Global Trends in Mangrove Forest Fragmentation

Fragmentation

— is a major driver of ecosystem degradation, reducing the capacity of habitats to provide many important ecosystem services

ubiquitous

Mangrove fragmentation was —; however, there are geographic disparities between mangrove loss and fragmentation; some regions, like Cambodia and the southern Caribbean, had relatively little loss, but their forests have been extensively fragmented.

aquaculture; rice plantations

In Southeast Asia, a global hotspot of mangrove loss, the conversion of forests to — and — were the biggest drivers of loss (>50%) and fragmentation.

Mangroves

— are intertidal wetlands found along coastlines in much of the tropical, subtropical and warm-temperate world. These forests provide valuable ecosystem services including preventing erosion1, providing habitat for fisheries species2, protecting coastal communities from extreme weather events3,4 and storing large reserves of blue carbon, thus mitigating global climate change5.

anthropogenic

The services provided by mangroves are threatened by — processes including deforestation6 and sea-level rise7,8.

3.6

Historically, mangroves were subject to high rates of deforestation of up to —% per annum9. However, since the turn of the millennium global mangrove deforestation rates have slowed, with annual loss rates of 0.2–0.7%10,11.

Southeast Asia; ~50

The majority of contemporary mangrove loss occurs in —, where —% of the remaining global mangrove forest area is located, with nations such as Indonesia, Malaysia and Myanmar continuing to show losses of 0.26, 0.41 and 0.70% per year, respectively10

True

T/F. For example, fragmented forests are likely to have a reduced capacity to ameliorate waves, and so will have higher through-flow of tidal waters leading to greater erosion of sediment substrate.

reduce

Increased sediment erosion may affect the capacity of mangroves to accrete and keep pace with sea level rise, so by increasing erosion fragmentation may — the ability of mangroves to adapt to sea level rise.

estuarine; fragmentation

Finally, the biological integrity of fragmented mangroves is compromised by lower species diversity of both birds and — fish. Thus, the capability for mangroves to provide critical habitat for many fished species may be jeopardised by —.

land-use

Fragmentation and loss were highly correlated in Southeast Asia, and this relationship was mediated by the specific — transition

Rank correlations

— indicate a strong relationship between the extent of loss and all fragmentation metrics (correlation coefficients ranged from 0.37 to 0.66, all correlations had p < 0.0001).

Mean patch area; mean nearest patch

— was the most responsive metric to loss (rank correlation coefficient of 0.66), while the — was the least responsive (rank correlation coefficient of 0.37).

aquaculture; ~0.15

Forests converted to — or rice plantations had the strongest correlation between fragmentation and deforestation, indicating a greater amount of fragmentation per unit area of deforestation for these types of land-use changes when compared to other types. The correlation coefficients for aquaculture and rice plantations were — higher for these two land-uses than all others.

oil palm

The relationship between fragmentation and deforestation was weakest for conversion to — plantations

lost

Changes in the fragmentation metrics for the nearest patch and mean patch size can either increase or decrease when mangroves are —.

Southeast Asia

— is one of the major areas of concern for mangrove conservation because it has the highest mangrove tree species diversity33, the greatest areal extent of mangrove forest globally, and high deforestation rates10.

patch size

Distance to the nearest neighbour and — are important for maintaining migration corridors and patch residency, respectively, meaning that distinct drivers of deforestation (not just the extent of deforestation) may have differing effects on mangrove ecosystem functionality.

mean patch size

For example, in landscapes dominated by mangrove regrowth (including regions with mangrove forestry), loss is highly correlated with — (r = 0.72) and less so for nearest mangrove forest (r = 0.31).

mangrove forestry

Accordingly, — may adversely impact the capacity of a forest to harbour species, without affecting its suitability as a faunal migration corridor.

land-use

We found the correlation between deforestation and fragmentation depends on what — mangroves were converted to.

aquaculture; rice paddies

Mangroves deforestation and fragmentation were more strongly linked for conversion to — or — than for conversion to oil-palm plantations.

acutely

Conversion to oil palm plantations may occur as single continuous blocks from the landward side, often removing larger and contiguous forest patches. In contrast, conversion to rice paddies or aquaculture may occur as many smaller intrusions and thus fragment mangroves more —.