TAGBILARAN CITY, Bohol (PIA) — Groups planning to plant mangroves in Bohol should first have their sites assessed by local agriculture or environment offices and should avoid seagrass beds, the Bohol Provincial Environment Management Office (BPEMO) said.
Maria Villa Pelindingue, head of the BPEMO Coastal Resource Management Division, said mangroves should be planted only in areas where they naturally occur.
“Our plea to coastal LGUs and interest groups and volunteers in Bohol: please coordinate with the Municipal Agriculture Offices or the Municipal Environment and Natural Resources Office on where you intend to plant so that you could be given the proper assessed area, and the kind of mangrove species fitted for the site,” Pelindingue said.
She said seagrass beds may appear to be open, unused areas, but they are a distinct ecosystem that works together with mangroves and coral reefs.
Planting mangroves in healthy seagrass beds disrupts that balance, she said.
Mangroves are salt-tolerant trees, shrubs, palms, and ferns — including nipa palms — that grow in the intertidal zones of tropical and subtropical coastlines, where they are regularly flooded by seawater and grow in waterlogged soils.
“Surviving this harsh environment, mangroves use specialized prop roots, stilt roots, or aerial roots that provide support and allow oxygen uptake in waterlogged soils, in areas that are alternately flooded and exposed by the tides,” Pelindingue said.
“The same root systems also make mangroves better at providing coastal protection by reducing effects of storm surges, waves, erosion, and flooding, while at the same time, providing for a nursery habitat for fish, crabs, shrimps, shellfish and supporting fishing, ecotourism, livelihoods by sustainable harvesting, and even providing habitat for several land species, domestic and migratory birds,” she said.
Pelindingue said mangroves also absorb and store large amounts of carbon, and that their root systems trap sediments, pollutants and debris that would otherwise reach and damage seagrass beds.
The three ecosystems function in sequence, she said. Mangroves trap sediment carried by rivers before it reaches the sea, filter nutrients and pollutants from land runoff and reduce shoreline erosion, allowing clearer water to reach seagrass beds and reefs.
Seagrasses, which grow in shallow water between mangroves and reefs, trap finer sediments, stabilize the seabed, and shelter juvenile fish that move out from mangrove areas as they mature.
Coral reefs break incoming waves and reduce wave energy, protecting both seagrass beds and mangrove shorelines from erosion.
“As mangroves provide coastal protection and long-term carbon storage, seagrass beds also store carbon, stabilize sediments, and purify water while coral reefs provide wave protection and marine biodiversity,” Pelindingue said.
She said interest in mangrove planting grew after coastal communities reported that mangrove stands reduced wave damage during Typhoon Yolanda in November 2013, prompting groups to expand plantings into open seagrass areas.
Pelindingue also said some mangrove species have stronger prop roots that allow them to survive in areas with heavier wave action, which is one of the reasons site assessment is important before planting.
She said mangroves were the preferred species for planting activities for Environment Month and Arbor Day last June, when Boholanos expect the dry season to reduce the survival rate of newly planted upland trees.
A 2019 review published in the Davao Research Journal documented 35 mangrove species in the Philippines and identified Bohol as having the country’s most diverse mangrove ecosystem, with 26 to 34 species recorded. (RAHC/PIA Bohol)
