Zoë Lindo

Bryophyte-cyanobacteria associations as regulators of the northern latitude carbon balance in response to global change

Ecosystems in the far north, including arctic and boreal biomes, are a globally significant pool of carbon (C). Global change is proposed to influence both C uptake and release in these ecosystems, thereby potentially affecting whether they act as C sources or sinks. Bryophytes (i.e., mosses) serve a variety of key functions in these systems, including their association with nitrogen (N2 )-fixing cyanobacteria, as thermal insulators of the soil, and producers of recalcitrant litter, which have implications for both net primary productivity (NPP) and heterotrophic respiration. While ground-cover bryophytes typically make up a small proportion of the total biomass in northern systems, their combined physical structure and N2 -fixing capabilities facilitate a disproportionally large impact on key processes that control ecosystem C and N cycles. As such, the response of bryophyte-cyanobacteria associations to global change may influence whether and how ecosystem C balances are influenced by global change. Here, we review what is known about their occurrence and N2 -fixing activity, and how bryophyte systems will respond to several key global change factors. We explore the implications these responses may have in determining how global change influences C balances in high northern latitudes.

A community of metacommunities: exploring patterns in species distributions across large geographical areas

Ecological communities show extremely complex patterns of variation in space, and quantifying the relative importance of spatial and environmental factors underpinning patterns of species distributions is one of the main goals of community ecology. Although we have accumulated good knowledge about the processes driving species distributions within metacommunities, we have few insights about whether (and how) environmental and spatial features can actually generate consistent species distributional patterns across multiple metacommunities. In this paper we applied the elements of metacommunity structure (EMS) framework to identify and classify metacommunities according to multiple but discrete patterns of species distributions. Given that each pattern has unique underlying structuring mechanisms, exploring and comparing such patterns across multiple metacommunities spanning large geographical areas provides a way to test the existence of general principles underlying species distributions within metacommunities. In this study, we applied the EMS framework into a data set containing about 9000 lakes distributed across 85 fish metacommunities across Ontario, Canada, and estimated the relative importance of local and spatial factors in explaining their distributional patterns. Nested and Clementsian gradients were the patterns that fitted most metacommunities; nested metacommunities were distributed throughout the province, while Clementsian gradient metacommunities were concentrated in the southeastern region. Sixty-five percent of nested metacommunities were located in low-energy watersheds (i.e., colder climate and shorter growing season), whereas metacommunities representing Clementsian gradients were present in high-energy watersheds (i.e., relatively warmer climate and longer growing season). Taken together, our results reveal that the environmental and spatial properties in which metacommunities are embedded are at least partially responsible for their species distributional patterns.

Enhanced carbon release under future climate conditions in a peatland mesocosm experiment: the role of phenolic compounds

Background and AimsFuture climate conditions (warmer, wetter) are expected to change aboveground plant communities with linked belowground alterations (e.g. porewater chemistry) that can influence carbon dynamics. The aims of this study were 1) to determine if porewater phenolic compound concentrations reflect the changing aboveground plant community and 2) to elucidate if changes in phenolic compounds alter belowground carbon release.MethodsWe monitored the changes in vegetation biomass, porewater phenolic compound concentrations, respired CO2 and phenol oxidase enzyme activity in 84 intact peatland mesocosms exposed to elevated atmospheric CO2, elevated temperature, and decreased water table conditions in a full factorial design.ResultsPhenolic compound concentrations were indicative of the vascular plant expansion that occurred under warmer and anaerobic conditions, suggesting that phenolic compounds could be a simple indicator of northern plant community dynamics. Ecosystem CO2 respiration increased with rising phenolic compound concentrations, suggesting that phenolic compounds can decrease microbial carbon use efficiency in northern peatlands.ConclusionsUsing an aboveground-belowground framework we present a previously unrecognized mechanism influencing northern carbon dynamics; wherein, climate change conditions can restructure the plant community composition in turn increasing porewater phenolic concentrations, which results in decreased microbial carbon use efficiency and enhanced carbon release.

New Primers for Discovering Fungal Diversity Using Nuclear Large Ribosomal DNA.

Metabarcoding has become an important tool in the discovery of biodiversity, including fungi, which are the second most speciose group of eukaryotes, with diverse and important ecological roles in terrestrial ecosystems. We have designed and tested new PCR primers that target the D1 variable region of nuclear large subunit (LSU) ribosomal DNA; one set that targets the phylum Ascomycota and another that recovers all other fungal phyla. The primers yield amplicons compatible with the Illumina MiSeq platform, which is cost-effective and has a lower error rate than other high throughput sequencing platforms. The new primer set LSU200A-F/LSU476A-R (Ascomycota) yielded 95–98% of reads of target taxa from environmental samples, and primers LSU200-F/LSU481-R (all other fungi) yielded 72–80% of target reads. Both primer sets have fairly low rates of data loss, and together they cover a wide variety of fungal taxa. We compared our results with these primers by amplifying and sequencing a subset of samples using the previously described ITS3_KYO2/ITS4_KYO3 primers, which amplify the internal transcribed spacer 2 (ITS2) of Ascomycota and Basidiomycota. With approximately equivalent read depth, our LSU primers recovered a greater number and phylogenetic diversity of sequences than the ITS2 primers. For instance, ITS3_KYO2/ITS4_KYO3 primers failed to pick up any members of Eurotiales, Mytilinidiales, Pezizales, Saccharomycetales, or Venturiales within Ascomycota, or members of Exobasidiomycetes, Microbotryomycetes, Pucciniomycetes, or Tremellomycetes within Basidiomycota, which were retrieved in good numbers from the same samples by our LSU primers. Among the OTUs recovered using the LSU primers were 127 genera and 28 species that were not obtained using the ITS2 primers, although the ITS2 primers recovered 10 unique genera and 16 species that were not obtained using either of the LSU primers These features identify the new primer sets developed in this study as useful complements to other universal primers for the study of fungal diversity and community composition.

Climate change effects on peatland decomposition and porewater dissolved organic carbon biogeochemistry

Carbon accumulation and storage is a defining characteristic of peatland ecosystems. Decomposition of peat releases dissolved organic carbon (DOC) to receiving waters and can be an important fraction of the peatland carbon budget, along with being an important modifier of downstream water quality. Changes in temperature and hydrological processes under future climate scenarios are expected to impact decomposition processes in peatlands with unclear ramifications for both the quantity and the quality of the DOC released. We experimentally examined the individual and interactive effects of increased temperature, elevated atmospheric carbon dioxide concentration, and lower water table position on peatland decomposition and the quantity and quality of porewater DOC in intact, replicated peat monoliths in a full factorial design. Decomposition rates and porewater DOC concentrations significantly increased under elevated temperature conditions; however, the quality of this carbon was variable, showing signs of both increased lability and recalcitrance. Lowered water table treatments also increased decomposition rates, although the high water conditions prompted greater porewater DOC concentrations and lability. It is expected that elevated decomposition rates under future climate scenarios will alter porewater DOC quantity in peatlands; however, we suggest that contributions from the aboveground system are needed to fully understand changes in DOC quality and subsequent ecosystem dynamics.

The inclusion of stakeholders and cultural ecosystem services in land management trade-off decisions using an ecosystem services approach.

ContextAn ecosystem service approach for land-use or conservation decisions normally uses economic or biophysical assessments for valuating nature’s services. In contrast, even though ecosystem services are required for human well-being, the actual use of services by differing stakeholder groups are rarely considered in typical ecosystem service assessments, especially the more intangible, cultural ecosystem services.ObjectivesThe aim of this research was to quantify different uses for 15 cultural and provisioning ecosystem service indicators across seven stakeholder groups in a watershed proposed with large hydroelectric dam development.MethodsWe used a large-scale survey to quantify use and frequency of use for ecosystem services.ResultsWe demonstrate that different stakeholder groups use ecosystem services differently, both in terms of specific ecosystem service indicators, as well as for frequency of ecosystem service use. Across all stakeholder groups, specific cultural ecosystem services were consistently more important to participants when compared to provisioning ecosystem services, especially aesthetic/scenic values.ConclusionsThis work is of global importance as it highlights the importance of considering cultural ecosystem services (e.g. aesthetic/scenic, sense-of-place values) along with multiple stakeholder groups to identify the trade-offs and synergies during decision-making processes for land-use or conservation initiatives.

Toward a global platform for linking soil biodiversity data

Soil biodiversity is immense, with an estimated 10-100 million organisms belonging to over 5000 taxa in a handful of soil. In spite of the importance of soil biodiversity for ecosystem functions and services, information on soil species, from taxonomy to biogeographical patterns, is incomplete and there is no infrastructure to connect pre-existing or future data. Here, we propose a global platform to allow for greater access to soil biodiversity information by linking databases and repositories through a single open portal. The proposed platform would for the first time, link data on soil organisms from different global sites and biomes, and will be inclusive of all data types, from molecular sequences to morphology measurements and other supporting information. Access to soil biodiversity species records and information will be instrumental to progressing scientific research and education. Further, as demonstrated by previous biodiversity synthesis efforts, data availability is key for adapting to, and creating mitigation plans in response to global changes. With the rapid influx of soil biodiversity data, now is the time to take the first steps forward in establishing a global soil biodiversity information platform.

Out on a limb: microarthropod and microclimate variation in coastal temperate rainforest canopies

Species richness of microarthropods in coastal temperate rainforests of western North America is enhanced by the presence of heterogeneous arboreal habitats (moss mats). We studied the relationship between species traits and microclimate as a structuring mechanism for understanding this high diversity. To examine whether community composition is associated with distinct microclimate zones we used Non‐metric Multidimensional Scaling ordination of environmental and community data. To link the traits of arboreal microarthropod species with observed environmental variables we used a trait‐based approach of RLQ and fourth‐corner analysis. Distinct microclimatic zones were observed in the canopy ecosystem stemming from gradients of moisture, temperature, and climatic stability associated with height in canopy and distance from trunk. Associated with these gradients is the growth and development of epiphytic bryophytes such as moss mats and suspended soils, which in turn, influence canopy microclimates. Microarthropod fauna displayed a community‐level response to microclimate gradients which was mediated and partially explained by a trait‐based analysis. A general decline in species richness was associated with harsher microclimate conditions. While many species possessed desiccation resistance traits under low‐moisture conditions, we posit that other species were able to persist by compensatory movements at very small spatial scales. In conclusion this study highlights the importance of environmental buffering associated with greater epiphytic biomass for preserving canopy microarthropod biodiversity, but also how developing an understanding of the species trait distributional shifts can enhance our understanding of communities under different environmental conditions, and for predicting future communities under global environmental change.

Boreal peat properties link to plant functional traits of ecosystem engineers

Background and aimsPlant species shape soil properties such as nutrient availability and carbon storage through functional traits. Understanding the role of plant functional traits, and the relationship between aboveground and belowground systems are especially important in boreal peatlands, which are important carbon sinks. Sphagnum as a key peat-forming bryophyte has long been considered an ecosystem engineer, whereas the engineering role of graminoids, also dominant in peatlands, has not traditionally been considered.MethodsWe quantified vegetation community composition, plant functional traits, and peat properties in two peatland sites differing in dominant vegetation (Sphagnum mosses and Carex sedges), and link plant traits with peat properties using ordination.ResultsWe show that plant traits significantly explain many peat properties, including organochemicals that are indicators of decomposition dynamics. Specifically, Carex-dominated sites had larger amount of ‘decomposition products’ while a larger proportion of ‘undecomposed materials’ was observed in Sphagnum-dominated sites.ConclusionFeedbacks in plant-soil systems are increasingly being recognised as drivers of ecosystem processes. In both peatland types, plant traits of the key ecosystem engineer drove properties of the belowground peat environment. Peat organochemical constituents between Sphagnum-dominated and Carex-dominated sites reveal differences in ecosystem function, and thus the conducive potential for carbon storage.

Drivers of decomposition and the detrital invertebrate community differ across a hummock-hollow microtopology in Boreal peatlands

ABSTRACT In boreal peatlands, low decomposition rate is the underlying cause of carbon sequestration. Decomposition of litter can be affected by factors relating to soil moisture and temperature, the quality of the litter, and by the biotic decomposer community, among others. Exploring how these drivers interact will provide better understanding of carbon dynamics in boreal peatlands. We measured the decomposition of three common peatland plant functional types (moss, sedge, shrub), and associated microarthropod communities using litterbags placed in hollows (wet depressions) and hummocks (dry, raised areas) of a boreal peatland in Ontario, Canada. Decomposition was significantly different between all plant litter types, and greatest in sedge, but was not significantly different between hummock and hollow microhabitats. The decomposer community displayed an opposite pattern, significantly affected by microhabitat where richness and abundance of microarthropods was greater in hollows than hummocks. Oribatid mites were the dominant microarthropod with respect to both richness and abundance. Plant litter type did not affect community structure in hollows, but was a determinant of oribatid dominance in hummocks. These results suggest that abiotic environmental conditions are the main drivers of community structure for decomposers, while plant litter quality is a more important determinant of decomposition dynamics in boreal peatlands.