Evaluation of mangrove structure and condition in two trans‐boundary areas in the Western Indian Ocean

Abstract

ABSTRACT1. The structure, forest condition and regeneration status of nine mangrove forests in two trans-boundary areas of Mozambique bordering Tanzania and South Africa were studied. The main objective was to estimate the cutting intensity in the selected sites -Saco and Sangala in southern Mozambique; Mecu´fi, Pemba, Ibo, Luchete, Ulo in northern Mozambique, and Mngoji 1 and Mngoji 2 in Tanzania.2. A total of 135, 10 m  10 m quadrats were set in the outer, middle and lower parts of the mangrove forests at all sampling sites. Measurements included stem diameter at breast height (DBH) and height of adult trees (i.e. all trees with stem diameter more than 2.5 cm). Young trees (with stem diameter of less than 2.5 cm) were classified as juveniles. To assess forest condition, trees within the quadrat were classified into intact, partially cut, coppiced, die back and stump. Pole quality was appraised through the classification of the lead stem into three categories-straight, semi-straight and crooked poles.3. The results indicate different levels of exploitation with Mngoji 1 and Mngoji 2, the most degraded sites, having stump densities of 959 stumps ha À1 and 592 stumps ha À1, respectively. Most sites had mostly poles of inferior quality (crooked poles), but high densities of straight and semi-straight poles were found in Mngoji 1 (742 stems ha À1 ) and Saco (636 stems ha À1). 4. Natural regeneration was observed in most sites but not for all species, with adequate regeneration in Saco (14 766 saplings ha À1) and Mecu´fi (14 706 saplings ha À1 ), while low regeneration was recorded in Mngoji 1 and 2 (2212 saplings ha À1 and 4799 saplings ha À1 , respectively). 5. These results indicate the need for improved mangrove management and replanting especially in mangrove depleted conservation areas of southern Tanzania.

Analysis of cover change (1995–2005) of Tanzania/Mozambique trans‐boundary mangroves using Landsat imagery

“…Both can occur as a result of natural phenomena and human activities: qualitative human-induced changes in landscapes include selective logging, whereas quantitative land-cover change occurs mostly as a result of forest clearing and agricultural and urban expansion (Seto et al, 2002). Our findings and those of Bandeira et al (2009) show that the selective cutting and logging may not be detectable with the 30 m sensor resolution.…”

“…Based on the results of this study, the area of mangrove along the Mtwara-Quirimbas Complex appears to be relatively stable, with an estimated overall increase of about 3% in mangrove cover between 1995 and 2005. However, this may be an incomplete depiction of reality as Bandeira et al (2009) found that all the sites showed varying degrees of disturbance due to cutting for construction and fuel.…”

Use of satellite remote sensing for coastal conservation in the Eastern African Coast: advantages and shortcomings

“…The comparison of mangrove distribution and cover in 1995 and 2005, presented and discussed in detail in Ferreira et al [2009a], showed an overall increase of about 3% in mangrove area estimated from large scale remote sensing alone. Integration of the results of dedicated field work, however, suggested that these results might be misleading regarding mangrove condition, as most of the sites studied in the field showed signs of disturbance due to selective logging for construction and fuel [Bandeira et al, 2009]. The map of coastal habitats for 2005 constituted a reference for subsequent studies, specifically for identifying smaller areas of interest that were looked at in greater detail.…”

Deteksi Perubahan Luasan Mangrove Teluk Youtefa Kota Jayapura Menggunakan Citra Landsat Multitemporal

“…Dampak dari mengkonversi dan penebangan mangrove tidak hanya berakibat terhadap hilangnya tutupan mangrove tapi yang lebih penting adalah berubahnya struktur komunitas mangrove (Ferreira et al, 2009). Beberapa hasil kajian menyatakan bahwa gangguan secara antropogenik maupun alami dapat berpengaruh terhadap kerapatan tegakan, basal area dan kompleksitas jika dibandingkan dengan mangrove yang tidak mengalami gangguan (Bandeira et al, 2009;Urrego et al, 2014).…”