Browsing by Subject "metsäplantaasit"
Now showing items 1-2 of 2
-
(2014)The most extensive dry forest and woodland formation in sub-Saharan Africa, including Mozambique, is formed by miombo woodlands. Because of their wide distribution, the miombo woodlands carry significance in global carbon cycle. Previous studies have indicated that while the miombo aboveground carbon stocks appear modest in comparison with tropical rainforests, they have a potential to retain high stocks of soil organic carbon. The miombo landscape is nowadays characterized by widespread deforestation and forest degradation, with woodlands being replaced by anthropogenic land uses such as small-scale agriculture and charcoal harvesting. A new land use type spreading in northern Mozambique is formed by industrial forest plantations. The emerging plantations further change the landscape in transition, allegedly affecting the carbon stocks in the process as well. The purpose of this study was to quantify carbon stocks on locally relevant land use classes in Niassa province, northern Mozambique, and evaluate the change of carbon stocks caused by forest plantations. Six major land use classes were identified: dense miombo, open miombo, other woody vegetation, fallow land, eucalypt plantations and pine plantations. A sample plot grid was laid on chosen areas representing each of the classes. Vegetation aboveground carbon stocks (trees, shrubs and herbaceous vegetation) were recorded in the inventory and topsoil (30 cm) was sampled for soil organic carbon content, to be determined in laboratory. Vegetation belowground carbon stocks were calculated based on existing root to shoot ratios. Since plantations were generally juvenile on the study area, their average yield during rotation period was estimated based on growth models to provide comparable results. Forest plantations were found to have carbon stocks of the same order of magnitude as the two miombo land use classes. Open and dense miombo carried mean vegetation aboveground carbon stocks of 27.47 ± 5.77 and 37.65 ± 7.20 Mg ha-1 respectively, and mean total carbon stocks of 67.81 ± 17.09 and 86.81 ± 18.91 Mg ha-1 respectively, which was consistent with pre-existing results. Pine plantations placed in between with a partially modelled total aboveground mean carbon stock of 34.59 Mg ha-1, whereas the corresponding figure for eucalypt plantations was 21.04 Mg ha-1. Dense miombo had the highest mean total carbon stock of all the land use classes, and fallow land the smallest with 42.59 Mg ha-1. Soil organic carbon did not demonstrate statistically significant differences between any of the land use classes. The result was unexpected, and may be explained either by (i) limited time frame since the land use conversions or (ii) soil mineralogical properties buffering carbon stock changes.
-
(2014)Purpose of this thesis is to estimate the carbon sequestration potential in eucalyptus plantations in Uruguay. This study also aims to show how beneficial these plantations are for carbon sinks. The aim of this research is calculate total carbon balance in eucalyptus plantations and compare the results to degraded lands. This study is first-of-its-kind study in Uruguay, but not unique globally. The objective was to use a modeling approach to formulate the results. The methodology of this study is based to the dynamic growth model (CO2fix V3.1). Model is developed to calculate and estimate forest carbon fluxes and stocks. In this study the model was utilized for estimating how much carbon is sequestered in eucalyptus plantations and soils. In this thesis the model was used to simulate eucalyptus forest plantations that stem from numerous studies and different data. Ad hoc Excel model was generated to form calculated results from the simulated data. A separate sensitivity analysis is also formulated to reveal a possible different outcome. The framework is based on a stand-level inventory data of forestry plantations provided by the Ministry of Uruguay (MGAP) and companies. Also multiple scientific reports and previous studies were used as guidelines for simulations and results. The forest stand, yield, soil and weather data used for this study are from three different departments. There are over 700 000 hectares of different species of eucalyptus plantations in Uruguay. The theoretical framework was tested computationally with eleven simulations. CO2fix was parameterized for fast-growing eucalyptus species used in different parts of Uruguay. The model gave outputs per hectare and then this result was scaled up to the national level. This study will also estimate how much grassland (Pampa) and former pasture land could sequester carbon. Situation prior to plantation is a baseline scenario and it is compared to the expected carbon sequestration of plantations. The model is also used to calculate the effect of changing rotation length on carbon stocks of forest ecosystem (forest vegetation and soil) and wood products. The results of this study show that currently the 707,674 hectares of eucalyptus plantations in Uruguay have the potential to sequester 65 million tonnes of carbon and reduce 238 million tonnes of CO2. The calculated carbon storage is 38 and simulated 25 million tonnes of C, products are deducted from the equation. During 22 years (1990–2012) the annual carbon sequestration benefit (afforestation-baseline) without products is 1 757 847 Mg C. The results suggest that it is reasonable to establish eucalyptus plantations on degraded, grassland (Pampa) and abandoned pasture land. The implications of the results are that eucalyptus plantations in Uruguay actually enhance carbon sequestration, are carbon sinks and store more carbon than grassland and abandoned pasture land. Plantations have a vast sequestration potential and are important in mitigating of CO2 emission and effects of the climate change. The findings endorse the significance of plantations to increase carbon sinks and this role will broaden in the future. The most relevant findings of this study are that afforestation increases the soil carbon in 10-year rotation plantations by 34% (101.1>75.6) and in 12-year rotation 38% (104.4>75.6 Mg Cha-1) in a 60-year simulation. The net (afforestation-baseline) average carbon stock benefit in the soil is 25.5 Mg C ha?1 in a 60-year simulation. The (CO2Fix) model indicate that the total average carbon sequestration for eucalyptus plantations is 92.3 Mg Cha?1. The average total carbon storage ranges from 25.8–138.5 Mg Cha?1 during a 60-year simulation. The simulations show that the net annual carbon storage in the living biomass is 29.1, 25.5 (soil) and 37.6 Mg C (products) on the average scenario. There is some fluctuation in the sequestration results in other 10 simulations. Previous studies have showed that the average carbon stock for eucalyptus plantations varies from 30–60 Mg C ha-1, when soil and products are deducted. The capacity of forest ecosystems to sequester carbon in the long run could be even more strengthened if a rotation length increases. Extending rotation from 10 to 12 years increased the average soil carbon stock from 25.5 to 28.8 Mg C (by 13%) in 60 year simulation. The results also indicate that mean annual precipitation (MAP) alters the carbon sinks of the forest ecosystem. There are some limitations in this study and they are clearly explained and analyzed. Hence, most of the results are estimations. Ministry and companies need to prolong planting of trees and even intensify annual programs in order to achieve carbon sequestration targets. Further research is needed to get an estimate of the total forest ecosystem carbon storages and fluxes.
Now showing items 1-2 of 2