research article nontimber forest product yield and income...

Research ArticleNontimber Forest Product Yield and Incomefrom Thaumatococcus daniellii under a MixedTree Plantation System in Ghana

Samuel Boadi1 Mark Baah-Acheamfour2

Francis Ulzen-Appiah1 and Ghulam Murtaza Jamro23

1 Department of Agroforestry Faculty of Renewable Resources KwameNkrumahUniversity of Science and Technology Kumasi Ghana2Department of Renewable Resources University of Alberta 4-37 ESB Edmonton AB Canada T6G 2H13 Faculty of Crop Production Sindh Agricultural University Tandojam Sindh 700600 Pakistan

Correspondence should be addressed to Mark Baah-Acheamfour mbaahachualbertaca

Received 16 August 2013 Revised 2 December 2013 Accepted 30 December 2013 Published 16 February 2014

Academic Editor Marney Isaac

Copyright copy 2014 Samuel Boadi et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Thaumatococcus daniellii is a wild sourced tropical understorey herb that is harvested for its foliage and fruits from whichthaumatinmdasha proteinous sweetenermdashis extracted With increased demand for natural sweeteners uncontrolled harvesting of Tdaniellii from the wild is suggested to be neither sustainable nor match industrial demands This study determined the implicationof controlled foliage harvesting of T daniellii under a mixed indigenous tree plantation stand T daniellii plants within plots ofdimension 3m times 4m were thinned to uniform foliage population of about 12 leavesm2 and subsequently harvested at 16 weeksinterval for 64 weeks at four different foliage harvesting intensities (i) no harvesting (control) (ii) 25 harvest (iii) 50 harvestand (iv) 75 harvest Data on agronomic characters and total income from the sale of fruit and harvested foliage were collectedand analysed We found that foliage harvest intensity affected (P lt 0001) number of flowers in the order 18 (control) gt 6 (25) ge 1(50) and 0 (75) Foliage harvest intensity also significantly (P = 0036) influenced fruit number and ranged from 11458ha for thecontrol to 4583ha for the 75 harvest Total income from fruit and foliage sales was greatest for the 50 harvest (US $ 1719132)followed by 75 harvest (US $ 12 31024) and lowest for the no harvest treatment (US $ 10744) Thus proper management ofT daniellii through controlled harvesting of the foliage under mixed tree plantation system could promote sustainable yield andincome to farmers

1 Introduction

Nontimber forest product (NTFP) exploitation has beenrecognized as potential alternative to forest managementpractices such as clear-cut logging [1] With a strong marketand long-term value accruing from the harvest of NTFPstheir economic benefits could override the short-term gainsof converting forests to other land-uses such as timber andagriculture [2] Thaumatococcus daniellii (Benn) Benth aperennial wild understorey herb is one of the promisingNTFPs whose economic potentials have not been fullyexploited in most African countries including Ghana Theplant belongs to the Maranthaceae family and in the orderZingiberales It grows throughout the hot humid tropical

rain forest and coastal zone of West Africa It is also knownto grow over large areas of East and Central Africa In Ghanait is distributed in secondary forests with humid conditions[2 3]

Thaumatococcus daniellii is harvested from thewild for itsfruits fromwhich a protein based sweetener called thaumatinis extracted from the arils Local people use thaumatinas sweeteners by licking the seeds to sweeten porridgeor fermented palm wine [4] Thaumatin is a recognizedfood additive and has potential in drug confectionariesand beverage manufacturing [1 5] The growing interestand increased demand for natural sweeteners and flavourenhancers combined with existing international approval ofthaumatin means the plant faces serious threat from massive

Hindawi Publishing CorporationInternational Journal of Forestry ResearchVolume 2014 Article ID 524863 8 pageshttpdxdoiorg1011552014524863

2 International Journal of Forestry Research

harvest in secondary forests [3 6 7] Additionally the leavesof T daniellii are used in local markets as packaging materialto wrap vegetables fish cola nuts and as a source of sup-plementary fodder for livestock in many African households[5 8]

Fruit collection is reported to have provided employmentto many people in Ghana [4 5] Ekpe and Ottou [4] reportedthat T daniellii fruits were sold at $050 kgminus1 in the localmarkets Between 1990 and 2012 the total production of arilsfrom T daniellii in Cote drsquo Ivoire ranged from 10250 kg to25600 kg Given $16 kgminus1 as average price for frozen aril thisproduction earned between $160000 and $400000 annuallyin exports to the UK [6] Hence there is an apparentlyuntapped potential to improve rural livelihoods in West andCentral Africa through cultivation of T daniellii [6]

The exploitation of T daniellii exclusively from thewild has been reported to be neither sustainable nor meetindustrial demand [3] Destruction of secondary forests dueto poor harvesting techniques has led to yield reductionacross its range Farmers are being forced to travel furtherinto reserved forests to find adequate supplies of foliage andfruits Massive fruits collection from primary forests mayresult in loss of food and habitat for the insects and rodentssuch as grass cutters (Thryonorays swinderianus) and ratsof the forest floor In addition during harvesting a lot ofstampeding occurs among harvesters resulting in seedlingstrampling and destruction of the natural ecosystem [4 6]Because T daniellii is a shade-tolerant plant it has beenargued that controlled harvesting under a mixed indigenousplantation system may promote sustainable yield therebyreducing the frequency of harvest in primary forests [3]Withmuch emphasis on poverty alleviation in Sub-SaharanAfricapromoting the cultivation and management of T daniellii inmixed tree-based systems may also serve as potential sourceof income generation to resource-poor farmers

For a plant like T daniellii interest in both the foliageand fruits warrants appropriate management techniques forsound decision making Despite both the foliage and fruitshaving great economic benefits it is currently unknownto what extent defoliation will influence fruit productionThis necessitates a study that could help to estimate thequantity of foliage that could be harvested at a time withoutadverse effects on fruiting To date the relationship betweendefoliation and fruiting with respect to T daniellii stands isnot well understood The objectives of this study were todetermine (i) the impacts of variable foliage harvesting onfruit yield (number and weight) flowering and specific leafarea of cultivated T daniellii under mixed stands of sevenmost common agroforestry tree species in central Ghanaand (ii) the potential income that could be obtained by localfarmers from leaf and fruit collection We hypothesized that(i) controlled foliage harvests of T daniellii will not reducefruit yield (ie fruit number and fruit wet weight) floweringand stimulate compensatory growth with respect to specificleaf area and (ii) management of T daniellii stands for bothleaf and fruit collection will be more profitable in termsof gross income to local farmers as compared to sole fruitcollection

2 Materials and Methods

21 Study Area and Site Description The present study wasconducted in Oda-Kotoamso (05∘ 521015840N 02∘ 291015840W) a townlocated in the Western Region of Ghana (Figure 1) The arealies in the hot humid tropical rain forest zone with an annualrainfall between 1400 and 2000mm There are two distinctrainy seasons from April to July and from September toNovember The highest rainfall is recorded in June and JulyThere is a short period of dry season from December toMarch A dry easterly wind the Harmattan blows in Januaryand February The average annual temperature is 26∘C [3]Local climate is largely influenced by the Sahara Dessert inthe north and the Atlantic Ocean in the south

Experimental plots were laid in 6-year old establishedstands of T daniellii under a uniformly spaced mixed standof agroforestry trees The tree stand averagely aged 10 yearsconsisted of species including Entandrophragma angolenseCeiba petandra (L) Milicia excelsa (Welw) Terminaliasuperba (Engl) Khaya ivorensis (Chev) Khaya senegalensis(Desr) and Antrocaryon micraster (Chev) The averagecrown diameter diameter at breast height and height of thetrees ranged from 20m to 170m 012m to 045m and 170mto 570m respectively

22 Experimental Design The experimental set up was arandomized complete block design There were four blocksand three foliage harvest treatments plus a controlThereweretotal of 16 treatment plots each with a dimension 3m times 4m(12m2) and were spaced 5m apart To ensure homogeneitytreatment plots were situated within a perimeter definedby four different tree species T daniellii plants on eachplot were then thinned to uniform leave population of 142(12 leavesm2) after which the treatments were imposedTreatments involved harvesting leaves and maintaining aspecified leaf population per plot out of 142 at 16 weeksinterval Harvest treatments imposed on the remaining 142leaves were T

1= no harvesting (control) T

2= 25 (36

leaves) T3= 50 (71 leaves) and T

4= 75 (106 leaves)

23 Data Collection Data were collected on fresh weight ofharvested foliage fruit number and fruit fresh weight over 64weeks at 16 weeks interval Number of flowers per treatmentwas monitored over 12 weeks at 3 weeks interval For specificleaf area (SLA) determination 10 uniformly sized leaves wereharvested from each treatment plot at week 64 The leafarea was measured with an AM-300 Leaf Area Meter (ABCBioScientific Ltd Herefordshire UK) The leaves were thenoven-dried at 60∘C for dry matter determination for threedays [9] Average leaf area and dry matter per treatment werethen calculated Specific leaf area was determined accordingto [9] as follows

SLA =Average leaf area (cm2)Average leaf biomass (g)

(1)

The market price of fresh fruits of T daniellii was obtained atthe fruit receiving station of the thaumatin extraction plant atSamartex Timber and Plywood Company Samreboi Ghana

International Journal of Forestry Research 3

Blolgatanga

Upper west

Wa

Upper east

Northem region

Tamale

BloB lgal tantangaga

Upper west

WaW

Uppper e eassttttttttt

Northem region

TamT ale

Large towncityMedium sized town

Small town (district capital)Other smaller town

Map of Africa

Cote Drsquolvoire

Brong Ahafo region

Sunyani Ashanti region

Kumasi Eastern region

Koforidua

CentralWestern regionGreater Accra

Gulf of Guinea

Accra

Volta

Togo

Ho

Cape coastSekondiTakoradi

Map of Ghana

N

Scale 1 3000000

Miles10005002500

1 48000000

Figure 1 Location of the study area Map of Africa (inset) and map of Ghana depicting the study area (marked with circle) within a humidtropical rainforest zone of Ghana

The total income from fruit sale (TFI) over 64 weeks wascalculated using the following

TFI = Price per kg of fresh fruits

times Total harvested fruits per treatmentha(2)

To determine the potential incomes that could be obtainedfrom the sale of leaves samples of fresh harvested leaves weregiven to leave sellers to be sold on the market Such leaveswere sold in bundles The fresh weights of 30 samples ofbundled leaves were measured from three different marketsand prices per bundle were recorded Average weights of

leave bundle and prices per bundles were calculated to obtaingeneral market price per kilogram The prices per kilogramof both fruit and leaves were converted into their dollarequivalent based on the prevailing local exchange rate Totalleaf income (TLI) that could be obtained from leaves salesover 64 weeks and percent reduction in fruit (PRF) yield werecalculated according to the following

TLI = Average price per kg leaf bundle

times Total harvested leaves per treatmentha(3)


PRF

= 100

minus

[Total fruit yield for harvest treatment times 100]Total fruit yield for control

(4)

24 Statistical Analyses Analyses of Variance (ANOVA) bySAS PROC MIXED procedure [10] and Tukeyrsquos studentizedranged (HSD) test (119875 lt 005) were used to compare theeffect of different harvesting intensities on measured growthparameters The assumption of normality and homogeneityof variance was assessed with the Kolmogorov-Smirnov testusing the PROC UNIVARIATE procedure in SAS (datanot shown) All data conformed to normal distribution AparametricWelchrsquosANOVA testwas used to dealwith nonho-mogeneous variances in situationwhere data transformationsdo not help achieve variance homogeneity The linear modelshown below was used as follows

119884119894119895= 120583 + 119867

119894+ 120573119895+ e119894119895 (5)

where 119884119894119895

is the value of measured parameter 120583 is thepopulation mean 119867

119894is the effect of the 119894th harvesting

treatment i=T1(control)T

2(25)T

3(50) andT

4(75)

Β119895is the effect of the jth block 119895 = 1 2 4 and e

119894119895is the

random variable error within the experimentA correlation analysis was also used to estimate the linear

relationship between fruit numbers fruit weight number offlowers and specific leaf area

3 Results and Discussion

31 Effect of Foliage Harvest on T Daniellii Growth Foliageharvest significantly (119875 = 0036) affected number offruits Fruit number decreased with increased foliage harvestintensity (Figure 2) Control stands produced the greatestnumber of fruits (11458ha) but it was not different from thatproduced from the 25 foliage harvest (8958ha) Howeverthe number of fruits produced from the control stands wassignificantly greater than what was produced from standswith 50 (4792ha) and 75 (4583ha) foliage removalsThe pattern of fruit production showed that fruit numberdeclined with time for all treatments except for the controlwhich recorded a sharp increase at week 64 (Figure 3) Apartfromweek 32 which recorded no fruits for the control standsfruit production was greatest for the control stands comparedto all other treatments over the 64 weeks This could suggesta greater potential of T daniellii to produce fruits if standsare not harvested No significant difference (119875 = 0163) wasrecorded among the different harvesting intensities in termsof overall weight of fruits produced (Figure 4)

The decreased fruit production of T daniellii in relationto foliage harvest intensity as reported by our study isconsistent with results from other studies For instancesevere aboveground biomass removal of velvet leaf (Abutilontheophrasti) and ruderal herb (Barbarea vulgaris) resultedin fruit number decline with increasing severity of harvest

a

ab

b b

200

2200

4200

6200

8200

10200

12200

14200

Control 25 50 75Harvesting treatments

Num

ber o

f fru

its (h

a)

Mean plusmn stderrControl 11458 plusmn 213203

25 8958 plusmn 74385

50 4792 plusmn 85271

75 4583 plusmn 173059

Figure 2 Effect of foliage harvest intensity on total fruit number ofT daniellii in the humid tropical rainforest zone of Ghana

0

1000

2000

3000

4000

5000

6000

7000

8000

16 32 48 64Weeks

Num

ber o

f fru

its (h

a)

Control25

5075

Figure 3 Total fruit number of T daniellii in response to differentfoliage harvest intensities over 64 weeks

[11 12] Conversely Caragana korshinskii compensated forfoliage harvesting by increasing fruit set seed number perpod and seed biomass and a decrease in fruit abortion [13]C korshinskii responses to foliage harvest were achievedby (i) drawing upon more nonstructural carbohydrate fromroots to supply flower bud development and the flush ofnew foliage and (ii) supplying more photosynthetic assim-ilation to fruit development owing to increases in leaf-level photosynthetic rates [13] The inability of T daniellii


aa

a

a

200

400

600

800

1000

1200

1400

1600


Frui

t wei

ght (

kgh

a)


25 867 plusmn 541

50 639 plusmn 339

75 597 plusmn 2579

Figure 4 Effect of foliage harvest intensity on fruit weight of TdanielliiMeans (plusmnSE) with similar letters do not differ significantlyat 5 probability level

to respond to increased foliage harvest through some ofthese physiological processes as exhibited by C korshinskiiperhaps accounted for the decreased fruit production Inaddition foliage harvest enhanced light penetration to thebase of T daniellii stands but possibly reduced leaf areathat caused a decline in photosynthate production [14] Withthe exception of the control the 25 50 and 75 offoliage harvest stands may have experienced rapid sheddingof matured leaves while new ones developed Howevernewly expanded leaves compete with older leaves for solarradiation mineral nutrients and assimilate such that leavesbegin to senescence in sequence according to age [14] Suchyoung leaves possibly invest more resources into vegetativegrowth to the detriment of fruit production on harvestedstands Thus the apparent availability of enough maturedfoliage on control stands could have facilitated the capture oflight for synthesis and photosynthate accumulation neededfor fruiting This phenomenon explains why control standsproduced more fruits than harvested stand

Harvesting of leaves may have a negligible effect onexploited plant population if (i) individual plants survivedthe process (ii) a sufficient number of healthy leaves areleft on each plant for photosynthesis (iii) the reproductivestructures and apical buds are not damaged and (iv) sufficienttime is allowed between successive harvests for the plantto produce new leaves [15] Collecting too many leavesfrom an individual plant can reduce the number of newones and the number of flowers and fruits produced [16]Although individual plants survived in our case biomassharvest may have reduced leaf population to the extentthat only few matured leaves remained for photosynthesis

Harvesting can also cause extensive damage to reproductivestructures for fruit production For example a study onBarbarea vulgaris indicated that injury from foliage harvestsignificantly affected seed production and also the plantsrsquo lifecycle Seed production was lower in injured plants comparedto in intact plants [11]

We found no significant (119875 = 0163) difference in termsof total fruit weight (Figure 4) This result could imply thatalthough control stands produced more fruits the sizes offruits could have been smaller than other harvested standsA study of harvest regimes on five varieties of summersquash (Cucurbita pepo L) reported significant influenceson fruit size [17] One variety produced larger fruits in therainy season when leaves were harvested compared to noleaf harvest This was attributed in part to high diseaseincidence in the rainy season that affected older leaves inthe ldquono harvestrdquo treatment compared to several young leavesthat emerged in the ldquoleaf harvestrdquo treatment These youngleaves may have photosynthesizedmore efficiently than olderdiseased leaves [17] For T daniellii possible differences infruit sizes could be due to increased demand to supportdense populations Hence control stands in addition tofruiting could have also channeledmore resources to supportphysiological activities of increased populations A study onRorippa palustris revealed that defoliation and removal ofaxillary buds induced growth of new shoots from root buds[18]Therefore decreased flowering with respect to increasedharvesting intensity of T daniellii could imply that harvestedstands invest resources into tiller production and replacementof lost tissues whereas control stands channelled resourcesto flowering The capacity for tiller recruitment was the mostpronounced morphological distinction between perennialbunchgrass (Schizachyrium scoparium) with contrasting his-tories of herbivory [19] Plants with a history of herbivorypossessed a greater competitive ability to recruit a greaternumber of tillers than plants with no herbivory history [19]Thus the T daniellii stands receiving various degrees ofharvesting produced significantly lower number of flowersthan the control

Number of flowers significantly (119875 lt 0001) decreasedwith increased harvesting rate (Figure 5) Mean number offlowers recorded at week 64 was greatest for control (18flowers) and lowest for 75 (no flower) The pattern offlowering of T daniellii in response to treatments over 12weeks showed that flower production decreased over timefrom week 51 in November to 60 in February (Figure 6)This could indicate that flowering peaks in the dry sea-son and decreases towards the onset of the rainy seasonResponse to herbivores increases with increased frequencyof defoliation Such response also explains why removalof Primula veris leaves resulted in a decrease in floweringfor 2 years [20] With the exception of control stands thatconsistently produced flowers over the 12 weeks none ofthe harvested stands recorded continuous flower productionThe 75 foliage harvesting resulted in no flower produc-tion over the 12 weeks (Figure 6) Though flowering wasobserved for 25 (6 flowers) and 50 (1 flower) foliageharvest fruit set was zero This could be due to high rateof abscission among young flowers limited pollination or


bb

b

a

0

5

10

15

20

25

Control 25 50 75

Harvesting treatment

Num

ber o

f flow

ers


25 6 plusmn 158

50 1 plusmn 076

75 0 plusmn 0

Figure 5 Effect of foliage harvest intensity on number of flowers ofT daniellii Means (plusmnSE) with different letters differ significantly at5 probability level

0

10

20

30

40

50

51 54 57 60Weeks

Num

ber o

f flow

ers

Control25

5075

Figure 6 Pattern of flowering of T daniellii in response to foliageharvest over 12 weeks

limited nutrients [21] on such stands during the dry sea-son

No significant (119875 = 0498) differences were observedamong harvest treatments with respect to SLA after 64weeks Specific leaf area ranged from 14387 cm2 gminus1 to14893 cm2 gminus1 (Figure 7) Control stands possessed morematured leaves than all other harvested stands In a relatedstudy conducted on several plant species no significantdifferences in SLA between recentlymatured leaves and older

aa

aa

140

142

144

146

148

150

152



25 1444 plusmn 317

50 1489 plusmn 339

75 1485 plusmn 145

Spec

ific l

eaf a

rea (

cm2

gminus1)

Figure 7 Specific leaf area response to T daniellii foliage harvestintensity Means (plusmnSE) with similar letters do not differ significantlyat 5 probability level

leaves were reported [22] Specific leaf area is the light-catching area deployed per unit of previously photosyn-thesized dry mass allocated and is a major contributor toresource capture usage and availability [9 23] DecreasingSLA has been associated with greater allocation of biomassto structural components of the leaf rather than metaboliccomponents [24] Leaf area reflects expected return onpreviously captured resources [25] For instance Lonicerajaponica allocated more C to secondary leaves and stemsdue to unlimited herbivory Plants usually compensate fordefoliation by replacing leaf tissue and changing intrinsicbiomass allocation patterns [26] In a study on the response oftwo grass species to a gradient of defoliation intensities from0 to 100 aboveground biomass removal plants showed thesame aboveground growth regardless of defoliation intensitydue to stimulation of relative growth rate by defoliation[27] Aboveground compensatory responses represent a keyfeedback process resulting in constant aboveground growthregardless of defoliation intensity [27] Also biomass allo-cation to a leaf is dependent on the overall plant demandduring its expansion and can be affected by concurrentevents such as fruit-set [28] Therefore lack of significant(119875 = 0498) differences in specific leaf area of T danielliicould suggest that harvested stands possibly supply morephotosynthate to leaf development owing to decreases in leaf-level photosynthetic rates whereas control stands possiblyinvest in fruiting and below ground storage

Fruit number had significant positive correlation withfruit weight (119903 = 091 Table 2) Hence an increase in fruitnumber is strongly associatedwith increases in fruit weight Astudy aimed at estimating fruit weight per grade of Cucumber(Cucumis sativus L) found also a strong relationship betweenfruit weight and fruit number within each grade [29] Alsocustard apple (Annona squamosa L) studied over three years


Table 1 An estimated income from fruit and leave harvest of T daniellii stands over 64 weeks

Foliage harvest Total fruits Fruit income at Total harvested leaf Leaf income at lowastTotal incomeintensity () (kgha) $021kg (kgha) US $055kg $haControl 51160 10744 0 0 1074425 34662 7279 1998253 1094144 110142350 25564 5368 3129875 1713764 171913275 23886 5016 2239077 1226008 1231024lowastTotal income = Fruit income + Leaf income

Table 2 Correlation coefficient (119903 value) among fruit number (FN)fruit weight (FW) and specific leaf area (SLA) of T daniellii foliageharvested over 64 weeks

Equation 119903 119875 valueFW = 001FN + 99775 091 0001lowastlowastlowast

FW = 123SLA minus 95977 014 0613ns

FN = 5983SLA minus 13135 007 0787nslowastlowastlowastSignificant correlation at 0001 probability level nsno significant relation-ship at 5 significance level

in Brazil reported significant relationship between numberof fruits and fruit yield (kg haminus1) In this study 993 of thevariation in yield was explained by the variation in number offruits [18 30] Specific leaf area had insignificant relationshipwith fruit number (119875 = 0787) and fruit weight (119875 = 0613)

32 Potential Incomes from Leaf and Fruit Harvest Thepotential income that could be generated from T danielliileave and fruit harvest over 64 weeks is presented in Table 1Generated income from fruit harvest increased with reducedfoliage harvest intensity Compared to the control whichgave the highest fruit yield of 51160 kgha and income of$10744 there were 323 500 and 533 reductions infruit yields respectively for 25 500 and 75 foliageharvest treatments Similarly the percentage in fruit yieldreductions between ldquono leaf harvestrdquo and ldquoleaf harvestrdquotreatments for some varieties of summer squash (Cucurbitapepo L) ranged between 2 and 45 [16 31] This couldsuggest that harvesting activities negatively impact on thefruiting of Thaumatococcus daniellii and cause a decline inincomes obtained from fruits as the degree of harvestingincreases [1 32] Thus decreased incomes of $7279 $5368and $5016 were obtained for 25 500 and 75 foliageharvest treatments respectively (Table 1)

Meanwhile the highest leaf income of US $ 1713764was obtained for 50 foliage harvest This suggests that50 leaf harvest of stands could be sufficient to sustainenough leaf production over an extended period of time Leafincome from 75 harvest stands US $ 1226008 was higherthan US $ 1094144 from 25 harvest stands Though noincome was generated for control stands from leaf harvest75 harvesting was also detrimental to fruit production andresulted in the lowest income of US $ 5016 (Table 1) Thehighest total incomewasUS $ 1719132 for 50 harvest standsfollowed by 75 and 25 harvest stands with incomes ofUS $ 1231024 and US $ 1101423 respectively The lowesttotal income US $ 10744 was obtained for the controldue to lack of supplementary income from leaf harvesting

(Table 1) The results suggest that management of T danielliifor both leaf and fruit collection could be more economicallybeneficial than for sole fruit collection [17 33]This is becauseincomes that accrue from leaf harvest could compensate forincomes lost due to reductions in fruit yield Considering thecurrent demand for NTFPs such as T daniellii this studyshowed how controlled harvesting ofT daniellii foliage insideagroforestry land-uses could reduce the over dependence onharvesting from wild sources and ultimately limit entry oflocal farmers into primary forest reserves

4 Conclusions

The present study showed that management of T daniellii forboth leaf and fruit harvest could be more beneficial to localfarmers as compared to fruit harvest only The number offruit per stand significantly decreased with increased foliageharvest Income from the sale of fruits and leaves was greatestfor the 50 harvest intermediate for 25 and 75 harvestand lowest for the no harvest treatment The study incomeprojection was based on the assumption of a ready marketfor both leaves and fruits We did not account for lossesincurred through rejection of rotten fruit by buyers dryingof foliage and transportation costs These among othereconomic factors can influence the income level of fruits andleaves sale and are worth investigating

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors are grateful to the Kwame Nkrumah Universityof Science and Technology (KNUST) Kumasi Ghana forfunding this research work and Samartex Timber and Ply-wood Company for granting us access to their plantationand providing us field support They also thank CrispinSuglo and his team of the agroforestry section of Samartexand Emmanuel Owusu of the Thaumatin Department ofSamartex for their help at the field site

References

[1] D Abbiw Some Useful Plants of Ghana Intermediate Technol-ogy Publications and the Royal Botanic Gardens London UK1990


[2] T C H Sunderland S T Harrison and O Ndoye ldquoCommer-cialisation of nontimber forest products in Africa historycontext and prospectsrdquo in Forest Products Livelihoods andConservation Case Studies of Non-Timber Forest Systems TSunderland and O Ndoye Eds pp 1ndash24 Center for Interna-tional Forestry Research Jakarta Indonesia 2004

[3] S O Yeboah T H Hilger and J Kroschel Thaumatococcusdaniellii A Natural Sweetener from the Rain Forest Zone inWest Africa with Potential for Income Generation in Small ScaleFarming Institute of Plant Production and Agroecology of theTropics and Subtropics Hohenheim University 2003

[4] K E Ekpe and R Ottou ldquoBenefiting from conservation howthe collection of Thaumatococcus daniellii fruits in Ghana isemerging as a forest industryrdquo Silvanet vol 19 no 1 pp 2ndash42006

[5] K A D Swift S Pearce and H Roth ldquoOut of Africa thechemistry and flavour properties of the protein thaumatinrdquo inAdvances in Flavours and Fragrances KAD Swift Ed pp 178ndash193 Royal Society of Chemistry 2002

[6] S Wojciech S Oppong J B Hall and F L Sinclair ldquoImpli-cations of local knowledge of the ecology of a wild supersweetener for its domestication and commercialization in WestandCentral AfricardquoEconomic Botany vol 59 no 3 pp 231ndash2432005

[7] D C J Chieh Thaumatin recovery via bioengineering routeand in-vitro culture of Thaumatococcus daniellii [PhD thesis]Universiti Sains Penang Malaysia 2008

[8] J Falconer ldquoNon-timber forest products in Southern Ghanardquo ASummary Report Natural Resources Institute Kent UK 1992

[9] S Gunn J F Farrar B E Collis and M Nason ldquoSpecificleaf area in barley individual leaves versus whole plantsrdquo NewPhytologist vol 143 no 1 pp 45ndash51 1999

[10] SAS Institute SAS userrsquos guide Statistics SASC Online DocRelease 920 SAS Cary NC USA 2012

[11] T D Lee and F A Bazzaz ldquoEffects of defoliation and competi-tion on growth and reproduction in the annual plant Abutilontheophrastirdquo Journal of Ecology vol 68 pp 813ndash821 1980

[12] J Martınkova J Klimesova and S Mihulka ldquoCompensationof seed production after severe injury in the short-lived herbBarbarea vulgarisrdquo Basic and Applied Ecology vol 9 no 1 pp44ndash54 2008

[13] R K M Hay and A J WalkerAn Introduction to the Physiologyof Crop Yield Longman Scientific and Technical Essex UK1992

[14] X Fang J Yuan G Wang and Z Zhao ldquoFruit productionof shrub Caragana korshinskii following above-ground partialshoot removal mechanisms underlying compensationrdquo PlantEcology vol 187 no 2 pp 213ndash225 2006

[15] H J Ndangalasi R Bitariho and D B K Dovie ldquoHarvesting ofnon-timber forest products and implications for conservationin two montane forests of East Africardquo Biological Conservationvol 134 no 2 pp 242ndash250 2007

[16] P J Anderson ldquoUsing ecological and economic informationto determine sustainable harvest levels of a plant populationrdquoin Incomes From the Forest Methods for the Developmentand Conservation of Forest Products for Local CommunitiesE Wollenberg and A Ingles Eds pp 137ndash155 Center forInternational Forestry Research SMT Grafika Desa PuteraIndonesia 1998

[17] L Bonnehin ldquoEconomic value and role of NTFP in the longterm management of forests resources in the Cote drsquoIviorerdquo in

Non-Timber Forest Products Values Use andManagement Issuesin Africa Including Examples from Latin America S A CrafterJ Awimbo and A J Broekhoven Eds pp 68ndash69 IUCN TheWorld Convention Union 1997

[18] J Martınkova M Kocvarova and J Klimesova ldquoResproutingafter disturbance in the short-lived herb Rorippa palustris(Brassicaceae) an experiment with juvenilesrdquo Oecologica vol25 no 3 pp 143ndash150 2004

[19] D D Briske and V J Anderson ldquoCompetitive ability of thebunchgrass Schizachyrium scoparium as affected by grazinghistory and defoliationrdquoVegetatio vol 103 no 1 pp 41ndash49 1992

[20] D F Whigham and A S Chapa ldquoTiming and intensity ofherbivory its influence on the performance of clonal woodlandherbsrdquo Plant Species Biology vol 14 no 1 pp 29ndash37 1999

[21] S N Pandey and B K Sinha Plant Physiology VIKAS Publish-ing House New Delhi India 4th edition 2006

[22] H Poorter and R De Jong ldquoA comparison of specific leaf areachemical composition and leaf construction costs of field plantsfrom 15 habitats differing in productivityrdquo New Phytologist vol143 no 1 pp 163ndash176 1999

[23] F Vendramini S Dıaz D E Gurvich P J Wilson K Thomp-son and J GHodgson ldquoLeaf traits as indicators of resource-usestrategy in floras with succulent speciesrdquo New Phytologist vol154 no 1 pp 147ndash157 2002

[24] P B Reich D S Ellsworth and M B Walters ldquoLeaf structure(specific leaf area) modulates photosynthesis-nitrogen rela-tions evidence from within and across species and functionalgroupsrdquo Functional Ecology vol 12 no 6 pp 948ndash958 1998

[25] P JWilson KThompson and J G Hodgson ldquoSpecific leaf areaand leaf dry matter content as alternative predictors of plantstrategiesrdquo New Phytologist vol 143 no 1 pp 155ndash162 1999

[26] K A Schierenbeck R N Mack and R R Sharitz ldquoEffectsof herbivory on growth and biomass allocation in native andintroduced species of Lonicerardquo Ecology vol 75 no 6 pp 1661ndash1672 1994

[27] M Oesterheld ldquoEffect of defoliation intensity on abovegroundand belowground relative growth ratesrdquo Oecologia vol 92 no3 pp 313ndash316 1992

[28] M Kang L Yang B Zhang and P De Reffye ldquoCorrelationbetween dynamic tomato fruit-set and sourcesink ratio acommon relationship for different plant densities and seasonsrdquoAnnals of Botany vol 107 no 5 pp 805ndash815 2011

[29] NV Shetty andTCWehner ldquoEstimation of fruit gradeweightsbased on fruit number and total fruit weight in cucumberrdquoHortScience vol 37 no 7 pp 1117ndash1121 2002

[30] K H Mariguele and P S L Silva ldquoRelationship between fruittraits of custard apple trees (Annona squamosaL)rdquoRevista CeresVicosa vol 57 no 4 pp 476ndash479 2010

[31] M A Adansi and H L O Holloway ldquoThe cultivation ofKatamfe (Thaumatococcus daniellii Benth)rdquo Acta Horticul-turae vol 53 pp 403ndash405 1997

[32] afrol News ldquoSweet industrial prospects in Ghanardquo 2012httpwwwafrolcomarticles10706

[33] O G E Arowosoge and L Popoola ldquoEconomic analysis ofThaumatococcus danielli (Benn) Benth (miraculous berry) inEkiti State Nigeriardquo Journal of Food Agriculture and Environ-ment vol 4 no 1 pp 264ndash269 2006

Submit your manuscripts athttpwwwhindawicom

Forestry ResearchInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Environmental and Public Health

Journal of



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MeteorologyAdvances in

EcologyInternational Journal of


Marine BiologyJournal of


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Applied ampEnvironmentalSoil Science

Volume 2014

Advances in


Environmental Chemistry

Atmospheric SciencesInternational Journal of



Waste ManagementJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal of

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Geological ResearchJournal of

EarthquakesJournal of


BiodiversityInternational Journal of


ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OceanographyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


ClimatologyJournal of


harvest in secondary forests [3 6 7] Additionally the leavesof T daniellii are used in local markets as packaging materialto wrap vegetables fish cola nuts and as a source of sup-plementary fodder for livestock in many African households[5 8]

Fruit collection is reported to have provided employmentto many people in Ghana [4 5] Ekpe and Ottou [4] reportedthat T daniellii fruits were sold at $050 kgminus1 in the localmarkets Between 1990 and 2012 the total production of arilsfrom T daniellii in Cote drsquo Ivoire ranged from 10250 kg to25600 kg Given $16 kgminus1 as average price for frozen aril thisproduction earned between $160000 and $400000 annuallyin exports to the UK [6] Hence there is an apparentlyuntapped potential to improve rural livelihoods in West andCentral Africa through cultivation of T daniellii [6]

The exploitation of T daniellii exclusively from thewild has been reported to be neither sustainable nor meetindustrial demand [3] Destruction of secondary forests dueto poor harvesting techniques has led to yield reductionacross its range Farmers are being forced to travel furtherinto reserved forests to find adequate supplies of foliage andfruits Massive fruits collection from primary forests mayresult in loss of food and habitat for the insects and rodentssuch as grass cutters (Thryonorays swinderianus) and ratsof the forest floor In addition during harvesting a lot ofstampeding occurs among harvesters resulting in seedlingstrampling and destruction of the natural ecosystem [4 6]Because T daniellii is a shade-tolerant plant it has beenargued that controlled harvesting under a mixed indigenousplantation system may promote sustainable yield therebyreducing the frequency of harvest in primary forests [3]Withmuch emphasis on poverty alleviation in Sub-SaharanAfricapromoting the cultivation and management of T daniellii inmixed tree-based systems may also serve as potential sourceof income generation to resource-poor farmers

For a plant like T daniellii interest in both the foliageand fruits warrants appropriate management techniques forsound decision making Despite both the foliage and fruitshaving great economic benefits it is currently unknownto what extent defoliation will influence fruit productionThis necessitates a study that could help to estimate thequantity of foliage that could be harvested at a time withoutadverse effects on fruiting To date the relationship betweendefoliation and fruiting with respect to T daniellii stands isnot well understood The objectives of this study were todetermine (i) the impacts of variable foliage harvesting onfruit yield (number and weight) flowering and specific leafarea of cultivated T daniellii under mixed stands of sevenmost common agroforestry tree species in central Ghanaand (ii) the potential income that could be obtained by localfarmers from leaf and fruit collection We hypothesized that(i) controlled foliage harvests of T daniellii will not reducefruit yield (ie fruit number and fruit wet weight) floweringand stimulate compensatory growth with respect to specificleaf area and (ii) management of T daniellii stands for bothleaf and fruit collection will be more profitable in termsof gross income to local farmers as compared to sole fruitcollection

2 Materials and Methods

21 Study Area and Site Description The present study wasconducted in Oda-Kotoamso (05∘ 521015840N 02∘ 291015840W) a townlocated in the Western Region of Ghana (Figure 1) The arealies in the hot humid tropical rain forest zone with an annualrainfall between 1400 and 2000mm There are two distinctrainy seasons from April to July and from September toNovember The highest rainfall is recorded in June and JulyThere is a short period of dry season from December toMarch A dry easterly wind the Harmattan blows in Januaryand February The average annual temperature is 26∘C [3]Local climate is largely influenced by the Sahara Dessert inthe north and the Atlantic Ocean in the south

Experimental plots were laid in 6-year old establishedstands of T daniellii under a uniformly spaced mixed standof agroforestry trees The tree stand averagely aged 10 yearsconsisted of species including Entandrophragma angolenseCeiba petandra (L) Milicia excelsa (Welw) Terminaliasuperba (Engl) Khaya ivorensis (Chev) Khaya senegalensis(Desr) and Antrocaryon micraster (Chev) The averagecrown diameter diameter at breast height and height of thetrees ranged from 20m to 170m 012m to 045m and 170mto 570m respectively

22 Experimental Design The experimental set up was arandomized complete block design There were four blocksand three foliage harvest treatments plus a controlThereweretotal of 16 treatment plots each with a dimension 3m times 4m(12m2) and were spaced 5m apart To ensure homogeneitytreatment plots were situated within a perimeter definedby four different tree species T daniellii plants on eachplot were then thinned to uniform leave population of 142(12 leavesm2) after which the treatments were imposedTreatments involved harvesting leaves and maintaining aspecified leaf population per plot out of 142 at 16 weeksinterval Harvest treatments imposed on the remaining 142leaves were T

1= no harvesting (control) T

2= 25 (36

leaves) T3= 50 (71 leaves) and T

4= 75 (106 leaves)

23 Data Collection Data were collected on fresh weight ofharvested foliage fruit number and fruit fresh weight over 64weeks at 16 weeks interval Number of flowers per treatmentwas monitored over 12 weeks at 3 weeks interval For specificleaf area (SLA) determination 10 uniformly sized leaves wereharvested from each treatment plot at week 64 The leafarea was measured with an AM-300 Leaf Area Meter (ABCBioScientific Ltd Herefordshire UK) The leaves were thenoven-dried at 60∘C for dry matter determination for threedays [9] Average leaf area and dry matter per treatment werethen calculated Specific leaf area was determined accordingto [9] as follows

SLA =Average leaf area (cm2)Average leaf biomass (g)

(1)

The market price of fresh fruits of T daniellii was obtained atthe fruit receiving station of the thaumatin extraction plant atSamartex Timber and Plywood Company Samreboi Ghana


Blolgatanga

Upper west

Wa

Upper east

Northem region

Tamale


Upper west

WaW


Northem region

TamT ale



Map of Africa

Cote Drsquolvoire

Brong Ahafo region



Koforidua


Gulf of Guinea

Accra

Volta

Togo

Ho


Map of Ghana

N

Scale 1 3000000

Miles10005002500

1 48000000










PRF

= 100

minus


(4)


119884119894119895= 120583 + 119867

119894+ 120573119895+ e119894119895 (5)

where 119884119894119895




2(25)T

3(50) andT

4(75)


119894119895is the






a

ab

b b

200

2200

4200

6200

8200

10200

12200

14200


Num

ber o

f fru

its (h

a)


25 8958 plusmn 74385

50 4792 plusmn 85271

75 4583 plusmn 173059


0

1000

2000

3000

4000

5000

6000

7000

8000

16 32 48 64Weeks

Num

ber o

f fru

its (h

a)

Control25

5075




aa

a

a

200

400

600

800

1000

1200

1400

1600


Frui

t wei

ght (

kgh

a)


25 867 plusmn 541

50 639 plusmn 339

75 597 plusmn 2579








bb

b

a

0

5

10

15

20

25

Control 25 50 75


Num

ber o

f flow

ers


25 6 plusmn 158

50 1 plusmn 076

75 0 plusmn 0


0

10

20

30

40

50

51 54 57 60Weeks

Num

ber o

f flow

ers

Control25

5075




aa

aa

140

142

144

146

148

150

152



25 1444 plusmn 317

50 1489 plusmn 339

75 1485 plusmn 145

Spec

ific l

eaf a

rea (

cm2

gminus1)









FW = 123SLA minus 95977 014 0613ns






4 Conclusions




Acknowledgments


References








































Journal of












Volume 2014

Advances in









Geophysics















Blolgatanga

Upper west

Wa

Upper east

Northem region

Tamale


Upper west

WaW


Northem region

TamT ale



Map of Africa

Cote Drsquolvoire

Brong Ahafo region



Koforidua


Gulf of Guinea

Accra

Volta

Togo

Ho


Map of Ghana

N

Scale 1 3000000

Miles10005002500

1 48000000










PRF

= 100

minus


(4)


119884119894119895= 120583 + 119867

119894+ 120573119895+ e119894119895 (5)

where 119884119894119895




2(25)T

3(50) andT

4(75)


119894119895is the






a

ab

b b

200

2200

4200

6200

8200

10200

12200

14200


Num

ber o

f fru

its (h

a)


25 8958 plusmn 74385

50 4792 plusmn 85271

75 4583 plusmn 173059


0

1000

2000

3000

4000

5000

6000

7000

8000

16 32 48 64Weeks

Num

ber o

f fru

its (h

a)

Control25

5075




aa

a

a

200

400

600

800

1000

1200

1400

1600


Frui

t wei

ght (

kgh

a)


25 867 plusmn 541

50 639 plusmn 339

75 597 plusmn 2579








bb

b

a

0

5

10

15

20

25

Control 25 50 75


Num

ber o

f flow

ers


25 6 plusmn 158

50 1 plusmn 076

75 0 plusmn 0


0

10

20

30

40

50

51 54 57 60Weeks

Num

ber o

f flow

ers

Control25

5075




aa

aa

140

142

144

146

148

150

152



25 1444 plusmn 317

50 1489 plusmn 339

75 1485 plusmn 145

Spec

ific l

eaf a

rea (

cm2

gminus1)









FW = 123SLA minus 95977 014 0613ns






4 Conclusions




Acknowledgments


References








































Journal of












Volume 2014

Advances in









Geophysics















PRF

= 100

minus


(4)


119884119894119895= 120583 + 119867

119894+ 120573119895+ e119894119895 (5)

where 119884119894119895




2(25)T

3(50) andT

4(75)


119894119895is the






a

ab

b b

200

2200

4200

6200

8200

10200

12200

14200


Num

ber o

f fru

its (h

a)


25 8958 plusmn 74385

50 4792 plusmn 85271

75 4583 plusmn 173059


0

1000

2000

3000

4000

5000

6000

7000

8000

16 32 48 64Weeks

Num

ber o

f fru

its (h

a)

Control25

5075




aa

a

a

200

400

600

800

1000

1200

1400

1600


Frui

t wei

ght (

kgh

a)


25 867 plusmn 541

50 639 plusmn 339

75 597 plusmn 2579








bb

b

a

0

5

10

15

20

25

Control 25 50 75


Num

ber o

f flow

ers


25 6 plusmn 158

50 1 plusmn 076

75 0 plusmn 0


0

10

20

30

40

50

51 54 57 60Weeks

Num

ber o

f flow

ers

Control25

5075




aa

aa

140

142

144

146

148

150

152



25 1444 plusmn 317

50 1489 plusmn 339

75 1485 plusmn 145

Spec

ific l

eaf a

rea (

cm2

gminus1)









FW = 123SLA minus 95977 014 0613ns






4 Conclusions




Acknowledgments


References








































Journal of












Volume 2014

Advances in









Geophysics















aa

a

a

200

400

600

800

1000

1200

1400

1600


Frui

t wei

ght (

kgh

a)


25 867 plusmn 541

50 639 plusmn 339

75 597 plusmn 2579








bb

b

a

0

5

10

15

20

25

Control 25 50 75


Num

ber o

f flow

ers


25 6 plusmn 158

50 1 plusmn 076

75 0 plusmn 0


0

10

20

30

40

50

51 54 57 60Weeks

Num

ber o

f flow

ers

Control25

5075




aa

aa

140

142

144

146

148

150

152



25 1444 plusmn 317

50 1489 plusmn 339

75 1485 plusmn 145

Spec

ific l

eaf a

rea (

cm2

gminus1)









FW = 123SLA minus 95977 014 0613ns






4 Conclusions




Acknowledgments


References








































Journal of












Volume 2014

Advances in









Geophysics















bb

b

a

0

5

10

15

20

25

Control 25 50 75


Num

ber o

f flow

ers


25 6 plusmn 158

50 1 plusmn 076

75 0 plusmn 0


0

10

20

30

40

50

51 54 57 60Weeks

Num

ber o

f flow

ers

Control25

5075




aa

aa

140

142

144

146

148

150

152



25 1444 plusmn 317

50 1489 plusmn 339

75 1485 plusmn 145

Spec

ific l

eaf a

rea (

cm2

gminus1)









FW = 123SLA minus 95977 014 0613ns






4 Conclusions




Acknowledgments


References








































Journal of












Volume 2014

Advances in









Geophysics



















FW = 123SLA minus 95977 014 0613ns






4 Conclusions




Acknowledgments


References








































Journal of












Volume 2014

Advances in









Geophysics




















































Journal of












Volume 2014

Advances in









Geophysics














research article nontimber forest product yield and income...

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