Biomass harvest of invasive Typha promotes plant diversity in a Great Lakes coastal wetland

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111287/1/rec12167.pd

Harvesting Invasive Plants to Reduce Nutrient Loads and Produce Bioenergy: An Assessment of Great Lakes Coastal Wetlands

In Laurentian Great Lakes coastal wetlands (GLCWs), dominant emergent invasive plants are expanding their ranges and compromising the unique habitat and ecosystem service values that these ecosystems provide. Herbiciding and burning to control invasive plants have not been effective in part because neither strategy addresses the most common root cause of invasion, nutrient enrichment. Mechanical harvesting is an alternative approach that removes tissue‐bound phosphorus and nitrogen and can increase wetland plant diversity and aquatic connectivity between wetland and lacustrine systems. In this study, we used data from three years of Great Lakes‐wide wetland plant surveys, published literature, and bioenergy analyses to quantify the overall areal extent of GLCWs, the extent and biomass of the three most dominant invasive plants, the pools of nitrogen and phosphorus contained within their biomass, and the potential for harvesting this biomass to remediate nutrient runoff and produce renewable energy. Of the approximately 212,000 ha of GLCWs, three invasive plants (invasive cattail, common reed, and reed canary grass) dominated 76,825 ha (36%). The coastal wetlands of Lake Ontario exhibited the highest proportion of invasive dominance (57%) of any of the Great Lakes, primarily from cattail. A single growing season\u27s biomass of these invasive plants across all GLCWs was estimated at 659,545 metric tons: 163,228 metric tons of reed canary grass, 270,474 metric tons of common reed, and 225,843 metric tons of invasive cattail, and estimated to contain 10,805 and 1144 metric tons of nitrogen and phosphorus, respectively. A one‐time harvest and utilization for energy of this biomass would provide the gross equivalent of 1.8 million barrels of oil if combusted, or 0.9 million barrels of oil if converted to biogas in an anaerobic digester. We discuss the potential for mitigating non‐point source nutrient pollution with invasive wetland plant removal, and other potential uses for the harvested biomass, including compost and direct application to agricultural soils. Finally, we describe the research and adaptive management program we have built around this concept, and point to current limitations to the implementation of large‐scale invasive plant harvesting

Biomass harvest of invasive Typha promotes plant diversity in a Great Lakes coastal wetland

Ecological and financial constraints limit restoration efforts, preventing the achievement of desired ecological outcomes. Harvesting invasive plant biomass for bioenergy has the potential to reduce feedback mechanisms that sustain invasion, while alleviating financial limitations. Typha × glauca is a highly productive invasive wetland plant that reduces plant diversity, alters ecological functioning, its impacts increase with time, and is a suitable feedstock for bioenergy. We sought to determine ecological effects of Typha utilization for bioenergy in a Great Lakes coastal wetland by testing plant community responses to harvest-restoration treatments in stands of two age classes and assessing community resilience through a seed bank study. Belowground harvesting increased light penetration, diversity, and richness, and decreased Typha dominance and biomass in both years post-treatment. Aboveground harvesting increased light and reduced Typha biomass in post-year 1 and in post-year 2, increased diversity and richness and decreased Typha dominance. Seed bank analysis revealed that young stands (30 years). In the field, stand-age did not affect diversity or Typha dominance, but old stands had greater Typha biomass and slightly higher richness following harvest. Harvesting Typha achieved at least two desirable ecological outcomes: reducing Typha dominance and increasing native plant diversity. Younger stands had greater potential for native recovery, indicated by more diverse seed banks. In similar degraded wetlands, a single harvest of Typha biomass would likely result in significant biodiversity and habitat improvements, with the potential to double plant species richness

Elevated atmospheric CO 2 alters leaf litter quality for stream ecosystems: an in situ leaf decomposition study

Trembling aspen ( Populus tremuloides ) seedlings were exposed to both elevated (720 ppm; ELEV) and ambient (370 ppm; AMB) concentrations of atmospheric CO 2 for a 6-month growing season after which senesced leaves were collected and analyzed for differences in chemical composition. Elevated levels of atmospheric CO 2 significantly increased total phenolic compounds, lignin levels, and C:N ratios, while decreasing the concentration of foliar nitrogen. ELEV and AMB leaf aggregates were placed into a headwater stream in the autumn of 1999 for 4 months to assess microbial activity, macroinvertebrate colonization, and leaf decomposition rates. Elevated CO 2 significantly reduced 30 day microbial community respiration (−36.8%), and percent leaf mass remaining after 30 and 120 days of stream incubation (−9.4% and −13%, respectively). Low resolution of the experimental design for testing macroinvertebrate responses to altered leaves, including the free movement of macroinvertebrates among leaf aggregates, may explain the lack of treatment effect on invertebrate distribution between AMB and ELEV leaves. Elevated CO 2 -induced increases in leaf litter total phenolic compounds, lignins, and C:N appear to have negative effects on leaf decomposition, especially in the early stages of the decay process where microorganisms play a dominant role.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42898/1/10750_2004_Article_5124449.pd

Elevated CO 2 alters leaf-litter-derived dissolved organic carbon: effects on stream periphyton and crayfish feeding preference

Elevated atmospheric CO2 increases plant C fixation, and much of the soluble C content of deciduous leaf litter entering streams is leached as dissolved organic C (DOC). The effects of DOC from trembling aspen (Populus tremuloides Michaux) leaf litter grown under elevated (ELEV ! 720 ppm) and ambient (AMB! 360 ppm) CO2 on stream periphyton were measured during a 35-d experiment in outdoor artificial stream chambers. Crayfish feeding preferences for periphyton grown in AMB and ELEV treatments were evaluated in short-term foraging trials using a Y-maze. Periphyton was sampled through time for ash- free dry mass (AFDM), chlorophyll a, total C:N, algal biovolume and species composition, and bacterial productivity and biomass. Leaf litter from plants grown under ELEV CO2 produced higher concentrations of refractory DOC than did leaf litter from plants grown under AMB CO2, and chlorophyll a concentrations were lower in periphyton enriched with ELEV DOC than in periphyton enriched with AMB DOC. ELEV DOC did not significantly affect bacterial productivity and biomass or total periphyton C:N, but cyanobacterial biovolume was higher in ELEValgal assemblages than in AMB algal assemblages after 35 d. AMB algal assemblages were dominated by the diatom Epithemia adnata var. proboscidea, which contains N- fixing endosymbionts. Orconectes virilis crayfish preferred AMB periphyton stimulus when offered the choice of AMB and ELEV stimuli or AMB and control stimuli. Our results suggest that DOC from trembling aspen leaf litter produced under ELEV CO2 alters algal accrual and species assemblages of stream periphyton, and this shift in basal resource quantity and quality could affect feeding preferences of crayfish

Alteration of Microbial Communities Colonizing Leaf Litter in a Temperate Woodland Stream by Growth of Trees Under Conditions of Elevated Atmospheric CO\u3csub\u3e2\u3c/sub\u3e

Elevated atmospheric CO2 can cause increased carbon fixation and altered foliar chemical composition in a variety of plants, which has the potential to impact forested headwater streams because they are detritus-based ecosystems that rely on leaf litter as their primary source of organic carbon. Fungi and bacteria play key roles in the entry of terrestrial carbon into aquatic food webs, as they decompose leaf litter and serve as a source of nutrition for invertebrate consumers. This study tested the hypothesis that changes in leaf chemistry caused by elevated atmospheric CO2 would result in changes in the size and composition of microbial communities colonizing leaves in a woodland stream. Three tree species, Populus tremuloides, Salix alba, and Acer saccharum, were grown under ambient (360 ppm) or elevated (720 ppm) CO2, and their leaves were incubated in a woodland stream. Elevated-CO2 treatment resulted in significant increases in the phenolic and tannin contents and C/N ratios of leaves. Microbial effects, which occurred only for P. tremuloides leaves, included decreased fungal biomass and decreased bacterial counts. Analysis of fungal and bacterial communities on P. tremuloides leaves via terminal restriction fragment length polymorphism (T-RFLP) and clone library sequencing revealed that fungal community composition was mostly unchanged by the elevated-CO2 treatment, whereas bacterial communities showed a significant shift in composition and a significant increase in diversity. Specific changes in bacterial communities included increased numbers of alphaproteobacterial and cytophaga-flavobacter-bacteroides (CFB) group sequences and decreased numbers of betaproteobacterial and firmicutes sequences, as well as a pronounced decrease in overall Gram-positive bacterial sequences

Typha (Cattail) Invasion in North American Wetlands: Biology, Regional Problems, Impacts, Ecosystem Services, and Management

Typha is an iconic wetland plant found worldwide. Hybridization and anthropogenic disturbances have resulted in large increases in Typha abundance in wetland ecosystems throughout North America at a cost to native floral and faunal biodiversity. As demonstrated by three regional case studies, Typha is capable of rapidly colonizing habitats and forming monodominant vegetation stands due to traits such as robust size, rapid growth rate, and rhizomatic expansion. Increased nutrient inputs into wetlands and altered hydrologic regimes are among the principal anthropogenic drivers of Typha invasion. Typha is associated with a wide range of negative ecological impacts to wetland and agricultural systems, but also is linked with a variety of ecosystem services such as bioremediation and provisioning of biomass, as well as an assortment of traditional cultural uses. Numerous physical, chemical, and hydrologic control methods are used to manage invasive Typha, but results are inconsistent and multiple methods and repeated treatments often are required. While this review focuses on invasive Typha in North America, the literature cited comes from research on Typha and other invasive species from around the world. As such, many of the underlying concepts in this review are relevant to invasive species in other wetland ecosystems worldwide

Reconstructing plant invasions using historical aerial imagery and pollen core analysis: T ypha in the L aurentian G reat L akes

Aim Determining the spatial‐temporal spread of an invasive plant is vital for understanding long‐term impacts. However, invasions have rarely been directly documented given the resources required and the need for substantial foresight. One method widely used is historical photography interpretation, but this can be hard to verify. We attempt to improve this method by linking historical aerial photos to a paleobotanical analysis of pollen cores. Location Laurentian G reat L akes coastal wetlands, U nited S tates of A merica. Methods We chose invasive cattail ( T ypha ) as our model species because it is identifiable from aerial imagery and has persistent, identifiable pollen, and its ecological impacts appear to be time‐dependent. We used G eographic I nformation S ystems, aerial photo‐interpretation and field verification to post‐dict the invasion history of T ypha in several wetland ecosystems. Using 210 P b and 137 C s sediment dating and pollen classification, we correlated the temporal dominance of T ypha to our estimates of per cent coverage at one site. The pollen record was then used to estimate the T ypha invasion dynamics for dates earlier than those for which aerial photos were available. Results Typha spread through time in all study wetlands. Typha pollen dominance increased through time corresponding with increased spatial dominance. Hybrid cattail, T .  ×  glauca increased in pollen abundance relative to T . angustifolia pollen through time. Main conclusions This study illustrates the value of generating historical invasion maps with publically available aerial imagery and linking these maps with paleobotanical data to study recent (< 100 years) invasions. We determined rates of T ypha expansion in two coastal wetland types, validated our mapping methods and modelled the relationship between pollen abundance and wetland coverage, enhancing the temporal precision and breadth of analyses. Our methodology should be replicable with similar invasive plant species. The combination of pollen records and historical photography promises to be a valuable additional tool for determining invasion dynamics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94878/1/ddi929.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/94878/2/ddi929-sup-0001-FigureS1.pd

Mechanisms of Dominance by the Invasive Hybrid Cattail Typha × Glauca

The mechanisms by which invasive plants displace native species are often not well elucidated, limiting knowledge of invasion dynamics and the scientific basis for management responses. Typha × glauca Godr. invades wetlands throughout much of North America. Like other problematic wetland invaders, Typha is large, grows densely, and leaves behind copious litter. It thus has the potential to impact wetlands both in life and after death. We assessed patterns in field settings and used simulated wetland-plant communities to experimentally test abiotic and community responses to live Typha, Typha litter, and water-level differences (confounded in the field) using a full-factorial design. In general, litter was a stronger driver of change than live Typha. The greatest impacts were seen where, as in nature, live and dead Typha co-occurred. Live-Typha treatments did not differ from controls in light or temperature conditions but did reduce community biomass and alter community composition. Litter strongly affected light, temperature and its variability, community and species-level plant biomass, and community composition. Interactions between live Typha and litter affected aspects of plant-community composition. Advantageously for Typha, interspecific litter effects were not mirrored by intraspecific suppression of live Typha. These findings clarify how Typha is such an effective invader. Similar mechanisms are likely involved in invasions by other plant species, particularly in wetlands. Managers should respond quickly to new Typha invasions and, when dealing with established stands, remove litter in addition to eradicating live plants