Greenhouse Production of Native Aquatic Plants

Wetland restoration is critical for improving ecosystem services, but many aquatic plant nurseries do not have facilities like those typically used for large-scale plant production. We questioned if we could grow littoral aquatic plant species in a variety of substrates and irrigation methods similar to those used for traditional greenhouse production. Plants were grown in pots with drainage holes that were filled with potting substrate, topsoil, coarse builders’ sand, or a 50/50 mix of topsoil and builders’ sand. These substrates were amended with 2 g of 15N–3.9P–10K controlled-release fertilizer per liter of substrate and were watered using either overhead irrigation or subirrigation. Plants were grown for 16 weeks, then scored for quality and height before a destructive harvest. Blue-eyed grass (Sisyrinchium angustifolium) and arrow arum (Peltandra virginica) performed best when subirrigated and cultured in potting substrate or sand. Golden club (Orontium aquaticum) and lemon bacopa (Bacopa caroliniana) grew best when plants were cultured in potting substrate and maintained under subirrigation. These experiments provide a framework for using existing greenhouses to produce these littoral species and give guidance to growers who wish to produce plants for the restoration market.

Vegetation Effects on Bacteria and Denitrifier Abundance in the Soils of Two Tidal Freshwater Wetlands in Virginia

This study examined the abundance of bacteria and nirS-type denitrifiers associated with the rhizospheres of three emergent macrophyte species (Juncus effusus, Typha latifolia, and Peltandra virginica) to gain a greater understanding of plant-microbe interactions in wetland soils. Sampling of plant and soil properties was performed during the growing season (June) and following plant senescence (November) at two tidal freshwater wetlands. Quantitative polymerase chain reaction was used to determine the abundance of bacteria (16S rRNA) and nirS-type denitrifier genes from the rhizosphere and rhizoplane of each plant species and from nearby unvegetated soils. For bacteria, there was a positive rhizosphere effect that did not differ significantly across plant species. In contrast, significant differences in the abundance of nirS-type denitrifiers were observed across the plant species. Rhizosphere abundance was ∼2-fold greater in Peltandra virginica and 4-fold greater in Typha latifolia compared to Juncus effusus. For both bacteria and nirS-type denitrifiers, plant effects were greater during the growing season, and abundance was highly correlated with soil pH, moisture, and organic matter content. Overall, these results demonstrate plant effects on the rhizosphere microbial community can be species‐specific and that there is a synergistic relationship between plant species and environmental conditions.

FOLLOW-UP STUDY ON OILED VEGETATION CUTTING ALONG THE DELAWARE RIVER

ABSTRACT In July 1992, the tank vessel Canadian Liberty spilled approximately 50 barrels of heavy Venezuelan crude oil into the Delaware River. Eight miles of New Jersey riverbank were oiled. The product clung to the vegetation, forming a bathtub ring about 20 cm wide at the high-tide mark. Cutting of vegetation was approved for areas with the highest waterfowl concentrations and highest degree of oiling, and in public-use areas. The objective of cutting was to remove impacted vegetation to prevent secondary oiling of waterfowl and to allow use of the public park. Emphasis was placed on limiting habitat degradation by selective manual cutting from boat and shore. A yearlong study was undertaken to monitor the recovery of the cut vegetation. Comparisons to uncut oiled vegetation and control sites were made. Nine monitoring stations were established in the area affected by the spill. Vegetation surveyed were Phragmites communis (common reed grass), Peltandra virginica (arrow arum), and Scripus olneyi (bulrush). One year after cleanup operations, cut and oiled vegetation appeared to have completely recovered. The distributions, densities, and heights of vegetation oiled and/or cut were not noticeably different from control transects of unimpacted vegetation.