Impact of private forestland tenure changes on forest cover, stocking and tree species diversity 

in Amani Nature Reserve, Tanzania

Mathew MpandaICRAF EA Region

Seminar presentation26th April 2011

Background• Forests and woodlands  in Tanzania occupy 37% (353 000 km2 ) of the land area

• These ecosystems makes Tanzania as one of the richest and most diverse countries in Africa in terms of both species and habitats

• These forests and woodlands comprise different vegetation types and serve for mitigation of and adaptation to climate change, for biodiversity conservation, watershed services, fuelwood and other services

Background cont…• The role of these forests has, however, been undermined by deforestation which is estimated between 150,000 ‐ 412,000 ha per annum

• Causes of deforestation are mainly human  induced disturbances including encroachment, wildfire, illegal mining, pit‐sawing, illegal harvesting for building materials and excessive collection of fuelwood and herbal medicines

• No forest ecosystem in the country has exception in regard to these causes of disturbances

Background cont…..• In 1970s – 1980s the East Usambara Mtns suffered intense destructions of habitats and species due unsustainable use including excessive mechanized logging

• By  mid 1980’s internal and external outcry on biodiversity loss and destruction of habitats was difficult to ignore

• This led to launching of AFIMP to see how best to reverse the negative trend to the East Usambara Mtns ecosystems(i) a need for biodiversity preservation by halting conversion of forestlands into other land uses, 

(ii) enhancement of forest connectivity of isolated forest blocks of East Usambara Mountains

Background cont…..

Period Reserve Area enlarged

(Ha)

Number of

Farmers involved

Amount paid

(TZS)

1993-1994 Kambai 1046 44 26 113 374

Mtai 1234 87 20 711 409

Mlinga 840 88 35 413 930

1994-1995 ANR 1230 658 25 685 970

Nilo 2253 676 111 766 328

Manga 120 96 7 381 782

2002-2006 Derema corridor 790 1128 2 730 326 407

Total 7,843 2,777 2 957 399 200

Consolidation of existing forests was further translated into enlargement /annexing of private lands and general lands

Why this study……..?• The enlargement/annexing exercise in ANR had to affect the following private land categories;1. Land under the Tea Company2. Land under the Smallholder farmers3. Land under the Sisal Company

• This had implications in the resources by;1. Re‐defined ownership of the forestland2. Re‐defined accessibility to forest resources

Why this study….?• These changes on forestland tenure in ANR had to institutionalize  the management aspect to capture the following;1. Enhance forest resources and other 

conservation aspects2. Address livelihood component to the 

surrounding communitiesThis study attempted to evaluate this 

tenure changes on forest resources from private to state ownership

Narrowing down of Forest resources

• This study specifically attempted to address the following questions;1. What is the impact of tenure changes on forest 

cover in ANR?2. What is the impact of tenure changes on stocking 

in ANR?3. What is the impact of the tenure changes on 

species diversity in ANR?

•EU Mountains are found in the north‐eastern part of Tanzania•Part of the Eastern Arc Mountains (global biodiversity hotspot)•ANR forms the largest block of EU Mountains•High biodiversity per unit area (both plants and invertebrates)•Over 3,450 species of vascular plants recorded•Over 1,000 plant species introduced from across the tropics btn 1902 ‐1930•Area of interest for research and biodiversity monitoring for the last 150 yrs

METHODS: Study site

Blue: Forestland converted from Tea company to state, 1065 haGreen: Forestland converted from smallholder farmers to state, 1112 haYellow: Forestland converted from Sisal company to state, 173 haGrey: Six merged forest reserves (tenure unchanged)

Methods: Data collection• Forest cover assessment1. Forest cover assessment was done using

remote sensing and GIS techniques2. Landsat TM satellite images of 2000 and

2006 were used.3. The 2000 image (taken on 22 January 2000)

was used to assess forest cover at the endof the private tenure regime

4. The 2006 image (taken on 23 February2006) was used to depict the situation aftersix years of state tenure regime

Forest Inventory1. In 1999/2000, a number

of permanent sampleplots (PSPs) wereestablished in ANR

2. The reserve was firstdivided into a rectangular450 x 900 m grid.

3. Then 50 x 20 m PSPs,altogether 180, weresystematically laid in thesouth-east corner ofeach rectangle

Methods: Data collection

4. In 2008 a repetitive survey was carried out on 28 PSPs belonging to the blocks that previously were under private tenure i.e. those experienced tenure changes

5. All trees greater or equal to 10 cm were re‐identified with respect to location and speciesby means of a botanist and local people, and re‐measurements were taken for diameter atbreast height (dbh)

6. Additional, height measurement of three treeper plot was taken

Methods: Data collection....Forest inventory

Methods: Data analysesForest cover analyses1. ERDAS Imagine, ArcView GIS 3.2 and ArcGIS Desktop 10 software 

were used in image data pre‐processing and analysis. Image sub‐setting was conducted to the images of 2000 and 2006 to obtain areas of interest

2. Forest cover maps for 2000 and 2006 were developed containing the following five classes: dense forest, semi‐closed forest, open forest/woodland, bush/grassland and open areas

3. Then post classification change detection was performed in which classified forest cover maps of 2000 and 2006 were compared. 

4. The areas extracted from classification results were used assuming linear relationship to make direct computation of percentage total and annual change;i. Total change (%) = ((Area year x – Area year x + t )/ (Area year x)) x 100%; ii. Annual change (%) = (Area year x – Area year x + t )/ (Area year x x t 

years))/ x 100%,

Methods: Data analyses….Forest inventory analyses• Identical procedures for estimating forest stocking and tree 

diversity were applied for the year 1999/2000 and 2008 data• Number of trees per plot was summarized and transformed 

into per hectare values (N)• The basal area for individual trees were calculated according to 

dbh, summarised and transformed into per hectare values for the plot (G)

• Finally, the volume of individual trees was summarized within plots and transformed into per hectare values (V)

• Shannon‐Wiener index was computed within each block and for the 1999/2000 and 2008 data

• The statistical significance of temporal changes for stocking parameters and Shannon‐Wiener index were analysed using two‐tailed t‐tests

RESULTS: Forest cover changes1. Results of forest cover analyses show positive 

changes for dense and semi‐closed forest in the block previously owned by the tea company

2. For the block previously under smallholder farmers the area with dense forest has decreased while the area of semi‐closed forest has increased

3. For the block previously owned by the sisal company the area of both dense and semi‐closed forests has decreased

RESULTS: Forest cover cont….Forest block Description Private       tenure 

(2000)State      tenure (2006)

Total change

Total change

Annual  change

Area (ha) (%) Area (ha) (%) (ha) (%) (%)

Tea company  Dense forest  697  71.8  729  75.1  +32  +5  +0.8 Semi‐closed forest  72  7.4  182  18.7  +110  +153  +25.5 Open Forest/Woodland  48  4.9  17  1.8  ‐31  ‐65  ‐10.8 Bushland/Grassland  119  12.3  31  3.2  ‐88  ‐74  ‐12.3 Open area  35  3.6  12  1.2  ‐23  ‐66  ‐11.0 All  971  100.0  971  100.0  ‐ ‐ ‐

Farmland  Dense forest  769  69.2  714  64.2  ‐55  ‐7  ‐1.2 Semi‐closed forest  133  12.0  183  16.5  +50  +38  +6.3 Open Forest/Woodland  45  4.0  39  3.5  ‐6  ‐13  ‐2.2 Bushland/Grassland  161  14.5  173  15.6  +12  +7  +1.2 Open area  4  0.4  3  0.3  ‐1  ‐25  ‐4.2 All  1112  100.0  1112  100.0  ‐ ‐ ‐

Sisal company  Dense Forest  46  26.6  33  19.1  ‐13  ‐28  ‐4.7 Semi‐closed Forest  21  12.1  12  6.9  ‐9  ‐43  ‐7.1 Open Forest/Woodland  26  15.0  21  12.1  ‐5  ‐19  ‐3.2 Bushland/Grassland  76  43.9  106  61.3  +30  +39  +6.6 Open area  4  2.3  1  0.6  ‐3  ‐75  ‐12.5 All  173  100.0  173  100.0  ‐ ‐ ‐

RESULTS: Forest cover changes…..

RESULTS: Forest structure• Results of the stocking levels and changes between 1999/2000 and 2008 shows an increase in number of stems, basal area and volume per hectare in all blocks except for number of stems per hectare in the block formerly owned by the tea company

• The changes however, were not statistically significant at 5% level

RESULTS: Forest structure……Forest block Parameters Private tenure

(1999/2000)State tenure

(2008)Change (% in brackets)

P-value

Mean SE Mean SE

Tea company (n=18) N (no.ha-1) 435 37 424 33 -11 (-2.5) 0.4027

G (m2h-1) 46.0 5.4 46.8 5.2 0.8 (1.7) 0.6369

V (m3ha-1) 946.5 133.2 965.3 131.2 18.8 (2.0) 0.6826

Farmland (n=7) N (no.ha-1) 290 32 310 35 20 (6.9) 0.1453

G (m2h-1) 28.7 4.9 32.8 4.8 4.1 (14.3) 0.3762

V (m3ha-1) 563.1 113.9 651.4 103.6 88.3 (15.7) 0.4696

Sisal company (n=3) N (no.ha-1) 137 64 163 55 26 (19.0) 0.2697

G (m2h-1) 11.5 5.9 13.2 6.5 1.7 (14.8) 0.0996

V (m3ha-1) 209.9 119.9 239.8 132.7 29.9 (14.2) 0.1476

RESULTS: Tree species diversity

• Number of species recorded in 1999/2000 and 2008 (in brackets) were 67 (76), 45 (49) and 24 (27) for the three forest blocks previously owned by the tea company, smallholder farmers and sisal company, respectively.

• Shannon‐Wiener diversity indices in 1999/2000 and 2008 were not significantly different

Forest block Private tenure (1999/2000)

State tenure (2008) Change P-value

Tea company (n=18) 3.50 3.49 -0.01 0.3943

Farmland (n=7) 3.36 3.39 +0.03 0.4650

Sisal company (n=3) 2.97 3.07 +0.10 0.2654

Main observation and explanation……Positive changes‐ Stable climatic conditions have been reported forthe whole of the Eastern Arc mountains over along period of time i.e. no incidences of extremeweather‐High growth rates of tree species andcolonization of forest gaps by fast growing species‐ Reduced human disturbances and compliance torules and regulations by adjacent communities‐ Promoted harvesting of tree from nearbyLonguza Forest Plantation, harvesting ofEucalyptus sp. woodlots in highland villages i.e.reduced wood demands

Main observation and explanation……

Negative changes‐ Uncontrolled fire e.g. adjacent farms preparation,hunting inside the reserve‐ Eruption of god rush in 2003‐ Competition between tree species and grasses i.e.ground covered by long grasses that hindersestablishment of tree species‐ Illegal extraction of timber and poles‐ Natural ecological processes e.g. death of biggertrees vs climbers, winds vs Maesopsis

Illegal gold mining inside ANR

Use of fire in farm preparations in the Western and Southern parts of ANR

Illegal timber extraction in ANR

Pole extraction in ANR

Main observation and explanation……

Are the changes enough/as expect‐ Short period of time to expect much changesespecially in natural forest of this nature‐ Generally conditions of most forests in theEastern Arc Mountains are relatively better, oneshould expect very small changes‐ Low number of sample plots and size of theblocks and high variations between plots

Main observation and explanation……

Spatial differences between blocks

1.Conditions of the forest resources were quite different for the three blocks around the time when tenure changes occurred

2.Other factors may explain the differences among the blocks as location and include human activities (e.g. accessibility and adjacency to villages) as well as natural conditions (e.g. terrain, elevation, vegetation)

ConclusionThe results for changes in forest conditions from when thetenure changed until 2006/2008 are somewhat ambiguous

There are several exceptions and modifications regarding differences between the blocks

When considering the three blocks as one entity one may in general maintain that there have been positive changes regarding forest cover as well as forest stocking and tree species diversity

Generally one may expect that without state intervention and a change of tenure major parts of the ANR could have accelerated into more clearing as appears in other areas under private ownerships in the East Usambara Mountains

Opening up forest patches for crop cultivation in Mbomole village

What are the gaps…?Human dimension in terms of livelihood and governance

Bradypodion fischeri

Thank you