| 1. |
- Ali, Arshad, et al.
(författare)
-
Disentangling the effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass in dry zone homegarden agroforestry systems
- 2017
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 598, s. 38-48
-
Tidskriftsartikel (refereegranskat)abstract
- The biodiversity – aboveground biomass relationship has been intensively studied in recent decades. However, no consensus has been arrived to consider the interplay of species diversity, and intraspecific and interspecific tree size variation in driving aboveground biomass, after accounting for the effects of plot size heterogeneity, soil fertility and stand quality in natural forest including agroforests. We tested the full, partial and no mediations effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass by employing structural equation models (SEMs) using data from 45 homegarden agroforestry systems in Sri Lanka. The full mediation effect of either species diversity or intraspecific and interspecific tree size variation was rejected, while the partial and no mediation effects were accepted. In the no mediation SEM, homegarden size had the strongest negative direct effect (? = ? 0.49) on aboveground biomass (R2 = 0.65), followed by strong positive direct effect of intraspecific tree size variation (? = 0.32), species diversity (? = 0.29) and interspecific tree size variation (? = 0.28). Soil fertility had a negative direct effect on interspecific tree size variation (? = ? 0.31). Stand quality had a significant positive total effect on aboveground biomass (? = 0.28), but homegarden size had a significant negative total effect (? = ? 0.62), while soil fertility had a non-significant total effect on aboveground biomass. Similar to the no mediation SEM, the partial mediation SEMs had explained almost similar variation in aboveground biomass because species diversity, and intraspecific and interspecific tree size variation had non-significant indirect effects on aboveground biomass via each other. Our results strongly suggest that a multilayered tree canopy structure, due to high intraspecific and interspecific tree size variation, increases light capture and efficient utilization of resources among component species, and hence, support the niche complementarity mechanism via plant-plant interactions.
|
|
| 2. |
- Ali, Arshad, et al.
(författare)
-
Individual tree size inequality enhances aboveground biomass in homegarden agroforestry systems in the dry zone of Sri Lanka
- 2017
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 575, s. 6-11
-
Tidskriftsartikel (refereegranskat)abstract
- Individual tree size variation, which is generally quantified by variances in tree diameter at breast height (DBH) and height in isolation or conjunction, plays a central role in ecosystem functioning in both controlled and natural environments, including forests. However, none of the studies have been conducted in homegarden agroforestry systems. In this study, aboveground biomass, stand quality, cation exchange capacity (CEC), DBH variation, and species diversity were determined across 45 homegardens in the dry zone of Sri Lanka. We employed structural equation modeling (SEM) to test for the direct and indirect effects of stand quality and CEC, via tree size inequality and species diversity, on aboveground biomass. The SEM accounted for 26, 8, and 1% of the variation in aboveground biomass, species diversity and DBH variation, respectively. DBH variation had the strongest positive direct effect on aboveground biomass (β = 0.49), followed by the non-significant direct effect of species diversity (β = 0.17), stand quality (β = 0.17) and CEC (β = − 0.05). There were non-significant direct effects of CEC and stand quality on DBH variation and species diversity. Stand quality and CEC had also non-significant indirect effects, via DBH variation and species diversity, on aboveground biomass. Our study revealed that aboveground biomass substantially increased with individual tree size variation only, which supports the niche complementarity mechanism. However, aboveground biomass was not considerably increased with species diversity, stand quality and soil fertility, which might be attributable to the adaptation of certain productive species to the local site conditions. Stand structure shaped by few productive species or independent of species diversity is a main determinant for the variation in aboveground biomass in the studied homegardens. Maintaining stand structure through management practices could be an effective approach for enhancing aboveground biomass in these dry zone homegarden agroforestry systems.
|
|
| 3. |
- Ali, Arshad, et al.
(författare)
-
Individual tree size inequality enhances aboveground biomass in homegarden agroforestry systems in the dry zone of Sri Lanka
- 2016
-
Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 575, s. 6-11
-
Tidskriftsartikel (refereegranskat)abstract
- Individual tree size variation, which is generally quantified by variances in tree diameter at breast height (DBH) and height in isolation or conjunction, plays a central role in ecosystem functioning in both controlled and natural environments, including forests. However, none of the studies have been conducted in homegarden agroforestry systems. In this study, aboveground biomass, stand quality, cation exchange capacity (CEC), DBH variation, and species diversity were determined across 45 homegardens in the dry zone of Sri Lanka. We employed structural equation modeling (SEM) to test for the direct and indirect effects of stand quality and CEC, via tree size inequality and species diversity, on aboveground biomass. The SEM accounted for 26, 8, and 1% of the variation in aboveground biomass, species diversity and DBH variation, respectively. DBH variation had the strongest positive direct effect on aboveground biomass (β = 0.49), followed by the non-significant direct effect of species diversity (β = 0.17), stand quality (β = 0.17) and CEC (β = − 0.05). There were non-significant direct effects of CEC and stand quality on DBH variation and species diversity. Stand quality and CEC had also non-significant indirect effects, via DBH variation and species diversity, on aboveground biomass. Our study revealed that aboveground biomass substantially increased with individual tree size variation only, which supports the niche complementarity mechanism. However, aboveground biomass was not considerably increased with species diversity, stand quality and soil fertility, which might be attributable to the adaptation of certain productive species to the local site conditions. Stand structure shaped by few productive species or independent of species diversity is a main determinant for the variation in aboveground biomass in the studied homegardens. Maintaining stand structure through management practices could be an effective approach for enhancing aboveground biomass in these dry zone homegarden agroforestry systems.
|
|
| 4. |
- Ali, Arshad, et al.
(författare)
-
Wood density is a sustainability indicator for the management of dry zone homegarden agroforests: Evidences from biodiversity–ecosystem function relationships
- 2019
-
Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X. ; 105, s. 474-482
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies have advanced our understanding regarding the niche complementarity and mass ratio effects on the ecosystem function, in both natural and experimental systems. However, biodiversity–ecosystem function (BEF) relationships may be fundamentally different across dense-wooded and light-wooded species, as they are clustered at two opposite extremes of the wood economics spectrum. Here we analyzed BEF relationships through mediations of functional dominance (i.e. community-weighted mean, CWM) and functional divergence (FDvar) of plant maximum height (H) while accounting for the effects of other characteristics of homegardens, across dense-wooded, light-wooded and all species, by using structural equation modelling (SEM) on 45 homegarden agroforestry systems in the dry zone of Sri Lanka. The dense-wooded SEM accounted for 69% variation in aboveground biomass through significant positive direct effects of CWM H (β = 0.51) and FDvar H (β = 0.20), and indirect effect of species diversity via FDvar H on aboveground biomass (β = 0.12). Although the light-wooded SEM accounted for 19% variation in aboveground biomass, the BEF relationships were non-significant. Regardless of SEMs, FDvar H but not CWM H was significantly positively related to species diversity. None of the BEF relationships was statistically significant when dense-wooded and light-wooded species were mixed. From a theoretical aspect, these positive BEF relationships are driven by both dominant and complementarity dense-wooded species. From a practical aspect, the positive BEF relationships support the feasibility of UN Reducing Emissions from Deforestation and Forest Degradation (REDD+) initiative in studied agroforests, which aims to enhance carbon storage in aboveground biomass while conserving biodiversity. Hence, this study suggests that wood density is a potential sustainability indicator for better management of agroforest-ecosystem while driving positive BEF relationships.
|
|
| 5. |
- Davis, Marion, et al.
(författare)
-
Sharing the Land: Restoring Degraded Ecosystems and Improving Livelihoods Through Agroforestry
- 2014
-
Ingår i: Stockholm Environment Institute: Swedish International Agricultural Network Initiative (SIANI) and Forest, Climate & Livelihood Research Network (Focali), “Forests, Landscapes and Food Security” theme brief. ; , s. 4-
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The challenge is daunting: how to feed more than 7 billionpeople – nearly 10 billion by 20501 – even as key resourcesbecome scarcer. Roughly 24% of the world’s land area is degrading,including more than a fifth of the cropland and nearly a third of the forests – yet 1.5 billion people directly depend on degraded areas. Some countries are particularly hard-hit:95% of Swaziland’s land is degraded, as is 66% of Angola’s, 64% of Gabon’s, 60% of Thailand’s, and 60% of Zambia’s. In China, 457 million people are affected by land degradation.
|
|
| 6. |
- Davis, Marion, et al.
(författare)
-
Trees in home gardens: Making the most of an age-old practice to improve food security and nutrition.
- 2014
-
Ingår i: Stockholm Environment Institute: Swedish International Agricultural Network Initiative (SIANI) and Forest, Climate & Livelihood Research Network (Focali), “Forests, Landscapes and Food Security” theme brief.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Home gardens have been vital to human societies for thousands of years: from clusters of beneficial trees and shrubs planted on forest edges in pre-historic times, to the lush ediblegardens grown traditionally in many tropical regions, to the tiny, densely planted backyards that dot cities worldwide.
|
|
| 7. |
- Eriksson, Mats, et al.
(författare)
-
Water, Forests, People: The Swedish Experience in Building Resilient Landscapes
- 2018
-
Ingår i: Environmental Management. - : Springer Science and Business Media LLC. - 0364-152X .- 1432-1009. ; 62:1, s. 45-57
-
Tidskriftsartikel (refereegranskat)abstract
- A growing world population and rapid expansion of cities increase the pressure on basic resources such as water, food and energy. To safeguard the provision of these resources, restoration and sustainable management of landscapes is pivotal, including sustainable forest and water management. Sustainable forest management includes forest conservation, restoration, forestry and agroforestry practices. Interlinkages between forests and water are fundamental to moderate water budgets, stabilize runoff, reduce erosion and improve biodiversity and water quality. Sweden has gained substantial experience in sustainable forest management in the past century. Through significant restoration efforts, a largely depleted Swedish forest has transformed into a well-managed production forest within a century, leading to sustainable economic growth through the provision of forest products. More recently, ecosystem services are also included in management decisions. Such a transformation depends on broad stakeholder dialog, combined with an enabling institutional and policy environment. Based on seminars and workshops with a wide range of key stakeholders managing Sweden’s forests and waters, this article draws lessons from the history of forest management in Sweden. These lessons are particularly relevant for countries in the Global South that currently experience similar challenges in forest and landscape management. The authors argue that an integrated landscape approach involving a broad array of sectors and stakeholders is needed to achieve sustainable forest and water management. Sustainable landscape management—integrating water, agriculture and forests—is imperative to achieving resilient socio-economic systems and landscapes.
|
|
| 8. |
- Karlson, Martin, 1980-, et al.
(författare)
-
Mapping Tree Canopy Cover and Aboveground Biomass in Sudano-Sahelian Woodlands Using Landsat 8 and Random Forest
- 2015
-
Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 7:8, s. 10017-10041
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate and timely maps of tree cover attributes are important tools for environmental research and natural resource management. We evaluate the utility of Landsat 8 for mapping tree canopy cover (TCC) and aboveground biomass (AGB) in a woodland landscape in Burkina Faso. Field data and WorldView-2 imagery were used to assemble the reference dataset. Spectral, texture, and phenology predictor variables were extracted from Landsat 8 imagery and used as input to Random Forest (RF) models. RF models based on multi-temporal and single date imagery were compared to determine the influence of phenology predictor variables. The effect of reducing the number of predictor variables on the RF predictions was also investigated. The model error was assessed using 10-fold cross validation. The most accurate models were created using multi-temporal imagery and variable selection, for both TCC (five predictor variables) and AGB (four predictor variables). The coefficient of determination of predicted versus observed values was 0.77 for TCC (RMSE = 8.9%) and 0.57 for AGB (RMSE = 17.6 tons∙ha−1). This mapping approach is based on freely available Landsat 8 data and relatively simple analytical methods, and is therefore applicable in woodland areas where sufficient reference data are available.
|
|
| 9. |
- Köhlin, Gunnar, 1963, et al.
(författare)
-
In Search of Double Dividends from Climate Change Interventions Evidence from Forest Conservation and Houshould Energy Transitions
- 2015
-
Rapport (refereegranskat)abstract
- Climate change is the greatest challenge facing humanity, and we are only starting to address it. Climate change scenarios indicate that poor people in developing countries will be particularly negatively affected, e.g. by increased temperature reducing their harvests or flooding due to sea-level rise and extreme weather events. There are also expectations that greenhouse gas (GHG) emissions can be costefficiently reduced in developing countries through for example reduced deforestation or improved stoves. It is therefore not surprising that climate interventions have become an increasingly important part of Overseas Development Assistance (ODA), reaching 15 % of the total bilateral ODA, or about 20 billion US dollars, by 2013. According to Sustainable Development Goal 13a, this is expected to grow to at least USD 100 billion by 2020. The same trend is seen with Swedish development assistance.
|
|
| 10. |
- Lindström, Sara, et al.
(författare)
-
Forest cover change in Sri Lanka: The role of small scale farmers
- 2012
-
Ingår i: Applied Geography. - : Elsevier BV. - 0143-6228. ; 34, s. 680-692
-
Tidskriftsartikel (refereegranskat)abstract
- Forest cover in Sri Lanka has decreased rapidly during the last century and only fragments of the once widespread natural forest cover remain. This paper analyzes forest cover change and small scale farmers' relation to natural forests around two protected forest areas in Sri Lanka; Kanneliya Forest Reserve and Knuckles Conservation Forest. Methods used are spatial analysis to observe changes in forest cover from the 1980s until 2010, interviews with small scale farmers and key informants as well as field observations. In Kanneliya Forest Reserve, a decrease in forest cover is observed, particularly due to population increase and expanding tea plantations. In Knuckles Conservation Forest on the other hand, we find an overall increase in forest cover due to expansion of tree plantations, a ban on shifting cultivation and emigration from the area followed by natural forest regeneration. Agriculture is the most common source of income in both study areas and there is a clear link between conversions of forests to agricultural expansion. The profits from agricultural activities are in general insufficient to sustain small scale farmers' needs and the most common alternative source of income is achieved through resources extracted from the forest. Since 2001, demarcation of forest boundaries around the two forest reserves has reduced encroachment and illegal felling of timber. However, this policy has simultaneously threatened the livelihoods of peripheral communities in the forest buffer zones, especially in the investigated villages around Knuckles Conservation Forest. Despite successful attempts to reduce deforestation rates through governmental interventions, further incorporation of local people into the management of forests as stipulated in the current forest policy should be continued. (C) 2012 Elsevier Ltd. All rights reserved.
|
|
