The unexpected long period of elevated CH4 emissions from an inundated fen meadow ended only with the occurrence of cattail (Typha latifolia)

Drainage and agricultural use transform natural peatlands from a net carbon (C) sink to a net C source. Rewetting of peatlands, despite of high methane (CH₄) emissions, holds the potential to mitigate climate change by greatly reducing CO₂ emissions. However, the time span for this transition is unknown because most studies are limited to a few years. Especially, nonpermanent open water areas often created after rewetting, are highly productive. Here, we present 14 consecutive years of CH₄ flux measurements following rewetting of a formerly long-term drained peatland in the Peene valley. Measurements were made at two rewetted sites (non-inundated vs. inundated) using manual chambers. During the study period, significant differences in measured CH₄ emissions occurred. In general, these differences overlapped with stages of ecosystem transition from a cultivated grassland to a polytrophic lake dominated by emergent helophytes, but could also be additionally explained by other variables. This transition started with a rapid vegetation shift from dying cultivated grasses to open water floating and submerged hydrophytes and significantly increased CH₄ emissions. Since 2008, helophytes have gradually spread from the shoreline into the open water area, especially in drier years. This process was periodically delayed by exceptional inundation and eventually resulted in the inundated site being covered by emergent helophytes. While the period between 2009 and 2015 showed exceptionally high CH₄ emissions, these decreased significantly after cattail and other emergent helophytes became dominant at the inundated site. Therefore, CH₄ emissions declined only after 10 years of transition following rewetting, potentially reaching a new steady state. Overall, this study highlights the importance of an integrative approach to understand the shallow lakes CH₄ biogeochemistry, encompassing the entire area with its mosaic of different vegetation forms. This should be ideally done through a study design including proper measurement site allocation as well as long-term measurements.     

Wetland Waterbird Food Resources Increased by Harvesting Invasive Cattails

The conservation of many freshwater marsh waterbirds (i.e., waterfowl, shorebirds, wading birds, and secretive marshbirds) in the Laurentian Great Lakes requires managing invasive emergent macrophytes, which degrade waterbird habitat by creating dense, litter-clogged stands, and excluding plants that produce nutritionally balanced and high-energy food (seeds, tubers, and submerged aquatic vegetation). The most commonly used management approach in the United States Great Lakes region involves the application of herbicides, which can stimulate waterbird forage plants but does not address the accumulation of plant litter, the underlying cause of plant community diversity loss and habitat degradation. We experimentally evaluated the effects of an alternative approach, harvesting invasive plants and their litter followed by flooding, on plant communities, focusing on the effects of these treatments to increase the abundance of high-energy wetland plants. At the Shiawassee National Wildlife Refuge in Michigan, USA, we experimentally treated an invasive cattail (Typha × glauca)-dominated wetland in August and September of 2016, 2017, and 2018, using a randomized block design with 4 blocks and 3 treatments (sediment surface harvest, above ground harvest, and control). We monitored the effects of these treatments on the abundance and dominance of waterbird forage-producing plants, plant diversity, and plant communities prior to (Jul 2016) and during the summer following each treatment (late Jul or early Aug 2017, 2018, and 2019). Additionally, we used pre- and post-treatment waterbird use-day data collected at the unit scale and compared values with satellite imagery-derived land cover changes. Compared to control plots, 3 years of harvesting and flooding significantly increased plant species diversity, increased the abundance of waterbird seed- and tuber-producing plant species by 5 times, and increased annual plant dominance by more than 10 times, while substantially reducing all measures of cattail and its litter. Use-days increased for total waterbirds, including waterfowl and dabbling ducks, following treatment. Cattail cover decreased and open water and non-cattail emergent vegetation cover increased. Harvesting invasive plant biomass coupled with flooding promoted a plant community composition and structure beneficial to waterbirds. © 2020 The Wildlife Society.     

Epifluorescent and histochemical aspects of shoot anatomy of Typha latifolia L., Typha angustifolia L. and Typha glauca Godr

Using epifluorescent and histochemical techniques, we examined anatomical differences in the shoot organs of Typha latifolia, T. angustifolia and T. glauca. The leaf lamina of T. latifolia and T. glauca had enlarged epidermal cells and a thickened cuticle above the subepidermal vascular bundles; that of T. angustifolia lacked these characteristics. Leaf sheaths were similar among the species and all lacked the epidermal thickenings found in the lamina. The fertile stems had typical scattered vascular bundles with a band of fibres that was most prominent in T. glauca. The sterile stems were only 1 cm in length and contained a multiseriate hypodermis and a uniseriate endodermis over part of their length. The rhizomes were similar except for a pronounced band of fibres surrounding the central core in T. angustifolia. The rhizome was also characterized by an outer cortical region with a large multiseriate hypodermis/exodermis and a uniseriate endodermis with Casparian bands, suberin lamellae and secondarily thickened walls.     

Tissue culture and wetland establishment of the freshwater monocots <Emphasis Type="Italic">Carex,Juncus, Scirpus</Emphasis>, and <Emphasis Type="Italic">Typha</Emphasis>

Summary Cell cultures of freshwater wetland monocots were regenerated, plants were grown in the greenhouse, and then established and evaluated in wetlands. Typha (cattail), Juncus (rushes), Scirpus (bulrushes), and Carex (sedges) were studied because they are common, dominant, high biomass wetland-adapted plants, tolerant of chemically diverse ecosystems. The goal was to define micropropagation and wetland establishment protocols. Tissue culture systems defined for numerous monocot crop species can be readily applied to wetland plants, with a few modifications. Issues addressed were selection of explant material, shoot and root regeneration conditions, culture age verses regenerability, greenhouse acclimatization needs, plant uniformity and requirements for wetland establishment. In vitro-germinated seedlings were an excellent source of pathogen-free regenerable tissue. T. latifolia, T. angustifolia, and J. accuminatus were regenerated from callus induced in the dark with picloram, then transferred to medium with benzyladenine in the light to promote shoot organogenesis. J. effusus, S. polyphyllus, and C. lurida could not be regenerated from callus, which turned black. They could be regenerated directly by culturing intact seedlings directly on cytokinin media in the light. Shoots rooted with little or no auxin. J. effusus rooting was promoted by the addition of charcoal to the medium. Covering plants for the first 2 wk with plastic facilitated greenhouse establishment. There were high rates of greenhouse and wetland survival. No abnormal plants were observed. These regeneration systems could be utilized for the production of wetland plants for potential application in habitat restoration and wetland creation, and would provide an alternative to field collection.     

Interactive effects of seed availability,water depth,and phosphorus enrichment on cattail colonization in an Everglades wetland

The relative importance of seed availability, waterdepth, and soil phosphorus (P) concentrations oncattail (Typha domingensis pers.) earlyestablishment in an Everglades wetland area wasexamined using seed bank analysis and controlledexperiments. The experiments measured seed germinationand seedling growth in tanks with cattail seedaddition subjected to two P concentrations(un-enriched vs. enriched) and water depth (saturatedvs. flooded soils). A limited seed bank (223 ± 69m²) of cattail was found in the surface soil ofthe area studied. The germination of added seeds wasinhibited under flooded conditions, and only 0.6% ofthe germination was found. In contrast,under-saturated soil conditions, a maximum of 6% and15% germination was observed in P-un-enriched andP-enriched treatments, respectively. High mortality ofseedlings occurred regardless of P treatments followinga cold spell. However, P enrichment resulted inincreased seedling growth and asexual propagation.These results suggested the importance of theconcurrence of appropriate hydrologic regimes, Penrichment, and air temperature on the recruitment ofplant species.     

Fibre cables in the lacunae of Typha leaves contribute to a tensegrity structure

Background and Aims

Cables composed of long, non-lignified fibre cells enclosed in a cover of much shorter thin-walled, crystal-containing cells traverse the air chambers (lacunae) in leaves of the taller species of Typha. The non-lignified fibre cables are anchored in diaphragms composed of stellate cells of aerenchyma tissue that segment the long air chambers into smaller compartments. Although the fibre cables are easily observed and can be pulled free from the porous-to-air diaphragms, their structure and function have been ignored or misinterpreted.

Methods

Leaves of various species of Typha were dissected and fibre cables were pulled free and observed with a microscope using bright-field and polarizing optics. Maximal tensile strength of freshly removed cables was measured by hanging weights from fibre cables, and Instron analysis was used to produce curves of load versus extension until cables broke.

Key Results and Conclusions

Polarized light microscopy revealed that the cellulose microfibrils that make up the walls of the cable fibres are oriented parallel to the long axis of the fibres. This orientation ensures that the fibre cables are mechanically stiff and strong under tension. Accordingly, the measured stiffness and tensile strength of the fibre cables were in the gigapascal range. In combination with the dorsal and ventral leaf surfaces and partitions that contain lignified fibre bundles and vascular strands that are strong in compression, the very fine fibre cables that are strong under tension form a tensegrity structure. The tensegrity structure creates multiple load paths through which stresses are redistributed throughout the 1–3 m tall upright leaves of Typha angustifolia, T. latifolia, T. × glauca, T. domingensis and T. shuttleworthii. The length of the fibre cables relative to the length of the leaf blades is reduced in the last-formed leaves of flowering individuals. Fibre cables are absent in the shorter leaves of Typha minima and, if present, only extend for a few centimetres from the sheath into the leaf blade of Typha laxmannii. The advantage of the structure of the Typha leaf blade, which enables stiffness to give way to flexibility under windy conditions, is discussed for both vegetative and flowering plants.     

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 2 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 (<20 years) had greater diversity, richness, seedling density, and floristic quality than old 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 2 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.     

Biomass and nutrient allocation of sawgrass and cattail along a nutrient gradient in the Florida Everglades

Biomass and nutrient allocation in sawgrass (Cladium jamaicense Crantz) and cattail (Typha domingensis Pers.) were examined along a nutrient gradient in the Florida Everglades in 1994. This north to south nutrient gradient, created by discharging nutrient-rich agricultural runoff into the northern region of Water Conservatio ea 2A, was represented by three areas (impacted, transitional and reference). Contrasting changes of plant density and size along the gradient were found for communities of both species. For the sawgrass community, more small plants were found in ref ce areas, whereas few large plants were found in impacted areas. In contrast, for the cattail community, bigger plants were found in reference areas, and smaller plants were found in impacted areas. Both species allocated approximately 60% of their total biomass to leaves and 40% to belowground tissues. However, sawgrass biomass allocation to leaves, roots, shoot bases and rhizomes (65%, 19%, 11%, and 5%, respectively) was similar among the three areas. In contrast, cattail plants growing in referen reas showed higher root allocation (27.3%), but lower leaf allocation (51.1%) than those growing in impacted areas (14.6% and 65.8% for root and leaf allocation, respectively). Cattail had higher phosphorus concentrations than sawgrass in tissues associated with growth functions (leaves, roots, and rhizomes). In contrast, sawgrass had higher phosphorus and nitrogen concentrations than cattail in tissues primarily associated with resource storage (shoot bases). From impacted to reference areas, for sawgrass, there was a decrease of leaf TP from 605 to 248 (mg/kg), root TP from 698 to 181 (mg/kg), rhizome TP from 1,139 to 142 (mg/kg), and shoot base TP from 5,412 to 400 to (mg/kg). For cattail, leaf TP decreased from 1,175 to 556 (mg/kg), root TP de sed from 1,100 to 798 (mg/kg), rhizome TP decreased from 1390 to 380 (mg/kg), and shoot base TP decreased from 2,990 to 433 (mg/kg). N/P ratios of sawgrass in reference areas were 27, 63, 38, and 50 for leaves, roots, rhizomes, and shoot bases, respectively, whereas in impacted areas they were 11, 21, 6, and 2, respectively. The greatest TP storage was found in impacted areas. Differences in seed output, seed number, and mean seed weight were found for both species as well. Each cattail flower stalk duced approximately 105 tiny seeds (0.048 ± 0.001 mg) while each sawgrass flower stalk produced about 103 large seeds (3.13 ± 0.005 mg). These results suggest that phosphorus is a limiting resource in the Everglades and that the two species have different life history strategies. These data provide an ecological basis for making informed management and planning decisions to protect and restore the Everglades.     

青藏高原东北部及其邻近地区无苞香蒲的谱系地理学

第四纪冰期气候的反复变化对青藏高原及邻近地区植物的种群地理分布及种群遗传结构产生了巨大的影响。本研究对青藏高原东北部及其邻近地区无苞香蒲(Typha laxmannii)的15个种群148个个体的叶绿体rpl32-trnL间隔区和核基因(植物螯合肽合成酶, PS)进行测序, 共发现2个叶绿体单倍型和8个核基因单倍型。所有的单倍型被共享, 高原种群没有特有的单倍型。邻近地区种群的叶绿体遗传多样性和核基因遗传多样性分别是高原种群的4倍和2倍。高原种群的遗传分化水平明显高于邻近地区种群, 其中高原种群的遗传分化主要存在于东部种群与西部种群之间。研究结果表明, 冰期后从多个避难所回迁至高原台面和由此产生的奠基者效应造成了无苞香蒲在青藏高原东北及邻近地区目前的遗传多样性和基因谱系地理分布格局。     

Foraging,roosting, and nesting habitats of the avian fauna of the Agmon wetland,northern Israel

The foraging, nesting and roosting habitats of the avian fauna of a newly created Agmon wetland and surrounding cultivated peat land (5 km2) in the Hula Valley, northern Israel, were evaluated (January 1996–February 1997) to assess the value as a habitat and for wildlife tourism. We recorded 180 bird species (herons, dabbling ducks, kingfishers, waders, wagtails and raptors) in different habitats (the lake, shores, cattail and reed-bed stands, trees, temporary inundated areas). The most heavily used habitat for foraging, breeding, and roosting was a large cattail stand in the southern third of the lake. The foraging habitat and diet data of 97 avian species were determined. The most intensively used foraging habitats were cultivated fields, lake shore reed-beds, shallow canals and the cattail stand. Forty six species nested in the wetland during March-October, with 2,040 colonial and solitary nests mostly in the cattail stand, near-shore reed-beds and young trees. Roosts, also mostly in the cattail and reed-bed stands and in trees, were used by 55 species. Based on this survey of available habitats, we identified several key habitats that are either missing or require further development (e.g., temporarily inundated mud flats, reed-beds and bare islands). We also provide suggestions for improving the delicate balance between requirements of this developing wetland ecosystem and of the adjacent agricultural areas.