Research On Biomass And Carbon Stocks Of Forests In Congo-brazzaville Area

Floristic inventory and diversity assessments are necessary to understand the present diversity status and conservation of forest biodiversity.Understanding major drivers of tree species distribution and tropical forest composition is imperative for biodiversity conservation.Studying the variation height-diameter woody provides insight into the general characteristics of the trees diversity pattern.Quantifying the tropical forests' carbon stocks is presently an important component in the implementation of the emerging carbon credit market mechanisms.This calls for appropriate allometric equations predicting biomass which currently are scarce.However,coarse woody debris(CWD;defined here as fallen and standing dead trees and tree branches)is a critical structural and functional component of forest ecosystems that typically comprises a large proportion of total aboveground carbon storage.However,CWD estimates for the tropics are uncommon,and little is known about how carbon storage in CWD will respond to climate change.Given the predominant role that tropical forests play in global carbon cycling,this information gap compromises efforts to forecast climate change impacts on terrestrial carbon balance.This study mainly focuses on aimed to:(1)assess the effectiveness of trees diversity and structure in two study sites.Trees diversity and structure of Ipendja forest were assessed,and its implications for sustainable development;(2)estimate aboveground biomass(AGB)and carbon stocks for aboveground biomass in Ipendja mixed evergreen lowland terra firme tropical forest and Lesio-louna protected area;(3)estimate belowground biomass(BGB)and carbon stocks for belowground biomass in study area;(4)identify the variation in diameter-height allometry of Ipendja mixed terra firme lowland tropical forest's trees;(5)quantify the coarse woody debris(CWD)stocks including standing dead trees(snags)and fallen dead trees and branches(logs)in Ipendja mixed tropical forest using allometric equations;(6)identify the variation in coarse woody debris(CWD)stocks between forest types(Old-growth and selective logging forests)and among the plots in Ipendja mixed evergreen lowland terra firme tropical forest(central Africa),and we examined the consequence for CWD carbon stocks estimation.The study was conducted in two parts of Republic of Congo:(i)at Ipendja forest management unit(UFA),close to Dongou district(Likouala Department),in Northern Republic of Congo;(ii)and at Lesio-louna forest,close to Igne district(Pool Department),in Teke-Plateau,Southern Republic of Congo.For Ipendja forest,the sampling design was systematic consisted of parallel transect 1 or 2 km part,and divided into consecutive rectangular plots,each 5000m2(25 x 200 m5 i.e.0.5 ha).Within eight plots censuses,all trees with a DBH>10 cm were identified and measured.In eight studied plots(4 plots per site),only trees with DBH?10cm were measured and identified.A total of 1340 trees has been recorded belonged 145 species and 36 families(n=607 and n=733,respectively in Mokelimwaekili and Sombo sites).The floristic data was calculated in order to obtain various indices of diversity,phytogeographical determination of species.The diversity indices were used since it provides detailed information on community composition and relative abundance.The analyses were conducted using allometric method for aboveground biomass(AGB)and belowground biomass(BGB)estimations.Also,the method of line intercepts sampling has been used in each studied site.A total number of 135 CWD samples of diameter?10 cm in the studied plots have been recorded.Data analysis has been performed using SPSS v.18.0,SigmaPlot v.10.0,PAST v.3.05 and ArcGIS v.9.3 softwares.The results show that the leading botanical families were Sapotaceae follows by Euphorbiaceae,Meliaceae,Caesalpiniaceae,Sterculiaceae,Annonaceae and Rubiaceae.The most representative species were C.mildbraedii,S.kamerunensis and P.oliveri,i.e.62.06%,30.34%and 28.27%respectively,demonstrated that they were the leading dominant species of this forest ecosystem.Shannon index were 4.29 bits for Mokelimwaekili and 4.22 bits for Sombo.While Pielou's evenness index was between 0.88 and 0.90,respectively for the Mokelimwaekili and Sombo sites.The similarity coefficient for Jaccard was 62%and 58%for Sorensen.Also,in Ipendja forest ecosystem the mean biomass was built up for AGB(346 Mg ha-1)as well as for BGB(81.3 Mg ha-1),with a significant difference between forest types(F=23.46,df=7.771,P=0.001).It was obvious that biomass in Mokelimwaekili(AGB:559.7 Mg ha-1,BGB:131 Mg ha-1)were higher than those of Sombo(AGB:291.8 Mg ha-1,BGB:68.5 Mg ha-1).It was obvious that stock of coarse woody debris in Mokelimwaekili site(mean:19.96 Mg ha-1;sum:79.84 Mg ha-1)were higher than those of Sombo site(mean:8.9 Mg ha-1;sum:35 Mg ha-1).About the coarse woody debris(CWD)storage,the most representative plot in study sites with high mass of coarse woody debris(CWD)were plot3(31.55 Mg ha-1;27%),followed by plot4(19%;21.46 Mg ha-1),and plot7(15%;17.48 Mg ha-1).Plot6(7.07 Mg ha-1;6%),plot5(6 Mg ha-1;5%),and plot8(5.1 Mg ha-1;5%)had a low frequency of coarse woody debris(CWD)mass.One-way ANOVA and Levene test showed a significant difference between standing dead trees stocks and fallen dead trees and branches stocks(F=17.97,df=7.089,p=0.003).Kruskal-Wallis test shows that there is a significant difference between fallen dead trees and branches mass and standing dead trees mass(p=0.0007).There was a significance difference in Ipendja forest about CWD stocks across two forest types and plots.There are highlight variations in tree diversity indices across sites and plots in Ipendja forest.Further study has been done to identify and determine the trees taxon for Ipendja tropical forest and their phytogeo graphical distribution.Flora of Ipenja has a remarkable diversity and the floristic richness is very considerable in its specific composition.By this study,Ipendja forest ecosystem has clearly variations on the diameter-height relationship and biomass across the plots and the sites.This finding suggests that values vary among forest types and that separate reference values should be adopted for estimates of undisturbed forest carbon stocks in the different ecosystems in Congo basin.Different reference values represent the variability of CWD among forest types and contribute to reducing uncertainties in current estimates of carbon stock in central African forest ecosystems.For Lesio-louna,the measurements were made in nine plots:three plots located in the Iboubikro forest,three plots in Blue Lake Forest and three plots in Ngambali forest(circular plots of 1,256 m2,i.e.40 m of plot diameter).Data was collected using the tree-ring or floristic inventory method and only trees with DBH?10cm were measured and identified.The floristic data was calculated in order to obtain various indices of diversity,phytogeographical determination of species.The diversity indices were used since it provides detailed information on community composition and relative abundance.The methodology of Allometric equations was used to measure the carbon stock of Lesio-louna tropical rainforest.Data analysis has been performed using SPSS v.18.0,SigmaPlot v.10.0,PAST v.3.05 and ArcGIS v.9.3 softwares.The results showed that,the Fabaceae had an important number of trees(17 species),with a relative diversity index of 20%followed by the Mimosaceae with 14 species and a relative diversity index of 16%.Millettia laurentii,Pentaclethra eetveldeana,Eriocoelum macrocarpum,Millettia pinnata and Sorindeia juglandifolia were listed as most important species in the area based on their relative frequency.The average diameter at breast height(DBH)for the studied plots was 30.80 cm.The investigation revealed that in this ecosystem Fabaceae(20%),Mimosaceae(16%),Sapindaceae(12%)and Annonaceae(9%)where the most representative families.Meanwhile,the average recorded diameter at breast height varied from 41.91 cm in plot 6 to 24.49 cm in plot4.The highest Shannon index recorded was in Iboubikro site(2.48 bit),while the lowest was recorded in Blue lake forest site(2.29 bit).Pielou's evenness index was 0.86 for Blue lake forest(86.9%)and 0.89 for Iboubikro(89.4%).Also,the results of this study show that the average carbon stock of aboveground biomass(AGB)in six plots was 170.6 t C ha-1.So,the average of carbon stock of aboveground biomass(ABG)in Iboubikro site was 204.6 t C ha-1 and in the Ngambali site was 136,6 t C ha-1.In this forest ecosystem,the high stock of carbon was obtained in Plot 3,which was in Iboubikro site.Further study has been performed to identify and determine the trees taxon for Lesio-louna tropical forest and their phytogeographical distribution.Flora of Lesio-louna protected area has a remarkable diversity and the floristic richness is very considerable in its specific composition.These findings indicate that,the forests in the study area are an important carbon reservoir,and they can also play a key role in mitigation of climate change.