Читать книгу Wetland Carbon and Environmental Management - Группа авторов - Страница 51

Wetlands can be sinks for a variety of allochthonous materials including sediment‐associated carbon (discussed in this section), organic detritus, and atmospheric inputs of dust, ash, and pollen. Organic detritus can take the form of plant material (e.g., leaves, wood) from terrestrial systems (Fetherston et al., 1995; Holgerson et al., 2016) as well as phytoplankton, macroalgae, and seagrass detritus from aquatic environments (Hanley et al., 2017; Kon et al., 2012). Treatment wetlands receive allochthonous carbon inputs in sewage (Nag et al., 2019). Carbon inputs associated with dust, ash, and precipitation are not often measured and probably are not important carbon sources in most wetlands.

Allochthonous sediment‐associated carbon can represent a major carbon input to wetlands that experience (semi)regular overbank flooding (González et al., 2014; Hupp et al., 2019; Neubauer et al., 2002). The deposition of allochthonous sediments varies as a function of suspended sediment availability in the water column; the degree of connectivity between the wetland and channel; the frequency, depth, and duration of flooding; and the biomass and physical structure of vegetation (Friedrichs & Perry, 2001; Hupp, 2000). The erosion of sediments from terrestrial landscapes (Wilkinson & McElroy, 2007) has caused increased deposition of allochthonous sediment (and carbon) to some riverine and estuarine wetlands (Khan & Brush, 1994), but others have seen reduced sediment inputs due to reservoirs and levees that restrict sediment movement (Blum & Roberts, 2009; Cabezas et al., 2009). Because wetlands occupy local topographic low spots, they can be sinks for sediment that is eroded from surrounding upland ecosystems (Gleason & Euliss, 1998; McCarty & Ritchie, 2002; S. M. Smith et al., 2001), even in the absence of overbank flooding.