| 1. |
- Andersson, Erik, et al.
(författare)
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Ambio fit for the 2020s
- 2022
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Ingår i: Ambio. - : Springer Nature. - 0044-7447 .- 1654-7209. ; 51:5, s. 1091-1093
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Axelsson, Petter, et al.
(författare)
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A pre-adaptive approach for tropical forest restoration during climate change using naturally occurring genetic variation in response to water limitation
- 2020
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Ingår i: Restoration Ecology. - : Wiley. - 1061-2971 .- 1526-100X. ; 28, s. 156-165
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Tidskriftsartikel (refereegranskat)abstract
- Effective reforestation of degraded tropical forests depends on selecting planting material suited to the stressful environments typical at restoration sites that can be exacerbated by increased duration and intensity of dry spells expected with climate change. While reforestation efforts in nontropical systems are incorporating drought-adapted genotypes into restoration programs to cope with drier conditions, such approaches have not been tested or implemented in tropical forests. As the first effort to examine genetic variation in plant response to drought in a tropical wet forest, we established a watering experiment using five replicated maternal lines (i.e. seedlings from different maternal trees) of five dipterocarp species native to Borneo. Apart from the expected species level variation in growth and herbivory (3-fold variation in both cases), we also found intraspecific variation so that growth in some cases varied 2-fold, and herbivory 3-fold, among genetically different maternal lines. In two species we found that among-maternal line variation in growth rate was negatively correlated with tolerance to water limitation, that is, the maternal lines that performed the best in the high water treatment lost proportionally more of their growth during water limitation. We argue that selection for tolerance to future drier conditions is not only likely to impact population genetics of entire forests, but likely extends from forest trees to the communities of canopy arthropods associated with these trees. In tropical reforestation efforts where increased drought is predicted from climate change, including plant material resilient to drier conditions may improve restoration effectiveness.
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| 3. |
- Axelsson, Petter, et al.
(författare)
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A trait-based plant economic framework can help increase the value of reforestation for conservation
- 2022
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- While reforestation is gaining momentum to moderate climate change via carbon sequestration, there is also an opportunity to use tree planting to confront declining global biodiversity. Where tree species vary in support of diversity, selecting appropriate species for planting could increase conservation effectiveness. We used a common garden experiment in Borneo using 24 native tree species to examine how variation among tree species in their support of beetle diversity is predicted by plant traits associated with "acquisitive" and "conservative" resource acquisition strategies. We evaluate three hypotheses: (1) beetle communities show fidelity to host identity as indicated by variation in abundance and diversity among tree species, (2) the leaf economic spectrum partially explains this variation as shown by beetle preferences for plant species that are predicted by plant traits, and (3) a small number of selected tree species can capture higher beetle species richness than a random tree species community. We found high variation among tree species in supporting three highly intercorrelated metrics of beetle communities: abundance, richness, and Shannon diversity. Variation in support of beetle communities was predicted by plant traits and varied by plant functional groups; within the dipterocarp family, high beetle diversity was predicted by conservative traits such as high wood density and slow growth, and in non-dipterocarps by the acquisitive traits of high foliar K and rapid growth. Using species accumulation curves and extrapolation to twice the original sample size, we show that 48 tree species were not enough to reach asymptote levels of beetle richness. Nevertheless, species accumulation curves of the six tree species with the highest richness had steeper slopes and supported 33% higher richness than a random community of tree species. Reforestation projects concerned about conservation can benefit by identifying tree species with a disproportional capacity to support biodiversity based on plant traits.
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| 4. |
- Axelsson, Petter, et al.
(författare)
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Ectomycorrhizal (dipterocarp) and arbuscular mycorrhizal (non-dipterocarp) tree hosts and their relative distribution in a tropical forest predict soil bacterial communities
- 2022
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 111, s. 251-262
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Tidskriftsartikel (refereegranskat)abstract
- The type of mycorrhizal associations (i.e. ectomycorrhizal [EM] or arbuscular mycorrhizal [AM]) formed by trees is of fundamental importance for a range of soil properties and processes in forests, yet their importance for the distribution of other important soil biota such as bacteria is largely unknown. We used an experimental common garden and amplicon sequencing to assess how abiotic and biotic variation differentially influenced bacterial communities associated with 13 climax tree species (8 EM members of the Dipterocarpaceae and 5 AM species from different families) planted into a secondary tropical forest in Borneo. Rhizosphere bacterial (RB) communities differed significantly between EM and AM trees but not among EM species and only marginally among AM species. RB communities were related to the density and size of neighbouring EM but not AM trees. Diversity of RB on AM trees responded positively to AM neighbours and negatively to EM neighbours but RB diversity associated with EM trees was unaffected by neighbourhood. Plant-growth-promoting taxa of RB assorted similarly to total RB but more strongly. Synthesis. Our results suggest that the distribution of RB communities is associated with plant mycorrhizal type and plant neighbourhood. Because rhizosphere bacteria alter nutrient cycling and influence plant species composition, their distributions are likely important for understanding ecosystem processes and plant demographics in forest ecosystems.
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| 5. |
- Axelsson, Petter, et al.
(författare)
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Elevational clines predict genetically determined variation in tropical forest seedling performance in Borneo: implications for seed sourcing to support reforestation
- 2023
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Ingår i: Restoration Ecology. - 1061-2971 .- 1526-100X. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- While much research has focused on genetic variation in plants in relation to abiotic clines in temperate and boreal forests, few studies have examined similar relationships in tropical forests. Genetic variation in desirable performance traits of trees, such as drought tolerance, fast-growth, and carbon sequestration rates, is widely used to improve reforestation efforts in nontropical systems. However, evolutionary processes such as local adaptation are poorly understood in tropical forests making it difficult to locate desired phenotypes. To test for genetic variation in growth rate in relationship to climatic clines, we conducted a common garden study over 18 months in a nursery using four dipterocarp tree species, represented by 9-12 half-sib families, sourced across an elevational gradient ranging from lowland to hill forests (circa 130-470 m above sea-level) in Malaysian Borneo. We found genetic variation in growth for all four species with fast-growing half-sib families growing 42-88% faster than poorly performing half-sib families. Furthermore, in three species we found that elevation of seedling origin predicted seedling performance; in Shorea fallax and S. johorensis, half-sib families originating from low elevations performed the best. In S. argentifolia half-sib families' seedlings from low elevations grew slowly. Because elevation is a good proxy for climate, the finding of elevational clines predicting genetic variation in growth provides evidence of evolution affecting the function of tropical tree species. Our research highlights opportunities to better understand evolutionary processes in tropical forests and to use such information to improve seed source selection in reforestation.
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| 6. |
- Axelsson, Petter, et al.
(författare)
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Mega El Niño's change the playing field for culturally important tree species and hence the foundation for human-nature interactions in tropical forests
- 2021
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Ingår i: Trees, Forests and People. - : Elsevier BV. - 2666-7193. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Humans have interacted with trees for millennia and the strength of such interactions determines the long-term social values of trees and forests. Such ecocultural linkages could be important to promote during reforestation efforts, potentially helping to turn the tide on the current rapid extinction of cultural and biological diversity. In addition, predicting the fate of ecoculturally important species to changing climates may help guide tree species selection best-suited to future climates. We assessed the vulnerability of four ecoculturally important tree species native to Southeast Asia to an extreme drought: Koompassia excelsa, Nephelium lappaceum, Shorea fallax and Shorea leprosula. These species provide distinct and unique products, and Koompassia excelsa is well-represented in local mythological stories and considered a Cultural Keystone Species (CKS). We used two complementary approaches: 1) an experimental common garden and 2) naturally occurring wild trees growing in a secondary forest and compared the performance of trees before, after, and during the 2016 El Niño event with record breaking low precipitation and high temperatures. We found that mortality of the CKS K. excelsa in the common garden, along with mortality and growth of wild trees were unaffected by the El Niño drought. In contrast, young trees of N. lappaceum and S. fallax planted in the common garden had mortality 4 and 3 times higher, respectively, during the El Niño drought compared to normal years. Growth rate of S. fallax in the wild was also significantly lower during the El Niño drought and this effect was particularly pronounced in highly disturbed forests. Our results demonstrate that the impact of extreme climatic events, that are predicted to become more common with climate change, on culturally important tree species is species specific. Management of such species may thus need species specific measures to maintain viable populations and hence provide the basic physical settings for human-nature interactions and associated cultural identities to persist. In this context, our findings that cultural keystone species such as K. excelsa could be drought tolerant is noteworthy, as investing on such species could prove to be beneficial for both local cultures and conservation of native ecosystems and biodiversity.
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| 7. |
- Axelsson, Petter, et al.
(författare)
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The road to recovery: a synthesis of outcomes from ecosystem restoration in tropical and sub-tropical Asian forests
- 2023
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Ingår i: Philosophical Transactions B: Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 378
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Tidskriftsartikel (refereegranskat)abstract
- Current policy is driving renewed impetus to restore forests to return ecological function, protect species, sequester carbon and secure livelihoods. Here we assess the contribution of tree planting to ecosystem restoration in tropical and sub-tropical Asia; we synthesize evidence on mortality and growth of planted trees at 176 sites and assess structural and biodiversity recovery of co-located actively restored and naturally regenerating forest plots. Mean mortality of planted trees was 18% 1 year after planting, increasing to 44% after 5 years. Mortality varied strongly by site and was typically ca 20% higher in open areas than degraded forest, with height at planting positively affecting survival. Size-standardized growth rates were negatively related to species-level wood density in degraded forest and plantations enrichment settings. Based on community-level data from 11 landscapes, active restoration resulted in faster accumulation of tree basal area and structural properties were closer to old-growth reference sites, relative to natural regeneration, but tree species richness did not differ. High variability in outcomes across sites indicates that planting for restoration is potentially rewarding but risky and context-dependent. Restoration projects must prepare for and manage commonly occurring challenges and align with efforts to protect and reconnect remaining forest areas.The abstract of this article is available in Bahasa Indonesia in the electronic supplementary material.This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.
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| 8. |
- Bargues Tobella, Aida, et al.
(författare)
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Explore before you restore: Incorporating complex systems thinking in ecosystem restoration
- 2024
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Ingår i: Journal of Applied Ecology. - 0021-8901 .- 1365-2664. ; 61, s. 922-939
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Forskningsöversikt (refereegranskat)abstract
- The global movement for ecosystem restoration has gained momentum in response to the Bonn Challenge (2010) and the UN Decade on Ecosystem Restoration (UNDER, 2021–2030). While several science-based guidelines exist to aid in achieving successful restoration outcomes, significant variation remains in the outcomes of restoration projects. Some of this disparity can be attributed to unexpected responses of ecosystem components to planned interventions.Given the complex nature of ecosystems, we propose that concepts from Complex Systems Science (CSS) that are linked to non-linearity, such as regime shifts, ecological resilience and ecological feedbacks, should be employed to help explain this variation in restoration outcomes from an ecological perspective.Our framework, Explore Before You Restore, illustrates how these concepts impact restoration outcomes by influencing degradation and recovery trajectories. Additionally, we propose incorporating CSS concepts into the typical restoration project cycle through a CSS assessment phase and suggest that the need for such assessment is explicitly included in the guidelines to improve restoration outcomes.To facilitate this inclusion and make it workable by practitioners, we describe indicators and methods available for restoration teams to answer key questions that should make up such CSS assessment. In doing so, we identify key outstanding science and policy tasks that are needed to further operationalize CSS assessment in restoration.Synthesis and applications. By illustrating how key Complex Systems Science (CSS) concepts linked to non-linear threshold behaviour can impact restoration outcomes through influencing recovery trajectories, our framework Explore Before You Restore demonstrates the need to incorporate Complex Systems thinking in ecosystem restoration. We argue that inclusion of CSS assessment into restoration project cycles, and more broadly, into international restoration guidelines, may significantly improve restoration outcomes.
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| 9. |
- Bargues Tobella, Aida, et al.
(författare)
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Forest restoration: Transformative trees
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 366, s. 316-317
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Bargues Tobella, Aida, et al.
(författare)
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Strategies trees use to overcome seasonal water limitation in an agroforestry system in semiarid West Africa
- 2017
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Ingår i: Ecohydrology. - : Wiley. - 1936-0584 .- 1936-0592. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Agroforestry parklands, in which annual crops are grown under scattered mature trees, constitute the most prevalent farming system in semiarid West Africa, covering vast areas of land. The most dominant tree species in these systems is Vitellaria paradoxa, an indigenous tree to West Africa. Despite the importance of this tree in the region, no study to our knowledge has examined its sources and patterns of water uptake. In this study, we used oxygen stable isotopes at natural abundance levels to investigate water sources used by V. paradoxa both in the dry and wet season in an agroforestry parkland in Burkina Faso. We found that during the wet season soil moisture was highest near the soil surface (< 10 cm depth), yet during this time V. paradoxa preferentially accessed water from slightly deeper soil depths, obtaining ca. 90% of its water from 10 to 50 cm depth. In contrast, soil moisture in the upper soil layers was significantly lower during the dry season and as a result V. paradoxa shifted to deeper water sources, obtaining ca. 30% of its water from groundwater and ca. 50% from 30 to 600 cm depth. We also found a negative relationship between tree size and the contribution of groundwater during the dry season, whereas during the wet season V. paradoxa predominantly used water near the soil surface regardless of tree size. Knowledge about the sources and patterns of tree water uptake provides crucial information to better understand how trees influence the local water balance.
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