of
Chinese fir plantation was grown and in the other the second rotation was
there, were set up on the experiment site of Huitong Research Station in 1961.
15 soil samples were taken respectively from each plot, and the ten soil pits
were marked with stone pillars for each and the adjacent characteristics of
each pit were recorded as well. In 1991, the site of first rotation had been
reafforested with Chinese fir and developed into second rotation of Chinese fir
plantation, and the second into the third. All the soil pits were re-visited
and a soil sample was collected from each pit. Every 15 samples were mixed into
one sample for each plot, and used to analyze the contents of available N, P
and K. When the plantation was regenerated from the site of first rotation of
Chinese fir plantation, the contents of soil available N, P and K decreased
respectively by 43.2%, 43.0% and 38.6% in the depth of 0-20cm. When the
plantation was replanted on the site of second rotation, the contents of soil
available N, P and K by 25.0%, and 48.8% and 6.3%(Table 5). The contents of
available N, P and K in the soil depth declined by different degrees as well.
Table 4 Relationship between rotation times and contents of soil
nutrients (g.kg-1)
|
Rotation times |
Sampling depth (cm) |
Humus Carbon |
N |
P |
K |
|
|
5-15 |
39.3 |
4.8 |
0.266 |
17.9 |
|
|
16-26 |
32.6 |
3.5 |
0.266 |
15.4 |
|
First |
30-40 |
31.4 |
3.3 |
0.266 |
12.4 |
|
|
55-65 |
19.1 |
4.4 |
0.178 |
12.1 |
|
|
Average |
31.5 |
4.0 |
0.244 |
14.5 |
|
|
5-15 |
34.6 |
3.9 |
0.266 |
16.2 |
|
|
16-26 |
32.3 |
3.5 |
0.266 |
14.5 |
|
Second |
30-40 |
21.1 |
2.9 |
0.178 |
13.9 |
|
|
55-65 |
17.5 |
2.6 |
0.178 |
11.6 |
|
|
Average |
26.4 |
3.2 |
0.222 |
14.1 |
|
|
5-15 |
32.0 |
3.3 |
0.133 |
13.4 |
|
|
16-26 |
19.8 |
2.7 |
0.089 |
13.3 |
|
Third |
30-40 |
16.8 |
2.2 |
0.089 |
13.3 |
|
|
55-65 |
15.0 |
2.0 |
0.044 |
11.8 |
|
|
Average |
20.9 |
2.6 |
0.089 |
13.0 |
Table 5 Variations of soil contents of available nutrients under
different rotations (mg.kg-1)
|
Plot No |
Sampling depth (cm) |
Time |
Rotation Times |
N |
P |
K |
|
F1 |
0-20 |
Pre-30 years |
First |
103.5 |
56.3 |
102.5 |
|
Post-30 years |
Second |
58.7 |
32.1 |
62.9 |
||
|
20-40 |
Pre-30 years |
First |
83.5 |
55.5 |
90.6 |
|
|
Post-30 years |
Second |
52.6 |
26.6 |
48.5 |
||
|
F2 |
0-20 |
Pre-30 years |
Second |
93.5 |
52.5 |
56.9 |
|
Post-30 years |
Third |
70.1 |
26.9 |
53.3 |
||
|
20-40 |
Pre-30 years |
Second |
47.5 |
49.7 |
65.9 |
|
|
Post-30 years |
Third |
46.3 |
22.7 |
27.6 |
The variations of available
nutrients under the first, second and third rotation of Chinese fir plantations
were monitored during a growing season. Over the whole growing season, contents
of soil NH4+-N for the different rotations were in the
order that first rotation the highest, the second the middle, the third the
lowest (Fig.1). Generally speaking, the contents of available P and K followed
the similar pattern to NH4+-N, with one exception,
respectively, for P, that the second rotation was lower than third rotation,
and for K, that the first rotation was lower than the second rotation, in June
(Fig.1).
Figure 1. Dynamics of soil NH4+-N,
available P and K within growing season of different rotations of Chinese fir
plantations.
Biochemical
activities of soil microbes
The pattern of soil nutrient
decline over different rotations could be mirrored in the biochemical
activities of soil microbes. Ammonification declined by 80%, ranging from 1.0
mg N.g-1 soil to 0.2 mg N.g-1 soil, when continuous
cropping of Chinese fir plantation took place for twice, nitrogen fixation by 53.9£¥, fibre decomposition by 58.3%, and respiration by 40.0%(Table
6).
Table 6 Effects of successive rotation practice of Chinese fir plantations
on biochemical activities of soil microbes.
|
Rotation times |
Ammonification (mg N. g-1soil) |
Nitrogen fixation (%) |
Fibre decomposition (CO2 mg.g-1 soil) |
Respiration (%) |
|
First |
1.0 |
14.1 |
3.6 |
1.5 |
|
Second |
0.7 |
12.8 |
0.7 |
1.2 |
|
Third |
0.2 |
6.5 |
1.5 |
0.9 |
III. Productivity of Chinese fir plantations over
different rotations
The above
mentioned soil nutrition consumption due to continuous cropping could lead to
the impact on the growth of Chinese fir trees. The investigation on Chinese fir
plantations of different rotations but with same ages of 20 years showed that
the average values and annual increments of the diameter at breast height
(DBH), height and volume decreased whilst the times of repeated rotations
increased. The average DBH, height and volume of the second rotation declined
by 13.3%, 11.0% and 31.5%, respectively, and for the third rotation by 21.7%,
35.5% and 54.7%, respectively (Table 7).
After the above
results were firstly published by researchers of Huitong Research Station of Forest Ecology, Chinese Academy
of Sciences, Hunan Province, China, many other researchers reported the similar
results. Fang (5) found in the same area that the tree height of the third
rotation of Chinese fir plantation was 11.0 m while the first was 14.2 m, declining
by 22.5%. The investigation on Chinese fir plantation continuously cropped for
one time in Guangxi Zhuang Nationality Autonomous Region by Wu (6) showed that
the decrease in the volume of the second rotation ranged from 10% to 50%
compared with the first rotation. Yu & Zhang ¡¯s (7) in Fujian Province and
Xu (8)¡¯s research in Anhui Province suggested the similar conclusion that
continuous cropping practice of Chinese fir plantation lead to decline in
productivity. Productivity decline due to the continuous cropping practice
became a general phenomenon for the Chinese fir plantation.
Since the end of 1970s, a lot of research interest
was put into solving the problems caused by the continuous cropping of Chinese
fir plantation. Different management practices were surveyed, such as turning
mono-culture into mixture of Chinese fir plantations, utilization of
fertilizers, cultivation of mixtures, shifting culture, etc (9).
Table 7 Relationship between rotation times
and productivity of Chinese fir plantations
|
Rotation times |
DBH |
Height |
Volume |
|||
|
Average (cm) |
Increment (cm.a-1) |
Average (m) |
Increment (m.a-1) |
Average (m3.hm-2) |
Increment (m3.hm-2.a-1) |
|
|
First |
14.3 |
2.3 |
15.5 |
1.35 |
383.0 |
129.5 |
|
Second |
12.4 |
2.0 |
13.8 |
1.20 |
262.5 |
89.5 |
|
Third |
11.2 |
1.8 |
10.0 |
0.95 |
173.6 |
58.5 |
Table 8 Comparison of
growth of tree species on degrading soil
|
Tree species |
Stand age (a) |
Site preparation practice |
Survival rate (%) |
Height (m) |
DBH (cm) |
Biomass (t.hm-2) |
|
Cunninghamia lanceolata |
6 |
Complete plowing |
35 |
2.19 |
2.45 |
3.05 |
|
Pinus elliottii |
6 |
Complete plowing |
95 |
4.50 |
7.62 |
37.45 |
|
Pinus massoniana |
6 |
Complete plowing |
92 |
3.49 |
4.52 |
27.63 |
|
Cunninghamia lanceolata |
6 |
Terraced field |
58 |
3.34 |
4.34 |
6.99 |
|
Pinus elliottii |
6 |
Terraced field |
98 |
4.86 |
8.58 |
44.67 |
|
Pinus massoniana |
6 |
Terraced field |
98 |
4.11 |
5.97 |
35.90 |
SOLUTIONS
I. Reforming of conventional management system
The conventional management
system on Chinese fir plantation has been used for over 1000 years, including
slash and burning, complete plowing for site preparation, clear cutting over a
large area, remove of felling residues, and monoculture. The system was blamed
to be responsible for leading to site degradation in replanting woodland of
Chinese fir plantation. Slash and burning was adopted to facilitate the
replanting operation, but it burned out organic matter and some nutrients, and
most minerals in the ash were lost when a rainfall happened. Complete plowing
significantly increased soil erosion and nutrients loss comparing with other
site preparation methods such as pit plowing and terrace preparing (10). Clear cutting caused soil and water
loss as well. In mountain areas of southern China, local peasants used the
residues from tree cutting as fuels, which increased the nutrient loss. All the
procedures of the management system tended to decrease stand growth of the
following rotation. Table 8 showed growth of different stands after the stumpy
land of Chinese fir plantation was either replanted with Chinese fir again or
shifted to other tree species-Pinus
elliotti and Pinus massoniana under
different site preparation of either complete plowing or terraced field. The
survival rate, mean height, mean diameter at breast height (DBH) irrespective
of site preparation were generally lower when the woodland was replanted with
Chinese fir (9). Biomass
production of Chinese fir was much less than the shift species, the former was
only 1/12-1/9 of the latter for the site preparation of complete plowing,
1/6-1/5 for the site preparation of terraced field (Table 8)(9). As of the
shift species, site preparation also affected their survival rate, height and
DBH growth and biomass production.
The conventional management system on Chinese fir plantation has to be
abandoned, and recently a rational and science-based management system, which
includes mild site preparation, clear-cutting in small area, burying of cutting
leftovers and multi-culturing, has been introduced.
II. Cultivation of the mixture
The critical problem in pure
Chinese fir plantation is litter¡¯s recalcitrance to decomposition because of
its high C/N ratio, and other serious problems also exist such as bad stability
and low resistance to pest attack due to its low biodiversity. The
mono-culturing practice has been gradually replaced with silviculture of
mixtures. The Chinese fir plantation mixtures could have higher productivity
and show positive improvement on soils if associated species was properly
selected and the mixing mode and proportion was rationally set up. A carefully
designed mixture of Chinese fir with Michelia
macclurei Dandy had 13.7% higher timber productivity than the pure Chinese
fir plantation, and simultaneously soil chemical and physical properties were
improved to certain degrees when the mixture was 8-years old(11). The
improvement mechanism has been explored. In the mixture, the amount of
litterfall and nutrient content were 2.3 and 1.8 times of those in the pure,
respectively(4,11). The fine-root turnover in the mixture was increased by
8.5%(12). The weight loss of decomposing Chinese fir litter was accelerated by
existence of M. macclurei leaf litter
(13,14).
Cultivation of Chinese fir
mixture also means culturing of understorey in pure Chinese fir plantation.
Shrubs and herbs were rich in nutrients and their litter decomposed easily. The
development of understoreys could be achieved by properly thinning the pure
plantation. For instance, at medium site quality, if only 1050 –1200 trees.ha-1
remained after final thinning, the understorey coverage could reach up to over
80%(15). The great quantity input of shrub and herb litter could improve soil
nutrient status at a high level, and soil biochemical activity was also
enhanced markedly.
III. Application of fertilizer
Fertilization is a direct
approach of nutrient input to the soil and a relatively expensive way of soil
improvement compared with the way of mixture cultivation. The fertilization
trials on Chinese fir plantation over large areas have been undertaken for over
ten years in China, most of which however were done on young Chinese fir
plantation below the age of 6 years. The effect of fertilization on growth of
Chinese fir plantation was not quite confirmative, and even some contradictory
results were found based on fertilizer trials of different areas, which
hindered the utilization of fertilizers in the field over large areas. Based on
the fertilization experiment on young Chinese fir plantation of 5-years old in
Jiangxi Province, China, Li et al(16)
concluded that application of phosphorus and potassium fertilizers could
increase stand growth. In another fertilizer trial on Chinese fir seedling in
Zhejiang Province of southern China, Ye(17) found that phosphorus fertilizer
increased growth at the beginning of fertilization, nitrogen fertilizer had no
effect, and potassium fertilizer showed negative effect. The fact that no long-term and
well-designed fertilization trials have up to now been conducted across the
distribution area of Chinese fir plantation could explain somewhat the reason
why the results of fertilization effect on Chinese fir growth was not convincing.
Both the above-mentioned
trials were on fertilizers of single nutrient element. The effect of compound
fertilizers of two or three nutrient elements of N, P and K in certain rates
was proved to be a different profile. When the amount of N, P, K in the
compound NPK fertilizer was in the proportion of 1:3:1, the compound fertilizer
increased tree height increment of Chinese fir growing in soil of the third
rotation by 75.4% and net production by 52.6% during one year¡¯s trial in the
pot culture, comparing with the control of non-fertilization (9). The results
were supported by other fertilization experiments (18, 19, 20). Generally
speaking, application of compound fertilizer containing phosphorus shows more
pronounced effects because soils in the distribution area of Chinese fir
plantation are in deficiency of phosphorus, and site index is also a limiting
factor (21).
CONCLUSIONS
The decline of forest soil
quality is a complex ecological problem, varieties of factors contributing to
it. First of all, the species has its own intrinsic properties, such as
restricted site quality for growing, recalcitrant litter, etc., which hindered
sustainable development of Chinese fir plantation ecosystems. Secondly, the
unreasonable management practices of replanting of monoculture have aggravated
the process of soil degradation. Thirdly, socioeconomic factors in that the
huge demand for the timber and good price in the market led to the existence of
conventional management system for hundreds of years. All the factors have made
the solution to the soil degradation much more difficulty as well as the
exploring of the mechanism of soil degradation, which will necessitate a long
term and comprehensive study to understand the dynamics of soil quality of
plantation forests under extensive management. The ecosystem-based management
approaches will probably provide promising solutions to the problems.
Acknowledgements
The authors were grateful to Prof. Chen
Chuying for providing quite a lot of information concerning the subject. This
study was financially supported by Chinese Academy of Sciences at grants No. KZ952-J1-202,
KZ951-A1-301 and KZ95T-04.
References
Li, W.H. and Li, F. 1996. Research of
forest resources in China. China Forestry Publishing House, Beijing, China, pp.
39-53(in Chinsese)
Editing Committee of Dendrology(ECD).
1978. Planting techniques for main plantation tree species of China.
Agricultural Press, Beijing, China, pp 3-29. (in Chinese )
Feng, Z.W., Chen, C.Y., Li, C.H., Xu,
G.H. and Zhou, C.L. 1982. Relations between the growth-development and
environment of Cunninghamia lanceolata
plantation in Huitong, Hunan Province. Journal
of Nanjing Technological College of Forest Products, (3): 19-38(in Chinese
with English abstract)
Chen, C.Y., Zhang, J.W., Zhou, C.L. and
Zheng, H.Y. 1990. Researches on improving the quality of forest land and the
productivity of artificial Cunninghamia
lanceolata stands. Chin. J. Appl.
Ecol., 1(2): 97- 106. (in Chinese with English abstract)
Fang, Q. 1987. Effect of replanted
Chinese fir plantation on soil fertility and its growth. Scientia Silvae Sinicae, 23(4): 389-397. (in Chinese with English
abstract)
Wu, S.N. 1986. On fertilization
efficiency of Chinese fir plantation. Guangxi
Forestry Sci. Tech., 3: 11-12. (in Chinese with English abstract)
Yu, X.T. and Zhang, Q.S. 1989. Studies
on the soil biochemical characteristics and soil fertility under the replanted
Chinese fir plantation. J. Fujian Fores.
Colle. 9(3): 256-262. (in Chinese with English abstract)
Xu, L.J. 1987. Considerations on causes
of soil degradation in Chinese fir plantation in Anhui. J. Anhui Forestry Sci. Tech., (1): 6-10(in Chinese with English
abstract)
Liao, L.P., Chen, C.Y., Zhang, J.W. and
Deng, S.J. 1996. Regulating strategies to sustainable development of plantation
ecosystems. Chin.J.Appl.Ecol.,
7(3):225-229. (in Chinese with English abstract)
Zhang, X.Y. 1986. The effects of
different types of site preparation on soil erosion and the growth of young
stands of Chinese fir. Scientia Silvae
Sinicae, 22(3):225-232(in Chinese with English abstract)
Feng, Z.W., Chen, C.Y., Zhang, J.W.,
Zeng, S.Y., Luo, R.H. & Chen W.Z. 1988. A coniferous broad-leaved mixed
forest with higher productivity and ecological harmony in subtropics—Study on
mixed forest of Cunninghamia lanceolata
and Michelia macclurei. Acta Phytoecol. et Geobot. Sin.,
12(3):165-180. (in Chinese with English abstract)
Liao,L.P., Chen, C.Y., Zhang, J.W. and
Deng,S.J. 1995. Turnover of fine roots in pure and mixed Cunninghamia lanceolata and
Michelia macclurei var. sublanea
forest. Chin.J. Appl. Ecol, 6(1):
7-10(in Chinese with English abstract)
Liao, L.P., Lindley,D.K.and Yang, Y.H.
1997. Decompositioin of mixed foliar litter I. A microcosm study. Chin. J.Appl. Ecol., 8(5):459-464(in
Chinese with English abstract)
Liao, L.P., Ma, Y.Q., Wang, S.L., Gao,
H. and Yu, X.J. 2000. Decomposition of leaf litter of Chinese fir in mixture
with major associated broad-leaved plantation species. Acta Phytoecol. Sin., 24(1):27-33(in Chinese with English abstract)
Yang, C.D. 1997. The reason and control
of site productivity of Chinese fir plantations. World Forestry Research, 10(4): 34-39(in Chinese with English
abstract)
Li, Y.Q., Xu, Q.Y. and Liu, Z.J. 1991. Early
five years¡¯ effect of fertilization on young Chinese fir plantation. Chin. J. Soil Sci., 22(11): 28-32( in
Chinese with English abstract)
Ye, Z.J. 1985. A superficial view of
fertilization on Chinese seedling culturing and planting. Journal of Zhejiang Forestry College, (1):13-20( in Chinese with
English abstract)
Wang, J.P. and Song, G.L. 1997.
Experimental trial on young forests of Chinese fir. J. Jiangxi Forestry Sci &Tech, 5: 17-20(in Chinese with English
abstract)
Zheng, D.H. 1998. Experimental study on
fertilization effect of young forests of Cunninghamia lanceolata. J. Fujian Forestry Sci &Tech, 25(2):
85-88(in Chinese with English abstract)
Liao, L.P., Liu, G.Y., Yu, X.J., Huang,
Z.Q. and Gao, H. 2000. Effect of fertilization on fine-root and biomass growth
of Chinese fir saplings planted in different soils of successive rotations. Chin. J. Appl. Ecol., 11(suppl):
221-225(in Chinese with English abstract)
Chen, J., Li, Y.Q. and Yang, C.D. 1998.
Research status of forest tree fertilization and nutrition diagnosis in China. World Forestry Research, 11(3): 58-65(in
Chinese with English abstract)