Secondary Ecological Succession of Mangrove in the 2004 Tsunami Created Wetlands of South Andaman, India

Andaman and Nicobar Islands (ANI’s) being situated in the Tropical zone is the cradle of multi-disasters viz., cyclones, floods, droughts, land degradation, runoff, soil erosion, shallow landslides, epidemics, earthquakes, volcanism, tsunami and storm surges. Mangroves are one of the first visible reciprocators above land and sea surface to cyclonic storms, storm surges, and tsunamis among the coastal wetlands. The Indian Ocean 2004 tsunami was denoted as one of the most catastrophic ever recorded in humankind’s recent history. A mega-earthquake of Magnitude (9.3) near Indonesia ruptured the Andaman-Sunda plate triggered this tsunami. Physical fury, subsidence, upliftment, and prolonged water logging resulted in the massive loss of mangrove vegetation. A decade and half years after the 2004 tsunami, a study was initiated to assess the secondary ecological succession of mangrove in Tsunami Created Wetlands (TCWs) of south Andaman using Landsat satellite data products. Since natural ecological succession is a rather slow process and demands isotope techniques to establish a sequence of events succession. However, secondary ecological succession occurs in a short frame of time after any catastrophic event like a tsunami exemplifying nature’s resilience. Band-5 (before tsunami, 2003) and Band-6 (after tsunami, 2018) of Landsat 7 and Landsat-8 satellite respectively were harnessed to delineate mangrove patches and TCWs in the focus area using ArcMap 10.5, Geographic Information Systems (GIS) software. From the study, it was understood that Fimbrisstylis littoralis is the pioneering key-stone plant followed by Acrostichum aureum and Acanthus ilicifolius facilitating Avicennia spp/Rhizopara spp for ecological succession in the TCWs.

Rising Seas and Agriculture Created Wetlands Along the U.S. East Coast

Most of the tidal marshes along the eastern coast of the United States formed within the past 6,000 years due to a combination of slowly rising seas and European colonization.

Divergent impact of grazing on plant communities of created wetlands with varying hydrology and antecedent land use

Destruction of natural wetlands has warranted the creation of wetlands to mitigate the reduction of valuable ecosystem functions and services. However, the complex interactions between key drivers of wetland community structure – hydrology, nutrient availability and herbivory – makes creation of functional wetland replacements challenging. We examined interactions among these drivers, and their impacts on plant communities and soil characteristics in two created wetlands with different hydrology and land use histories: a shallow emergent marsh on a previous gravel depository and a seasonally flooded marsh on a former cattle pasture. In paired plots open to or protected from large wetland grazers we observed seasonal variation in grazing impacts on plant communities and an increase in effect size over time. At the permanently flooded marsh with high grazing waterfowl densities and low nutrients, open plots had significantly reduced plant growth and diversity, and an increase in submerged vegetation. In contrast, grazer density was lower and nutrients were higher in the seasonally flooded marsh, where grazer access enhanced plant diversity and reduced invasive plant cover. These results suggest the possibility of long-term grazer-induced shifts in community composition and delivery of key ecosystem services in young, vulnerable created wetlands. To improve created wetland design and function, we suggest that in addition to hydrologic conditions, the impact of prior land use on present nutrient availability be considered. Further, enhanced heterogeneity of spatial and bathymetric structure can provide conditions for diverse plant communities and balanced habitat use by wetland grazers.

Green Infrastructure as a Solution to Hydrological Problems: Bioswales and Created Wetlands

Green infrastructure is an ecological landscaping method that was first theorized in a 1994 Floridian report titled Creating a Statewide Greenways System, which was presented to the governor at the time, Lawton Chiles (Florida Greenways Commission, MacKay, & Reed 1994). As defined by the European Commission, green infrastructure is “a strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services” (Communication from The Commission to The European Parliament, 2013, p. 3). This paper will examine two green infrastructure strategies – bioswales and created wetlands – which are crucial in solving some of the water problems that Florida faces. Bioswales are engineered green spaces that collect runoff and remove harmful pollutants from the stormwater before it is discharged into surface water sources. This paper will examine how bioswales function. Besides polluted storm water, the other major water problem is eutrophication. Created wetlands are effective ecological tools for mitigating eutrophication, which is the result of excessive nutrients in water bodies that cause algal blooms and subsequently suffocate other organisms in the water by depleting oxygen. Freedom Park in Naples, Florida is composed of four created freshwater marshes, which filter runoff and reduce heavy metals and nutrients in the stormwater before it enters the Gordon River. This paper examines Freedom Park in Naples, Florida to assess how created wetlands can assist in reducing nutrient loads, mitigating pollutants in stormwater before it enters natural waterways, and restore habitat.