·ＶＩＩＩ·
A STUDY ON THE CLASSIFICATIONOF BAMBOO
STANDS
Professor Zhou Fangchun
(Bamboo Research
Institute,
Bamboo are widely distributed in
Growth classes of bamboo stands
Average stand
diameter at breast height can be used to evalute the bamboo stand growth. The
better the bamboo stand grows, the large the average stand diameter is. Hence,
on the basis of average stand diameter we grouped bamboo stands into five
growth classes (G)(Table 7-1). Class 1stands with an average diameter above
The average
weight of individual culms can be estimated according to following equation.W=0.1547(15
Table 7-1 Growth class and average diameter
|
Growth class |
1 |
2 |
3 |
4 |
5 |
|
Average diameter(cm) |
＞12 |
12~10 |
10~8 |
8~6 |
＜6 |
Table 7-2 Average height and weight of culms in
different growth
|
Growth
class |
1 |
2 |
3 |
4 |
5 |
|
Total
height(m) Clear
height(m) Total
weight (kg) culm
weight(kg) Branch and
leaf weight(kg) |
17.14 8.33 49.97 41.03 8.94 |
15.12 6.77 35.57 28.24 7.33 |
13.01 5.12 23.78 18.78 5.73 |
10.77 3.65 14.42 10.30 4.12 |
8.37 2.35 7.56 5.05 2.51 |
Then the culm
weight* of the stand can be estimated fromW = N × WWhere N is the density
of stand.For example,
if a bamboo stand is of growth class 3 with a density of 1,800 culms/hm2, the culm weight per
hectare thereby can be estimated fromW 1,800 × 18.4 = 33.12(T/hm2)By the similar process,
if the growth class of age and the number of culms in this age class are known,
the culm weight of this age class can also be estimated.
Table 7-3 Culm weight and growth class.
|
Growth class |
1 |
2 |
3 |
4 |
5 |
|
|
Average
weight of individualculms(kg) |
0.0 0.2 0.4 0.6 0.8 |
40.93 38.25 35.66 33.17 30.76 |
28.47 26.26 24.00 22.14 20.22 |
18.40 16.66 15.02 13.48 12.02 |
10.65 9.37 8.18 7.07 6.06 |
5.12 4.27 3.15 2.82 2.21 |
Site type and site class
of bamboo stands
1.
Site type
The combination of ecological factors as climate, topogiaphy, soil
and biota is called the habitat (site) of bamboo stands with alike site
condition are considered to be of same site type, within a climatic region, the
topography-soil conditions are the main factors affecting on bamboo growth. The
topographysoil
conditions can be grouped into 12 types (Table 7-4).Humus rich loam is black
and sometimes dark brown in colour, rich in organic matter, loose, well
structured, well drained with better aeration and less gravel content. Soils of
this group are most favourable to bamboo growth. They occur in the valley,
piedmont, the middle amd upper parts of low hills.Humus moderate loam is
yellow or red in colour, loosely textured, well drained, with good aeration,
less gravel content and thinlayered Ahorizon. The bamboo growth is about average. Soils of this
kind occur in the middle and lower parts of low hills.
Table 7-4 Topography and soils
|
Topog-raphy |
Humusrich loam |
Humusmoderate loam |
Clayransoil |
Graveldoils |
|
Valley |
Deep humusrich loam |
Deep humusmoderte loam |
Deep claypansoil |
Deep gravelsoil |
|
Slope |
Medium deep Humus rich |
Medium deephumus
deep |
Medium deepclay pan |
Medium deepgvavel
soil |
|
Table Labd |
LoamShallow humusrech loam |
Shallow humusmoderate loam |
SoilShallow claypan soil |
Shallowgravel soil |
Clay pan soil
is yellow or red, heavy clay, poorly textured, easy to be waterlogged, with heavy clay
and very thin Ahorizon, and
unfavourable to bamboo growth. They mainly occur in tableland.Gravel soils are characterized
by having a large proportion of gravels and distributed along valleys and on
piedmont with satisfactory water condition and fertile alluvial soil in the
gaps of gtavels. The growth of bamboo is about average. But on the hilltop they are
shallow,droughty and sterile, and sterile, and the bamboo growth is very poor.In order to understand
the relation between topography and the growth class, we investigated 182
sample plots and estimated the relative frequency of each growth class on
various topogaphics. The valleyland is best for the bamboo growth due to its deep and
fertile soil,satisfactory water condition and less wind destruction.Along the valley, growth
class I and II may amount to 70%. On hill ridge where soils are shallow,
sterile and droughty and bamboos are easy to be uprooted by wind, the relative
frequency of growth class IV and V is up to 73%. Both the soil and
microclimatic conditions of slopes are less favourable than those in valley, but
much better than those on hilltop to bamboo growth. Accordingly, the bamboo growth on
slope is intermediate.Since the site type is counstituted of topograysoil type and the microclimates,
it can be named by heading the topograpysoil type with its locality,
such as “Yexing shallow-humus rich loam.”
Table 7-5 Topography and growth class
|
Topography |
Numbersof plots |
Growth class |
|||||
|
1 |
2 |
3 |
4 |
5 |
Total |
||
|
Tableland Valley
Lower moderate
slope Upper steep slope Ridge |
11 40 50 66 15 |
25.0 8.0 6.0 |
9.1 45.0 40.0 24.3 6.7 |
54.5 22.5 28.0 30.3 20.0 |
2.5 22.0 27.3 26.7 |
36.4 5.0 2.0 12.1 46.6 |
100 100 100 100 100 |
2.
Site classes
of bamboo stands
The growth of
bamboos and the production of bamboo stands vary with different site type. We
grouped the 12 site types into 5 site classes according to their favourableness
to bamboo growth. They indicate the potential productivity of bamboo
stands(Table 7-6).Site class
I:“Deephumus rich
loam”in valley, most favourable to bamboo growth average stand diameter 10~
Table 7-6 Topography and site class
|
Topography |
Humusrich loam |
moderateloam |
Clay pansoil |
Gravelsoil |
|
Valley-land Slope Tableland |
I(＞ I(10~12) III(8~10) |
II(10~12) III(8~10) IV(6~8) |
III(8~10) IV(6~8) V(＜6) |
III(8~10) IV(6~8) V(＜6) |
Management types of
bamboo stands
1.The classfication of
silvicultural treatment of bamboo stands.
Fora long
time Chinese peasants have accumulated much silvicultural experiences specially
dealing with the manafement of bamboo stands.They are commonly known as
weeding, soil conditioning, organic matter mulching, fertilization, shootculm protection, pest
and disease controlling, rational harvesting and water soil conservation, etc..
These treatments are aimed to regulate and improve the bambooenvironment relationship
in order to promote the production of bamboo stands.Based on the intensity
of management, silvicultural treatments of bamboo stands, can be grouped into
three grades and eight sub-grades (Table 7-7).Grade I includes all the
treatments needed to improve the productive conditions of bamboo stands such as
weeding, soil conditioning, organic mulching, fertilization, water and soil
conservation. Besides, shoot and culm protection, disedse and pest control and
rational harvesting should be taken into consideration.Grade II includes the
treatments operated to suppress the undergrowth or ground cover. Except soil
conditioning and fertilization, all treatments are same to those in grade I.Grade III is of
extensive management in which only selective cutting is ptacticed to adjust the
composition, density and age of bamboo stand.
Table 7-7 Silvicultural treatments and management
grades
|
Grades |
I |
II |
III |
||||||
|
Subgrades |
A |
B |
A |
B |
C |
A |
B |
C |
|
|
Major |
Fertilization mulching |
Soil condi －tioning |
Weedingyearly |
Weeding very twoyears |
Weedingirregularly |
Rationalhavesting |
Irregularcutting |
Lack ofmanagment |
|
These grades
mentioned above are general categories arranged for silvicultural treatments.
With increase in the intensity of management each grade may have additional
treatments. All the grades are interrelated. Good results can be expected if intensive
measures are taken on the basis of
extensive management, for example, in addition to weeding soil
conditioning always brings about desirable production of bamboo stands.The intensive management
differs from the rational management. Obviously the intensive management means
the intersity of management that does not necessarily yield agreeable economic
rescults. While the rational management may be less intensive, but could bring
about desirable consequences.As results of rational management, the production
and quality of culms can be improved correspondentlly and yield more economic
benefits. Therefore, any silvicultural practice should be based on economical
consideration.
2,management type of
bamboo stands
Amanagement type of bamboo stands can be realized by applying a
series of silviculural treatments repeatedly to a number of bamboo stands
during a long period. If this series of treatments is replaced or modified, the
management type coulds change from one to the other.But such a change usually
takes 6~8 years to become stablized. For example, if the treatments of grade I
are continually practiced in a stand for more than 6 years, this stand could
fully exert the correspondent productivity and thus can be grouped into
management type I.The mayor
features of management types are described as following:Type I, Bamboo stands of
this type are commonly located in vallyland and lower moderate
slope with humus rich loam or humus moderate loam soils of site classes I. II.
III. and are continually practiced with intensive measures of grade I.
Accordingly the stands are pure, moderately dense and highly productive. The
culms are uniformly largesized and relatively even spaced. Generally, this management
system is often practiced in areas, with convenient transportation, urgent
needs of bamboos, and abundant labour supply.
Type II, Bamboo stands located in areas with convenient
transportation and sufficient labour are selected and continually be treated
with measures of grade II, the site quality varies greatly with site classes
I~V. The stands are pure, occasionally mixted with other tree species,
moderately dense and productive. Ground cover exists.Type III, Bamboo stands
of this management type are either distributed in remote mountains where
transportaition is poor and labour supply is short or located in areas where
transportation is convenint, but bamboo supply is short. In the former case,
bamboo stands remain in natural condition, no silvicultural treatments are
practiced but regular cuttings, the stands are often mixed with other tree
species and undergrowth. In
the latter case, overharvesting is
the most important factor causeing the deteriotation of stands, undergrowth is
luxuriant, the stand density is low, culms are small. The site quality varies
greatly with site classes I- V and theirproduction is changeable accordingly.
The determination of
bamboo stand type
A bamboo stand type is a group of bamboo stands with same
management type, same site class and same growth class and can be expressed by
three numerals. The first indicates the management type,the second the site
class and the third the growth class of bamboo.For example, the “234 bamboo
stand”shows that this bamboo stand belongs to management type II, site class
III, and growth class IV.Theoretically a site class should correspond to a growth
class, the better site quality, the better bamboo growth. If the growth class
of a stand is higher than its site class (for example “132 bamboo stand”),this
stand is rationally managed. On the contrary, if the growth class is lower than
its site class (for example“234 bamboostand”), the management of this stand is
undesirable. Obviously its potential productivity is not fully exerted.It
should be pointed out that the management type, site class and growth class are
closely related to each other. They are the three aspects of bamboo stands.
Site class is the material basis of production; management type indicates the
silvicultural activities and the growth of bamboo stand is influenced by site
quality and management activities. Growth class, therefore, can be used for
eveluating site and management qualities.
The bamboo stand types and the
management activities
The yield and
quality of bamboo stands are linked with their type.As shown in Table 7-3, the
higher is the growth class, the larger is theaverage diameter and the heavier
is the average culm weight,accordingly a higher yield can be expected. In
higher site class,however, the culm size increases, the volume weighte
decreases and the mechanical properties become degraded consequently.
Apparently the stand prescription must be based on the stand type.In Chinam, the total
area of Phylostachys pubescens stands
is about 2.3 million hectares 70%~75% of them are of management type III. For
promoting bamboo production, attention should be paid to the bamboo stand of
manfgement type III. On the basis of their habital and growth, the bamboo
stands can be properly treated with appropriate silvicultural measures and gradually be
transfered to the management type II. The unit production will i ncrease
greatly.
References
Fong,C.W.et al. 1959. Research
methods of artifical forest types.Forestry Mono graph No.4. Science Press.
Hsiung, W.Y. et al, 1959. High productive bamboo stands in
Li,C.H. et al.1959. Artificial stands of Cunninghamial anceolata
and theirtypes. Forestry Monograph No.4
Science Press.Sukachev, B.H.1958. Research
mehhods of forest types . Forestry Press.
Zhou,F.C et al. 1959 Silvicultural management of bamboo stands.
High Education Press. Hec Tepo B B.T. 1958.