| 1. |
- ter Steege, Hans, et al.
(författare)
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Mapping density, diversity and species-richness of the Amazon tree flora
- 2023
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Ingår i: COMMUNICATIONS BIOLOGY. - 2399-3642. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution. A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.
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| 2. |
- Sandberg, Gustaf, 1982, et al.
(författare)
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L- and P-band backscatter intensity for biomass retrieval in hemiboreal forest
- 2011
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257 .- 1879-0704. ; 115:11, s. 2874 - 2886
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Tidskriftsartikel (refereegranskat)abstract
- At present, the greatest source of uncertainty in the global carbon cycle is in the terrestrial ecosystems. In orderto reduce these uncertainties it is necessary to provide consistent and accurate global estimates of the worldforest biomass. One of the most promising methods for obtaining such estimates is through polarimetric SARbackscatter measurements at low frequencies. In this paper, the relation between polarimetric SAR backscatterat L- and P-bands and forest biomass is investigated using data acquired within the BioSAR-I campaign insouthern Sweden during 2007. Methods for estimating biomass on stand level using these data are developedand evaluated, and the results for the two frequency bands are compared. For L-band data, the best results wereobtained using HV-polarized backscatter only, giving estimation errors in terms of root mean square errors(RMSE) between 31% and 46% of the mean biomass for stands with biomass ranging from 10 to 290 t/ha, and an(adjusted) coefficient of determination (R2) between 0.4 and 0.6. For P-band data, the results are better thanfor L-band. Models using HV- or HH-polarized P-band backscatter give similar results, as does a modelincluding both HV and HH. The RMSEs were between 18 and 27%, and the R2 values were between 0.7 and 0.8.
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| 3. |
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| 4. |
- Sandberg, Gustaf, 1982, et al.
(författare)
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Comparison of L- and P-band biomass retrievals based on backscatter from the BioSAR campaign
- 2009
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Ingår i: Proceedings of IGARSS 2009 Symposium, Earth Observation – Origins to Applications, Cape Town, South Africa, 13-17 July, 2009. - 9781424433957 ; IV, s. 169-172
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- With the continued threat of global warming, the need to obtain consistent and accurate measurements of the carbon stored in forests is strong. L- and P-band SAR backscatter data have shown to be sensitive to forest biomass, which in turn is coupled to the stored carbon. In this paper a biomass retrieval method is developed for L- and P-band using data from the BioSAR campaign conducted in Sweden during thespring 2007 over hemi-boreal forest. The results show that the use of L-band data gives an underestimation of biomass for stands with high biomass; while for P-band no such underestimation is seen. RMSEs are found to be 30-40% of the mean biomass for L-band and about 25% for P-band for stands with biomass ranging from 10 to 290 tons/ha.
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| 5. |
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| 6. |
- Holmgren, Eva, et al.
(författare)
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Swedish forest commons : A matter of governance?
- 2010
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Ingår i: Forest Policy and Economics. - : Elsevier BV. - 1389-9341 .- 1872-7050. ; 12:6, s. 423-431
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Tidskriftsartikel (refereegranskat)abstract
- Around 100 years ago, when Crown land in the interior of northern Sweden was privatized, part of the forest land was set aside as forest commons. Today, there are 33 such forest commons jointly managed and owned in common mainly by private forest owners. The forest commons may be looked upon as a means by which the state controls the production of and returns from the forests belonging to small and less affluent forest owners. Further, an attempt has been made to use the forests as a tool to move the self-interests of these small forest owners closer to providing public goods. Forest commons thus hold a contested status, as private lands under public control and as a partly de-regulated form of ownership. This paper examines the extent to which forest commons are currently managed directly by the government, comparing this with the general trend in forest policy towards governance and less prescriptive measures, which often take account of market and participative goals. Building upon Appelstrand (2007), this paper describes the major policy instruments relevant for forest commons from 1861 to 2005. We conclude that direct government management remains dominant, with the major legislation pertaining to forest commons dating back to the 1950s. While governance may seem to be inherent in the forest commons concept, the development of governance has not been fully realised given the relatively strict government-steered framework.
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| 7. |
- Lidestav, Gun, et al.
(författare)
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Shareholder perceptions of individual and common benefits in Swedish forest commons
- 2013
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Ingår i: International Journal of the Commons. - Utrecht : Igitur publishing. - 1875-0281. ; 7:1, s. 164-182
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Tidskriftsartikel (refereegranskat)abstract
- In the period 1861 to 1918, thirty-three commons were established in Northern Sweden. This was linked to the finalisation of the Great Redistribution of Forest Holdings in Dalarna and the delimitation process in Västerbotten and Norrbotten. They were intended to serve as an instrument for improved and sustained forest production, the viability of farmers and the liveability of the rural communities in the areas where they were established. The aim of this paper is to describe the results of a study examining how three of these forest commons, one from each region, have benefitted the local shareholders and their community. The perceptions among forest common shareholders were assessed using a questionnaire. The study also assessed economic impact on shareholders in terms of extent and use of the dividend from each of the commons for the period 1958-2007, highlighting the extent of the economic support to individual shareholders and to the local community. Results reveal large differences between the three cases; there was a positive correlation between the extent of the economic support and contentment among the shareholders.
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| 8. |
- Rydin, E., et al.
(författare)
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Compensatory nutrient enrichment in an oligotrophic mountain reservoir : effects and fate of added nutrients
- 2008
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Ingår i: Aquatic Sciences. - : Springer Science and Business Media LLC. - 1015-1621 .- 1420-9055. ; 70:3, s. 323-336
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Tidskriftsartikel (refereegranskat)abstract
- Most Scandinavian rivers are impounded for power production. High altitude reservoirs retain water during summer and fall for power production during winter and spring. The oligotrophic lakes Mjölkvattnet and Burvattnet were impounded in 1942. Annual water level fluctuations caused by regulation have resulted in a loss of littoral habitat, and Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) populations have declined. To assess compensatory nutrient enrichment as a remedy against declining fish populations, we added dissolved phosphate and nitrate to Mjölkvattnet in June and July in 2002 and 2003, and used the upstream lake Burvattnet as a reference system. Nutrient addition doubled water column total phosphorus concentration, from 3 to 6 μg P/L and increased nitrogen concentration by about 20 μg/L. Half of the added phosphorus settled out as organic matter, and about one third was lost downstream. Phytoplankton production and biomass increased, but species composition remained principally unchanged. Rotifers and cladocerans responded rapidly, as did the condition of fish. After two years of nutrient addition, five year old Arctic char had doubled in weight and increased significantly in length, reaching pre-impoundment conditions.
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| 9. |
- Ståhl, Göran, et al.
(författare)
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Why ecosystem characteristics predicted from remotely sensed data are unbiased and biased at the same time – and how this affects applications
- 2024
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Ingår i: Forest Ecosystems. - : Elsevier. - 2095-6355 .- 2197-5620. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Remotely sensed data are frequently used for predicting and mapping ecosystem characteristics, and spatially explicit wall-to-wall information is sometimes proposed as the best possible source of information for decision-making. However, wall-to-wall information typically relies on model-based prediction, and several features of model-based prediction should be understood before extensively relying on this type of information. One such feature is that model-based predictors can be considered both unbiased and biased at the same time, which has important implications in several areas of application. In this discussion paper, we first describe the conventional model-unbiasedness paradigm that underpins most prediction techniques using remotely sensed (or other) auxiliary data. From this point of view, model-based predictors are typically unbiased. Secondly, we show that for specific domains, identified based on their true values, the same model-based predictors can be considered biased, and sometimes severely so.We suggest distinguishing between conventional model-bias, defined in the statistical literature as the difference between the expected value of a predictor and the expected value of the quantity being predicted, and design-bias of model-based estimators, defined as the difference between the expected value of a model-based estimator and the true value of the quantity being predicted. We show that model-based estimators (or predictors) are typically design-biased, and that there is a trend in the design-bias from overestimating small true values to underestimating large true values. Further, we give examples of applications where this is important to acknowledge and to potentially make adjustments to correct for the design-bias trend. We argue that relying entirely on conventional model-unbiasedness may lead to mistakes in several areas of application that use predictions from remotely sensed data.
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| 10. |
- Ulander, Lars, 1962, et al.
(författare)
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BIOSAR 2010 - A SAR campaign in support to the BIOMASS mission
- 2011
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Ingår i: Proceedings of IGARSS 2011 Symposium, Vancouver, Canada, 24-29 July, 2011. - 9781457710056 ; , s. 1528-1531, s. 1528-1531
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The ESA funded campaign BioSAR 2010 was carried out at the forestry test site Remningstorp in southern Sweden, in support to the BIOMASS satellite mission under study. Fully polarimetric SAR data were successfully acquired at L- and P-band using ONERA's multi-frequency system SETHI. In addition with other data types gathered, e.g. LiDAR and in-situ measurements, the compiled data set will be used for analyses and comparisons with biomass estimation results obtained at the same test site in the campaign BioSAR 2007, in which DLR's E-SAR made the SAR imaging. Detection of forest changes, robustness of biomass retrieval algorithms and long-term P-band coherence will be in focus as well as cross-validations between the two SAR sensors.
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