Step 1: Ecological Site Evaluation

Reading the landscape before planning restoration

Mangrove restoration begins long before planting or nursery work. It begins with understanding the site as a living system shaped by water, soil, vegetation, storm history, and the surrounding landscape. Step 1 is a careful, unhurried walk through the area, observing how the ecosystem functions today and how it may have changed over time. The goal is not to diagnose every problem immediately, but to build a grounded ecological picture that will guide decisions in later steps.

This stage requires your attention, not instruments. By reading the subtle patterns of water, sediment, and vegetation, you can determine whether the site is functioning as a tidal wetland or showing signs of stress that must be addressed before restoration can succeed.

Seeing the Landscape in Its Full Context

As you first approach the site, take a wide view. Mangrove health is influenced by forces that extend beyond the forest itself. Notice whether the site is a fringing shoreline, a sheltered lagoon, or a basin that fills only during spring tides. Look upslope to see what feeds into the wetland: hillside drains, culverts, roads, agricultural land, or forest cover. These features shape how freshwater reaches the site throughout the year, especially during the wet season.

Historical images and local memory are invaluable here. Many of Grenada’s struggling mangrove areas once supported dense, healthy stands before hydrology shifted due to infilling, redirected storm drains, storm surge deposition, or road construction. Beginning with this broader context helps you understand what has changed and why.

Note: Many mangrove and coastal wetland areas in Grenada are adjacent to or overlie archaeological deposits. While Step 1 focuses on ecological conditions, responsible restoration always includes a cultural heritage check before any excavation or hydrological work. A dedicated page on this site provides guidance on how to do this.

Walking the Site and Observing Water Movement

Water movement is the organising force of a mangrove ecosystem. Healthy sites “breathe” with each tide: water flows in, circulates through the forest, and drains away. As you walk the site, pay attention to whether this rhythm is still intact.

Look for how water enters and exits the area. Are channels open? Are they shallow and natural, or have they been altered by storms, debris, or construction? Does water drain freely at low tide, or does it linger in pockets that never empty? Even small changes—like a raised road edge or a blocked culvert—can isolate parts of a wetland and push them into long-term stagnation.

Seasonality matters. A site observed only during the dry season may seem stable, while wet-season conditions reveal persistent flooding or altered flow paths. Storm history also matters: storm surge can cut new channels, deposit wrack, or block old drainage routes. Step 1 asks you to see these patterns as part of the site’s story.

Reading the Soil and Sediment

Mangrove soils are naturally waterlogged and anoxic below a thin surface layer. This is a normal, healthy condition. What matters is whether the sediment shows a functional anoxic gradient supported by tidal flushing, or the uniform stagnation that develops when water is trapped and cannot circulate.

Healthy sediment often has a light grey or brown surface underlain by darker reduced soil. When disturbed, it releases a mild organic smell, and the texture is soft but cohesive. Mangrove roots in these soils are firm and pale inside, and propagules tend to survive.

Stagnant sediment sends a different signal: a strong hydrogen sulphide odor; jet-black mud from the surface down; a soupy, collapsing texture; or continuous bubbling when probed. These features indicate prolonged waterlogging and sulphide accumulation, conditions lethal to seedlings and incompatible with restoration until hydrology is repaired.

The soil beneath your feet is one of the clearest indicators of ecological function. A simple stick test—pressing gently, twisting, and lifting—reveals texture, smell, and aeration patterns that tell you whether the site is receiving tidal renewal.

Letting the Vegetation Tell Its Story

Mangrove vegetation is a map of long-term ecological processes. As you move through the forest, observe which species grow where and how healthy they appear. Look at the canopy: is it continuous, or thinning at the edges? Are trees producing new leaves and prop roots, or are branches dying back? Are pneumatophores short and abundant, or unusually elongated due to hypoxia?

Patterns in vegetation often mirror patterns in water movement. A sudden change from healthy Rhizophora to dying Avicennia can reveal shifts in salinity, hydroperiod, or sediment chemistry long before instruments could.

Pay close attention to natural regeneration. Clusters of surviving seedlings indicate areas that still function ecologically, while repeated seedling mortality points toward deeper issues like sulphide toxicity, altered hydroperiod, or shading. If propagules accumulate but fail to root, ask what has changed in the soil or water dynamics.

Elevation, Microtopography, and Hydroperiod

Small changes in elevation create large differences in flooding patterns. As you walk, notice low points where water lingers, slightly raised mounds where trees appear healthier, and storm-deposited ridges that alter flow paths. These microtopographic features determine whether the hydroperiod—a site’s pattern of tidal flooding—is still within the range tolerated by mangrove species.

A few centimeters can decide whether seedlings survive or drown. Recognizing these subtle variations helps determine which species can grow where and whether hydrological repair is needed.

Freshwater Influence and Watershed Inputs

Grenada’s mangrove systems often sit at the receiving end of hillside runoff. During the wet season, freshwater pulses can bring sediment, nutrients, or debris. In the dry season, the absence of freshwater may shift salinity to levels some species find stressful. Notice how the site responds across seasons and whether runoff is natural or shaped by drainage infrastructure.

Freshwater influence also affects sediment chemistry: too much freshwater can trap fine sediments, while too little can concentrate salts. These patterns inform the site’s restoration potential.

Clues from Ecological History

Sometimes the site contains physical traces of what used to exist: buried peat layers, old root mats, or shell deposits associated with former mangrove edges. These features help determine whether mangroves historically occupied the site and which species were present. They can also indicate how much sediment has accumulated over time and how hydrology has shifted.

Documenting Your Observations

Throughout Step 1, take photographs of:

water levels in different parts of the site,
sediment colour and structure,
vegetation patterns,
blockages and channels,
storm debris or altered flow paths.

Sketch simple site maps noting where water drains, where it lingers, and where vegetation changes. These records will be essential in Step 2 when you begin diagnosing site hydrology.

Bringing the Site’s Story Together

By the end of Step 1, you should have a clear narrative of the site’s ecological condition:

how water moves through the area and where it gets trapped,
whether the soil reflects healthy tidal exchange or prolonged stagnation,
what vegetation patterns reveal about stress or resilience,
how microtopography shapes flooding,
how freshwater and storm processes influence the site,
where human modifications have altered hydrology, and
what evidence remains of past mangrove cover.

This understanding is the foundation of all restoration decisions. Step 2 will build on this by examining hydrology in detail and determining what must be restored before planting can succeed.