SMALL-HOLDER TIMBER PRODUCTION:
TREE INVENTORIES/BIOMASS SURVEYS
INTERNATIONAL WORKSHOP ON SMALL-HOLDER TIMBER PRODUCTION
ICRAF HOUSE 29TH NOVEMBER 2004
PAUL M. NJUGUNA
PRESENTATION SUMMARY:
•What is Farm Inventory/Biomass Survey?
•Why conduct an inventory on farms?
•What do you need for the survey?
•Kenya: Biomass Surveys History and case studies.
What is farm Inventory/Biomass Survey:
Entails collection of tree data on farms
including:
•Tree Species
•Size (DBH)
•Age
•Growing Place-Homestead, Homegarden,
Cropland, Boundary, Grazing Area,
Woodland, Woodlot.
•Main use-Timber, fuelwood, herbs, fruit,
amenity,
•Germplasm Origin
-Aims at getting Densities, Distribution and
Volumes
Why Conduct a farm Inventory/Biomass Survey:
•Baseline Data For the Planning and later implementation of
farm Tree based planting projects
Status at Inception of a Tree Planting Project on Farms
•Evaluation after a farm based Tree Planting programme
What is the Project impact?
Is there a need for another phase and the required emphasis?
•Timber Marketing/tree sales
What tree stock is available, how is it distributed in terms of
geographical coverage species, age, Growing place.
How can sustainability be planned?
What do you need for a farm inventory:
•Personnel, Equipment, Transport
•Objective Sampling Frame-Remote sensing images,
photographs, vegetation Maps, topographical maps, GPS
•Sample Farms/plots
•Data Entry and Analysis facilities
•Data Presentation
History of farm inventories in Kenya
•1991 under the Intensified Forestry Project
Nyandarua Districts-(“Miti Mingi Project”)
•LANDSAT images were used,
H
i
s
int Nakuru
o
r
y
and
•Gave volume estimates on forested areas but no detailed species
differentiation,
•Scale too small to give sufficient information to Project
management team especially on small holder farms.
•Recommended another survey using Aerial photographs
•January 1993: Aerial photographs were taken at a scale of
1:10,000 using 8 flight lines at an interval of 1Km.
600 photographs were taken
•Enlargement to 1:2,500 done at centre of photographs:
•All photographs falling on Forests, or without small holder farms
or without a complete small farm were rejected-200 photos
rejected.
•Photo-interpretation had shortcoming due to shading
•Round and Irregular crowns of indigenous species and old Eucalyptus
•Young planted seedling could not be identified.
•Project management decided to conduct ground inventory
on 20% of the farms
•Farms systematically selected along the flight lines
(every 5th photograph); 62 farms selected and 100% enumeration
was done-38 in Nakuru and 24 in Nyandarua
•The Intensified Forestry project ended in 1995 (project duration
• 1990-1995)
•Kenya Forestry Masterplan came out in 1994-The Masterplan
indicated that 65% of all wood products in high and medium
potential areas were from farms and predicted that by 2015,
85% would be from Farms;
Proposed farm based tree planting projects.
1996: The Farm Forestry Project started in Nakuru and Nyandarua
1998: Evaluation earlier Project done by re-inventorying
the 62 farms done in 1993
Comparison between 1993 and 1998 inventories
1993
1998
difference
Trees per 656
farm
250
Trees/Ha
Vol/farm 25m3
1137
Up 73%
397
Up 59%
56.9m3
Up 128%
19.9m3
Up 107%
Vol/Ha
9.6m3
Usable
7.5m3
Vol/farm
(30% of
Vol/ha)
17.07m3
Replicability of the methodology
•2000: Biomass surveys in Ukambani Districts of Machakos,
Makueni, Kitui and Mwingi
•180 sample plots taken-Biggest in Kenya-Covered farms,
ranches (sparsely tree populated areas) and also woodlands
(densely tree populated areas)
•Sample plots randomly selected-used soil maps as indicator
of vegetation. Plots proportionally distributed depending
on geographical coverage of each soil type.
Formed Baseline Data for a 5 year Belgium Funded Programme
•Report not yet published but being used by project
management
•2001: Detailed farm inventories done on 35 farms earlier
randomly selected by the Tree Diversity Trials Programme
in Nchoroiboro, Kigane and Egoji villages in Meru Central
•2002; Farm Inventories for the Timber MarketingProgramme
(ICRAF, FAN and GOK programme)
• 35 farms within an area supplying tree products covering the
Coffee growing Zone and the Cotton/ tobacco Growing Zone
in Meru Central
Tree shapes used for
Farm based
Surveys..(1,2, 3, 4)
Equations used to
calculate tree volumes
and constant for the
four form factors used.
Tree type parameter (a)
Computing usable volume (stem volume
from stump to tip)
ln(v)=a+b ln(d)
V-usable volume (dm3)
D-diameter at breast height (cm)
a ad b are constants constants and are for
different tree forms
Parameter(b)
Source
1
-2.2945
2.5703
Laasasenaho 1982
2
-1.7322
2.3992
Pukkala 1989
3
-1.6493
2.3567
Pukkala 1989
4
-1.6840
2.2406
Pukkala 1989
Tree Cutting on farms-Giaki Area in Meru Central
•Fuelwood is a
salvage operation after
Sawmillers remove
the logs
•Most of the splitting
done on farm using
Tractor driven circular
Saws and Powersaws
Grevillea Boundary Planting in Giaki Area-Meru Central
Silvicultural Operations such as thinning not done since
the tree were not meantfor timber production at initiation.
Splitting of Grevillea logs using PowersawsKigane Village, Meru Central
Some findings from on farms biomass surveysTimber Marketing Programme…
282
269
volume (m3) coffee
206
volume (m3) cotton
175
143
138
124
99
76
56
72
58
70
>45
41 - 45
36 - 40
31 - 35
26 - 30
21 - 25
16 - 20
9 11
58
26 34
11 - 15
3 2
6 - 10
•More species composition in Cotton
zone than coffee zone
300
250
200
150
100
50
0
1-5
•More stems in the cotton zone than
coffee zone
DBH Class/Vol. Distribution
Volumes in cubic Meters
•More woody biomass in the
Cotton zone than coffee zone
DBH class
800
stems coffee zone
stems cotton zone
600
400
200
DBH cLass
>45
41 - 45
36 - 40
31 - 35
26 - 30
21 - 25
16 - 20
11 - 15
6 - 10
0
1-5
•Total biomass count over 35 farms
found ca 267 species per farm
DBH Class/No of stems distribution
No. of stems
•Grevillea robusta, Vitex Keniensis
and Cordia The most popular
species
Some findings from on farms biomass surveysTimber Marketing Programme
TREE USES
Use
(m3)
Fuelwood
Charcoal
Fruit tree
Herbal
Timber
Honey
Fodder
Carving
Others
No. of stems
1448
15
547
45
3032
16
13
93
186
5395
Volume
298.651
8.641
17.083
197.751
1,295.250
16.446
11.767
47.949
17.417
1,910.955
Some findings from on farms biomass surveysTimber Marketing Programme
DISTRIBUTION OF DBH CLASSES
DBH CLASS
1-5
6 - 10
11 - 15
16 - 20
21 - 25
26 - 30
31 - 35
36 - 40
41 - 45
>45
No. of stems
1325
725
662
682
592
642
252
240
125
150
5395
Volume (m3)
4.867
20.406
60.019
131.904
195.630
368.316
201.030
278.350
193.486
456.947
1,910,955
Some findings from on farms biomass surveys
-Timber Marketing Programme
Growing place
No. of stems
Volume
(m3)
Homestead
289
120.543
Border
2733
941.808
Grazing
212
90.816
Cropland
1939
698.951
Home garden
53
17.008
Woodlot
83
16.925
Woodland
86
5395
24.905
1,910.955
Some findings from on farms biomass surveys
-Timber Marketing Programme
DISTRIBUTION OF AGE CLASSES
Age class
No. of stems
Volume (m3)
<6
2080
46.974
6 - 10
1081
213.202
11 - 15
1269
568.629
15 - 20
602
501.173
21 - 25
95
104.086
26 - 30
169
191.677
> 30
99
5395
285.216
1,910.955
DIAMETER CLASS DISTRIBUTION BY VOLUME
500
456.9
450
400
368.3
VOLUME (M3)
350
300
278.3
250
201.0
195.6
200
193.5
131.9
150
100
60.0
50
4.9
20.4
0
1-5
6 - 10
11 - 15
16 - 20
21 - 25
26 - 30
31 - 35
DIAMETER CLASS (CM)
36 - 40
41 - 45
>45
For the data/information from Farm the inventories
to be useful
•It requires to be presented in a use friendly format,
•It needs to be combined with socio-economic information,
•It needs markets information
•THANKYOU