全 文 ：Journal of Forestry Research, 12 (2): 105-108 (2001) 105
Dynamics of nitrogen and phosphorus concentrations of fine roots in
a mixed forest of Cunninghamia lanceolata and
Tsoongiodendron odorum
YANG Yu-sheng, CHEN Guang-shui, XIE Jing-sheng, LI Xiu-fang, CHEN Yin-xiu
(Fujian Agricultural and Forestry University, Nanping 353001, P.R. China)
Abstract: From September 1999 to July 2000, N and P concentrations of fine roots were measured with the method of
sequential soil core at bimonthly intervals in a mixed forest of Tsoong’s tree (Tsoongiodendron odorum Chun) and Chinese fir
(Cunninghamia lanceolata (Lamb.) Hook.) in Sanming, Fujian. The results showed that N, P concentration of Chinese fir and
Tsoong’s tree in fine roots were negatively related to root diameter size. The concentrations of N and P in living roots and dead
roots were compared. The order of N concentration in fine roots in different samples was Tsoong’s tree >undergrowth >Chinese
fir, while that of P was undergrowth > Tsoong’s tree > Chinese fir. For Chinese fir, the seasonal change of N, P concentrations in
fine roots with various diameter classes showed a single-apex curve with a maximum in September. For Tsoong’s tree,
maximized concentration of N in fine roots appeared in July or September and maximized P concentration in May.
Key words: Fine root; Chinese fir; Tsoong’s tree; Mixed forest; Nitrogen; Phosphorus
CLC number: S791.27.01 Document code: A Article ID: 1007-662X(2001)02-0105-04
Introduction 1
Fine roots are an important source in terrestrial
ecosystems. Plants depend on fine roots (<2mm in
diameter) for water and mineral. The primary net production
belowground can be greater than that of aboveground
organs (e.g., Nadelhoffer et al. 1985). In many cases of
studies, fine roots have higher nutrient concentrations (e.g.,
Meier et al. 1985) and shorter life-spans than foliages (Vogt
et al. 1983). Nutrient released from decomposing roots is
an important pathway of nutrient flux in terrestrial
ecosystems (Joslin et al. 1987; Fahey et al. 1988). In
forests, for example, the amount of carbon and nutrients in
the soil from fine roots may equal or exceed that from leaf
litter (Joslin et al. 1987; Raich et al. 1989).
In the relatively short life-spans of fine roots, the
dynamics of nutrient concentration in fine roots is important
in estimating nutrient cycling relationship between fine root
diameter classes and nutrient contents. In this paper, we
examined the difference of nutrient concentration contents
in fine roots among conifer, broadleaved and undergrowth,
and the relationship between nutrient content and fine root
diameter classes.
Foundation item: The project was supported by The Foundation of
Post-doctoral Research of China (1999, No 10), the Foundation for
University Key Teacher by the Ministry of Education, and the Research
Programs on Basic Theory of Fujian Province (2000F004).
Biography: YANG Yu-sheng (1964-), male, professor in Fujian
Agricultural and Forestry University, Nanping 353001, P.R. China.
Received date: 2001-03-15
Responsible editor: Zhu Hong
Sites
The study sites are located in Xiaohu experimental area
of Xinkou Experimental Forestry Farm of Fujian Agricultural
and Forestry University, Sanming, Fujian Province
(26°11¢30²N, 117°26¢00²E). This area has a sub-tropical
monsoonal climate with an annual mean temperature of
19.1 , an annual precipitation of 1 749 mm, an annual
mean transpiration of 1 585.0 mm, an annual relative
humidity of 81%, and a frost-free period of around 300 d.
The soil is red soil derived from sand-sale. The mixed forest
of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.)
and Tsoong’s tree (Tsoongiodendron odorum Chun) was
established with seedling in 1973 with a planting density of
3 000 stems per hectare. The mixed pattern is strip spacing,
with three rows of Chinese fir spaced by one row of
Tsoong’s tree. At the time of survey (at age 27), Chinese fir
had a density of 907 stems per hectare and Tsoong’s tree
for 450 stems per hectare. The mean tree height and D.B.H
(diameter at breast height) were 20.88 m and 25.1 cm for
Chinese fir, and 17.81 m and 17.0 cm for Tsoong’s tree,
respectively. The crown density was of 0.95 and the
undergrowth coverage was of 80%.
Methods
From September 1999 to July 2000, 30 soil cores were
collected at random to a depth of 100 cm within different
samples (Chinese fir, Tsoong’s tree and undergrowth) at
bimonthly intervals using a steel core (6.8 cm in inner
diameter, 120 cm in length). Soil samples were washed in
tap water to remove adhering soil and accompanying
organic debris, then the roots of object trees and
YANG Yu-sheng et al. 106
undergrowth were detached with the help of magnifying
glass, scissors and tweezers, etc.. At the same time fine
roots (<2mm in diameter) were picked up, and separated
into live and dead categories according to their respective
appearance, color, flexibility and the cohesion between
cortex and periderm. The fine roots of object trees were
further sorted into three diameter classes (1-2 mm, 0.5-1
mm, <0.5 mm). All the roots were oven-dried (80 ) and
weighed. The standing crops of fine roots were calculated
using the following formula:
C=W 100/ ( (6.8/2)2)
Where:
C--the standing crop of fine roots (t«hm-2);
W--dry weight of fine roots per core (g).
Root samples for nutrient analysis were oven-dried. For
the determination of N, root samples were digested in
K2Cr2O7-H2SO4 solution and then N was determined by
micro-Kjeldahl technique. Samples for P analysis were in a
mixture of HNO3, H2SO4 and HClO4 solution, and
concentration of P was analyzed by a Molybdenum blue
colorimetrical procedure (Department of Science and
Technology of the Ministry of Forestry 1991).
Results and discussion
Concentrations of N and P in the fine roots
There was a significant inverse relationship between root
diameter and nutrient concentration for N and P examined.
The mean nutrient concentration in both live and dead roots
decreased significantly among root diameters of<0.5 mm,
0.5-1 mm and 1-2 mm (P<0.001). A strong decline in the
concentrations of N and P with an increase in diameter
classes of fine roots has also been found in an Abies
amabilis stand (Vogt et al. 1983), in a range of hardwood
and pine forests (McClaugherty et al. 1982), in Douglas-fir
for N, P, K, Ca and Mg (Fogel et al. 1983), and in Pinus
radiata for N, P and Ca (Nambiar 1987). Nambiar (1987)
had reported that concentration of N decreased by 26% as
the root diameter of Pinus radiata increased from <0.5 mm
to 0.5-1.0 mm, and increased by 83% when root diameter
was >5 mm.
Comparison of live and dead roots of various diameter
classes showed that nutrient was likely to retransfer, but the
amount of nutrient transfer was somewhat small. The
differences in nutrient concentration between living and
dead roots were insignificant (P<0.03) and differences in
mean concentration were less than 10% (Table 1). It was in
line with other reports that only a small amount of nutrients
was transferred out from the senesced fine roots
(McClaugherty et al. 1982; Nadelhoffer et al. 1985).
Nutrient concentration in fine roots (<2mm in diameter)
differed significantly among three samples (P<0.001). The
mean N concentration showed a tendency of Tsoong s tree
> undergrowth > Chinese fir. And P concentration showed a
tendency of undergrowth >Tsoong’s tree >Chinese fir. It
seemed that there was a sense of cooperation among
undergrowth, T. odorum and Cunninghamia lanceolata in
utilization of N and P, which is advantageous to make full
use of nutrients in mixed forest.
Table 1. The concentrations of N and P in fine roots in the mixed forests (g«kg-1)
Root diameter
1-2 mm 0.5-1 mm <0.5 mm <2 mm
Species Fine roots
N P N P N P N P
Chinese fir Living 5.748 0.335 6.875 0.410 9.189 0.548 8.009 0.476
Dead 5.435 0.306 6.488 0.383 9.100 0.537 7.965 0.467
Average 5.664 0.327 6.770 0.403 9.161 0.545 7.996 0.474
Living 7.718 0.857 10.846 0.973 15.568 1.355 13.376 1.207
Tsoong’s tree Dead 7.255 0.744 10.487 0.843 13.805 1.143 11.726 1.004
Average 7.571 0.823 10.738 0.932 15.119 1.301 12.924 1.151
Tree layer 7.083 0.502 9.093 0.581 12.518 0.834 10.753 0.719
Living 9.432 1.938
Undergrowth Dead 9.226 1.732
Average 9.387 1.865
Community 8.698 0.763
Seasonal change in concentration of N and P in fine
roots of mixed forest
The monthly change in concentration of N and P in fine
roots of various diameter classes for Chinese fir was similar,
showing a single-apex curve during the whole year (Fig. 1,
2). The nutrient concentration was low in March, then rose
gradually and reached a maximum in September, at last
declined again thereafter. This seasonal trend was related
to the growth pattern of Chinese fir and the change of
climate in a year. The lower nutrient concentration in winter
was due to the cease of root activity and furthers the
suspension of nutrient absorption. In early spring (March),
the minimum nutrient concentration was largely due to the
dilution of nutrients by a large quantity of new roots. In
summer, the increased nutrient concentration was related
to the increase in root activity, nutrient absorption and
nutrient accumulation, and then maximum nutrient
concentration of fine roots in autumn.
The seasonal change of N and P concentration in fine
roots of Tsoong’s tree showed similar single-apex curves, N
concentration peaked in July and that of P reached a
Journal of Forestry Research, 12 (2): 105-108 (2001) 107
maximum in May (Fig. 3, 4). The time of maximum
concentrations of N or P for Tsoong’s tree was prior to that
of Chinese fir. This difference may be largely contributed to
the differences in biological properties or superiority in
competition for nutrients between the two species. On the
one hand, the time of initial nutrient absorption and
maximum nutrient concentration for Tsoong’s tree roots
was earlier than that of Chinese fir roots. On the other hand,
the roots of Tsoong’s tree got inferior position in competition
for nutrients with roots of Chinese fir; thus, roots of
Tsoong’s tree were suppressed when roots of Chinese fir
speeded up their nutrient absorption.
The seasonal trend for concentrations of N and P in fine
roots of undergrowth was similar to those of Tsoong’s tree,
concentration of N peaked in July and that of P peaked in
May (Fig. 5, 6).
3
4
5
6
7
8
9
10
11
12
13
14
1 3 5 7 9 11
Sampling time (Month)
N
c
on
ce
nt
ra
tio
n
/g
·k
g
-1
Fig. 1 Seasonal change of N concentration in fine roots of
Chinese fir in mixed forest
- - dead root diameter of 0.5-1 mm; - - living root diameter of 0.5-1
mm; - - living root diameter of <0.5 mm; - - dead root diameter of 1-2
mm; -〇- living root diameter of 1-2 mm; - - dead root diameter of <0.5
mm
0.3
0.4
0.5
0.6
0.7
1 3 5 7 9 11
Sampling time (Month)
P
c
on
ce
nt
ra
tio
n
/g
·k
g-
1
Fig. 2 Seasonal change of P concentration in fine roots of
Chinese fir in mixed forest
- - dead root diameter of 0.5-1 mm; - - living root diameter of 0.5-1
mm; - - living root diameter of <0.5 mm; - - dead root diameter of 1-2
mm; - - living root diameter of 1-2 mm; - - dead root diameter of <0.5
mm
4
6
8
10
12
14
16
18
20
1 3 5 7 9 11
Sampling time (Month)
N
c
on
ce
nt
ra
tio
n
/g
·k
g
-1
Fig. 3 Seasonal change of N concentration in fine roots of
Tsoong’s tree in mixed forest
- - dead root diameter of 0.5-1 mm; - - living root diameter of 0.5-1
mm; - - living root diameter of <0.5 mm; - - dead root diameter of 1-2
mm; - - living root diameter of 1-2 mm; - - dead root diameter of <0.5
mm
0.0
0.5
1.0
1.5
2.0
2.5
1 3 5 7 9 11
Sampling time (Month)
P
c
on
ce
nt
ra
tio
n
/g
·k
g-
1
Fig. 4 Seasonal change of P concentration in fine roots of
Tsoong’s tree in mixed forest
- - dead root diameter of 0.5-1 mm; - - living root diameter of 0.5-1
mm; - - living root diameter of <0.5 mm); - - dead root diameter of
1-2 mm; - - living root diameter of 1-2 mm; - - dead root diameter of
<0.5 mm
Detailed reports on the seasonal change in nutrients of
fine roots in forests are rare. McClaugherty et al. (1982)
reported that in a mixed hardwood forest and red pine
plantation, although N percentage showed some seasonal
pattern, these fluctuations were small and not significant. In
a Picea sitchensis plantation, N concentration in live roots
with <1mm in diameter showed relatively small seasonal
fluctuations, and it was suggested that the fluctuations may
represent redistribution within roots or accumulation of
nitrogen compounds in winter (Alexander, 1985). Nambiar
(1987) reported that there was no evidence of a seasonal
pattern in roots nutrient concentration of Pinus radiata. The
YANG Yu-sheng et al. 108
discordance in results might result from the differences in
tree characteristics and climate conditions.
7
8
9
10
11
12
13
1 3 5 7 9 11
Sampling time (Month)
N
c
on
ce
nt
ra
tio
n
/g
·k
g-1
Fig. 5 Seasonal change of N concentration in fine roots of
undergrowth
- -Mixed forest; - - Mixed forest; - -pure forest; - - pure forest
1.5
2.0
2.5
1 3 5 7 9 11
Sampling time (Month)
P
c
on
ce
nt
ra
tio
n
/g
·k
g-
1
Fig. 6 Seasonal change of P concentration in fine roots of
undergrowth
- -Mixed forest; - - Mixed forest; - -pure forest; - - pure forest
Conclusions
In the mixed forest of Chinese fir and Tsoong’s tree, the
order of N concentration in fine roots of various
components was Tsoong’s tree >undergrowth >Chinese fir,
while that of P was undergrowth >Tsoong’s tree > Chinese
fir. It seemed that there was one sense of cooperation
between Tsoong’s tree and undergrowth in utilization of N
and P. For Chinese fir, seasonal change of N, P
concentrations in fine roots of various diameter classes
showed a single-apex curve with a maximum in September.
For Tsoong’s tree, maximized concentration of N in fine
roots appeared in July or September and maximized P
concentration in May.
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Chinese abstracts
ii
荔 枝 Litchi chinensis 和山杜英 Elaeocarpus
sylvestris两种群有基本型聚集分布的特点并表现出个体间
的聚集现象 橄榄 Canarium album有可能随着密度的增大
而趋于均匀分布 树种的空间分布格局依赖于其繁殖特性之
外 还受该次生季雨林保护的影响 这些主要建群种的空间格
局表明进行该林区保护的迫切性
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杉木与观光木混交林中细根的 N P浓度动态研究/杨玉盛
陈光水 谢锦升 李秀芳 陈银秀 福建农林大学 南平
353001//Journal of Forestry Research. -2001,
12(2).-105-108
从1999年9月至2000年7月隔月应用连续土芯法对福
建三明莘口林场杉木与观光木的混交林的细根进行取样并测
定活 死细根的N P养分浓度 结果表明 混交林中杉木
观光木和地下植被的细根的 N P浓度均与细根径级呈负相
关 混交林中细根的N浓度大小顺序为观光木>林下植被>杉
木 而P的浓度则为林下植被>观光木>杉木 混交林中杉木
各径级细根的NP浓度的动态变化表现为单峰型 在9月最
高 观光木细根的N P浓度的动态变化亦表现为单峰型 但
N浓度高峰出现在7月或9月 而P浓度则在5月最高
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吉林省森林生态建设面临的问题和对策/王宪成 徐程杨 刘
福金 梁万军 韩国辉 张忠辉 吉林省林业科学研究院
长春市 130031//Journal of Forestry Research, -2001,
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林业对策
红皮云杉人工林和天然林管胞性状的变异研究/任旭琴 王秋
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异 管胞的性状从隋心到树皮都呈现出增加的趋势 天然林
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北京林业大学森林资源与环境学院 北京100083孟秀芹
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本文从木材的化学组成和微观结构出发 从理论上推导
出木材导温系数的理论表达式 应用该表达式计算20种左右
木材弦向和径向导温系数 并与实验值对照 得出木材弦向
导温系数与理论值的平均误差在7.2%木材径向导温系数与
理论值得误差为6.2%
关键词 导温系数 理论表达式 木材
大兴安岭兴安落叶松林和针阔混交林物种多样性的对比/宋
关玲 淄博学院 淄博 255000杨国亭 东北林业大学
哈 尔 滨 150040//Journal of Forestry
Resea ch.-2001,12(2).-136-138
本文运用Simpson多样性指数(D) Shannon--Wiener多
样性指数(H ) Pielou均匀度指数(Jsw &Jsj) Alatalo均匀
度指数(Ea)和物种多样性指数(S) 对大兴安岭地区物种多样