Evaluation of the mangrove system in the estero "Arroyo los Coamiles" (Punta de Mita, Nayarit, Mexico)

In March 2019, the current state of the mangrove structure in the Arroyo los Coamiles estuary (Punta Mita Bay, Nayarit) was evaluated. The method of circular plots centered on a point was used (Cottam and Curtis, 1956). The mangrove structure is made up of the species Laguncularia racemosa, Avicennia germinans, Conocarpus erectus and Rhizophora mangle. The greatest forest development is found in the second third of the estuary with a bordercontinental structure. The average height of the mangroves was 6.17 m, (SD 7.35 m), the diameter at breast height was 19.21 cm and the total basal area was 57.36 m2 . The data are associated with young trees in a good state of development and conservation. The C / N ratio was determined as an index of the quality of the soil organic substrate, the values ranged between 3.74 and 14.91 and the percentage of organic matter was from 1.45 to 8.04. The fragility of the soils reinforce the proposal to take care of the natural drainage of the property. Mangroves have been impacted by tourist developments around the world, the environmental and economic benefits that these ecosystems provide are ignored by inhabitants and authorities, which allow their destruction.

ANALISIS STRUKTUR KOMUNITAS MANGROVE DI KAWASAN SEKITAR PT. CONCH KABUPATEN BOLAANG MONGONDOW

This research was conducted for four months of April-July 2020. The purpose of this study was to determine species density, species relative density, species frequency, species relative frequency, species cover, species relative cover, index of the importance of mangrove species in the area around PT. Conch Lolak District, Bolaang Mongondow Regency, North Sulawesi Province. This research was conducted for four months of April-July 2020. The method used was a quadratic plot of 6 stations. Data collection at each station was made with a plot size of 10 × 10 m2 to measure the diameter of a tree at breast height (DBH), which has a minimum trunk circumference of 16 cm. The results showed that there were five types of mangroves, namely R. apiculata, R. mucronata, B. gymnorhiza, S. alba, and X. granatum. The highest relative density of species at station 2, namely R. mucronate 62.96%, while the lowest value at station 3, namely R. mucronata 8.77%, the highest relative frequency value at station 4, namely R. mucronata 33.33%, whereas the lowest value was at station 5, namely B. gymnorhiza 25.00%, the highest relative closure value was at station 5, namely R. mucronata 30.91%, while the lowest was at station 2, namely R. apiculata 12.88%, and the important value index the highest was at station 3, namely R. apiculata 138.09% and the lowest value was at station 5, namely X. granatum 35.05%.Kata Kunci: Mangrove, Structure in areas around PT. Conch. Conch, Rhizopora Abstrak Penelitian ini dilakukan selama 4 bulan April-Juli 2020. Tujuan penelitian ini adalah untuk mengetahui kerapatan jenis, kerapatan relatif jenis, frekuensi jenis, frekuensi relatif jenis, penutupan jenis, penutupan relatif jenis, indeks nilai penting jenis mangrove yang ada di kawasan sekitar PT. Conch Kecamatan Lolak, Kabupaten Bolaang Mongondow, Provinsi Sulawawesi Utara. Penelitian ini dilakukan selama 4 bulan April-Juli 2020. Metode yang dipakai adalah plot kuadrat sebanyak 6 stasiun. Pengambilan data pada setiap stasiun dibuat plot dengan ukuran 10 × 10 m2 untuk mengukur diameter pohon setinggi dada (DBH) yang memiliki lingkar batang minimal 16 cm. Hasil penelitian menunjukkan bahwa ada 5 jenis mangrove yaitu R. apiculata, R. mucronata, B. gymnorhiza, S. alba dan X. granatum. Kerapatan relatif jenis tertinggi pada stasiun 2, yaitu R. mucronata 62,96%, sedangkan nilai terendah pada stasiun 3, yaitu R. mucronata 8,77%, nilai Frekuensi relatif jenis tertingi pada stasiun 4, yaitu R. mucronata 33.33%, sedangkan nilai terendah pada stasiun 5, yaitu B. gymnorhiza 25.00%, nilai Penutupan relatif jenis tertinggi pada stasiun 5, yaitu R. mucronata 30,91%, sedangkan terendah pada stasiun 2, yaitu R. apiculata 12,88%, dan Indeks nilai penting tertinggi pada stasiun 3, yaitu R. apiculata 138,09% dan nilai terendah pada stasiun 5, yaitu X. granatum 35,05%.Kata Kunci: Mangrove, kawasan sekitar PT. Conch, Rhizopora

An R package for computation of mangrove forest structural parameters using plot and plotless methods

Mangrove structure is influenced not only by the magnitude and periodicity of favorable energy inputs (temperature, hydroperiod, tides, sunlight, and nutrients), but also by stressors (salinity, drought, storms, and frost), which may have a diminishing effect on forest structure. In worldwide characterization of mangrove forests, researchers use several structural parameters to inform, compare, classify, and evaluate mangrove communities for both research and management. However, the calculation of these structural parameters involves a multi-step series of protocols and formula applications that are error-prone and time consuming. Using standard mangrove structure methodologies found in the literature, the mangroveStructure package for R was developed to deliver a simple tool to quickly calculate mangrove forest structure based on either plot or plotless methods. Outputs of the package include density, diameter, basal area, height, as well as relative values of density, dominance, frequency, and importance value. Output also includes common structural indices (complexity index and mean stand diameter) and visual representations of relative values, diameter and height histograms, and canopy height distributions along the transect line. This package will be useful to scientists interested in mangrove field surveys and those seeking a better understanding of mangrove ecosystems structural variability. To familiarize users with its many features, the package includes example data sets collected in the mangroves of Darién, Panama, and south Florida, USA.

Mapping the Mangrove Forest Canopy Using Spectral Unmixing of Very High Spatial Resolution Satellite Images

Despite the low tree diversity and scarcity of the understory vegetation, the high morphological plasticity of mangrove trees induces, at the stand level, a very large variability of forest structures that need to be mapped for assessing the functioning of such complex ecosystems. Fully constrained linear spectral unmixing (FCLSU) of very high spatial resolution (VHSR) multispectral images was tested to fine-scale map mangrove zonations in terms of horizontal variation of forest structure. The study was carried out on three Pleiades-1A satellite images covering French island territories located in the Atlantic, Indian, and Pacific Oceans, namely Guadeloupe, Mayotte, and New Caledonia archipelagos. In each image, FCLSU was trained from the delineation of areas exclusively related to four components including either pure vegetation, soil (ferns included), water, or shadows. It was then applied to the whole mangrove cover imaged for each island and yielded the respective contributions of those four components for each image pixel. On the forest stand scale, the results interestingly indicated a close correlation between FCLSU-derived vegetation fractions and canopy closure estimated from hemispherical photographs (R2 = 0.95) and a weak relation with the Normalized Difference Vegetation Index (R2 = 0.29). Classification of these fractions also offered the opportunity to detect and map horizontal patterns of mangrove structure in a given site. K-means classifications of fraction indeed showed a global view of mangrove structure organization in the three sites, complementary to the outputs obtained from spectral data analysis. Our findings suggest that the pixel intensity decomposition applied to VHSR multispectral satellite images can be a simple but valuable approach for (i) mangrove canopy monitoring and (ii) mangrove forest structure analysis in the perspective of assessing mangrove dynamics and productivity. As with Lidar-based surveys, these potential new mapping capabilities deserve further physically based interpretation of sunlight scattering mechanisms within forest canopy.