Re-visiting Meltsner: Policy Advice Systems and the Multi-Dimensional Nature of Professional Policy Analysis

10.2139/ssrn.15462511-2

Pinus banksiana in the Trout Lake, Michigan peatlands: an evaluation of growth in two habitats.

http://deepblue.lib.umich.edu/bitstream/2027.42/53710/1/2145.pdfDescription of 2145.pdf : Access restricted to on-site users at the U-M Biological Station

New England salt marsh pools: A quantitative analysis of geomorphic and geographic features

New England salt marsh pools provide important wildlife habitat and are the object of on-going salt marsh restoration projects; however, they have not been quantified in terms of their basic geomorphic and geographic traits. An examination of 32 ditched and unditched salt marshes from the Connecticut shore of Long Island Sound to southern Maine, USA, revealed that pools from ditched and unditched marshes had similar average sizes of about 200 m2, averaged 29 cm in depth, and were located about 11 m from the nearest tidal flow. Unditched marshes had 3 times the density (13 pools/ha), 2.5 times the pool coverage (83 m pool/km transect), and 4 times the total pool surface area per hectare (913 m2 pool/ha salt marsh) of ditched sites. Linear regression analysis demonstrated that an increasing density of ditches (m ditch/ha salt marsh) was negatively correlated with pool density and total pool surface area per hectare. Creek density was positively correlated with these variables. Thus, it was not the mere presence of drainage channels that were associated with low numbers of pools, but their type (ditch versus creek) and abundance. Tidal range was not correlated with pool density or total pool surface area, while marsh latitude had only a weak relationship to total pool surface area per hectare. Pools should be incorporated into salt marsh restoration planning, and the parameters quantified here may be used as initial design targets. © 2005, The Society of Wetland Scientists

Mitigating the legacy effects of ditching in a New England salt marsh

The legacy effects of mosquito ditching have made salt marshes more vulnerable to flooding impacts from climate change, presenting management challenges in New England where the majority of salt marshes have been ditched and greater rates of sea level rise and storm events are being observed. One legacy effect of mosquito ditching appears to be subsidence of the marsh, with greater effects near the ditches and extending into the marsh plain. We found an average of 9 cm subsidence midway between ditches that averaged 14 m apart. Ditch Remediation is a new approach to filling ditches that uses existing hydrology and vegetation to mend ditches from the bottom up to restore marsh plain elevations. Smaller, auxiliary ditches are selected for treatment. Hay is mown, allowed to dry, and rolled into the treatment ditch where it is held using twine. Nine ditches in four areas were treated in fall 2014 and 2015. Depth of treated ditches decreased an average of 18 cm by fall 2017, and Spartina alterniflora colonized the ditch centers (plant cover and stem density increased). It is unknown whether the trajectory of filling and revegetation of the ditches will continue on their own or if the reduction in drainage depth will stimulate marsh plain building. Ditch remediation could remove excessive drainage effects of half the ditches, thereby approaching an optimal drainage density that may allow tidal marshes to rebuild elevation. This simple and inexpensive technique to reduce ditch impacts should be considered by partnerships that include mosquito control agencies

Elevation change and the vulnerability of Rhode Island (USA) salt marshes to sea-level rise

Salt marshes persist within the intertidal zone when marsh elevation gains are commensurate with rates of sea-level rise (SLR). Monitoring changes in marsh elevation in concert with tidal water levels is therefore an effective way to determine if salt marshes are keeping pace with SLR over time. Surface elevation tables (SETs) are a common method for collecting precise data on marsh elevation change. Southern New England is a hot spot for SLR, but few SET elevation change datasets are available for the region. Our study synthesizes elevation change data collected from 1999 to 2015 from a network of SET stations throughout Rhode Island (RI). These data are compared to accretion and water level data from the same time period to estimate shallow subsidence and determine whether marshes are tracking SLR. Salt marsh elevation increased at a mean overall rate of 1.40 mm year−1 and ranged from −0.33 to 3.36 mm year−1 at individual stations. Shallow subsidence dampened elevation gain in mid-Narragansett Bay marshes, but in other areas of coastal RI, subsurface processes may augment surface accretion. In all cases, marsh elevation gain was exceeded by the 5.26 mm year−1 rate of increase in sea levels during the study period. Our study provides the first SET elevation change data from RI and shows that most RI marshes are not keeping pace with short- or long-term rates of SLR. It also lends support to previous research that implicates SLR as a primary driver of recent changes to southern New England salt marshes

Quantifying vegetation and nekton response to tidal restoration of a New England salt marsh

Tidal flow to salt marshes throughout the northeastern United States is often restricted by roads, dikes, impoundments, and inadequately sized culverts or bridge openings, resulting in altered ecological structure and function. In this study we evaluated the response of vegetation and nekton (fishes and decapod crustaceans) to restoration of full tidal flow to a portion of the Sachuest Point salt marsh, Middletown, Rhode Island. A before, after, control, impact study design was used, including evaluations of the tide-restricted marsh, the same marsh after reintroduction of tidal flow (i.e., tide-restored marsh), and an unrestricted control marsh. Before tidal restoration vegetation of the 3.7-ha tide-restricted marsh was dominated by Phragmites australis and was significantly different from the adjacent 6.3-ha Spartina-dominated unrestricted control marsh (analysis of similarities randomization test, p \u3c 0.001). After one growing season vegetation of the tide-restored marsh had changed from its pre-restoration condition (analysis of similarities randomization test, p \u3c 0.005). Although not similar to the unrestricted control marsh, Spartina patens and S. alterniflora abundance increased and abundance and height of Phragmites significantly declined, suggesting a convergence toward typical New England salt marsh vegetation. Before restoration shallow water habitat (creeks and pools) of the unrestricted control marsh supported a greater density of nekton compared with the tide-restricted marsh (analysis of variance, p \u3c 0.001), but after one season of restored tidal flow nekton density was equivalent. A similar trend was documented for nekton species richness. Nekton density and species richness from marsh surface samples were similar between the tide-restored marsh and unrestricted control marsh. Fundulus heteroclitus and Palaemonetes pugio were the numerically dominant fish and decapod species in all sampled habitats. This study provides an example of a quantitative approach for assessing the response of vegetation and nekton to tidal restoration