Fossil carbon emissions and energy use in harvesting and manufacture increased when the rotation length was shortened and pulpwood harvests increased, especially in the spruce chain. We concluded that longer rotation length at the sites of both tree species would be favourable to carbon sequestration.
The costs of this would be decreased timber harvests and decreased revenues of landowners. Our results demonstrate the importance of accounting for the whole wood-production and wood-use chain, including fossil carbon emissions, when analysing the effects of rotation length on forest carbon sequestration.
AB - Regulating the rotation length of tree stands is an effective way to manage the carbon budget of forests. Overview Fingerprint. Abstract Regulating the rotation length of tree stands is an effective way to manage the carbon budget of forests.
Access to Document Fingerprint Dive into the research topics of 'Which rotation lenght is favourable to carbon sequestration? Together they form a unique fingerprint. The volume calculations were based on diameter and height parameters [27]. The reason for comparing with the [26] is the ground truths taken from plantation, while the growth and yield tables were not considered as they are often made in fully stocked stands and the plantations are established on some fixed spacing.
Biomass regression equations were employed in our calculations for estimating the biomass of the tree components branches, foliage and stems. When the stem biomass were estimated using basic wood density of the rubber, the result closely resembles the estimates of [26] models, so in the present study their models for estimation of biomass of branches, foliage and roots were observed. Mean temperature and rainfall for the region is required for computation of potential evapotranspiration for the region, important in determining rates of decline.
The size of non-woody litter, finer and coarse litter pools is determined by inputs from diverse sources of litter, minus the fractionation rate per pool. The proportion allocated to soluble compounds, holocellulose, and lignin-like compounds is in turn determined by fractionation rates and litter quality classes [22]. The baseline situation for simulation in the current study is shown in Table 2.
To demonstrate the mechanism that determines the effect of rotation length on the C stocks, five different rotations 25, 30, 35, 40 and 45 years in rubber plantation were considered. This is because the time of production increased with the increasing rotation length.
The total C stocks differed significantly across all the rotation lengths with the highest Likewise, at the end of the other rotations 30,35, 40 and 45 years the contributions in percentage of above ground biomass were Likewise, the percentage contribution from below ground biomass also varied significantly with the changing rotation length.
The study revealed that percentage contribution of the below ground biomass in total C stocks at short rotations 25, 30 and 35 years remained non significant, but it becomes significantly varied at longer rotations of 40 and 45 years Similarly, the contribution of above ground biomass was higher than below ground biomass at shorter rotation lengths as compared to longer rotation lengths.
The study revealed that the C stocks of entire ecosystem increased with longer the rotation length Fig. The 40 years rotation length showed the maximum rate of C input 2.
So 40 years rotation is best for rubber grown in Xishuangbanna SW China in the context of the maximum C sink. The study also determined the C stocks dynamics in four consecutive cycles of different rotation by running simulations. The simulation results showed that at the end of four consecutive rotations of 25 years i-e years, these stocks changed to Similarly the other rotation length also increased the stock with the significantly different growth rate Fig.
The data received from the institute of land planning and environmental protection, farm management committee, Jinghong, Xishuangbanna revealed that based on the rubber production data from 8—43 years old plantation, the production of rubber is increased with the increase in years Table 3.
The regression analysis showed a polynomial Fig. Using this regression model, production in 25, 30, 35, 40 and 45 years was determined. Reliability of the results of this study depends on, first how realistically CO 2 FIX model describes C cycling in forest and plantations and, second, the parameter values used. We evaluated the overall reliability of our results by comparing them to various studies carried out on carbon budgeting of the rubber plantations not only in Xishuangbanna but in other parts of the world Table 4.
The estimates of the soil carbon were found to be comparable to the literature reviewed. An average of Moreover, C stocks of The soil carbon stocks at a depth of 1 m in rubber plantation of Xishuangbanna are In rubber plantation of Brazil for the depth of 0—50 cm, the average soil carbon is documented as The total C stocks at the end of the simulation period were higher than those at the end of first rotation due to accumulation of biomass and soil carbon with time.
Determinants of C stocks include plantation age, the rate of volume, increment and wood density [33] , [34]. Rubber plantations had highest CAI and wood density, thus the results are consistent with the findings of the authors who reported higher C stocks in stands with higher rates of diameter increments and wood densities [35] , [36]. In the present study C stocks and simulations were carried out at 25, 30, 35, 40 and 45years in order to find the most efficient rotation for rubber in light of Article 3.
In comparison, the biomass carbon reserves in the rubber plantation ecosystem of Xishuangbanna at the age of 3, 7, 9, 21, 27, 34 years were 2. With the development of the rubber tree, the average rate of C accumulation was reported as 2. Fastest C accumulation rate 3. From 9 to 27 years, the accumulation rate of rubber forest biomass carbon decreased, but, the accumulation rate of 27—34 years old rubber plantation is slightly higher than 21—27 years old plantation, but still below the average 3—34 year old 1.
At the age of seven year rubber, modelling of the tree biomass carbon accumulation [38] reported less value. The four consecutive cycle regime allows for higher carbon stocks in all rotation ages because the shunt gap ensures that the replanted section reaches productive maturity before the next section is cut, and there is relatively less material available for fuel wood, decomposition and consequent emission of CO 2 per unit time [33].
This growth in C stocks with rotation length is consistent with findings by [30] , [39] and [40] by using the same simulation model. Through litter fall during the growth phase and higher inputs when the plantations are cut at the end of each rotation, soil C increases with time [41].
Such soil sequestration from biomass inputs is determined by the proportion of non-woody, fine and coarse litter fractions as well as rates of oxidation, decomposition and leaching. When C-rich biomass inputs are high and decompose slowly, the rates of leaching and oxidation are low, resulting in higher sequestration potential [42]. The rate of C input at the age of 45 gradually decreased due to gradual decrease in CAI of tree biomass.
The increment in the tree biomass gradually increased from 25 to 40 years and then started declining, which affected the C inputs per year later on. So 40 years rotation age has been advocated as a larger carbon sink for rubber plantation from this study in light of Article 3.
Moreover, the economics of the rubber plantation pointed out that by enhancing the rotation would lead to more production as well as income from sales. The increase in rubber production with increasing age by planting certain clones has also been reported by [43]. The investigation of the economics income of the rubber production and the ecology C stocking pointed out that an increase in both income and C stocks can be achieved by changing the rotation of rubber under the light of Article 3.
These species may include Coffea arabica, Theobroma cacao, Myristica yunnanensis, Bennettiodendron leprosipes, Gmelina arborea, Mesua ferrea, Erythrophleum fordii, Podocarpus fleuryi, Shorea chinensis, Dipterocarpus tubinatus. Moreover, comprehensive models that can pay attention to the variables which creates effects of high magnitudes of outputs should be develop with the incorporation of economics as well as ecological inputs and outputs. Future studies using these models should be conducted to serve as a guide to mitigate the risk to ecology on existing plantations and how the future expansions could incorporate the lessons learnt with the existing plantations.
The loss of biodiversity and soil fertility should also be considered. We are thankful to Prof. Special gratitude for Mr. Yan-Mei Zhang and Dai-Qiang Xiao, Institute of land planning and environmental protection, Farm management committee, Jinghong, Xishuangbanna for helping in data collection and providing information about management of rubber plantation.
Browse Subject Areas? Click through the PLOS taxonomy to find articles in your field. Abstract Extension of the rotation length in forest management has been highlighted in Article 3. Introduction Forest plantations have been considered to measure carbon sequestered from the atmosphere and mitigate future climate change [1].
Carbon stored in living biomass Biomass module considered C stocks per unit area of the biomass, as affected by the growth of the stem including bark , foliage, branches, roots, and the mortality of the vegetations and logging. Model parameters Area characteristics. Download: PPT. Biomass module. Soil module. Results C stocks of the ecosystem To demonstrate the mechanism that determines the effect of rotation length on the C stocks, five different rotations 25, 30, 35, 40 and 45 years in rubber plantation were considered.
Figure 1. Rate of C input in above and below ground biomass The study revealed that the C stocks of entire ecosystem increased with longer the rotation length Fig. Figure 2. Simulations of C stocks for four consecutive cycles in extended rotations The study also determined the C stocks dynamics in four consecutive cycles of different rotation by running simulations. Figure 3. Simulation of C stocks Total C stocks, above and below ground C stocks for consecutive four cycles at different rotation lengths in Rubber Plantation.
Economics and ecology of the rubber plantation The data received from the institute of land planning and environmental protection, farm management committee, Jinghong, Xishuangbanna revealed that based on the rubber production data from 8—43 years old plantation, the production of rubber is increased with the increase in years Table 3.
Figure 4. Figure 5. Table 3. Discussion Reliability of the results Reliability of the results of this study depends on, first how realistically CO 2 FIX model describes C cycling in forest and plantations and, second, the parameter values used.
Table 4. Comparison of biomass, aboveground and soil C stocks in different studies of rubber plantations. Effect of Rotation Length on Carbon Stocks at different age The total C stocks at the end of the simulation period were higher than those at the end of first rotation due to accumulation of biomass and soil carbon with time. Conclusion The investigation of the economics income of the rubber production and the ecology C stocking pointed out that an increase in both income and C stocks can be achieved by changing the rotation of rubber under the light of Article 3.
Acknowledgments We are thankful to Prof. References 1. View Article Google Scholar 2. View Article Google Scholar 3.
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