scholarly journals Modeling the Effects of Global Change on Ecosystem Processes in a Tropical Rainforest

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 213
Author(s):  
Ann E. Russell ◽  
William J. Parton

Research Highlights: Ongoing land-use change and climate change in wet tropical forests can potentially drive shifts in tree species composition, representing a change in individual species within a functional group, tropical evergreen trees. The impacts on the global carbon cycle are potentially large, but unclear. We explored the differential effects of species within this functional group, in comparison with the effects of climate change, using the Century model as a research tool. Simulating effects of individual tree species on biome-level biogeochemical cycles constituted a novel application for Century. Background and Objectives: A unique, long-term, replicated field experiment containing five evergreen tree species in monodominant stands under similar environmental conditions in a Costa Rican wet forest provided data for model evaluation. Our objectives were to gain insights about this forest’s biogeochemical cycles and effects of tree species within this functional group, in comparison with climate change. Materials and Methods: We calibrated Century, using long-term meteorological, soil, and plant data from the field-based experiment. In modeling experiments, we evaluated effects on forest biogeochemistry of eight plant traits that were both observed and modeled. Climate-change simulation experiments represented two climate-change aspects observed in this region. Results: Model calibration revealed that unmodeled soil processes would be required to sustain observed P budgets. In species-traits experiments, three separate plant traits (leaf death rate, leaf C:N, and allocation to fine roots) resulted in modeled biomass C stock changes of >50%, compared with a maximum 21% change in the climate-change experiments. Conclusions: Modeled ecosystem properties and processes in Century were sensitive to changes in plant traits and nutrient limitations to productivity. Realistic model output was attainable for some species, but unusual plant traits thwarted predictions for one species. Including more plant traits and soil processes could increase realism, but less-complex models provide an accessible means for exploring plant-soil-atmosphere interactions.

2021 ◽  
Author(s):  
Kristel van Zuijlen ◽  
Johan Asplund ◽  
Snorre Sundsbø ◽  
Oda Sofie Dahle ◽  
Kari Klanderud

Alpine and arctic bryophytes have been found to respond negatively to climate change, but since they are often analysed as one functional group, there is limited knowledge on species-specific responses. In this study, we examine how nearly two decades of experimental warming by open top chambers (OTC) and ambient warming have affected the bryophyte community structure in an alpine Dryas octopetala heath in Finse, southwest Norway. In contrast to what we expected, we found that bryophyte abundance, species richness and evenness increased over time in the control plots, indicating a positive response to ambient warming. However, the increase in bryophyte abundance and cover was suppressed in experimentally warmed plots compared to control plots. Bryophyte community composition changed in a similar direction in response to both ambient and experimental warming. Acrocarpous mosses were not affected stronger by warming than pleurocarpous mosses, but individual species and taxa showed contrasting responses. Our study highlights the importance of studying bryophyte responses to environmental change, as well as combining long-term observations with experimental warming.


Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 849
Author(s):  
Begoña de la Fuente ◽  
Santiago Saura

The invasive pine wood nematode (PWN), Bursaphelenchus xylophilus, causal agent of pine wilt disease, was first reported in Europe, near Lisbon, in 1999, and has since then spread to most of Portugal. We here modelled the spatiotemporal patterns of future PNW natural spread in the Iberian Peninsula, as dispersed by the vector beetle Monochamus galloprovincialis, using a process-based and previously validated network model. We improved the accuracy, informative content, forecasted period and spatial drivers considered in previous modelling efforts for the PWN in Southern Europe. We considered the distribution and different susceptibility to the PWN of individual pine tree species and the effect of climate change projections on environmental suitability for PWN spread, as we modelled the PWN expansion dynamics over the long term (>100 years). We found that, in the absence of effective containment measures, the PWN will spread naturally to the entire Iberian Peninsula, including the Pyrenees, where it would find a gateway for spread into France. The PWN spread will be relatively gradual, with an average rate of 0.83% of the total current Iberian pine forest area infected yearly. Climate was not found to be an important limiting factor for long-term PWN spread, because (i) there is ample availability of alternative pathways for PWN dispersal through areas that are already suitable for the PWN in the current climatic conditions; and (ii) future temperatures will make most of the Iberian Peninsula suitable for the PWN before the end of this century. Unlike climate, the susceptibility of different pine tree species to the PWN was a strong determinant of PWN expansion through Spain. This finding highlights the importance of accounting for individual tree species data and of additional research on species-specific susceptibility for more accurate modelling of PWN spread and guidance of related containment efforts.


2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Xavier Morin ◽  
Lorenz Fahse ◽  
Hervé Jactel ◽  
Michael Scherer-Lorenzen ◽  
Raúl García-Valdés ◽  
...  

2020 ◽  
Author(s):  
Inger Alsos ◽  

<p>Arctic and alpine species are disproportionally affected by climate change, and knowledge about their ability to survive or disperse is essential for their long-term conservation. Ancient sedimentary DNA (sedaDNA) has improved as a proxy for reconstructing past floras, and may now be applied in high throughput analyses. Our lab has analysed, or is in the process of analysing, sedaDNA from ~40 long (up to 26 000 years old) and 11 short (0-1000 years old) lake sediment cores from the Europe (Alps, Norway, Svalbard, Iceland, Polar Urals). Both general and site-specific patterns have emerged from these data. For example, the taxa recorded in sedaDNA often indicate a warmer climate than that which has been inferred based on pollen records; this is in concordance with macrofossil evidence. Also, the limits of past northern tree lines may have been underestimated based on pollen studies. Some heathland species, such as Vaccinium spp. and Empetrum, often show a time lag in arrival compared with other species with similar climatic requirements. Thus, despite the fact that they have berries and therefore are well adapted to long-distance dispersal by birds, our data show they are constrained from rapid responses to climate changes. Other patterns are site-specific. For example, we see a stepwise doubling of floristic richness from the Last Glacial Maximum to the Holocene in the Polar Urals, which is barely detectable in the pollen analyses. Further, the majority of taxa with a mainly arctic-alpine distributions survived the early-Holocene climate warming, when shrub and trees entered the region, probably due to a very heterogeneous landscape that allows co-existence of species with different requirements. In contrast, arctic-alpine taxa disappear from the catchment a subset of the lakes studied in North Norway after shrub and forest expansion. Linking this type of information to characteristics of these biogeographic regions may provide useful when planning for future nature reserves. In the near future, the combination of many sites, complete DNA reference libraries, and emerging molecular methods will allow for the tracking of individual species through time and space.</p>


2005 ◽  
Vol 53 (4) ◽  
pp. 337 ◽  
Author(s):  
Nicholas Goodwin ◽  
Russell Turner ◽  
Ray Merton

Mapping the spatial distribution of individual species is an important ecological and forestry issue that requires continued research to coincide with advances in remote-sensing technologies. In this study, we investigated the application of high spatial resolution (80 cm) Compact Airborne Spectrographic Imager 2 (CASI-2) data for mapping both spectrally complex species and species groups (subgenus grouping) in an Australian eucalypt forest. The relationships between spectral reflectance curves of individual tree species and identified statistical differences among species were analysed with ANOVA. Supervised maximum likelihood classifications were then performed to assess tree species separability in CASI-2 imagery. Results indicated that turpentine (Syncarpia glomulifera Smith), mesic vegetation (primarily rainforest species), and an amalgamated group of eucalypts could be readily distinguished. The discrimination of S. glomulifera was particularly robust, with consistently high classification accuracies. Eucalypt classification as a broader species group, rather than individual species, greatly improved classification performance. However, separating sunlit and shaded aspects of tree crowns did not increase classification accuracy.


2020 ◽  
Author(s):  
Sebastian Fiedler ◽  
José A.F. Monteiro ◽  
Kristin B. Hulvey ◽  
Rachel J. Standish ◽  
Michael P. Perring ◽  
...  

ABSTRACTEcological restoration increasingly aims at improving ecosystem multifunctionality and making landscapes resilient to future threats, especially in biodiversity hotspots such as Mediterranean-type ecosystems. Successful realisation of such a strategy requires a fundamental mechanistic understanding of the link between ecosystem plant composition, plant traits and related ecosystem functions and services, as well as how climate change affects these relationships. An integrated approach of empirical research and simulation modelling with focus on plant traits can allow this understanding.Based on empirical data from a large-scale restoration project in a Mediterranean-type climate in Western Australia, we developed and validated the spatially explicit simulation model ModEST, which calculates coupled dynamics of nutrients, water and individual plants characterised by traits. We then simulated all possible combinations of eight plant species with different levels of diversity to assess the role of plant diversity and traits on multifunctionality, the provision of six ecosystem functions (covering three ecosystem services), as well as trade-offs and synergies among the functions under current and future climatic conditions.Our results show that multifunctionality cannot fully be achieved because of trade-offs among functions that are attributable to sets of traits that affect functions differently. Our measure of multifunctionality was increased by higher levels of planted species richness under current, but not future climatic conditions. In contrast, single functions were differently impacted by increased plant diversity. In addition, we found that trade-offs and synergies among functions shifted with climate change.Synthesis and application. Our results imply that restoration ecologists will face a clear challenge to achieve their targets with respect to multifunctionality not only under current conditions, but also in the long-term. However, once ModEST is parameterized and validated for a specific restoration site, managers can assess which target goals can be achieved given the set of available plant species and site-specific conditions. It can also highlight which species combinations can best achieve long-term improved multifunctionality due to their trait diversity.


Author(s):  
Stefan Friedrich ◽  
Torben Hilmers ◽  
Claudia Chreptun ◽  
Elizabeth Gosling ◽  
Isabelle Jarisch ◽  
...  

AbstractForest management faces growing uncertainty concerning environmental conditions and demand for ecosystem services. To help forest managers consider uncertainty, we applied a robust and multi-criteria approach to select the optimal composition of a forest enterprise from 12 stand types. In our simulation, the forest enterprise strives for either financial return or a multi-criteria forest management considering financial return, carbon storage and forest ecosystem stability. To quantify the influence of climate change on these decision criteria, we used the concept of analogous climate zones. Our results provide recommendations for long-term strategies for tree species selection in a Southeast German forest enterprise. The results show that considering both uncertainty and multifunctionality in forest management led to more diversified forest compositions. However, robust and multi-criteria optimisation required the forest enterprise to pay a premium in terms of lower income. Financial returns decreased when forest composition accounted for uncertainty or multiple objectives. We also found that adaptation measures could only partly financially compensate the effects of climate change. As the study is limited to two tree species, including additional tree species, variants of mixing proportions and further silvicultural strategies in the optimisation appears a promising avenue for future research.


Botany ◽  
2014 ◽  
Vol 92 (4) ◽  
pp. 303-311 ◽  
Author(s):  
Steven W. Kembel ◽  
Rebecca C. Mueller

The aerial surface of plants, known as the phyllosphere, represents a widespread and diverse habitat for microbes, but the fungal communities colonizing the surface of leaves are not well characterized, and how these communities are assembled on hosts is unknown. We used high-throughput sequencing of fungal communities on the leaves of 51 tree species in a lowland tropical rainforest in Panama to examine the influence of host plant taxonomy and traits on the fungi colonizing the phyllosphere. Fungal communities on leaves were dominated by the phyla Ascomycota (79% of all sequences), Basidiomycota (11%), and Chytridiomycota (5%). Host plant taxonomic identity explained more than half of the variation in fungal community composition across trees, and numerous host functional traits related to leaf morphology, leaf chemistry, and plant growth and mortality were significantly associated with fungal community structure. Differences in fungal biodiversity among hosts suggest that individual tree species support unique fungal communities and that diverse tropical forests also support a large number of fungal species. Similarities between phyllosphere and decomposer communities suggest that fungi inhabiting living leaves may have significant roles in ecosystem functioning in tropical forests.


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