RELATIONSHIP BETWEEN CLIMATIC CONDITION AND MANGROVE FOREST STRUCTURE ON NORTHERN COAST OF VIETNAM

The differences in mangrove forest structure, climate, and the linear relationship between climate and mangrove forest structure on the northern coast of Vietnam were analyzed using mangrove forest data measured in 28 sample plots (Dong Rui-8, Xuan Thuy National Park-12 and Lach Sung-8) and climate data collected at the meteorological stations near the study sites (Dong Rui-Tien Yen station, Xuan Thuy National Park-Van Ly station and Lach Sung-Thanh Hoa station) in the period of 1994 - 2012. Results showed that the differences in mangrove forest structure (stem diameter, biomass and basal area) and climate (temperature and rainfall) among study sites were significant (p < 0.05). Stem diameter, tree height, basal area and biomass had positive linear relationship with annual average temperature and January average temperature, and negative linear relationship with annual rainfall. A consistently low regression coefficient of less than 0.66 was found among the variables. However, all the regression models were statistically significant (p < 0.05). The results could be used to develop multiple linear regression models to predict the change of mangrove ecosystems.

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Mangrove Forest Landcover Changes in Coastal Vietnam: A Case Study from 1973 to 2020 in Thanh Hoa and Nghe An Provinces

Forests ◽

10.3390/f12050637 ◽

2021 ◽

Vol 12 (5) ◽

pp. 637

Author(s):

Huong Thi Thuy Nguyen ◽

Giles E. S. Hardy ◽

Tuat Van Le ◽

Huy Quoc Nguyen ◽

Hoang Huy Nguyen ◽

...

Keyword(s):

Mangrove Forest ◽

Monsoon Season ◽

Coastal Development ◽

Northern Coast ◽

Mangrove Forests ◽

Visual Interpretation ◽

Mangrove Restoration ◽

Coast Of Vietnam ◽

Landsat Satellite

Mangrove forests can ameliorate the impacts of typhoons and storms, but their extent is threatened by coastal development. The northern coast of Vietnam is especially vulnerable as typhoons frequently hit it during the monsoon season. However, temporal change information in mangrove cover distribution in this region is incomplete. Therefore, this study was undertaken to detect change in the spatial distribution of mangroves in Thanh Hoa and Nghe An provinces and identify reasons for the cover change. Landsat satellite images from 1973 to 2020 were analyzed using the NDVI method combined with visual interpretation to detect mangrove area change. Six LULC classes were categorized: mangrove forest, other forests, aquaculture, other land use, mudflat, and water. The mangrove cover in Nghe An province was estimated to be 66.5 ha in 1973 and increased to 323.0 ha in 2020. Mangrove cover in Thanh Hoa province was 366.1 ha in 1973, decreased to 61.7 ha in 1995, and rose to 791.1 ha in 2020. Aquaculture was the main reason for the loss of mangroves in both provinces. Overall, the percentage of mangrove loss from aquaculture was 42.5% for Nghe An province and 60.1% for Thanh Hoa province. Mangrove restoration efforts have contributed significantly to mangrove cover, with more than 1300 ha being planted by 2020. This study reveals that improving mangrove restoration success remains a challenge for these provinces, and further refinement of engineering techniques is needed to improve restoration outcomes.

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Site Factors Influence on Herbaceous Understory Diversity in East Texas Pinus palustris savannas

International Journal of Biology ◽

10.5539/ijb.v11n1p1 ◽

2018 ◽

Vol 11 (1) ◽

pp. 1 ◽

Cited By ~ 2

Author(s):

Brooke McCalip ◽

Brian P. Oswald ◽

Kathryn R. Kidd ◽

Yuhui Weng ◽

Kenneth W. Farrish

Keyword(s):

Forest Structure ◽

Longleaf Pine ◽

Basal Area ◽

Pinus Palustris ◽

East Texas ◽

Site Factors ◽

Understory Species ◽

Solar Exposure ◽

Site Characteristics ◽

Study Sites

Longleaf pine (Pinus palustris) savannas were once dominant across the southeastern U.S., including East Texas and parts of western and central Louisiana. The diverse understory associated with these historical savannas may occasionally be seen today, but not often in longleaf pine ecosystems. This project aimed to define east Texas site characteristics that are necessary to support these ecosystems with a dense and diverse herbaceous understory with little to no midstory cover. Fifty-nine plots across three study sites were established to evaluate the influence of overstory cover, basal area, aspect, elevation, and slope on the number of plant genera present. Forest structure and site characteristics had significant effects on the number of plant genera found. The number of genera increased with higher elevation and slope; as elevation increased, there was a decline in basal area and overstory cover, leading to a more diverse, understory layer. In order to re-establish and maintain a diverse, herbaceous understory in longleaf pine savannas, sites with more open canopies and on slopes with the most solar exposure should be given priority, particularly when planting desired understory species.

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Recovery of Forest Structure Following Large-Scale Windthrows in the Northwestern Amazon

Forests ◽

10.3390/f12060667 ◽

2021 ◽

Vol 12 (6) ◽

pp. 667

Author(s):

J. David Urquiza Muñoz ◽

Daniel Magnabosco Marra ◽

Robinson I. Negrón-Juarez ◽

Rodil Tello-Espinoza ◽

Waldemar Alegría-Muñoz ◽

...

Keyword(s):

Forest Structure ◽

Large Scale ◽

Tree Mortality ◽

Basal Area ◽

Forest Recovery ◽

Old Growth ◽

Study Region ◽

Central Amazon ◽

Old Growth Forest ◽

Study Sites

The dynamics of forest recovery after windthrows (i.e., broken or uprooted trees by wind) are poorly understood in tropical forests. The Northwestern Amazon (NWA) is characterized by a higher occurrence of windthrows, greater rainfall, and higher annual tree mortality rates (~2%) than the Central Amazon (CA). We combined forest inventory data from three sites in the Iquitos region of Peru, with recovery periods spanning 2, 12, and 22 years following windthrow events. Study sites and sampling areas were selected by assessing the windthrow severity using remote sensing. At each site, we recorded all trees with a diameter at breast height (DBH) ≥ 10 cm along transects, capturing the range of windthrow severity from old-growth to highly disturbed (mortality > 60%) forest. Across all damage classes, tree density and basal area recovered to >90% of the old-growth values after 20 years. Aboveground biomass (AGB) in old-growth forest was 380 (±156) Mg ha−1. In extremely disturbed areas, AGB was still reduced to 163 (±68) Mg ha−1 after 2 years and 323 (± 139) Mg ha−1 after 12 years. This recovery rate is ~50% faster than that reported for Central Amazon forests. The faster recovery of forest structure in our study region may be a function of its higher productivity and adaptability to more frequent and severe windthrows. These varying rates of recovery highlight the importance of extreme wind and rainfall on shaping gradients of forest structure in the Amazon, and the different vulnerabilities of these forests to natural disturbances whose severity and frequency are being altered by climate change.

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

Madera y Bosques ◽

10.21829/myb.2019.2511696 ◽

2019 ◽

Vol 25 (1) ◽

Cited By ~ 1

Author(s):

Rafael J. Araújo ◽

Geoffrey S. Shideler

Keyword(s):

Forest Structure ◽

Mangrove Forest ◽

Structural Parameters ◽

Basal Area ◽

R Package ◽

South Florida ◽

Mangrove Forests ◽

Importance Value ◽

Transect Line ◽

Mangrove Structure

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.

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Mangrove forest structure and composition along urban gradients in Puerto Rico

10.1101/504928 ◽

2018 ◽

Cited By ~ 2

Author(s):

Benjamin Branoff ◽

Sebastian Martinuzzi

Keyword(s):

Puerto Rico ◽

Surface Water ◽

Water Chemistry ◽

Forest Structure ◽

Vegetation Cover ◽

Mangrove Forest ◽

Canopy Cover ◽

Basal Area ◽

Surface Water Chemistry ◽

Nitrogen Concentrations

Urban forests are repeatedly characterized as distinct in composition and structure in comparison with their non-urban counterparts. This holds true for mangroves, although previous studies lack quantified representations of urbanness as well as any inclusion of hydrology or water chemistry, which are important influences on mangrove forest structure, composition, and function. This study uses LiDAR and ground-based measurements of mangroves within well quantified urban gradients in Puerto Rico to test for the relative importance of urbanization alongside flooding metrics and surface water chemistry in explaining observed patterns of forest structure and composition. In simple regression, urban metrics were the most powerful predictors of forest composition but not structure. Results show higher tree diversity but lower mangrove diversity in the most urban forests. Structural measurements, however, were best explained by flooding, surface water chemistry, and non-urban land cover metrics. Nitrogen concentrations best explained stem density and tree size, while flooding metrics best explained stand biomass and basal area, and surrounding vegetation cover best explained canopy cover and height metrics. In multiple regression, land cover and surface water chemistry were more important than flooding, with population density again being the most important variable in explaining mangrove forest diversity. Results show that urbanization is an important influence on mangrove composition and basal area, leading to higher tree diversity and lower basal area, consistent with patterns in terrestrial forests. But urban mangrove forests are also lower in mangrove diversity and tend to have representation only by Laguncularia racemosa. Nitrogen concentrations and surrounding vegetation cover, both of which are indirectly influenced by urbanization, were positively related to tree size and canopy cover and height, respectively. These tests suggest urbanization is an important influence on mangrove forest structure and composition, but that flooding and water chemistry must also be considered when managing these forests.

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Big trees drive forest structure patterns across a lowland Amazon regrowth gradient

Scientific Reports ◽

10.1038/s41598-021-83030-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tassiana Maylla Fontoura Caron ◽

Victor Juan Ulises Rodriguez Chuma ◽

Alexander Arévalo Sandi ◽

Darren Norris

Keyword(s):

Forest Structure ◽

Natural Regeneration ◽

Basal Area ◽

Significant Decline ◽

Forest Regrowth ◽

Large Trees ◽

Amazonian Forests ◽

Mammal Diversity ◽

Structure Patterns ◽

Plot Type

AbstractDegraded Amazonian forests can take decades to recover and the ecological results of natural regeneration are still uncertain. Here we use field data collected across 15 lowland Amazon smallholder properties to examine the relationships between forest structure, mammal diversity, regrowth type, regrowth age, topography and hydrology. Forest structure was quantified together with mammal diversity in 30 paired regrowth-control plots. Forest regrowth stage was classified into three groups: late second-regrowth, early second-regrowth and abandoned pasture. Basal area in regrowth plots remained less than half that recorded in control plots even after 20–25 years. Although basal area did increase in sequence from pasture, early to late-regrowth plots, there was a significant decline in basal area of late-regrowth control plots associated with a decline in the proportion of large trees. Variation in different forest structure responses was explained by contrasting variables, with the proportion of small trees (DBH < 20 cm) most strongly explained by topography (altitude and slope) whereas the proportion of large trees (DBH > 60 cm) was explained by plot type (control vs. regrowth) and regrowth class. These findings support calls for increased efforts to actively conserve large trees to avoid retrogressive succession around edges of degraded Amazon forests.

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Sorption and desorption of phenanthrene and fluorene in mangrove forest soils of the Morrocoy National Park, Venezuelan Caribbean

GEOCHEMICAL JOURNAL ◽

10.2343/geochemj.2.0621 ◽

2021 ◽

Vol 55 (2) ◽

pp. 103-115

Author(s):

Katya Reategui ◽

Rosa Amaro ◽

Laxmi Rodríguez ◽

Carelys Salazar ◽

Raiza Fernández ◽

...

Keyword(s):

Forest Soils ◽

Mangrove Forest ◽

National Park

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The role of forest deadwood in rockfall protection

10.5194/egusphere-egu21-10791 ◽

2021 ◽

Author(s):

Adrian Ringenbach ◽

Peter Bebi ◽

Perry Bartelt ◽

Andrin Caviezel

Keyword(s):

Basal Area ◽

Spruce Forest ◽

Runout Distance ◽

In Situ Sensors ◽

Efficient Protection ◽

Cost Efficient ◽

Study Sites ◽

Rockfall Protection

<p>Forests with a high density and basal area of living trees are known for their function as natural and cost-efficient protection against rockfall. The role of deadwood, however, is less understood. We address this knowledge gap in this contribution as we present the results of repeated real-scale experiments in a) a montane beech-spruce forest with and without deadwood and b) in a subalpine scrub mountain pine-spruce forest with deadwood. We used artificial rocks with either an equant or platy shape, masses between 45 kg and 800 kg (&#8776; 0.3 m3), and equipped with in-situ sensors to gain insights into rotational velocities and impact-accelerations. Clusters of deadwood and erected root plates reduced the mean runout distance at both study sites. For site a), we found that more rocks were stopped behind lying than living trees and that the stopping effect of deadwood was greater for equant compared to platy rock shapes. Site b) revealed a braking effect of scrub mountain pines for relatively small (45 kg), but also a visible reduction in rotational velocities for the 800 kg rocks sensor stream. We conclude that deadwood must be taken into account in rockfall modeling and the management of rockfall protection forests.</p>

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Excavation of Red Squirrel (Tamiasciurus hudsonicus) Middens by Bears (Ursus spp.) in Limber Pine (Pinus flexilis) Habitat in Banff National Park, Alberta

The Canadian Field-Naturalist ◽

10.22621/cfn.v130i4.1918 ◽

2017 ◽

Vol 130 (4) ◽

pp. 281 ◽

Cited By ~ 2

Author(s):

David Hamer

Keyword(s):

National Park ◽

Forest Cover ◽

Habitat Characteristics ◽

Tamiasciurus Hudsonicus ◽

Red Squirrel ◽

Limber Pine ◽

Banff National Park ◽

Pine Stands ◽

Study Sites ◽

Pinus Spp

Bears (Ursus spp.) in North America eat the seeds of several pines (Pinus spp.), including Limber Pine (P. flexilis E. James). Information on use of Limber Pine in Canada is limited to a report of three bear scats containing pine seeds found in Limber Pine stands of southwestern Alberta. After my preliminary fieldwork in Banff National Park revealed that bears were eating seeds of Limber Pine there, I conducted a field study in 2014–2015 to assess this use. Because bears typically obtain pine seeds from cone caches (middens) made by Red Squirrels (Tamiasciurus hudsonicus), I described the abundance, habitat characteristics, and use by bears of Red Squirrel middens in and adjacent to Limber Pine stands at six study sites. On Bow River escarpments, I found abundant Limber Pines (basal area 1–9 m2/ha) and middens (0.8 middens/ha, standard deviation [SD] 0.2). Of 24 middens, 13 (54%) had been excavated by bears, and three bear scats composed of pine seeds were found beside middens. Although Limber Pines occurred on steep, xeric, windswept slopes (mean 28°, SD 3), middens occurred on moderate slopes (mean 12°, SD 3) in escarpment gullies and at the toe of slopes in forests of other species, particularly Douglas-fir (Pseudotsuga menziesii). At the five other study sites, I found little or no use of Limber Pine seeds by bears, suggesting that Limber Pine habitat may be little used by bears unless the pines are interspersed with (non-Limber Pine) habitat with greater forest cover and less-steep slopes where squirrels establish middens. These observations provide managers with an additional piece of information regarding potential drivers of bear activity in the human-dominated landscape of Banff National Park’s lower Bow Valley.

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