scholarly journals Dynamique des peuplements ligneux dans le Parc National de Manda, au sud du Tchad

2019 ◽  
Vol 42.1 ◽  
pp. 7139-7152
Author(s):  
Guiguindibaye MADJIMBE ◽  
Goy SARADOUM ◽  
Touroumgaye GOALBAYE ◽  
Esaïe WAYA ◽  
Jonathan POUNAKOUMNA
Keyword(s):  
National Park ◽  
Basal Area ◽  
Average Density ◽  
Anthropogenic Pressure ◽  
Average Volume ◽  
Specific Composition ◽  
Gradual Evolution ◽  
Standing Timber ◽  
Composition Spécifique ◽  
Structure Des Peuplements

1 RÉSUMÉ La présente étude a pour but d’étude la dynamique des peuplements ligneux dans le Parc National de Manda. Elle vise à déterminer les caractéristiques structurales, la composition spécifique et la régénération des peuplements ligneux. Quatre sites ont été implantés depuis 2012. Nous avons procédé à la caractérisation des peuplements ligneux par des relevés dendrométriques. La flore ligneuse dans l’ensemble des sites est riche de 87 espèces reparties en 56 genres et 22 familles. Les sites 1 et 2 ont des effectifs plus élevés en 2019 comparativement en 2014 et en 2012. Une forte régénération s’est effectuée durant l’année 2019. Contrairement aux sites, 1 et 2, les sites 3 et 4 présentent pour l’année 2019 une forte baisse des effectifs de jeunes plants. Ces jeunes plants sont très sensibles non seulement à la disponibilité des ressources en eau pour franchir la saison sèche mais aussi à l’intensité et à la fréquence de passage des feux. Les résultats ont permis de noter que la densité moyenne entre 2012 et 2014 s’est accrue et à partir de 2014 elle s’est stabilisée. La surface terrière par hectare est, en moyenne de 10,12 m2/ha pour 2012 ; 11,16 m2/ha pour l’année 2014 et de 11, 65 m2/ha pour l’année 2019. Pour l’ensemble des sites expérimentaux, on évalue le volume moyen de bois sur pieds à 12,31 m3/ha en 2012, à 12,46 m3/ha en 2014 et 12,08 m3/ha en 2019. Ces valeurs indiquent que les variations de volume moyen de bois sur pieds sont très faibles pour les sites pris dans leur ensemble. Les résultats obtenus, montrent aussi que 8 espèces se situent dans un processus d’évolution régressive et 4 autres dans un processus d’évolution progressive. La structure des peuplements ligneux n’a pas beaucoup évolué en 8 ans mais, elle apparaît fortement tributaire de la topographie et de la pression anthropique. ABSTRACT Dynamic of the woody populations in the National Park of Manda, to the south of Chad The purpose of this study is to study the dynamics of woody stands in the Manda National Park. It aims to determine the structure, specific composition and regeneration of woody stands. Four sites have been established since 2012. We have characterized the woody stands by dendrometric surveys. The woody flora in all sites is rich in 87 species divided into 56 genera and 22 families. Sites 1 and 2 have higher numbers in 2019 compared to 2014 and 2012. Strong regeneration took place in 2019. Unlike sites 1 and 2, sites 3 and 4 present for the year 2019 a sharp decline in the number of young plants; these seedlings are very sensitive not only to the availability of water resources to cross the dry season but also to the intensity and frequency of fire. The results showed that the average density between 2012 and 2014 increased and from 2014 it stabilized. The basal area per hectare is, on average, 10.12 m2 / ha for 2012; 11.16 m2 / ha for the year 2014 and 11, 65 m2 / ha for the year 2019. For all the experimental sites, the average volume of standing timber is estimated at 12.31 m3/ ha in 2012, 12.46 m3 / ha in 2014 and 12.08 m3 / ha in 2019. These values indicate that variations in average volume of standing timber are very low for sites taken as a whole. The results obtained also show that 8 species are in a process of regressive evolution and 10 in a process of gradual evolution. The structure of woody stands has not changed much in 8 years, but it appears highly dependent on topography and anthropogenic pressure.

scholarly journals Vegetation Dynamics in Treeline Ecotone of Langtang National Park, Central Nepal

1970 ◽  
Vol 11 ◽  
pp. 107-114 ◽  
Author(s):  
NP Gaire ◽  
YR Dhakal ◽  
HC Lekhak ◽  
DR Bhuju ◽  
SK Shah
Keyword(s):  
Tree Species ◽  
National Park ◽  
Basal Area ◽  
Anthropogenic Pressure ◽  
Climatic Warming ◽  
Seedling Density ◽  
Treeline Ecotone ◽  
Central Nepal ◽  
Abies Spectabilis ◽  
The Impact

A study was carried out at the treeline ecotone (3,730m-3,950m asl) of Langtang National Park in central Nepal with an aim to document the impact of climatic warming on ecological chracteristics. Three sampling sites were selected at Chaurikharka and Lauribina, where no serious anthropogenic pressure was noticed. The nearest meteorological station has records of climatic warming in recent years. Six tree species and three shrub species belonging to seven families were enumerated from the study plots. The average basal area for tree species was found to be 20.56 m2 per ha while average tree density was found to be 734 trees per ha with Abies spectabilis as dominant species. The mean DBH (diameter at breast height) of tree species was found to be 15.8 cm (max. 115.5cm). Density of dead trees accounted 2 no. per ha with basal area 0.195m2 per ha. Average sapling and seedling density of tree species per ha was observed to be 1,590 and 831 respectively. The average sapling and seedling density of A. spectabilis was 255 and 350 per ha respectively. Similarly, average shrub density (per ha) for the area was found to be 9,609 no/ha. The stand character showed that there was high level of recruitment of A. spectabilis in the recent years. The presence of sapling and seedling of A. spectabilis at higher altitude showing linear relationship with canopy coverage indicated prospects for a gradual and upward shift of A. spectabilis with increased temperature. Key words: Abies spectabilis; regeneration; climate change; DBH DOI: 10.3126/njst.v11i0.4132Nepal Journal of Science and Technology 11 (2010) 107-114

scholarly journals Vegetation Composition and Biomass Production in Community Forest in Sikre VDC adjoining Shivapuri National Park, Kathmandu

1970 ◽  
Vol 11 ◽  
pp. 133-138
Author(s):  
Sudip Pandey ◽  
Siddhartha Bajra Bajracharya
Keyword(s):  
Tree Species ◽  
National Park ◽  
Basal Area ◽  
Sampling Technique ◽  
Shannon Index ◽  
Systematic Sampling ◽  
Anthropogenic Pressure ◽  
Community Forest ◽  
Eupatorium Adenophorum ◽  
Castanopsis Indica

The present study describes the structural and floral composition of the vegetation of Sikre Village Development Committee (VDC) at Shivapuri National Park. Systematic sampling technique was used to analyze the vegetation of the forest. A quadrat size of 10mx10m was plotted at respective point for tree study and within 5mx5m plots for shrubs and 1mx1m for herbs analysis. The study recorded a total of 18 tree species from 13 families in the forest area. Among the trees, Uttis (Alnus nepalensis D. Don) and Chilaune [Schima wallichii (DC.) Korth.] were the most dominant species. The major shrubs of the forest areas comprised of Yurilo (Hypericum uralum Buch.-Ham. ex D. Don), Chutro (Berberis aristata DC.) and Angeri (Melastoma melabathricum L.). Among the herbs Bhui Amala (Phyllanthus freternus Webster), Unyu [Dryopteris filix-mas (L.) Schott.] and Banmara (Eupatorium adenophorum Spreng.) were dominant ones in forest ground. The aboveground biomass of tree species was found to be 4021.41kg/ha in which Dhalne katus [Castanopsis indica (Roxb.) Miq.] constituted the large percent of biomass of the forest. The estimated resources demand and supply showed the annual deficit of 112.038t/yr and the carbon stock was calculated to be 2.01t/ha. The Shannon Index of diversity was highest for tree (2.33) followed by shrub (2.22) and herb (2.17) respectively. The density of cut stumps and the density of lopping were 184/ha and 216/ha respectively, which showed that the anthropogenic pressure on community forest was prominent. Key words: basal area; biomass; species diversity; systematic sampling DOI: 10.3126/njst.v11i0.4135Nepal Journal of Science and Technology 11 (2010) 133-138

STRUCTURAL AND FLORISTIC CHARACTERIZATION OF THE OULED BECHIH FOREST (ALGERIA)

2021 ◽  
Author(s):  
Touafchia Boutheyna ◽  
Kadi Zahia ◽  
Redjaimia Lilia ◽  
Rached-Kanouni Malika
Keyword(s):  
Diversity Index ◽  
Basal Area ◽  
Woody Species ◽  
Quercus Suber ◽  
Average Density ◽  
Quercus Canariensis ◽  
Rational Management ◽  
Sustainable Conservation ◽  
Total Structure

The objective of this study is the rational management of forest ecosystems for sustainable conservation of floristic biodiversity. Two types of analysis are carried out: structural analysis and analysis of the main species. A total of 22 families were identified, divided among 32 species. The dominant woody species are Quercus suber and Quercus canariensis. Fagaceae is the most represented family. The average values of species richness and Shannon diversity index are 4 ± 1.8 and 0.9 ± 0.30 species/plot respectively. The average density of woody species in the Oueld Bechih forest was 158 ± 28 tree/ha with an average basal area of 32.67 ± 0.74m²/ha. The height structure shows that trees in height classes is ≥ 6 has very high density, evidence of almost no natural regeneration. The total structure indicates that larger trees are more abundant. In effect, this work provides a database for the forest, but it represents only one facet to be considered in protecting and restoring it.

scholarly journals Bioecological and statistical risk assessment of toxic metals in sediments of a worldwide important wetland: Gala Lake National Park (Turkey)

2017 ◽  
Vol 43 (1) ◽  
pp. 34-47 ◽  
Author(s):  
Cem Tokatli
Keyword(s):  
Ecological Risk ◽  
National Park ◽  
Risk Index ◽  
Sediment Quality ◽  
Potential Ecological Risk ◽  
Irrigation Canal ◽  
Anthropogenic Pressure ◽  
Ecological Risk Index ◽  
Potential Ecological Risk Index ◽  
Biological Risk

Abstract Gala Lake National Park that has an international importance is one of the most important wetland ecosystems for Turkey. As same as many aquatic habitats, Gala Lake is under a significant anthropogenic pressure originated from agricultural activities conducted around the lake and from industrial discharges by means of Ergene River. The aim of this study was to evaluate the sediment quality of Gala Lake and Irrigation Canal by investigating some toxic element accumulations (As, B, Ni, Cr, Pb, Cd, Zn and Cu) from a statistical perspective. Pearson Correlation Index (PCI) and Factor Analysis (FA) were applied to detected data in order to determine the associated contaminants and effective factors on the system. Potential Ecological Risk Index (RI) and Biological Risk Index based sediment quality guidelines (mERM-Q) applied to detected data in order to assess the ecological and biological risks of heavy metals in the ecosystem. Also Geographic Information System (GIS) technology was used to make visual explanations by presenting distribution maps of investigated elements. According to the results of PCI, significant positive correlations were recorded among the investigated toxic elements at 0.01 significance level. According to the results of FA, two factors, which were named as “Agricultural Factor” and “Industrial Factor”, explained 86.6% of the total variance. According to the results of Potential Ecological Risk Index, cadmium was found to be the highest risk factor and according to results of Biological Risk Index, nickel and chromium were found to be the highest risk factors for Gala Lake and Irrigation Canal. As a result of the present study, it was also determined that heavy metal contents in sediments of Gala Lake National Park reached to critical levels and the system is intensively under effect of agricultural and industrial originated pollution.

scholarly journals Altitudinally coordinated pattern of plant community structure in the Shivapuri National Park, Nepal

1970 ◽  
Vol 18 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Shalik Ram Sigdel
Keyword(s):  
Community Structure ◽  
Species Diversity ◽  
Plant Species ◽  
Plant Community ◽  
National Park ◽  
Climatic Factors ◽  
Flower Colour ◽  
Basal Area ◽  
Plant Community Structure ◽  
Closed Canopy

Study on plant community structure was undertaken in different altitudinal ranges of Shivapuri National Park. The general objective of this study is to analyse different plant community structure in Shivapuri National Park with regards to altitudinal variation. The forest was divided into three distinct altitudinal ranges on the basis of dominancy. In each altitudinal range standard quadrats method was applied for vegetation analysis. The highest number of species was found in site II. All the ecological parameters of the plant species were higher in site II except Basal Area of tree that was highest in site III. The pattern of distribution of plant species was not uniform according to altitude. At higher elevation, the forest was mature with almost closed canopy and trees were large; so the tree density was low. Species richness was highest in site II. Species diversity among tree and shrub species was higher in site I. But for herb species diversity was higher in site II for both seasons. Such type of variations may be due to nature of soil i.e. acidity, nutrient availability and other micro-climatic factors. The most noteworthy thing was that variation in flower colour of Rhododendron arboreum i.e. deep scarlet at low altitude, but it gradually changed into pinkish white as altitude increased. Key words: Altitude, Density, Plant community, Species diversity doi: 10.3126/banko.v18i1.2161 Banko Janakari, Vol. 18, No. 1, 11-17

scholarly journals RIQUEZA ESPECÍFICA EM ÁREAS DE CAMPO NATIVO IMPACTADAS POR VISITAÇÃO TURÍSTICA E PASTEJO NO PARQUE NACIONAL DOS CAMPOS GERAIS, PR

FLORESTA ◽  
2011 ◽  
Vol 41 (2) ◽  
Author(s):  
Karine Dalazoana ◽  
Rosemeri Segecin Moro
Keyword(s):  
Species Diversity ◽  
National Park ◽  
Anthropogenic Factors ◽  
Species Number ◽  
Anthropogenic Pressure ◽  
Grassland Community ◽  
Campos De Altitude ◽  
Resistant Species ◽  
Native Grassland ◽  
Selection Of

O Parque Nacional dos Campos Gerais (PNCG) detém áreas de campos de altitude sob forte pressão antrópica, com a expansão das atividades agrícolas, pecuária, silvicultura e visitação turística desordenada. Devido ao impacto gerado, existe uma tendência à diminuição da riqueza específica, através da seletividade de espécies. Este trabalho analisa a resposta das comunidades campestres em termos de composição de espécies aos impactos de pastejo, roçada e pisoteio humano. Em quatro estações de coleta, foram determinados 107 táxons distribuídos em 23 famílias botânicas. As famílias com maior riqueza específica foram Asteraceae e Poaceae, ambas com 24 táxons, e Fabaceae, com 14 táxons. A riqueza específica variou de 27 a 75 espécies, com maior riqueza na estação não pastejada nem roçada, apenas visitada por turistas. O levantamento mostrou que, apesar da pressão antrópica, as áreas estudadas exibem considerável riqueza específica quando comparadas a outros trabalhos na região, mantendo ainda seu potencial biótico dinâmico. Floristicamente, os impactos gerados por gado ou por manejo com roçadeira se equivalem. Seis gêneros têm potencial para serem utilizados como bioindicadores de áreas conservadas: Croton, Galactia, Periandra, Cuphea, Pavonia e Commelina, mas há necessidade de ampliação das áreas estudadas para estabelecer mais claramente seu valor de bioindicação.Palavras-chave: Campo nativo; Campos Gerais; área impactada; pastejo; visitação turística. AbstractThe species diversity in native grassland areas that are under impact of tourism and grazing at Campos Gerais National Park, Parana, Brazil. Campos Gerais National Park (PNCG) has areas of grassland under high anthropogenic pressure, as expansion of agricultural activities, livestock, forestry and disorderly tourism. Due to these impacts, there is a tendency to decrease local biodiversity by selection of more resistant species. This paper focuses the grassland community answers to mowing, grazing and tourism. In four sampling sites it was determined 107 taxa belonging to 23 botanic families. The main families are Asteraceae (24 taxa), Poaceae (24 taxa) and Fabaceae (14 taxa). Species diversity varied from 27 to 75 species. In relation to species number, non-grazed areas presented greater diversity than other ones; it points to that touristic visitation may cause lower impact than grazing or mowing. In spite of the anthropogenic factors, the focused sites presented high specific diversity in relation to related areas. In relation to species diversity, grazing or mowing are equal. Six genera presented potentiality as bioindicators of preserved environments: Croton, Galactia, Periandra, Cuphea, Pavonia, and Commelina, although more sample areas are necessary to reliable results.Keywords: Grasslands; Campos Gerais; impacted area; grazing; touristic activities.

Dynamics of Forest Clumps on Chenier Plains, Cobourg Peninsula, Northern Territory

1990 ◽  
Vol 38 (6) ◽  
pp. 593 ◽  
Author(s):  
DMJS Bowman ◽  
WJ Panton ◽  
L Mcdonough
Keyword(s):  
National Park ◽  
Field Experiments ◽  
Calcareous Soils ◽  
Basal Area ◽  
Woody Species ◽  
Acacia Auriculiformis ◽  
Tree Crown ◽  
Bos Javanicus ◽  
Preferred Habitat ◽  
Monsoon Forest

Forest clumps occur scattered throughout Sorghum plumosum grasslands on chenier plains at Gurig National Park, Cobourg Peninsula, a preferred habitat for the introduced banteng (Bos javanicus.). The clumps are dominated by Pandanus spiralis, Acacia auriculiformis, Alstonia actinophylla, Timonius timon and Casuarina equisetifolia and vary in size from the radius of one tree crown to large patches of over several hectares. Fifteen of the 32 woody species recorded in 42 clumps occurred as juveniles less than 1 cm diameter at breast height. Both the clumps and grasslands occur on uniform calcareous soils. The clumps are thought to be a stage in a succession towards monsoon forest. Field experiments showed that seedlings from a range of monsoon forest and savanna species can grow on the plains. Interpretation of aerial photography taken in 1963 and 1982 suggests that the clumps have expanded. Fire is thought to control the succession. A fire on the plains was found to kill between one and two-thirds of the basal area of Pandanus spiralis and A. auriculiformis and stimulated the establishment of six times more A. auriculiformis seedlings than in nearby unburnt clumps. Monsoon forest juveniles that invade the clumps typically resprout following fire. Stunted, fire-damaged monsoon forest species (e.g. Timonius timon, Alstonia actinophylla) occur in low densities in the grasslands. It is unclear whether banteng promotes the succession by reducing fuel loads in the grasslands and spreading A. auriculiforms seeds.

Status, diversity and trends of the bird communities in Volcanoes National Park and surrounds, Rwanda

2019 ◽  
Vol 30 (1) ◽  
pp. 1-20 ◽  
Author(s):  
MIA A. DERHÉ ◽  
DEO TUYISINGIZE ◽  
WINNIE ECKARDT ◽  
FAIDA EMMANUEL ◽  
TARA STOINSKI
Keyword(s):  
National Parks ◽  
National Park ◽  
Mixed Forest ◽  
Basal Area ◽  
Bird Community ◽  
Bird Communities ◽  
Population Pressure ◽  
Bird Diversity ◽  
Albertine Rift ◽  
1960S And 1970S

SummaryThe Volcanoes National Park (VNP) in Rwanda, part of the Virunga massif in the Albertine Rift region, boasts some of Rwanda’s best remaining natural vegetation and is home to many endangered and endemic species. The park has suffered from high levels of degradation and destruction, reducing in size by 50% during the 1960s and 1970s, and remains under threat from illegal activities, human population pressure and climate change. This study is the first to investigate the status and trends of bird communities in the VNP, using a multi-year dataset. We use a five-year dataset, totalling over 3,200 point-counts, both within and around the VNP, to assess the conservation value of the VNP for birds in comparison with other national parks and non-protected areas. We assess bird communities and population trends within and around the parks and identify important habitat factors for birds within the VNP. We found that the VNP hosts a unique bird community compared to other localities, with several Albertine Rift endemics and threatened species occurring in the VNP. Hagenia/ Hypericum woodland, herbaceous vegetation, brush ridge and mixed forest host the highest levels of bird diversity in the VNP, whilst the park’s waterbodies provide key habitat for the endangered Albertine Rift endemic Grauer’s Swamp-warbler (Bradypterus graueri). Elevation had a negative effect on bird diversity in the VNP, whilst the basal area of dead trees, Hagenia and vines had a positive effect. Both inside and outside the VNP, there was a significant decline in abundance and species richness over the sampling years; however, we advocate for further monitoring to confirm these trends. Based on our findings, we recommend effective, targeted management of key habitats for birds within the park, including those identified in this study, in order to mitigate bird declines and conserve the unique bird communities in the VNP.

Long-term aspen dynamics, trophic cascades, and climate in northern Yellowstone National Park

2016 ◽  
Vol 46 (4) ◽  
pp. 548-556 ◽  
Author(s):  
Robert L. Beschta ◽  
Luke E. Painter ◽  
Taal Levi ◽  
William J. Ripple
Keyword(s):  
Populus Tremuloides ◽  
Cervus Elaphus ◽  
Yellowstone National Park ◽  
National Park ◽  
Average Density ◽  
Drought Severity ◽  
Quaking Aspen ◽  
Climatic Trend ◽  
Predator Prey

We report long-term patterns of quaking aspen (Populus tremuloides Michx.) recruitment for five ungulate exclosures in the northern ungulate winter range of Yellowstone National Park. Aspen recruitment was low (<3 aspen·ha−1·year−1) in the mid-1900s prior to exclosure construction due to herbivory by Rocky Mountain elk (Cervus elaphus Linnaeus, 1758) but increased more than 60-fold within 25 years after exclosure construction despite a drying climatic trend since 1940. Results support the hypothesis that long-term aspen decline in Yellowstone’s northern range during the latter half of the 20th century was caused by high levels of ungulate herbivory and not a drying climate. Gray wolves (Canis lupus Linnaeus, 1758) were reintroduced during 1995–1996. For the period 1995–2012, we summarized annual predator–prey ratios, ungulate biomass, and drought severity. The average density of young aspen increased from 4350 aspen·ha−1 in 1997–1998 to 8960 aspen·ha−1 in 2012; during the same time period, those >1 m in height increased over 30-fold (from 105 to 3194 aspen·ha−1). Increased heights of young aspen occurred primarily from 2007 to 2012, a period with relatively high predator–prey ratios, declining elk numbers, and decreasing browsing rates. Consistent with a re-established trophic cascade, aspen stands in Yellowstone’s northern range have increasingly begun to recover.

scholarly journals Trophic Scaling and Occupancy Analysis Reveals a Lion Population Limited by Top-Down Anthropogenic Pressure in the Limpopo National Park, Mozambique

PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e99389 ◽  
Author(s):  
Kristoffer T. Everatt ◽  
Leah Andresen ◽  
Michael J. Somers
Keyword(s):  
National Park ◽  
Anthropogenic Pressure ◽  
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