Author response for "Stress gradients interact with disturbance to reveal alternative states in salt marsh: multivariate resilience at the landscape scale"

Coastal salt marshes are biologically productive ecosystems that generate and sequester significant quantities of organic matter. Plant biomass varies spatially within a salt marsh and it is tedious and often logistically impractical to quantify biomass from field measurements across an entire landscape. Satellite data are useful for estimating aboveground biomass, however, high-resolution data are needed to resolve the spatial details within a salt marsh. This study used 3-m resolution multispectral data provided by Planet to estimate aboveground biomass within two salt marshes, North Inlet-Winyah Bay (North Inlet) National Estuary Research Reserve, and Plum Island Ecosystems (PIE) Long-Term Ecological Research site. The Akaike information criterion analysis was performed to test the fidelity of several alternative models. A combination of the modified soil vegetation index 2 (MSAVI2) and the visible difference vegetation index (VDVI) gave the best fit to the square root-normalized biomass data collected in the field at North Inlet (Willmott’s index of agreement d = 0.74, RMSE = 223.38 g/m2, AICw = 0.3848). An acceptable model was not found among all models tested for PIE data, possibly because the sample size at PIE was too small, samples were collected over a limited vertical range, in a different season, and from areas with variable canopy architecture. For North Inlet, a model-derived landscape scale biomass map showed differences in biomass density among sites, years, and showed a robust relationship between elevation and biomass. The growth curve established in this study is particularly useful as an input for biogeomorphic models of marsh development. This study showed that, used in an appropriate model with calibration, Planet data are suitable for computing and mapping aboveground biomass at high resolution on a landscape scale, which is needed to better understand spatial and temporal trends in salt marsh primary production.

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Competitive Interactions Between Two Salt Marsh Halophytes Across Stress Gradients

Wetlands ◽

10.1007/s13157-013-0479-9 ◽

2013 ◽

Vol 34 (1) ◽

pp. 31-42 ◽

Cited By ~ 9

Author(s):

Hem Nalini Morzaria-Luna ◽

Joy B. Zedler

Keyword(s):

Salt Marsh ◽

Competitive Interactions ◽

Stress Gradients

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Spatially non-continuous relationships between biological invasion and fragmentation of mangrove forests

10.1101/2021.04.16.440248 ◽

2021 ◽

Author(s):

Zhen Zhang ◽

Jing Li ◽

Yi Li ◽

Wenwen Liu ◽

Yuxin Chen ◽

...

Keyword(s):

Salt Marsh ◽

Biological Invasion ◽

Large Scale ◽

Coastal Wetland ◽

Biodiversity Loss ◽

Landscape Scale ◽

Fragmented Landscape ◽

Mangrove Forests ◽

Management Actions ◽

Geographical Variations

Rapid and large-scale biological invasion results in widespread biodiversity loss and degradation of essential ecosystem services, especially in mangrove forests. Recent evidence suggests that the establishment and dispersal of invasive species may exacerbated in fragmented landscape, but the influence of mangrove fragmentation on coastal biological invasion at landscape scale remains largely unknown. Here, using the derived 10-m resolution coastal wetland map in southeast coast of China, we examine the relationships between fragmentation of mangrove forests and salt marsh invasion magnitude and quantify the geographical variations of the relationships across a climatic gradient. Our results show that mangrove forests with small size, large edge proportion, and regular boundary shape tend to suffer more serious salt marsh invasions, indicating a positive correlation between mangrove fragmentation and its invaded magnitude. In particular, such fragmentation-invasion relationships in subtropics are shown to be more intensive than in tropic. Our findings provide the first spatially explicit evidence of the relationships between mangrove fragmentation and biological invasion on a landscape scale, and highlight an urgent need for conservation and management actions to improve mangrove connectivity, which will increase resistance to invasions, especially for small-size subtropical mangrove forests.

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