THE STUDY SITESTHE STUDY SITESThe study was conducted in Begasheka and Debreikidan watersheds, Tigray, northern Ethiopia (Fig. 2)

Life formsLife forms 19 woody plant species were identified and the life form composition is indicated in table 1

Table 1 Life forms (from Debrekidan watershed) indicating regeneration status of four dominate species

DSH vs BiomassDSH vs Biomass

CONCLUSION CONCLUSION From this reach it was possible to draw the following two major conclusions:

•The enclosures in both sites haven given a considerable amount of biomass production & regeneration capacity which can offer some socio-economic benefit in addition to the environmental service to the community

•Though, the regeneration pattern of most species in the enclosures is expanding type, some species like Senna sengueana, Mytenus senegalnesis, & Olea africana formed distorted type of natural regeneration curve, which is an indicator of interference.

The potentials of enclosures in increasing woody biomass & The potentials of enclosures in increasing woody biomass & regenerationregeneration

(A case study of (A case study of BegashekaBegasheka and and DebrekidanDebrekidan watersheds, Tigray, watersheds, Tigray, northernnorthern Ethiopia)Ethiopia)

Ermias Aynekulu1* Emiru Birhane1 and Nigussu Begashaw1

1 Faculty of Dryland Agriculture and Natural Resources, Mekelle University, P.O.Box 231, Mekelle, Ethiopia* Corresponding author: e-mail: ermias8@yahoo.com Fax: +251 344 409304

Fig. 2 The study sites: Debrekidan (right-top) and Begasheka (right-bottom) on the map of Tigray METHODSMETHODSThe procedures followed in the study is summarized in Fig. 3

Watersheds delineated using GPS

Random plots generated using excel

Plot centers navigated using GPS

Inventory made on each plot

Fresh & oven-dried wt. of samples taken based on

diameter class

Regeneration & diversity of species

analyzed

Biomass & regeneration in the enclosures

Fig. 3 Schematic diagram depicting the major process of the study

Fig. 4 Biomass field data collection (top and bottom)

Plant nameNumber of seedlings

Number of saplings

Number of trees

Becium grandifoliume 238 5 2

Dodonea Angstofolia 57 64 17

Euclea shcimpri 22 85 30

Acacia saligna 10 32 10

All species 399 243 89

DSH vs Biomass

y = -0,0223x2 + 0,7129x - 0,0282

R2 = 0,5552

0

1

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3

4

5

6

7

0 5 10 15 20

DSH (cm)

Bio

ma

ss (

kg

)

All woody plants

0

100

200

300

400

<0.3cm 0.3-5cm >5cm

diameter class

num

ber

of in

divi

dual

s

RESULTSRESULTSSummerySummeryBiomass produced in the Begasheka and Debre-kidan were 6.86 ton/ha and 3.8 ton/ha respectively.

745 individuals representing 30 species & 731 individuals representing 19 species were found in Begasheka & Debre-kidan respectively.

Fig. 5 The structural composition of the all species was found to be healthy in both Debrekidan (left) and Begasheka (right) watersheds

Fig. 6 Diameter at Stump Height (DSH) poorly explain the variability in biomass (example from Debrekidan watershed)

0

100

200

300

400

500

1 2 3 4 5

Diameter class (cm)

No

. o

f in

div

idu

als

All woody plants

From the two watersheds, 45 plots with a radius of 5.6 m were used in this study and laid down randomly in the enclosures. Height, diameter at stump height (DSH), diameter at breast height (DBH), Crown diameter, number, identity and life forms were recorded. Single tree-sampling method, destructive, was used to estimate the above ground woody biomass of each species. Sample trees were cut, dried in oven to estimate their moisture content and biomass.

INTRODUCTIONINTRODUCTION

General:General:Area closure development is one of the most commonly practiced strategies to restore degraded dryland environments in most part of Northern Ethiopia. However,

•Performance of closures are not well studied,

•High scarcity of fuel wood in the area, competes with protection

•Unwise utilization of resource developed after rehabilitation

Therefore, it was necessary to study the impact of area enclosures on enhancing woody biomass accumulation, & regeneration pattern in order to determine future development of enclosures.

Fig. 1 Impact of enclousre in vegetation cover in Begasheka watershed: Unclosed & degraded area (left) and enclousre (about 10 years) showing restoration of vegetation (right).

Objective:Objective:GeneralGeneral Investigate the role of enclosures in rehabilitating degraded drylands that would ultimately offer viable promises for both environmental & socio-economic benefits to the society.

SpecificSpecific

•Estimate the biomass accumulated in the enclosures in the study area

•Assess regeneration of species in the enclosures