Browsing by Subject "Eucalyptus"

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  • D'Amato, D.; Rekola, M.; Wan, M.; Cai, D.; Toppinen, A. (2017)
    This paper addresses the current research void on local community views of changes in ecosystem services associated with rapid land use transformation in the context of plantation-based forestry. This interview-based study, conducted in southern China, aims at assessing the perspectives of local communities of: 1) the effects of Eucalyptus industrial plantations on selected ecosystem services and on local development; and 2) opportunities for future community livelihood development, based on the relations with the government and with forest industry operating locally. We analysed data from semi-structured interviews with 70 villagers for their views on changes in ecosystem services after the establishment of plantations, and their future expectations on the local livelihood development. Most interviewees mentioned some negative development on environmental quality after the establishment of the industrial plantations, especially on soil and water. Furthermore, the reduced productivity of cropland surrounding industrial plantations, coupled with other financial drivers, induced several villagers to switch from agricultural crops to household plantations. In the absence of destructive typhoons, household plantations can provide owners more free time, higher income, while industrial plantations provided some employment opportunities. Interviewees' expectations for the future included receiving financial support and capacity building for household plantations and crops, support to local roads and schools, and higher employment opportunities. Some interviewees suggested that solutions should be implemented for improving degraded water quality, while others suggested reducing forestry operations. Even though being highly context-specific, our findings open up the discussion about the further community development opportunities in the context of plantation forestry. In particular, the potential of value sharing mechanisms between the private sector and the local communities should be further studied. (C) 2017 The Authors. Published by Elsevier Ltd.
  • Juntheikki, Joni (Helsingfors universitet, 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.
  • Zhao, Hengwei; Zhong, Yanfei; Wang, Xinyu; Hu, Xin; Luo, Chang; Boitt, Mark; Piiroinen, Rami; Zhang, Liangpei; Heiskanen, Janne; Pellikka, Petri (2022)
    Some invasive tree species threaten biodiversity and cause irreversible damage to global ecosystems. The key to controlling and monitoring the propagation of invasive tree species is to detect their occurrence as early as possible. In this regard, one-class classification (OCC) shows potential in forest areas with abundant species richness since it only requires a few positive samples of the invasive tree species to be mapped, instead of all the species. However, the classical OCC method in remote sensing is heavily dependent on manually designed features, which have a limited ability in areas with complex species distributions. Deep learning based tree species classification methods mostly focus on multi-class classification, and there have been few studies of the deep OCC of tree species. In this paper, a deep positive and unlabeled learning based OCC framework—ITreeDet—is proposed for identifying the invasive tree species of Eucalyptus spp. (eucalyptus) and Acacia mearnsii (black wattle) in the Taita Hills of southern Kenya. In the ITreeDet framework, an absNegative risk estimator is designed to train a robust deep OCC model by fully using the massive unlabeled data. Compared with the state-of-the-art OCC methods, ITreeDet represents a great improvement in detection accuracy, and the F1-score was 0.86 and 0.70 for eucalyptus and black wattle, respectively. The study area covers 100 km2 of the Taita Hills, where, according to our findings, the total area of eucalyptus and black wattle is 1.61 km2 and 3.24 km2, respectively, which represent 6.78% and 13.65% of the area covered by trees and forest. In addition, both invasive tree species are located in the higher elevations, and the extensive spread of black wattle around the study area confirms its invasive tendency. The maps generated by the use of the proposed algorithm will help local government to develop management strategies for these two invasive species.
  • Yan, Dongjun (Helsingfors universitet, 2009)
    Industrial plantations of eucalyptus are sharply increasing in Asia. Although supplying raw material for the pulp and paper industry, easing deforestation on native forests and increasing carbon sequestration to help counter global warming, there are several concerns about the environmental effects of industrial eucalyptus plantations. These concerns include invasiveness of eucalyptus and loss of biodiversity, loss of land for food production, loss of soil fertility due to short rotation times and biomass removal, and excessive water-use and reduced catchment water yields. With protagonists on both sides, there is a need to research and examine the environmental effects of industrial eucalyptus plantations in southern China. We modelled and mapped the spatial distribution of water balance components across a small (752 ha) catchment in Guangxi province in relation to land-use, including industrial and local community plantations of eucalyptus and agriculture. Studies about the spatial distribution of water-use by eucalyptus across the landscape are few. WATBAL, a water balance model with a monthly time step, was parameterized and used to derive water balance components for 180 selected locations in the catchment. From the model output, continuous (predictive) surfaces for monthly (long-term average) potential (PET) and actual evapotranspiration (AET), evapotranspiration deficit (PET- AET), surface runoff and drainage below rooting zone were generated using GIS (ArcGIS 9.2). Averaged across the catchment, annual (October- September) actual evapotranspiration accounted for 77 %, surface runoff for 15 % and drainage below rooting zone for 8 % of rainfall. Differences between land-use types were relatively small, but areas of highest actual evapotranspiration and lowest surface runoff were associated with the oldest (6-7 years old) forested areas, including pure and mixed eucalyptus industrial plantations and local community, coppiced plantations on the slopes. The areas with the lowest actual evapotranspiration were associated with agricultural crops in the bottom of the catchment. The clear dominance of actual evapotranspiration in the water balance of all land-use types reflects the dominating role of the evaporative potential of the climate, with land-use cover, soil and topography factors playing secondary roles. While water-use was the highest for the forested areas, eucalyptus per se did not use more water than mixed plantations or those of the local community. Tree cover in general reduced surface runoff and therefore would reduce the risk of erosion. Using our modelling and mapping approach, we were able to assess the water-use and other components of the water balance of eucalyptus plantations and other land use types for this catchment. The study showed the importance of having suitable and adequate ground truth data in order to derive reliable and useful interpolation surfaces using ArcGIS.