Past, Present and Future Global Mangrove Primary Productivity

Abstract

Mangrove productivity plays an important role in the global carbon cycle. However, productivity research has been limited to temporal changes on small local scales or to focusing on large global patterns in productivity at one point in time, with little research into global/regional temporal trends in mangrove productivity. This study leveraged previously published data on mangrove leaf litter to model global and regional scale mangrove productivity on a monthly timescale from 1980 to 2094. Regions were defined by the Marine Ecoregions of the World marine provinces framework. Models revealed minimal change to NPP, as global productivity rates dropped by only ~1.4% from 239.2 ±87.6 Tg yr-1 between 1980 and 1990 to 235.9 ±81.9 Tg yr-1 between 2085 to 2094. Despite little global change in NPP, significant regional change was detected, particularly in the subtropics. Particularly dramatic increases were found for the Southwest Australian Shelf (60.58 ±97.9%), the Warm Temperate Northeast Pacific (43.75 65.7%) and the Warm Temperate Northwest Pacific (31.55 55.7%). While significant decreases in NPP relative to historical rates are forecasted for the Southeast Asian marine provinces, the Java Transitional province (11.45 ±6.2%) and the Western Coral Triangle (7.61 9.6%). This study is the first to predict monthly global and regional mangrove NPP into the 21st century. The models reveal significant regional changes not previously reported. These findings have implications for future mangrove carbon sequestration and coastal habitat carbon cycling. The relative shifts in NPP reported here would impinge on the input rates of mangrove derived organic matter and would greatly increase or decrease mangrove litter export to neighbouring ecosystems.

Keywords: Mangrove productivity, Mangrove litterfall, Climate change, Global mangrove ecology