Specimens of the forest species such as
Pentaclethra macrophylla,
Petersianthus macrocarpus,
Pycnanthus angolensis and
Terminalia superba have been sampled from LUKI Biosphere reserve in the
Democratic Republic of the Congo in order to determine their wood density with the perspective to decarbonisation. These parameters have been found out experimentally utilizing a drying technique in an oven including techniques of immersion in an Erlenmeyer full of water. The corresponding results indicated that the four species wood density is respectively 0.85, 0.80, 0.77 and 0.51. These preliminary results will be useful in our ongoing project on carbon dioxide absorption capacity of Congo rainforest tree species.
This work is the preliminary study of the ongoing project on carbon dioxide absorption capacity of some Congo rainforest tree species. In this regard, the essential objective is to discover the wood density of Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba to select the best species for decarbonisation. It is important to mention that all these species are characteristic of the Congo rainforest, which plays a key role in preventing excessive accumulation of carbon dioxide in the atmosphere. [1] [2] [3] A such accumulation is a root of the degradation of ozone layer (Scheme 1). [4] Consequently, this kind of decomposition of the ozone layer essentially leads to global warming and unexpected climate modifications, which disturb the welfare of living organisms. [4]
It is interesting to remember that the potential to transform carbon dioxide to generate corresponding products could be proportional to the wood density of a plant species (Scheme 2). [5] In other words, the volume of water in plant tissues could explain the aptitude of plants to convert carbon dioxide, for example, during the photosynthesis process (Scheme 2). [5]
Wood density of the studied Congolese rainforest trees in the perspective of decarbonisation has not been reported. In this regard, investigations on Congo Basin Forest have been reported in the literature, but they have no connection with the forest species as well as the objectives of this current research. [6] [7] Indeed, wood density has been disclosed in the literature in the context different from that of our research.
2. Experimental Procedures2.1. Plant Taxonomy
We started this study by identifying and classify the four plant samples (Table 1). [8] - [17] We also described each sample before determining the density. [8] - [17]
2.1.1. Pentaclethra macrophylla
Pentaclethra macrophylla is a tree of at least 21 m in height with more or less extensive domed crown. [8] - [17] This tree is dense partially sinuous reaching 40 cm in diameter. This species is greyish, red orange when it is cut and it is little thick. It has young twigs puberulent, and leaves with linear stipules. [8] - [17] According to the experimental observations reported in the scientific literature, this species is a useful pharmacological plant. [8] - [17] Nucleophilic organic compounds, such as flavonoids and alkaloids, have been also detected in this plant. [18]
Classification of plant samples
Pentaclethra macrophylla
Petersiqnthus macrocarpus
Pycnanthus angolensis
Terminalia superba
Kingdom
Plantae
Plantae
Plantae
Plantae
Subkingdom
Angiosperms
Angiosperms
Angiosperms
Tracheobionta
Division
Dicotyledons
Dicotyledons
Dicotyledons
Magnoliophyta
Class
Rosids
Rosids
Rosids
Magnoliopsida
Subclass
Fabids
Asterids
Magnoliids
Rosids
Order
Fabales
Euricales
Magnoliales
Myrtales
Family
Fabaceae
Lecythidaceae
Myristicaceae
Combretaceae
Genus
Pentaclethra
Petersianthus
Pycnanthus
Terminalia
Species
macrophylla Benth
Macrocarpus (p. Beav) Liben
Angolensis (Welw) Warb
Superba (Eugl and Diels)
2.1.2. Petersianthus macrocarpus
Petersianthus macrocarpus is a large, leafy deciduous tree reaching 45 m high and 60 cm in diameter. [19] [20] [21] This species has a deeply fissured rhytidome longitudinally as well as very fibrous bark including unpleasant smell, and yellowish white sapwood. It has a reddish wood quite hard and a spherical crown, spiral leaves grouped at the end of branches along with a petiole of about 17 mm long. [19] [20] [21] It has been reported that the stem back of Petersianthus macrocarpus is used traditionally as medicine to ease pain, and fever connected with malaria. [19] [20] [21] Phenolic organic compounds have been reported due to the phytochemical analysis of this species. [19] [20] [21]
2.1.3. Pycnahthus angolensis
It is monoecious or dioecious flowering plant. Branches are gathered at the top and more or less perpendicular to the trunk. [22] [23] [24] [25] [26] It has hairy twigs and grayish brown bark and few leaves. [22] [23] [24] [25] [26] This species is useful in African medicine as well as in Asian medicine due to its therapeutic properties, and in this perspective this plant should be protected because it could disappear as a consequence of uncomfortable human activities. [22] [23] [24] [25] [26]
2.1.4. Terminalia superba
It is a plant of around 30 m in height and 1.10 m in diameter, provided with winged buttresses up to 5 m in height. [22] [23] [24] [25] [26] This plant has a broadly spreading domed crown, young twigs with golden russet hairs. It has leaves with petiole from 3.5 to 5 long possessing a pair of marginal glandes into its upper half, pubescent when young, cuneate at the base, short and obtusely acuminate at apex throughout 9 cm long and wide. [22] [23] [24] [25] [26]
3. Sampling
Samples for the four studied species were collected from the Congo rainforest by a team of environmentalists accompanied by native people. Three samples for each species have been utilized in this experimental study.
4. Density Determination
Wood density of the studied forest species was calculated by determining the mass and volume of each species. Indeed, samples wrapped in aluminium foil were placed into an oven set at 105 degrees Celsius, and regularly weighed using an analytical balance (brand KERN 440-35N) until a constant weight was obtained (Tables 2-4). Regarding the volume, each species was placed in a container filled with water and the overflowing water was collected into a graduated cylinder to determine the corresponding volume (Table 5). This experiment was repeated three times for each forest species, and the mass to volume ratio gave us the expected wood density (Table 6).
5. Results and Discussion
In the course of our ongoing decarbonisation research, we report herein our preliminary results regarding the determination of wood density four Congolese rainforest species. In this perspective, each plant species was divided into three samples and each sample was heated into an over to remove its quantity of water. During dehydration, we noticed that the samples weights decreased as heating time increased, and the constant weights were reached from the 96th hour (Tables 2-4, Table 7). In this regard, the forest species, which have a significant density, are very good for decarbonisation (Scheme 2).
Terminalia superba
Initial weight (g)
Sample 1 249
Sample 2 331
Sample 3 354
Average weight 311
Time (h)
133
24 48 72 96 120 144
105 102 99 99 98 98
153 149 145 144 144 144
164 161 159 157 157 157
Pentaclethra macrophylla
Initial weight (g)
Sample 1 220
Sample 2 380
Sample 3 405
Average weight 335
Time (h)
142
24 48 72 96 120 144
96 95 93 92 92 92
164 163 162 160 160 160
179 175 174 174 174 174
Pycnanthus angolensis
Initial weight (g)
Sample 1 252
Sample 2 462
Sample 3 474
Average weight 396
Time (h)
180
24 48 72 96 120 144
111 110 110 109 109 109
216 213 213 212 212 212
223 222 220 220 220 220
Wood volume
Forest species
Sample 1
Sample 2
Sample 3
Total (ml)
Average (ml)
T. superba P. macrophylla P. angolensis P. macrocarpus
294 200 271 280
280 192 267 268
213 105 160 150
787 497 698 698
262 166 234 233
Wood density
Forest species
Average weight
Average volume
Density
T. superba P. macrophylla P. angolensis P. macrocarpus
133 142 180 186
262 166 234 233
0.51 0.85 0.77 0.80
Petersianthus macrocarpus
Initial weight (g)
Sample 1 207
Sample 2 437
Sample 3 445
Average weight 363
Time (h)
186
24 48 72 96 120 144
97 94 92 92 92 92
233 229 228 227 227 227
245 243 241 240 240 240
6. Conclusion
We have obtained encouraging preliminary results to pursue our project upon decarbonisation. This project aims to constitute a Congo rainforest plant best species library capable of absorbing a sufficient amount of carbon dioxide. These categories of plants will be adequately preserved and when deforestation occurs, a proper reforestation programme is essential in order to maintain the Congolese rainforest green because this particular forest is fundamental to minimise the carbon dioxide repercussions upon the ozone layer (Scheme 1).
Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this paper.
Cite this paper
Mwene-Mbeja, T.M., Jeannette, L.M., Katanku, B.K., Junior, K.K., N’senda, B.K.K., Gaby, K.K., Jean-Claude, L.I., Dénis, L.O. and Alain, M.M. (2023) Wood Density Determination with the Perspective to Decarbonisation of Tropical Forest Species from the Luki Biosphere Reserve in the Democratic Republic of the Congo. Green and Sustainable Chemistry, 13, 162-169. https://doi.org/10.4236/gsc.2023.132009
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