Floristic and structural contrasts between natural savannas and anthropogenic pastures in a tropical dry landscape

2007 ◽  
Vol 29 (2) ◽  
pp. 181 ◽  
Author(s):  
L. I. López-Olmedo ◽  
J. A. Meave ◽  
E. A. Pérez-García
Keyword(s):  
Species Richness ◽  
Floristic Composition ◽  
Southern Mexico ◽  
Deterioration Process ◽  
Isthmus Of Tehuantepec ◽  
Dominance Indices ◽  
Vegetation Samples ◽  
Severe Deterioration ◽  
Biological Differentiation ◽  
Sørensen Index

The magnitude of the biological differentiation between natural savannas and pastures (anthropogenic grasslands) coexisting in a single landscape, in terms of their floristic composition and community structure, was studied in the Nizanda region, Isthmus of Tehuantepec, Oaxaca State, southern Mexico. Vegetation samples of 15 m2 each were taken at 20 savanna and 11 pasture sites. Cover- and species richness-based diversity and dominance indices were calculated. Geomorphological and edaphic characteristics were also compared. Savannas generally occurred in hill summits with very shallow and stony, discontinuous and acidic soils; contrastingly, pastures were located in piedmonts and floodplains, with more neutral and less stony soils. Savanna sites differed from pasture sites in species richness and Shannon diversity. They did not differ in Simpson dominance index, but the identity of the dominant species was different in each community: Trachypogon spicatus (L.f.) Kuntze in savanna and Megathyrsus maximus (Jacq.) B.K.Simon et S.W.L.Jacobs in pasture. A low species-level similarity (Sørensen Index) was observed between them (8.2%), and genus-level similarity was only slightly higher (27.1%). The magnitude of the biological differentiation in both community floristics and structure between these two grass-dominated communities was larger than anticipated. Current management of savannas as pasture lands may potentially trigger a severe deterioration process involving both the landscape and its plant components.

scholarly journals Estructura y composición florística del Cerrado en el Parque Nacional Noel Kempff Mercado, Santa Cruz, Bolivia

2017 ◽  
pp. 25
Author(s):  
Bonifacio Mostacedo-C. ◽  
Thimoty J. Killeen
Keyword(s):  
Species Richness ◽  
Floristic Composition ◽  
Santa Cruz ◽  
Floristic Similarity ◽  
Lower Stratum ◽  
Cerrado Vegetation ◽  
Number Of Species ◽  
Different Types ◽  
Plant Families ◽  
Sørensen Index

We studied the structure and floristic composition of the Cerrado vegetation in two sites at the Parque Nacional "Noel Kempff Mercado", Santa Cruz, Bolivia. The results indicated that the sites are located within two different types of Cerrado communities: 1) cerrado and, 2) cerradao. The lower stratum (50 cm) was dominated by grasses, while higher strata were dominated by shrubs and sub-shrubs in the cerrado, and by trees in the cerradao. We founded 41 families, 90 genera, and 112 species in the cerrado, and 37 families, 39 genera and 106 species in the cerradao. For both sites, the plant families with greater coverage and species richness were: Gramineae (29 species, 51 % cover), Leguminosae (23 species, 4.8-5. 7% cover) and Guttiferae (3 species, 1-20% cover). Other important families were: Myrtaceae, Rubiaceae, Euphorbiaceae and Melastomataceae, with 7,6 species; 4,6 species; 8, 2 species; 2, 6 species for cerrado and cerradao, respectively. Herbs are the most important for the number of species, followed by grasses and shrubs in the cerrado and by shrubs, followed by herbs and grasses in the cerradao. Floristic similarity between the two communities was relatively low (39% according to Sorensen index).

Diversity metrics, species turnovers and nestedness of bird assemblages in a deep karst sinkhole

2017 ◽  
Vol 63 (2) ◽  
pp. 8-16 ◽  
Author(s):  
Corrado Battisti ◽  
Marco Giardini ◽  
Francesca Marini ◽  
Lorena Di Rocco ◽  
Giuseppe Dodaro ◽  
...  
Keyword(s):  
Species Richness ◽  
Random Distribution ◽  
Diversity Index ◽  
Species Turnover ◽  
Floristic Composition ◽  
Bird Assemblages ◽  
Β Diversity ◽  
Stick Model ◽  
Karst Sinkhole

We reported a study on breeding birds occurring inside an 80 m-deep karst sinkhole, with the characterization of the assemblages recorded along its semi-vertical slopes from the upper edge until the bottom. The internal sides of the sinkhole have been vertically subdivided in four belts about 20 m high. The highest belt (at the upper edge of the cenote) showed the highest values in mean number of bird detections, mean and normalized species richness, and Shannon diversity index. The averaged values of number of detections and species richness significantly differ among belts. Species turnover (Cody’s β-diversity) was maximum between the highest belts. Whittaker plots showed a marked difference among assemblages shaping from broken-stick model to geometric series, and explicited a spatial progressive stress with a disruption in evenness towards the deepest belts. Bird assemblages evidenced a nested subset structure with deeper belts containing successive subsets of the species occurring in the upper belts. We hypothesize that, at least during the daytime in breeding season, the observed non-random distribution of species along the vertical stratification is likely due to (i) the progressive simplification both of the floristic composition and vegetation structure, and (ii) the paucity of sunlight as resources from the upper edge to the inner side of the cenote.

Monitoring of small rock pools reveals differential effects of chronic anthropogenic disturbance on birds and mammals in the Calakmul region, southern Mexico

2021 ◽  
pp. 1-10
Author(s):  
Carlos M. Delgado-Martínez ◽  
Fredy Alvarado ◽  
Melanie Kolb ◽  
Eduardo Mendoza
Keyword(s):  
Species Richness ◽  
Anthropogenic Disturbance ◽  
Forest Cover ◽  
Biosphere Reserve ◽  
Bird Diversity ◽  
Small Scale ◽  
Rock Pools ◽  
Southern Mexico ◽  
Wildlife Species ◽  
The Impact

Abstract Great attention has been drawn to the impacts of habitat deforestation and fragmentation on wildlife species richness. In contrast, much less attention has been paid to assessing the impacts of chronic anthropogenic disturbance on wildlife species composition and behaviour. We focused on natural small rock pools (sartenejas), which concentrate vertebrate activity due to habitat’s water limitation, to assess the impact of chronic anthropogenic disturbance on the species richness, diversity, composition, and behaviour of medium and large-sized birds and mammals in the highly biodiverse forests of Calakmul, southern Mexico. Camera trapping records of fauna using sartenejas within and outside the Calakmul Biosphere Reserve (CBR) showed that there were no effects on species richness, but contrasts emerged when comparing species diversity, composition, and behaviour. These effects differed between birds and mammals and between species: (1) bird diversity was greater outside the CBR, but mammal diversity was greater within and (2) the daily activity patterns of birds differed slightly within and outside the CBR but strongly contrasted in mammals. Our study highlights that even in areas supporting extensive forest cover, small-scale chronic anthropogenic disturbances can have pervasive negative effects on wildlife and that these effects contrast between animal groups.

scholarly journals Effect of fire on a monodominant floating mat of Cyperus giganteus Vahl in a neotropical wetland

2015 ◽  
Vol 75 (1) ◽  
pp. 114-124 ◽  
Author(s):  
M. Rocha ◽  
CC. Santos Júnior ◽  
GA. Damasceno-Júnior ◽  
VJ. Pott ◽  
A. Pott
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Annual Variation ◽  
Floristic Composition ◽  
Large Area ◽  
Characteristic Species ◽  
Cyperus Giganteus ◽  
Pantanal Wetland ◽  
Floating Mat ◽  
Adult Plants

The rhizomatous Cyperus giganteus, abundant in the Pantanal wetland, can dominate extense floodable areas as monodominant communities. The Jacadigo lake has a large area of C. giganteus, where we performed an evaluation on community structure during two months in 2010, before it was hit by a wildfire which top-killed the vegetation, compared to ten months post-fire. We utilized 40 plots of 1m × 1m, along permanent trails, assessing two strata: the upper, near the inflorescence of adult plants, and the lower, close to the water level. Our results show that fire does not affect dominance of C. giganteus, as it maintained the same cover as before fire; species richness is not much altered either - 28 before fire and 34 thereafter. Fire changed the floristic composition, due to the annual variation of species and the ability of some plants to colonize gaps and to regrow after fire from underground organs and seeds. The stratification of the vegetation with characteristic species of upper and lower strata was similar after fire.

scholarly journals Floristic composition of the Montane Forest in the Almadina-Barro Preto axis, Southern Bahia, Brazil

2014 ◽  
Vol 14 (1) ◽  
Author(s):  
Macielle Macedo Coelho ◽  
André Márcio Amorim
Keyword(s):  
Species Richness ◽  
Tropical Forests ◽  
Atlantic Forest ◽  
Floristic Composition ◽  
Woody Species ◽  
Life Forms ◽  
Montane Forest ◽  
Forest Remnants ◽  
Southern Bahia ◽  
Arboreal Habit

The aim of this study is to survey the angiosperms of two montane forest remnants in the southern Bahia, Brazil: Corcovado (SCO) and Pedra Lascada (SPL). Both fragments are located in the municipality of Almadina and Barro Preto, respectively, and are 18 km distant from each other. We sampled 899 species of angiosperms distributed in 437 genera and 116 families. The SCO was the richest area with 678 species, distributed in 367 genera and 100 families. SPL showed 466 species in 269 genera and 88 families. The percentage of species identified was 85.8% and of this total, 37.7% are endemic to the Atlantic Forest, 11.2% are endemic to southern Bahia and northern Espírito Santo and 7% are disjunct between the Atlantic Forest and Amazon. The remaining percentages (44.3%) were of species widely distributed. The richest families in the two areas were Orchidaceae (10%), Rubiaceae (7%), Bromeliaceae (5.5%), Melastomataceae (4.2%) and Poaceae (4%). The richest genera were Psychotria (2%),Piper (1.8%), Ocotea (1.6%),Vriesea (1.5%) and Peperomia (1.4%). More than half of the recorded species showed non-arboreal habit, regarding life forms documented. That comes against the assertion that many authors in the tropical forests, where species richness in angiosperms is expected for non-woody species, especially in montane forests. Twelve species have been identified as new, but seven others already described from collections previously obtained in these two areas. Orchidaceae, Rubiaceae, Poaceae and Bromeliaceae showed significant richness in this study these families are commonly reported as the richest in other inventories in the Atlantic Forest in southern Bahia reinforcing their importance to the regional flora. The high levels of richness, endemism, and the growing numbers of new taxonomic discoveries from the SPL and SCO sites indicate the biological importance of these two forest remnants. The implementation of parks or other protected environmental reserves would be essential to the conservation of its species.

scholarly journals Restauración de bosques en territorios indígenas de Chiapas: modelos ecológicos y estrategias de acción

2017 ◽  
pp. 11
Author(s):  
Mario González-Espinosa ◽  
Neptalí Ramírez-Marcial ◽  
Angélica Camacho-Cruz ◽  
Silvia C. Holz ◽  
José María Rey-Benayas ◽  
...  
Keyword(s):  
Population Growth ◽  
Forest Restoration ◽  
Social Issues ◽  
Floristic Composition ◽  
Forest Resources ◽  
Research Development ◽  
Viable Option ◽  
Ecological Processes ◽  
Southern Mexico ◽  
Appropriate Practices

Montane forests of southern Mexico have been severely fragmented and their structure and floristic composition have been altered because of traditional agriculture and population growth. In extensive areas of Chiapas, forest restoration is not only an urgent need, but it also represents a viable option for the recovery of products and services that could be used in the future in a sustainable way. Forest restoration should be based upon the understanding of basic ecological processes followed by the design of appropriate practices, and taking into account economic and social issues that may guide an adaptive approach of the action programs. Research, development, and outreach experiences spanning more than a decade lead us to suggest models for some of the ecological, technical, and social issues underlying the recovery, conservation, and rational use of forest resources

Nowcasting and multifractal features of the seismicity in the subduction zone of Tehuantepec Isthmus, southern México

2021 ◽  
Author(s):  
Alejandro Ramírez-Rojas ◽  
Elsa Leticia Flores-Márquez
Keyword(s):  
Main Shock ◽  
B Value ◽  
Fluctuation Analysis ◽  
Southern Mexico ◽  
Multifractal Detrended Fluctuation Analysis ◽  
Middle America Trench ◽  
Seismicity Distribution ◽  
Isthmus Of Tehuantepec ◽  
Temporal Rate ◽  
Detrended Fluctuation

<p>After the M8.2 earthquake occurred on September 07, 2017 at Isthmus of Tehuantepec, notable spatial and temporal changes where<br>registered, the temporal rate of occurrence increased and the spatial seismicity distribution showed a clear clusterization along<br>the region of collision of the Tehuantepec Transform/Ridge with the Middle America Trench off Chiapas. Also, the b-value in the<br>Gutenberg-Richer law showed changes in time. On the basis of that behavior we studied the sequence of magnitudes of the<br>earthquakes occurred within the Isthmus of Tehuantepec at southern Mexico from 2010 to 2020, by using the nowcasting method<br>and the multifractal detrended fluctuation analysis. Our findings suggest the b-value could depend on time and after the main-shock<br>M8.2, the underlying dynamics in the Tehuantepec ridge has been changed, which is clearly described by our analyses based on<br>nowcasting method and in the multifractality estimated changes.</p>

A new species of treefrog of the genus Ptychohyla (Anura: Hylidae) from Southern Mexico

Zootaxa ◽  
2017 ◽  
Vol 4317 (2) ◽  
pp. 279 ◽  
Author(s):  
LUIS CANSECO-MÁRQUEZ ◽  
J. LUIS AGUILAR-LÓPEZ ◽  
RICARDO LURÍA-MANZANO ◽  
EDUARDO PINEDA ◽  
ITZUE W. CAVIEDES-SOLÍS
Keyword(s):  
New Species ◽  
Tropical Forests ◽  
Habitat Degradation ◽  
Habitat Modification ◽  
New Taxon ◽  
Southern Mexico ◽  
Number Of Species ◽  
Pale Pink ◽  
Isthmus Of Tehuantepec ◽  
A New Species

We describe a new species of treefrog of the genus Ptychohyla from southern Mexico occurring to the east of the Isthmus of Tehuantepec. This new species can be distinguished from Mexican congeners by a combination of a pale pink iris and the presence of nuptial excrescences in breeding males. Including this new taxon, the number of species of Ptychohyla increases to 14, with seven of these occurring in Mexico. The new species is relatively common in pristine tropical forests, but appears to be sensitive to habitat degradation and has not been found in human modified habitats, suggesting that habitat modification is a threat for this hylid frog. 

scholarly journals Liana species composition differs, in spite of trait similarities, in two adjacent forest types in Central Brazil

2017 ◽  
Vol 65 (3) ◽  
pp. 1215 ◽  
Author(s):  
Ana Carolina Souza Brito ◽  
Alexandre Ferraro ◽  
Robyn J. Burnham ◽  
Ângela Lúcia Bagnatori Sartori ◽  
Vivian Almeida Assunção
Keyword(s):  
Species Richness ◽  
Deciduous Forest ◽  
Morphological Characteristics ◽  
Floristic Composition ◽  
Dry Forest ◽  
Forest Fragments ◽  
Vegetation Types ◽  
Forest Types ◽  
Climbing Plants ◽  
Dispersal Syndromes

In the Parana basin, the Serra de Maracaju juxtaposes the Seasonal Dry Forest and the cerradão (a phytophysiognomy of Cerrado), two distinct vegetation types that differ in canopy height, tree density, and composition of the understory. In the same way, these differences may be reflected in the composition of climbing plant species found in these two forest types. Thus, in this study we compared the climbing species in two forest fragments of Serra de Maracaju to understand: (1) Are species richness and floristic composition of climbing plants similar in cerradão and seasonal deciduous forest?, (2) What degree of floristic compositional difference exists between the two vegetation types?, (3) Do the two vegetation types differ significantly in climbing mechanisms, life forms, and dispersal syndromes represented among climbing species? For this, we established and sampled four plots per forest type over 24 months. Species were identified and each one classified, based on three discrete traits. Proportional differences were analyzed using chi-square tests. Our results showed that species richness and floristic composition of climbing plants in the cerradão and the seasonal deciduous forest were not similar. Climber species richness in cerradão was 37 while in the seasonal deciduous forest it was 31; they share only 13 species. Four families, Dioscoreaceae, Fabaceae, Malpighiaceae, and Sapindaceae, included over 60% of the climbing species. The morphological traits most common in both forest types were herbaceous life form, apical twining mechanism, and wind dispersal. Dioscoreaceae was found to be the dominant family, but is the first time to be reported for this condition in Brazil. Bignoniaceae and Passifloraceae ocurred only in the cerradão, and Asteraceae and Combretaceae in the seasonal deciduous forest; some species were found exclusively in a type of forest. Floristic composition of the cerradão and seasonal deciduous forest fragments were substantially different, in spite of physical proximity. However, their climbing species are not statistically distinct in morphological characteristics, possibly due to uniform climatic conditions and the similarity of species because of a shared ancestry (similar families).

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