TDA-IME Project Final Report June, 2013 63 Connectivity High species diversity implies a broad range of connections and interactions between species, thereby promoting ecosystem stability. Ecosystems with few links have been shown to be vulnerable to the removal of any given species. Although it has yet to be demonstrated empirically, it seems likely that species connectivity within mangrove habitats promotes resilience. It can be concluded further that connectivity between mangrove habitats is important in maintaining diversity within habitats. Moreover, connectivity between mangroves and other ecosystems, such as the open sea, coral reefs or rivers, may also promote resilience across ecosystems. Conclusion: transboundary mangrove management would help to maintain connectivity between mangrove habitats; and between mangroves and other coastal ecosystems, which must benefit ecosystem resilience to climate change overall. Adaptation Mangrove trees and the mangrove fauna may experience considerable daily fluctuations in temperature, salinity and inundation: in general, they show remarkable physiological tolerance or resistance to environmental conditions. The trees have well-described mechanisms to exclude, tolerate, or excrete salt, for example (Tomlinson, 1986). Mangrove crabs combine great salinity tolerance with an ability to retreat into burrows to avoid temperature extremes (Edney 1961, Jones, 1984; Eshky et al., 1995,). However, the limits to this tolerance are reflected in the latitudinal constraints on the distribution of mangrove forests (Hogarth, 2007), which are determined primarily by temperature. Conclusion: in general, the ecological characteristics of mangrove communities endow them with considerable resilience against changing environmental conditions, as demonstrated by their exposure to wide daily fluctuations in temperature, inundation and salinity. Mangrove Ecosystem Responses to Climate Change While mangroves are considered to be resilient, when the impact of environmental stressors increases beyond a certain threshold an ecosystem may change irreversibly to a different state. The following analysis documents how mangroves might respond to the predicted changes in climate. Rise in atmospheric CO2 Carbon dioxide concentration in the atmosphere has already risen from 275-285 ppm (parts per million) to 379 ppm. The rate of rise is increasing, and atmospheric CO2 is predicted to double by 2100, to 730-1020 ppm (Solomon et al., 2007; Hoegh-Guldberg and Bruno, 2010). A direct effect of an increase in atmospheric CO2 may be increased productivity and growth, but varying between species and depending on other environmental circumstances (Gilman et al., 2008). In experimental situations, usually involving seedlings or young plants, experimentally raising CO2 generally increases water-use efficiency, enhances growth, and results in earlier reproductive maturity, although species respond differently, and in some cases growth may actually be reduced (Ball and Munns, 1997; Ball et al., 1997; Farnsworth et al., 1998; Snedaker and Araújo 1998). In an area subject to changes in the pattern of precipitation (see below), altered freshwater availability would interact with changes in water use efficiency, At an ecosystem level, the effect is difficult to predict, but might involve the expansion of mangroves into areas where their distribution is at present restricted by high salinity, together with some shift in species composition. In salt marsh communities, raised CO2 levels have
Transboundary Diagnostic Analysis of Indochina Mangrove Ecosystems
To see the actual publication please follow the link above