Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems

Vol 2 | Issue 1 | Pages 60-70 Journal of Botany Research ISSN: 2643-6027

Original Research Paper DOI: 10.36959/771/562 Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon Awe Djongmo Victor1*, Noiha Noumi Valery1,2, Zapfack Louis3, Ali Ahmed Davy1 and Madou Chantal1,4

1Department of Biological Sciences, University of Ngaoundere, Cameroon 2Higher Teacher Training College (ENS) of Bertoua, Cameroon 3Department of Biology and Plant Physiology, University of Yaounde, Cameroon 4IRAD of Garoua, Garoua, Cameroon

Abstract This work highlights the critical role of deadwood in maintaining balance within forest ecosystems and in conserving biodiversity associated with it. Thus the general objective of this work was the quantification of carbon in dead wood biomass of savannah ecosystems in Northern region Cameroon. The investigations were made by the transect method. The experimental device using was a split plot. The results obtained showed that the highest standing deadwood and soil carbon stock was observed in arborescent savannah (7.50 ± 2.12 tC/ha) and woody savannah (8.92 ± 3.65 tC/ha) in Mayo-Rey department. Average total deadwood carbon stocks are higher in the Mayo-Rey biotopes (8.70 ± 3.71 tC/ha) and the highest total deadwood carbon stock was observed in the fields of Benue (14.24 ± 3.12 tC/ha). These results also showed that, according to the advanced low and intermediate decomposition, Mayo-Rey Department biotopes store more carbon in the dead wood biomass with general averages of 4.64 ± 1.79 tC/ha and 2.89 ± 1.59 tC/ha. But according to advanced decomposition, the habitats of Mayo-Loutii department store more carbon in biomass dead wood or an average of 1.31 ± 0.84 tC/ha. The distribution of deadwood carbon stock in terms of diameter is L-shaped and shows

that the biotopes studied have a lot of small deadwood that stores more carbon. The quantities of teqCO2 in dead wood

habitats issued by Mayo-Rey department were highest (15.64 ± 4.11 teqCO2/ha). In all four departments, dead wood in

the Fields have carbon sequestration (9.99 ± 3.69 tC/ha or 17.96 ± 1.12 teqCO2/ha). These results confirm the important role of savannah ecosystems as a long term store of wells organic carbon in biomass dead wood. These results will help in Developing reliable REDD + Mechanisms in Cameroon. Keyword Deadwood, Carbon stock, Biomass, Savannah ecosystems, Cameroon

Introduction Dead wood has a key role in maintaining balance in forest ecosystems and the preservation of biodiversity as- Dead wood, consists of snags and dead trees on the sociated with it. However, in managed ecosystems, dead ground, is a key structural component of forest ecosys- wood is removed and represents a volume 10 to 20 times tems [1]. Dead wood is an essential element in the balance lower than that observed in the forests without manage- of forest ecosystems, biodiversity and forest production, ment [4], notably for aesthetic reasons, financial, or safety dead wood is better taken into account in forest manage- and health [5]. There is an awareness of the managers who ment [1]. Dead wood is part of the natural forest environ- want to manage their forest “sustainable”. Nevertheless, it ments [2]. Numerous studies have shown its importance is necessary to also take into account the possible negative ecologically. It was thus demonstrated its role in local abi- otic changes but also the survival of forest species that find *Corresponding author: Awe Djongmo Victor, Faculty of Sci- food source and shelter [3]. It thus contains a biodiversi- ence, Department of Biological Sciences, University of Ngaoun- ty that own and which varies according to the essence of dere, PO Box: 454, Ngaoundere, Cameroon the tree, its diameter, the exposure or the form in which it presents: upright shaft, split in two, uprooted or decay- Accepted: October 19, 2019 ing to the ground [2]. A dead but still standing tree will be Published online: October 21, 2019 colonized by both and animal plant species. Some lichens Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon and insects have a preference for strains exposed to strong Stocks in Dead Wood Biomass of Savannah Ecosystems in light and prefer an upright shaft [3]. Northern Region Cameroon. J Bot Res 2(1):60-70

Copyright: © 2019 Victor AD, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and SCHOLARS.ScholaDrlyIRECT Pages reproduction in any medium, provided the original author and source are credited.

Open Access | Page 60 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70 effects of dead wood such as the spread of pests and fire of deadwood for its integration into the soil and carbon se- risks in Southern regions. It is therefore important for a questration. The interest of the present work is to show the manager to consider all points of view to reconcile forest contribution of dead wood to carbon retention of savannah management and biodiversity maintenance. Dead wood, ecosystems in ecosystem management context of the north- consisting mainly snags and dead trees on the ground, is a ern region Cameroon. key structural component of forest ecosystems [1,6]. Dead- wood plays many ecological roles, including biodiversity, in Materials and Methods the productivity of ecosystems and the geomorphology of Study area the media [1,6-8]. The amount of dead wood in an ecosystem results from the balance between tree mortality and The study was conducted in Northern Region Cameroon. decay, smolder or export of wood [6]. Besides the natu- This region is located between latitude 9° 18’ North and ral aging of the trees, their formation is favored by distur- longitude 13° 23’ East [14] (Figure 1). The terrain is a wide bances, such as fire, wind, insect outbreaks, wind throw, pediplain Between the Mandara Mountains (1442 m) in the or logging [1,9,10]. Dead wood is a substantial amount of North and the plateau of the Adamawa to the south. The cli- organic matter in the forest floor soil and an important car- mate is Sudano-sahelian type with two seasons: A dry sea- bon pool in the forest ecosystem [1]. Yet their contribution son of duration of six months (November-May) and a rainy in carbon and nutrient cycles is not well defined [1]. Dead season of duration of six months (June-October) [15]. The wood also plays an important role in the carbon cycle. mean monthly temperature evolving from 26 °C in August to The decomposition of dead wood is influenced by climate 40 °C in March. The soil is ferruginous type characterized by (temperature, humidity, light conditions) [5], soil conditions an acidity (pH = 5.5 to 6), and a low cation exchange capacity (drainage, nutrients), quality bedding (litter type, species, [15,16]. The vegetation is a savannah shrub Sudanian zone size, degree of carbonization) and the nature of the micro- having an aspect of clear savannah and degraded around the organisms (bacteria, fungi) and fauna [5]. Even before the villages [17]. Agriculture is the main activity of the popula- death of the tree [11]. The death of the tree generates snags tions in Northern region. The population practice subsistence or balls on the ground, which rapidly pass through the first farming (corn; peanut and mil) [18]. stages of decomposition [12]. The rate of fall snags increases with decomposition [1,13] and when the stumps fall, they Data collection usually incorporate advanced stages of decomposition. Dead- Dead trees lying on the ground or those still standing, wood progresses in different stages of decomposition to be a set of quantitative data dendrometric (diameter and buried and incorporated into the soil organic matter. Dead height) and qualitative (degree of degradation, the ground wood is generally broken down more slowly [6], due to its position and feet) was collected in the following ecosys- physical structure [1,12] and chemical composition[13] . Dead tems: Arborescent savannah, Shrubby savannah, Thatched, wood could thus promote the retention of soil carbon [5,11]. Woody savannah, Inselberg, Fields, Meadow, Swampy Yet few studies have examined the importance of the quality area, Degraded area in the following states: Benue; Faro;

Figure 1: Location map of the study area.

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 61 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70

Figure 2: Sampling of dead wood by the transect method. Transect of 100 m × 50 m for the inventory of dead wood according to the direction → of the sampling in the strips of 12.50 m × 50 m .

Mayo-Loutii and Mayo-Rey. Sampling was conducted in 100 Carbon stock in dead wood m × 50 m transects using the methodology already used by The calculation of the volume of dead timber was done several authors [17]. The inventory of dead wood is made thanks to the formula used by Mund [19] below: = π* * * from the first band to the last. Inventories of dead wood (Dbh/2) 2 where V: Volume of death timber (m3); Dbh: Di- on the ground and on feet were carried out in the 5000 m2 ameter at breast height of a man (m); H: Height푉 of deathℎ 푓 (100 m × 50 m) transects with non-variable surface area. At timber (m); f = form factor (0.627). Calculating lying dead the beginning of the realization of each transect, a refer- wood volume was made using the formula used by Waren ence point is found for the choice of the azimuth using the and Olsen [20]; in Awe, et al. [18] below: = Π² (Σdi²)/8L compass. From the base stake, the second angle is aimed, with V: Volume of wood debris (m3. ha-1); Di: Diameter of the distance measured at 12.50 m and 50 m thanks to a each wood debris sampled (m); L: length of푉 the quadrant decameter, and the post is fixed. Thanks to the compass, (m) = 100 m in the case of our study. Translating the results the ten stakes will be planted by adding to each value of obtained from the bulk volume was made by setting the the azimuth 90 °C as one turns in the direction of the clock- value of wood density to 0.47 KgMS.m-3 [18,21]. According wise, or by subtracting 90 °C to the value of the azimuth, to the state of decomposition, we obtain: ρ = specific grav- according to the displacement in the trigonometrically di- ity (g/cm3) bonded to the level of decomposition of dead rection. Four 50 m equidistant square stakes are used to wood, ρ = 0.8: little advanced decomposition; ρ = 0.5: mod- unwind a 50-m nylon line, then tied to the 12.50 m stakes erately advanced decomposition; ρ = 0.3: very advanced that form the transect. The 5000 m2 trunk is then subdi- decomposition. The portion of the dry mass of carbon stock vided into 4 sub-quadrats or 12.50 m × 50 m strips in the is made by the following equation: Carbon stock in dead same direction. With seven pieces of 50 m strings and ten wood = Quantity of dry matter (MS) × 0.5 [19,22,23]. In cal- stakes at 12.50 m intervals (Figure 2). Sampling is done in culating the carbon losses dead wood from deforestation, each 625 m2 band to reduce counting errors. In each plot, biomass values obtained after biomass data collection year only dead wood within a sub-quadrat has been measured. were considered and processed in carbon equivalent value Unmarked dead wood from outside the sub-quadrat that by applying equation the following formula: FEBM = BBMˣ fell inside it has not been measured, while unmarked dead FCFCMSBMˣ FCC; with FEBM: Wood emission factor death, wood from the interior of the sub-plot that has not been BBM: Dead wood biomass FCFCMSBM: Conversion factor measured. Fell outside of it was measured. All dead woods of the carbon fraction of solids in the dead wood or FCF- were counted and classified according to their diameter (0 CMSBM = 0.49; FCC: Carbon Conversion factor equivalent CO = 44/12 [24]. to 5 cm, 5 to 10 cm, 10 to 15 cm, 15 to 20 cm, 20 to 25 cm, 2 25 to 30 cm and more than 35 cm). For standing deadwood, Data analysis DBH and height were measured using live tree methods using the decameter. 36 ha of the device, dead trees 120 The data were encoded in the software EXCEL and Then lying on the ground were measured on a total surface of 18 Analyzed using the Statgraphics plus 5.0 software. The signif- ha, and 207 dead trees were inventoried of about 46, 42% icance and correlation tests were examined with an analysis of the total surface. The experimental device is installed of variance (ANOVA) and the Duncan test at 5%. a split-plot constituents the four departments (Benue, Results Faro, Mayo-Loutii and Mayo-Rey) as the main treatment; nine habitats (Arborescent savannah, Shrubby savannah, Carbon stocks in dead wood on the floor and Thatched, Woody savannah, Inselberg, Fields, Meadow, feet biotope studied in four departments Swampy area, Degraded area) selected from each department are considered secondary treatment and 72 plots of Table 1 presents the results to estimation of Carbon 100 m × 50 m as rehearsals. stocks in dead wood of different habitats studied. Between

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 62 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70

Table 1: Carbon stocks in dead wood on the floor and feet biotope studied.

Departments Sites SCBMSP (tC/ha) SCBMC (tC/ha) SCBMT (tC/ha) Benue Arborescent savannah 3.59 ± 0.12d 2.65 ± 0.57b 6.24 ± 1.32e Shrubby savannah 2.68 ± 0.16c 1.46 ± 0.10a 4.14 ± 1.05cd Thatched 1.51 ± 0.11ab 0.14 ± 0.02a 1.65 ± 0.45a Woody savannah 0.52 ± 0.01a 1.52 ± 0.11a 2.04 ± 0.76b Inselberg 2.26 ± 0.13c 4.26 ± 1.03cd 6.52 ± 1.32e

Fields 5.59 ± 1.12e 8.65 ± 2.13f 14.24 ± 3.12k

Meadow 3.68 ± 0.16d 1.46 ± 0.10a 5.14 ± 1.13de

Swampy area 2.51 ± 0.15c 5.14 ± 1.12d 7.65 ± 2.10f

Degraded area 1.52 ± 0.11ab 1.52 ± 0.11a 3.04 ± 0.98c

M ± STDEV 2.65 ± 1.49BC 2.97 ± 2.63AB 5.62 ± 3.82AB Faro Arborescent savannah 0.57 ± 0.01a 1.32 ± 0.10a 1.89 ± 0.98b Shrubby savannah 0.48 ± 0.01a 1.38 ± 0.10a 1.86 ± 0.43b Thatched 0.51 ± 0.01a 1.04 ± 0.10a 1.55 ± 0.54ab Woody savannah 0.52 ± 0.01a 2.18 ± 0.14ab 2.70 ± 1.53bc Inselberg 0.48 ± 0.01a 5.02 ± 1.06d 5.5 ± 2.65de

Fields 0.59 ± 0.01a 6.11 ± 1.54de 6.7 ± 3.01e

Meadow 0.60 ± 0.02a 1.07 ± 0.10a 1.67 ± 0.76ab

Swampy area 0.51 ± 0.01ab 0.14 ± 0.02a 0.65 ± 0.10a

Degraded area 1.52 ± 0.11ab 0.85 ± 0.10a 2.37 ± 1.12bc

M ± STDEV 0.64 ± 0.33A 2.12 ± 2.04A 2.76 ± 1.99A Mayo-Loutii Arborescent savannah 2.02 ± 1.01c 3.64 ± 1.43c 5.66 ± 2.03de Shrubby savannah 3.08 ± 1.12d 1.46 ± 0.16a 4.54 ± 1.86cd Thatched 1.01 ± 0.12a 5.03 ± 1.76d 6.04 ± 2.87e Woody savannah 1.02 ± 0.12a 6.08 ± 1.76de 7.1 ± 3.34f Inselberg 4.11 ± 1.23d 6.03 ± 0.98de 10.14 ± 4.09h

Fields 4.07 ± 1.12d 7.86 ± 2.12ef 11.93 ± 4.87i

Meadow 1.78 ± 0.16ab 5.04 ± 1.43d 6.82 ± 2.76ef

Swampy area 1.34 ± 0.12ab 5.22 ± 1.72d 6.56 ± 2.96e

Degraded area 3.42 ± 1.32c 1.02 ± 0.42a 4.44 ± 2.60cd

M ± STDEV 2.42 ± 1.25B 4.59 ± 2.21AB 7.02 ± 2.49B Mayo-Rey Arborescent savannah 7.50 ± 2.12f 6.04 ± 2.02de 13.54 ± 4.87jk Shrubby savannah 5.98 ± 1.43e 6.86 ± 2.76e 12.84 ± 4.07j Thatched 3.05 ± 1.04c 5.14 ± 1.76d 8.19 ± 3.12 g Woody savannah 3.43 ± 1.43c 8.92 ± 3.65f 12.35 ± 3.64ij Inselberg 3.26 ± 1.32c 7.26 ± 2.45e 10.52 ± 2.32h Fields 1.09 ± 0.54a 6.02 ± 2.12de 7.11 ± 3.93f Meadow 2.83 ± 0.81c 1.66 ± 0.65 a 4.49 ± 1.76cd

Swampy area 3.51 ± 1.65c 0.94 ± 0.11a 4.45 ± 1.23cd

Degraded area 3.76 ± 158c 1.09 ± 0.3a 4.85 ± 2.01d

M ± STDEV 3.82 ± 1.86C 4.88 ± 2.93B 8.70 ± 3.71B

SCBMSP: Carbon Stock in Death Timber (tC/ha); SCBMC: Carbon Stock in Dead Wood Floor (tC/ha); SCBMT: Total Carbon Stocks In Dead Wood (tC/ha); M: Mean; STDEV: Standard Deviation. The valuesassigned the same letter are not statistically different (p > 0.05; Duncan test).

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 63 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70 the different habitats, Carbon stocks in dead timber of the ent study areas. The average carbon stock in dead wood study area varies 0.48 ± 0.01 at 7.50 ± 2.12 tC/ha. Analysis at the highest ground was observed in Mayo-Rey depart- of variance confirms a significant difference (F = 6.12; P = ment and lowest was recorded in Faro department. The 0.0458 < 0.05) carbon stock of death timber between dif- carbon stocks in dead wood floor are much higher than ferent biotopes studied. Carbon stock in dead timber on those of death timber between the study areas. The aver- the higher foot was observed to arborescent savannah in age total carbon stocks in dead wood varies from site to Mayo-Rey and lowest was recorded to shrubby savannah site; and have an average lower in Faro (2.76 ± 1.99 tC/ha) in Faro (Table 1). By cons between areas, Carbon stocks in and higher in Mayo-Rey (8.70 ± 3.71 tC/ha). Between the dead wood of the study area varies 0.64 ± 0.33 at 3.82 ± different habitats, the total carbon stocks in dead wood in 1.86 tC/ha. Analysis of variance does not evidence signifi- the study area varies 0.65 ± 0.10 at 14.24 ± 3.12 tC/ha. The cant difference (F = 0.12; P = 0.7654 > 0.05) carbon stock in average carbon stock in dead wood at the highest ground dead wood between the different study areas. The average was observed in the Fields of Benue (14.24 ± 3.12 tC/ha) Carbon stock in dead wood on the higher foot was observed compared to other biotopes. Analysis of variance does not in the Mayo-Rey department and lowest was recorded in evidence significant difference (F = 0.22; P = 0.9854 > 0.05) Faro department (Table 1). Carbon stocks in dead wood on of the total carbon stock of dead wood between the differ- the ground also varied from one site to another. Between ent zones studied (Table 1). the different habitats, carbon stocks in dead wood on the Carbon stocks in dead wood according to degree ground in study area varies 0.14 ± 0.02 at 8.92 ± 3.65 tC/ ha. Analysis of variance confirms a significant difference (F of degradation in the sites studied = 6.52; P = 0.0498 < 0.05) Carbon stocks in dead wood floor In Benue department, the LAD represents about 47.95% between different biotopes studied. Carbon stock in dead of the total carbon stock in dead wood followed by MAD wood was highest ground observed to woody Savannah in with 35.81% of the total carbon stock deadwood and to the Mayo-Rey and lowest was recorded to Shrubby savannah VAD with 16.24% of the total carbon stock in dead wood in Benue and Swampy area with respectively Faro each (Table 2). By Faro department, the LAD represents about 0.14 ± 0.02 tC/ha (Table 1). By cons between areas, carbon 46.72% of the total carbon stock in dead wood followed by stocks in dead wood on the ground of the study area varies MAD with 36.89% of the total carbon stock in dead wood 2.12 ± 2.04 to 4.88 ± 2.93 tC/ha. Analysis of variance does and to the VAD with 16.39% of the total carbon stock in not evidence significant difference (F = 1.02; P = 0.8654 dead wood. Yet in Mayo-Loutii department where LAD > 0.05) carbon stock in death timber between the differ- represent about 48.08% of the total carbon stock in dead

Table 2: Total Carbon Stocks in dead wood according to the states of decomposition in the studied habitats.

Departments Sites Little advanced Moderately advanced Very advanced Total dead wood decomposition (LAD) decomposition (MAD) decomposition (VAD) carbon (TDWC) Benue Arborescent savannah 4.12 ± 0.28e 2.00 ± 0.19c 0.12 ± 0.02a 6.24 ± 1.32e Shrubby savannah 2.35 ± 0.19c 1.54 ± 0.13b 0.25 ± 0.01a 4.14 ± 1.05cd Thatched 1.05 ± 0.10b 0.45 ± 0.05a 0.15 ± 0.00a 1.65 ± 0.45a Woody savannah 1.04 ± 0.12b 0.76 ± 0.02a 0.24 ± 0.01a 2.04 ± 0.76b Inselberg 3.52 ± 0.24d 2.50 ± 0.17c 0.50 ± 0.02a 6.52 ± 1.32e

Fields 7.84 ± 1.10h 4.24 ± 0.23e 2.16 ± 0.11d 14.24 ± 3.12k

Meadow 3.46 ± 0.22d 1.54 ± 0.13b 0.14 ± 0.00a 5.14 ± 1.13de

Swampy area 4.65 ± 0.27ef 2.35 ± 0.19c 0.65 ± 0.04a 7.65 ± 2.10f Degraded area 2.00 ± 0.18c 1.00 ± 0.11b 0.04 ± 0.00a 3.04 ± 0.98c M ± STDEV 3.33 ± 2.11B 1.82 ± 1.14AB 0.47 ± 0.16AB 5.62 ± 3.82AB Faro Arborescent savannah 1.24 ± 0.11b 0.36 ± 0.07a 0.29 ± 0.01a 1.89 ± 0.98b Shrubby savannah 1.24 ± 0.11b 0.34 ± 0.05a 0.28 ± 0.01a 1.86 ± 0.43b Thatched 1.05 ± 0.10b 0.35 ± 0.05a 0.15 ± 0.00a 1.55 ± 0.54ab Woody savannah 1.64 ± 0.12b 1.02 ± 0.10b 0.04 ± 0.00a 2.70 ± 1.53bc Inselberg 2.85 ± 0.16c 1.85 ± 0.12b 0.80 ± 0.10a 5.5 ± 2.65de

Fields 4.04 ± 1.02e 1.62 ± 0.11b 1.04 ± 0.10ab 6.7 ± 3.01e

Meadow 1.17 ± 0.14b 0.28 ± 0.05a 0.22 ± 0.03a 1.67 ± 0.76ab Swampy area 0.35 ± 0.00a 0.25 ± 0.04a 0.05 ± 0.00a 0.65 ± 0.10a Degraded area 1.14 ± 0.11b 1.01 ± 1.10b 0.22 ± 0.02a 2.37 ± 1.12bc M ± STDEV 1.63 ± 1.11A 0.78 ± 0.61A 0.34 ± 0.34A 2.76 ± 1.99A

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 64 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70

Mayo-Loutii Arborescent savannah 2.24 ± 0.16c 1.88 ± 0.12b 1.54 ± 0.10bc 5.66 ± 2.03de Shrubby savannah 2.36 ± 0.12c 1.64 ± 0.11b 0.54 ± 0.00a 4.54 ± 1.86cd Thatched 2.25 ± 0.16c 1.95 ± 0.13b 1.84 ± 0.11cd 6.04 ± 2.87e Woody savannah 3.04 ± 0.21d 2.04 ± 0.13bc 2.02 ± 0.18d 7.1 ± 3.34f Inselberg 6.52 ± 1.01g 2.50 ± 0.17c 1.12 ± 0.10ab 10.14 ± 4.09h Fields 5.25 ± 0.98f 3.84 ± 0.23d 2.84 ± 0.13e 11.93 ± 4.87i Meadow 3.14 ± 0.23d 2.44 ± 0.10bc 1.24 ± 0.10ab 6.82 ± 2.76ef Swampy area 4.26 ± 0.42e 1.65 ± 0.08b 0.65 ± 0.01a 6.56 ± 2.96e Degraded area 2.24 ± 0.12c 2.12 ± 0.15c 0.08 ± 0.00a 4.44 ± 2.60cd M ± STDEV 3.47 ± 1.54B 2.22 ± 0.67B 1.31 ± 0.84C 7.02 ± 2.49B Mayo-Rey Arborescent savannah 7.24 ± 2.28 5.04 ± 1.10f 1.26 ± 0.11ab 13.54 ± 4.87jk Shrubby savannah 4.26 ± 1.16e 5.04 ± 1.10f 3.54 ± 0.23f 12.84 ± 4.07j Thatched 5.56 ± 1.13f 1.48 ± 0.10b 1.15 ± 0.10ab 8.19 ± 3.12 g Woody savannah 7.04 ± 2.21g 4.05 ± 1.02de 1.26 ± 0.11ab 12.35 ± 3.64ij Inselberg 5.50 ± 1.26f 3.50 ± 0.24d 1.52 ± 0.10bc 10.52 ± 2.32h

Fields 4.01 ± 1.24e 3.00 ± 0.20cd 0.10 ± 0.01a 7.11 ± 3.93f

Meadow 2.87 ± 0.26cd 1.08 ± 0.10b 0.54 ± 0.04a 4.49 ± 1.76cd

Swampy area 2.45 ± 0.21c 1.45 ± 0.11b 0.55 ± 0.04a 4.45 ± 1.23cd

Degraded area 2.85 ± 0.23cd 1.45 ± 0.11b 0.55 ± 004a 4.85 ± 2.01d M ± STDEV 4.64 ± 1.79B 2.89 ± 1.59B 1.16 ± 1.00BC 8.70 ± 3.71B

M: Mean; STDEV: Standard Deviation. The values assigned the same letter are not statistically different (p > 0.05; Duncan test). wood followed by MAD with 35.91% of the total carbon ble 2). But according advanced decomposition, biotopes stock in dead wood and to the VAD with 16.01% of the to- of Mayo-Loutii department store more carbon in dead or- tal carbon stock in dead wood (Table 2). And finally, in the ganic matter (dead wood) an average of 1.31 ± 0.84 tC/ha Mayo-Rey department where LAD represent over 49.51% compared to other biotopes in Faro, Benue and Mayo-Rey of the total carbon stock in dead wood followed by MAD departments respectively 0.34 ± 0.34 tC/ha; 0.47 ± 0.16 tC/ with 36.66% of the total carbon stock in dead wood and ha and 1.16 ± 1.00 tC/ha (Table 2). to the VAD with 13.83% of the total carbon stock in dead wood (Table 2). Overall, there was significant difference Carbon stocks in dead wood by diameter with respect to the average carbon stocks in dead wood As part of this work, carbon stocks in dead organic mat- according to little advanced decomposed (F = 8.38; P = ter (dead wood) by diameter classes of amplitude equal 0.0417 < 0.05), the moderately advanced decomposition (F to 05 cm have been prepared (Figure 3). The distribution = 11.39; P = 0.0342 < 0.05), very advanced decomposition of the carbon stock in dead organic matter (dead wood) (F = 7.25; P = 0.0492 < 0.05) between the biotopes within depending on the diameter of the different habitats in the four departments (Table 2). Generally, between savannah four departments shows that the carbon stock in dead or- ecosystems, there is significant difference with regard to ganic matter (dead wood) by diameter classes decreases carbon stocks of dead wood according to little advanced with increasing diameter. However, carbon stock in dead decomposed (F = 4.86; P = 0.0067 < 0.05), moderately ad- wood of different habitats highest belong to the class of vanced decomposition (F = 6.00; P = 0.0023 < 0.05), very diameter < 5 cm. The analysis of this figure shows that all advanced decomposition (F = 3.75; P = 0.0204 < 0.05) be- distributions of habitats sampled in the four departments tween the four departments (Table 1). according to the little decomposed, biotopes of Mayo-Rey department store have increasing exponential shape (L) with high slope more carbon stock in dead organic matter (dead wood) an equation: y = 0.70 e-5.287x (For biotopes Benue) (Figure average of 4.64 ± 1.79 tC/ha compared to other biotopes 3A); y = 5.155e-070x (for biotopes Faro) (Figure 3B); y = in Faro, Benue and Mayo-Loutii departments respectively 6.503e-0.67x (for biotopes Mayo-Loutii) (Figure 4C); y = 1.63 ± 1.11 tC/ha ; 3.33 ± 2.11 tC/ha and 3.47 ± 1.54 tC/ha 7.08e-0.76x (for biotopes Mayo-Rey) (Figure 3D). These 2 (Table 2). For against, according advanced decomposition four distributions have determinations coefficients (R ) average, biotopes of Mayo-Rey department store more ranging from 0.927-0.981; centered on the class diameter carbon in dead organic matter (dead wood) an average < 5 cm. Analysis of variance confirms that there is a high- of 2.89 ± 1.59 tC/ha compared to other biotopes in Faro, ly significant difference (p = 0.0000 < 0.05) at the carbon Benue and Mayo-Loutii departments respectively 1.63 ± stock in dead organic matter (dead wood) by diameter 1.11 tC/ha ; 3.33 ± 2.11 tC/ha and 2.22 ± 0.67 tC/ha (Ta- classes in the four distributions (Figure 3).

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 65 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70

Figure 3: Carbon stocks in dead wood by diameter class distribution.

Table 3: Pearson correlation matrix between carbon stocks in dead wood on feet on the ground and total carbon stocks according to the decomposition of dead wood (LAD: Little Advanced Decomposition; MAD: Moderately Advanced Decomposition; VAD: VeryAdvanced Decomposition).

Pearson Correlation variables LAD (tC/ha) MAD (tC/ha) VAD (tC/ha) Min Max Mean (CV) SCBMSP (tC/ha) 0.51* 0.59* 0.24ns 0.48 7.5 2.38 (72.28%) SCBMC (tC/ha) 0.71**** 0.68** 0.56* 0.14 8.92 3.64 (72.25%) SCBMT (tC/ha) 0.88*** 0.90**** 0.59* 0.65 14.24 6.03 (61.35%)

SCBMSP: Carbon Stock of Death Timber (tC/ha); SCBMC: Carbon Stock Dead Wood Floor (tC/ha); SCBMT: Total carbon stocks of dead wood (tC/ha). Min: Minimum; Max: Maximum. CV: Coefficient of variation. The coefficients p < 0.05 were significantly correlated;* : P ≤ 0.05; **p ≤ 0.01; ***p < 0.001 (Pearson test); ns = not significant (p > 0.05).

Relationship enter here title advanced decompo- MAD and SCBMSP (R2 = 0.51; p ≤ 0.05) is also quite strong sition (LAD); moderately advanced decomposi- and significant. The correlation between MAD and SCBMC follows the same trend (R2 = 0.68; p ≤ 0.01). But a very tion (MAD); very advanced decomposition (VAD) strong and significant correlation was observed between and SCBMSP; SCBMC; SCBMT the MAD and SCBMT (R2 = 0.90; p < 0.0001). The results The minimum and maximum values SCBMSP, SCBMC, in Table 3 show that there is not significant and positive 2 SCBMT and are respectively 0.48 to 7.50 tC/ha; 0.14 to correlation between VAD and SCBMSP (R = 0.24; p > 0.05); 8.92 tC/ha and from 0.65 to 14.24 tC/ha with 72.28% of and an average correlation between strong and positive 2 2 variation coefficients respectively; 72.25% and 61.35% (Ta- VAD and SCBMC (R = 0.56; p ≤ 0.05); SCBMT (R = 0.59; p ble 3). Among all the variables measured, the coefficient ≤ 0.05) (Table 3). of variation of the SCBMT (61.35%) is the lowest compared The principal component analysis (PCA) is based on two to the other two. The correlation is quite strong and sig- axes (F1 = 86.24%) and (F2 = 13.09%). The axis (F1 and F2) nificant between LAD and SCBMSP (R2 = 0.51; p ≤ 0.05). By allows a better distribution of the carbon stock in dead wood against a strong and highly significant correlation was ob- habitats (Figure 4A) and in the four departments (Figure 4B). served between the LAD and SCBMC (R2 = 0.71; p < 0.0001); The four departments have a positive and highly significant SCBMT (R2 = 0.88; p < 0.0001). The correlation between correlation (p ≤ 0.001) (Figure 4B). And also the habitats have

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 66 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70

Figure 4: Correlation between (A) and four departments (B) according to the total carbon stocks in dead wood. noted a positive and highly significant correlation (p ≤ 0.001) Analysis of variance does not evidence significant difference (Figure 4A). This summarizes one very significant distinction in carbon stock in dead wood (F = 1.28; P = 0.2943 > 0.05) and between the dead wood habitats and between departments. emission factor of dead wood (F = 1.22; P = 0.2704 > 0.05) It is noted that the axis F1 allows a better distribution of the between different biotopes studied (Table 4). carbon stock in dead wood between departments. Mayo- Table 5 shows that the amount of dead wood teqCO Mayo-Rey Loutii and have a low correlation and negative (Fig- 2 ure 4B). These two departments have carbon stocks in dead emission, found in habitats of Mayo-Rey department (15.64 ± wood very close. 4.11 teqCO2/ha) are higher than those emission by biotopes Mayo-Loutii department (12.62 ± 3.01teqCO2/ha), The Benue

Emission factors for dead wood habitats and ar- (10.10 ± 4.12 teqCO2/ha) and Faro (4.96 ± 2.766 teqCO2/ha). eas (departments) Analysis of variance does not evidence significant difference (F = 0.92; P = 0.9754 > 0.05) emission factor of deadwood In all four departments, the dead wood in the Fields have between different areas studied (Table 5). more carbon sequestration (9.99 ± 3.69 tC/ha or 17.96 ±

1.12 teqCO2/ha). They are the following inselberg with 8.17 Discussion ± 2.53 tC/ha or 14.69 ± 0.13 teqCO /ha of arborescent savan- 2 The carbon stocks in dead wood on the foot of the nah (6.83 ± 4.86 tC/ha or 12.28 ± 0.12 teqCO2/ha), Woody study area vary 0.48 ± 0.01 at 7.50 ± 2.12 tC/ha. These re- savannah (6.04 ± 4.76 tC/ha or 10.86 ± 0.01 teqCO2/ha), sults are not close to 9.45 ± 6.6 tC/ha obtained by Bocko, Shrubby savannah (5.84 ± 4.81 tC/ha or 10.50 ± 0.16 teqCO2/ et al. [25] in a forest swamp of Likouala (Northern Congo). ha), Swampy area (4.82 ± 3.08 tC/ha or 8.66 ± 0.15 teqCO2/ And also those of Vogt [26] and Gough, et al. [27] in tem- ha), Meadow (4.53 ± 4.53 tC/ha or 8.14 ± 0.16 teqCO2/ha),

Thatched (4.35 ± 3.30 tC/ha or 7.82 ± 0.11 teqCO2/ha) and perate forest area where they respectively obtained 1.1

Degraded area (3.67 ± 1.16 tC/ha or 6.59 ± 0.11 teqCO2/ha). tC/ha and each of the values 0.32 ± 0.21 tC/ha and 2.35 ±

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 67 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70

Table 4: Dead wood emission factors by habitats. point out that carbon stocks in dead wood vary between sites and study methods. The requirements for sampling of Sites SCBMT (tC/ha) FEBM (teqCO2/ha) dead wood on the ground can also justify the low carbon Arborescent savannah 6.83 ± 4.86ab 12.28 ± 0.12ab stock obtained in this study in comparison with the val- Shrubby savannah 5.84 ± 4.81ab 10.50 ± 0.16ab ues found in the literature. Indeed, the sampling method Thatched 4.35 ± 3.30ab 7.82 ± 0.11ab requires that the length of the line is set to at least 100 m [25]. And a piece of dead wood should be measured Woody savannah 6.04 ± 4.76ab 10.86 ± 0.01ab if and only if: More than 50% of dead wood is above the Inselberg 8.17 ± 2.53ab 14.69 ± 0.13ab ground and the sampling line crossing at least 50% of the Fields 9.99 ± 3.69b 17.96 ± 1.12b diameter the piece of fallen dead wood [25,35]. Thus, any Meadow 4.53 ± 4.53ab 8.14 ± 0.16ab dead wood did not permit the inclusion of these conditions of measurement was not sampled. In this study we Swampy area 4.82 ± 3.08ab 8.66 ± 0.15ab used a transect line 100 m only study site, which was not Degraded area 3.67 ± 1.16a 6.59 ± 0.11a the case in other studies in tropical areas [18,21,29,31,34] Total 54.24 ± 2.03 97.5 ± 3.65 used 100 m transect lines, 400 m, 160 m and 800 m per study plot, respectively in northern Cameroon, southern The values assigned the same letter are not statistically different (p Peru, Congo and Gabon. Their results help emphasize that > 0.05; Duncan test). stocks of dead wood carbon therefore also increase with Table 5: Dead wood emission factors by zones. the length of the study transect line. The structures obtained show that the studied habitats have many small

Areas SCBMT (tC/ha) FEBM (teqCO2/ha) dead wood to maintain the balance in the forest ecosys- Benue 5.62 ± 3.82ab 10.10 ± 4.12ab tem, the first level is the intelligence of sustainable management indicators of savanna ecosystems studied. This is Faro 2.76 ± 1.99a 4.96 ± 2.766a the main characteristic of savanna ecosystems supposed Mayo-Loutii 7.02 ± 2.49b 12.62 ± 3.01b to be in balance, with lots of little dead wood and few large Mayo-Rey 8.70 ± 3.71b 15.64 ± 4.11b dead woods. These structures that form the carbon reservoir in living biomass directly supply the carbon reservoir The values assigned the same letter are not statistically different (p dead wood. According to the decomposition and mean lit- > 0.05; Duncan test). tle advanced, the habitats of Mayo-Rey department store 0.31 tC/ha obtained by Saidou, et al. [28] in the shea but- more carbon in dead wood biomass with general average ter and the locust tree. The differences in carbon stocks in of 4.64 ± 1.79 tC/ha and 2.89 ± 1.59 tC/ha. According to dead wood could explain rated by Baker, et al. [29] who Kurz, et al. [36] the decomposition of dead wood results point out that carbon stocks in dead wood vary between in the emission of a large fraction of the carbon it contains into the atmosphere while the rest is transferred to the sites and study methods. Carbon stock of dead wood on carbon pools of organic and mineral soils. Therefore, the the higher foot was observed in to arborescent savannah reservoir of dead wood is a step of binding transition in in Mayo-Rey and lowest was recorded to shrubby savan- the carbon cycle. Gradually, as they decay, the characteris- nah in Faro. Carbon dead wood stock at the highest ground tics of woody debris evolve. Eventually, they end up being was observed to woody Savannah in Mayo-Rey and lowest incorporated to the stable fraction of soil organic matter was recorded to Shrubby savannah in Benue. The total car- as it helps to retain soil moisture, directly through its own bon stocks in dead wood in the study area varies 0.65 ± ability to absorb water, and indirectly through its role in 0.10 at 14.24 ± 3.12 tC/ha. Reviews this was due to the fact development and maintenance of the soil structure. The that farmer’s harvested firewood is dead trees or stumps importance of organic matter to the soil water retention to Shrubby savannah in Benue. The average total carbon increases gradually as the sand content increases. The soil stocks in dead wood are higher in habitats of Mayo-Rey organic matter also contributes significantly to the nutri- department (8.70 ± 3.71 tC/ha) and total carbon stock in ent retention. But according to advanced decomposition, dead wood highest was observed to Fields in Benue de- the habitats of Mayo-Loutii department store more carbon partment (14.24 ± 3.12 tC/ha). The average carbon stocks in biomass dead wood or an average of 1.31 ± 0.84 tC/ in dead wood are very contrasting in tropical areas and ha. This is justified by Duval & Grigal [37] carbon reservoir are higher than those found by Vogt [26] and Gough, et al. dead wood changes with the ecosystem of development. [27] in temperate forest zone (1.1 tC/ha). The estimated During the establishment phase of the new settlement, all average carbon stock in dead wood is higher than those these dead wood from an ancient settlement and presence found by some authors in the tropics [6,12,13,25,29-34]. allows to decrease the reduction of total reservoir atoms This allows to mention as many authors as carbon stock in of a crop due to the ecosystem. At this stage, the com- dead wood varies between forest types and between study petition and mortality are negligible and changes in dead sites [18,32] and that it is not neglected in the overall es- wood carbon pool come mainly from decomposition. The timation of forest carbon. In addition to the factors cited accumulation of new dead wood begins at the stage of above, other facts could explain the differences in carbon self-thinning mortality with a high number of stems which stocks of dead wood recorded by Baker, et al. [29] who however are small. Therefore, this addition of small diam-

Victor et al. J Bot Res 2019, 2(1):60-70 Open Access | Page 68 | Citation: Victor AD, Valery NN, Louis Z, et al. (2019) Carbon Stocks in Dead Wood Biomass of Savannah Ecosystems in Northern Region Cameroon. J Bot Res 2(1):60-70 eter rods has little impact on the carbon reservoir dead carbon sink market carbon credits through small projects wood. Subsequently, mortality decreases, but the affect- of the Clean Development Mechanism. ed trees are stronger dimensions [37]. They break down more slowly than small rods, increasing the carbon resi- Acknowledgments dence time stored in this dead wood category [36]. As We thank all the Referred whose contributions have the population ages, the carbon reservoir of dead wood been very significant for the improvement of this manu- approach of a hypothetical equilibrium between mortal- script. ity and decay [36]. 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DOI: 10.36959/771/562

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