- There has been a trend in the last seventy years of mangrove encroachment on salt marshes.
- “Over the past ~70 years, mangrove encroachment has resulted in the conversion of ~30% or more of salt marsh to mangrove forest across south-eastern Australia…” (1107)
- “At a global scale, mangrove encroachment of salt marsh may be driven by a suite of changing environmental factors favouring mangrove, including rising sea level, elevated atmospheric CO2 and higher temperatures…” (1098)
- “Such a change in ‘blue carbon’ habitats – that is, C-rich, marine habitats – could have significant implications for regional and global C pools, as mangroves (trees and shrubs) and salt marshes (communities of grasses, succulent herbs, rushes and low shrubs) are disproportionately important in sequestering C relative to their spatial extent…” (1097)
- Nutrient limitation has been linked to increases in biomass carbon storage.
- “...mangrove biomass and forest architecture are known to vary substantially according to nutrient status, ranging from growth of vigorous tall trees in nutrient-rich riverine settings down to dwarf trees in nutrient-poor areas near the coastal fringe…-a trend generally consistent with biomass differences in our study.” (1104-1105)
- Rise in salinity levels have been linked to increases in biomass carbon storage.
- “...growth studies have shown increased growth of A. marina seedlings under lower salinities (20–80% seawater concentrations)... and, more specifically, declines in photosynthetic capacities of both A. marina and A. corniculatum with increasing salinity.” (1104)
- Changed in sedimentation levels have been linked to increases in biomass carbon storage.
- “...differences in sedimentation among sites may alter the sensitivity of mangrove growth to nutrient enrichment and alter nutrient and carbon cycling.” (1105)
- This encroachment has caused a rise in aboveground biomass accumulation.
- “Aboveground biomass increase was seen at both study sites, as mangroves encroached areas previously vegetated by salt marsh species.” (1104)
- “This may not be surprising, considering the low biomass of salt marshes relative to mangroves…” (1104)
- “The increase in biomass measured aboveground as mangroves encroach salt marsh was also observed belowground in cores analysed for bulk C content.” (1106)
- “...significant increases in belowground C coincided with fine root development of mangroves, with fine root biomass dominating sediment volume in surface layers of encroached areas.” (1106)
- This encroachment has caused a rise in belowground biomass accumulation.
- “The results of two contrasting wetland settings in our study show that in the absence of extreme winter events, and given sufficient time, significant increases in belowground C stocks do become apparent under mangrove encroachment.” (1106)
- It is predicted that below and above ground biomass will continue to accumulate, which translates into increased C storage.
- “While the exact timing and rates of change of mangrove encroachment cannot be determined at a regional scale with current data, extrapolation of findings from the present study suggests a significant increase in blue C stocks has already occurred.” (1107)
- “Based on a 30% conversion of the current extent of salt marsh in New South Wales… biomass increases of 1618–4044 Mg yr-1 (113,239–283,097 Mg over 70 years) and belowground C increases of up to 7155 Mg C yr-1 (500,864 Mg C over 70 years; extrapolated from Georges River rate only) may have already occurred over the past 70 years in New South Wales alone.” (1107-1108)
- “If mangroves continue to further encroach salt marshes in the region, as is predicted to happen, annual additions to above and belowground C stores of the magnitude reported here may continue.” (1108)