scholarly journals A year in a Cerrado wet grassland: a non-seasonal island in a seasonal savanna environment

2008 ◽  
Vol 68 (3) ◽  
pp. 495-501 ◽  
Author(s):  
MV. Cianciaruso ◽  
MA. Batalha
Keyword(s):  
Species Richness ◽  
Plant Density ◽  
Spatial Scales ◽  
Regional Scale ◽  
Basal Area ◽  
Species Density ◽  
Cerrado Vegetation ◽  
Wet Grassland ◽  
Wet Grasslands ◽  
Cylindrical Volume

In some Cerrado regions where the water table is superficial and soils are hydromorphic, we may find wet grasslands. We studied temporal changes in some community descriptors, such as species density, plant density, basal area, and cylindrical volume in a Cerrado wet grassland in four different seasons of the year. We also compared the species richness and composition of the wet grassland with a hyperseasonal cerrado, and a seasonal cerrado. We found significant differences among the seasons only for species density. Chao-Sørensen similarity values varied from 0.86 to 0.99 and, in the wet grassland, were not different among the seasons. On the contrary, similarity values between the wet grassland and hyperseasonal and seasonal cerrados were low. Species richness was lower in the wet grassland and higher in the seasonal cerrado. As long as savannas are highly dynamic on all temporal and spatial scales, the wet grassland stability, at least in a short-term view, introduces an important heterogeneity in regional scale. Wet grasslands are also important in the Cerrado domain to increase b-diversity, since they are floristically dissimilar with cerrado vegetation.

scholarly journals Short-term community dynamics in seasonal and hyperseasonal cerrados

2009 ◽  
Vol 69 (2) ◽  
pp. 231-240 ◽  
Author(s):  
MV. Cianciaruso ◽  
MA. Batalha
Keyword(s):  
Rainy Season ◽  
Community Dynamics ◽  
Plant Density ◽  
Floristic Composition ◽  
Species Density ◽  
Environmental Filters ◽  
Floristic Similarity ◽  
Different Seasons ◽  
Cylindrical Volume ◽  
Vegetation Form

In South America, the largest seasonal savanna region is the Brazilian cerrado. Our aim was to study temporal changes in some community descriptors, such as floristic composition, richness, species density, plant density, and cylindrical volume, in a seasonal cerrado, comparing it to a nearby hyperseasonal cerrado. In four different seasons, we placed randomly ten 1 m² quadrats in each vegetation form and sampled all the vascular plants. Seasonal changes in floristic composition, species density, and plant density were less pronounced in the seasonal than in the hyperseasonal cerrado. Floristic similarity between the vegetation forms was lower when the hyperseasonal cerrado was waterlogged. Richness and species density were higher in the seasonal cerrado, which reached its biomass peak at mid rainy season. The hyperseasonal cerrado, in turn, reached its biomass peak at early rainy season and, despite the waterlogging, maintained it until late rainy season. In the hyperseasonal cerrado, waterlogging acts as an environmental filter restricting the number of cerrado species able to withstand it. The seasonal cerrado community was more stable than the hyperseasonal one. Our results corroborated the idea that changes in the environmental filters will affect floristic composition and community structure in savannas.

A structural gradient in cerrado vegetation of Brazil: changes in woody plant density, species richness, life history and plant composition

2002 ◽  
Vol 18 (5) ◽  
pp. 775-794 ◽  
Author(s):  
Luci Ferreira Ribeiro ◽  
Marcelo Tabarelli
Keyword(s):  
Life History ◽  
Species Richness ◽  
Species Composition ◽  
Woody Plant ◽  
Plant Density ◽  
Lower Layer ◽  
Sensu Stricto ◽  
Life History Strategies ◽  
Cerrado Vegetation ◽  
Structural Types

Four structural types of cerrado vegetation were examined to test the following hypotheses: (1) there are predictable changes in woody plant density, species richness and life-history strategies from one structural type to another; and (2) plant species composition in the less-rich structural types represent particular and impoverished subsets of those found in the richer ones. The study was conducted at Fazenda Palmares (5°33′S, 42°37′W) Piauí State, Brazil. A 47% decrease in woody plant density between cerradão (forest) and the least-dense type of cerrado sensu stricto (scrub) was associated with a 40% decrease in species richness. The percentage of lower-layer species was reduced by 29% in the least dense type of cerrado sensu stricto compared to cerradão. The proportion of species that flower and fruit during the rainy season was also reduced by one third. Species were not distributed as impoverished subsets along the cerradão–cerrado sensu stricto gradient. It is argued that the reduction in woody plant density and richness is partly due to factors limiting the occurrence of species with particular life-history strategies. The species composition of structural types is affected by the ‘mass effect’ and also by surrounding biotas, which provide species that colonize particular types of cerrado vegetation. Both these processes reduce the likelihood that the species composition in the poorer structural types are simple subsets of those present in the richer types.

scholarly journals Biodiversity of Tropical Forests

2016 ◽  
Author(s):  
A. Tovo ◽  
S. Suweis ◽  
M. Formentin ◽  
M. Favretti ◽  
Jayanth R. Banavar ◽  
...  
Keyword(s):  
Species Richness ◽  
Tropical Forests ◽  
Rare Species ◽  
Spatial Scales ◽  
Regional Scale ◽  
Global Scale ◽  
Practical Reasons ◽  
Ecological Change ◽  
Mass Extinctions ◽  
Vast Number

The quantification of tropical tree biodiversity worldwide remains an open and challenging problem. In fact, more than two-fifths of the global tree population can be found either in tropical or sub-tropical forests1, but species identities are known only for ≈ 0.000067% of the individuals in all tropical forests2. For practical reasons, biodiversity is typically measured or monitored at fine spatial scales. However, important drivers of ecological change tend to act at large scales. Conservation issues, for example, apply to diversity at global, national or regional scales. Extrapolating species richness from the local to the global scale is not straightforward. Indeed, a vast number of different biodiversity estimators have been developed under different statistical sampling frameworks3–7, but most of them have been designed for local/regional-scale extrapolations, and they tend to be sensitive to the spatial distribution of trees8, sample coverage and sampling methods9. Here, we introduce an analytical framework that provides robust and accurate estimates of species richness and abundances in biodiversity-rich ecosystems, as confirmed by tests performed on various in silico-generated forests. The new framework quantifies the minimum percentage cover that should be sampled to achieve a given average confidence in the upscaled estimate of biodiversity. Our analysis of 15 empirical forest plots shows that previous methods10,11 have systematically overestimated the total number of species and leads to new estimates of hyper-rarity10 at the global scale11, known as Fisher’s paradox2. We show that hyper-rarity is a signature of critical-like behavior12 in tropical forests13–15, and it provides a buffer against mass extinctions16. When biotic factors or environmental conditions change, some of these rare species are more able than others to maintain the ecosystem’s functions, thus underscoring the importance of rare species.

Landscape- and site-level responses of woody structure and ground flora to repeated prescribed fire in the Missouri Ozarks

2019 ◽  
Vol 49 (8) ◽  
pp. 1004-1014 ◽  
Author(s):  
Calvin J. Maginel ◽  
Benjamin O. Knapp ◽  
John M. Kabrick ◽  
Rose-Marie Muzika
Keyword(s):  
Species Richness ◽  
Prescribed Fire ◽  
Prescribed Burning ◽  
Spatial Scales ◽  
Basal Area ◽  
Fire Effects ◽  
Ground Flora ◽  
In Fire ◽  
Community Restoration ◽  
Site Types

Landscape-scale prescribed burning may be appealing for natural community restoration due to operational efficiency and possible heterogeneity in fire effects across broad spatial scales. We monitored plant community responses for >15 years with variable prescribed fire frequencies applied across a Missouri Ozarks landscape stratified into distinct ecological site types. Through the study period, burning had no effect on the overstory tree density or basal area. Midstory stem densities decreased rapidly in periodically burned units and more gradually with annual fire. Burning increased total ground flora cover and the cover of forbs, grasses, and legumes. The effect of burning on species richness differed among site types, with increased species richness through time on exposed slopes. There was no effect of prescribed burning on species richness on two of three protected slope site types, and annual burning decreased species richness in upland waterways. Among the site types, the upland waterways had the most species associated with pre-burn communities. We conclude that (i) burning consistently increased cover of ground layer vegetation across the landscape, while decreasing the midstory stem densities, and (ii) site type moderated ground flora richness response, with more pronounced effects of prescribed burning on exposed sites than on protected sites.

Resistance, resilience, and patchiness of invertebrate assemblages in native tussock and pasture streams in New Zealand after a hydrological disturbance

2003 ◽  
Vol 60 (6) ◽  
pp. 731-739 ◽  
Author(s):  
Adriano S Melo ◽  
Dev K Niyogi ◽  
Christoph D Matthaei ◽  
Colin R Townsend
Keyword(s):  
Species Richness ◽  
New Zealand ◽  
Spatial Scales ◽  
Patch Dynamics ◽  
Natural Disturbance ◽  
Species Density ◽  
Land Uses ◽  
Invertebrate Abundance ◽  
Invertebrate Assemblages

We generated hydrological disturbances to investigate the role of disturbance in New Zealand streams in two land uses: native tussock grasslands and exotic pasture catchments. We tested whether physical differences in streambed structure confer higher resistance and resilience in tussock sites than in pasture sites. We also investigated changes in patchiness (at spatial scales larger than 0.06 m2) caused by the disturbance. Invertebrate abundance decreased immediately after the disturbance. Species density remained unchanged, but species richness (rarefied) increased. Eight days after the disturbance event, abundance and species richness (rarefied) were similar to those of samples collected immediately before the disturbance. Resistance (measured as decrease in abundance) and resilience (measured as recovery within 8 days) did not differ significantly between the land uses. Patchiness increased in both stream types immediately after the disturbance but decreased to predisturbance levels after 8 days. Disturbance caused a redistribution of individuals among patches, some receiving individuals, others losing individuals, and some remaining unchanged. Our results conform with predictions of the patch dynamics concept and are consistent with results of studies of natural disturbance caused by floods.

Savanna fires govern community structure of ungulates in Bénoué National Park, Cameroon

2008 ◽  
Vol 24 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Erik Klop ◽  
Janneke van Goethem
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Body Mass ◽  
National Park ◽  
Virtual Communities ◽  
Spatial Scales ◽  
West African ◽  
Species Density ◽  
Savanna Fires ◽  
Occurrence Patterns

Abstract:We studied the effects of savanna fires on the structure of local ungulate communities in a West African woodland savanna. The distribution of 11 ungulate species over 9−15 burned sites (the number of which increased as burning activity continued during the dry season) and 7−13 unburned sites was compared with a variety of null models or randomized ‘virtual communities’. Five different parameters of community structure were examined: body mass distribution, co-occurrence patterns, species richness, species density and guild dominance. Overall, ungulate species were not randomly distributed over burned and unburned sites. The regular spacing of body masses in the set of species recorded on burned and unburned sites indicated competition, since species similar in body mass are more likely to compete than species of different size. However, co-occurrence patterns on burned sites were random, indicating absence of competition at fine spatial scales due to differential habitat use within the burned landscape. Although the attractiveness of the regrowth on burned sites resulted in higher numbers of ungulates compared with unburned sites, species richness was not different. Grazers were the dominant guild on burned sites, but there were no differences in species richness or species density between grazers and browsers on unburned sites.

scholarly journals Disentangling structural patterns of natural forest fragments in a savanna matrix in the eastern Brazilian Amazon

2017 ◽  
Vol 47 (2) ◽  
pp. 111-122
Author(s):  
Iêda Leão do AMARAL ◽  
William Ernest MAGNUSSON ◽  
Francisca Dionízia de Almeida MATOS ◽  
Ana Luisa K. ALBERNAZ ◽  
Yuri Oliveira FEITOSA ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Density ◽  
Fragment Size ◽  
Negative Relationship ◽  
Basal Area ◽  
Average Diameter ◽  
Diameter Distribution ◽  
Forest Fragments ◽  
Continuous Forest ◽  
Individual Trees

ABSTRACT Natural fragments are an important source of richness for the management and conservation of a local flora. The objective of this study was to evaluate the effect of fragmentation on the structure and composition of the plant communities of forest fragments (FF) in Alter do Chão, eastern Brazilian Amazonia. The study sample consisted of 25 FF and nine continuous forest (CF) sites. We compared plant density and species richness between site categories by t-tests, analyzed the differences in composition by cluster analysis, and assessed the effect of fragment size and distance to CF on the basal area and diameter of FF assemblages by linear regression. Individual trees and shrubs with DBH ≥1.27 cm were measured in 2x250 m plots. 17,078 individuals were recorded - 75.32% in FF and 24.68% in CF, comprising 475 species, 216 genera and 64 families. Myrtaceae and Fabaceae were the most abundant families in both FF and CF. Average species richness in FF and CF was statistically different. The 20 species with the highest importance values were similar in FF and CF. The average plant diameter was similar in FF and CF, suggesting that both are "mature" forests composed of thin individuals. Average diameter and total basal area showed a negative relationship with distance to CF and fragment area, respectively. Similarity analysis revealed two groups, one composed exclusively of portions of fragmented forest. Fragments and continuous forest differed in species composition, but were similar in structure. Diameter distribution in fragments was similar to that of primary forests.

scholarly journals Land cover drives large scale productivity-diversity relationships in Irish vascular plants

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7035 ◽  
Author(s):  
Hannah J. White ◽  
Willson Gaul ◽  
Dinara Sadykova ◽  
Lupe León-Sánchez ◽  
Paul Caplat ◽  
...  
Keyword(s):  
Species Richness ◽  
Land Cover ◽  
Large Scale ◽  
Vegetation Index ◽  
Scale Effects ◽  
Spatial Scales ◽  
Vascular Plant ◽  
Regional Scale ◽  
The Impact ◽  
The Relationship

The impact of productivity on species diversity is often studied at small spatial scales and without taking additional environmental factors into account. Focusing on small spatial scales removes important regional scale effects, such as the role of land cover heterogeneity. Here, we use a regional spatial scale (10 km square) to establish the relationship between productivity and vascular plant species richness across the island of Ireland that takes into account variation in land cover. We used generalized additive mixed effects models to relate species richness, estimated from biological records, to plant productivity. Productivity was quantified by the satellite-derived enhanced vegetation index. The productivity-diversity relationship was fitted for three land cover types: pasture-dominated, heterogeneous, and non-pasture-dominated landscapes. We find that species richness decreases with increasing productivity, especially at higher productivity levels. This decreasing relationship appears to be driven by pasture-dominated areas. The relationship between species richness and heterogeneity in productivity (both spatial and temporal) varies with land cover. Our results suggest that the impact of pasture on species richness extends beyond field level. The effect of human modified landscapes, therefore, is important to consider when investigating classical ecological relationships, particularly at the wider landscape scale.

scholarly journals Vascular grassland plants of Tibagi River Spring, Ponta Grossa, Brazil

Check List ◽  
2011 ◽  
Vol 7 (3) ◽  
pp. 257 ◽  
Author(s):  
Bianca Ott Andrade ◽  
Carina Kozera ◽  
Gustavo Ribas Curcio ◽  
Franklin Galvão
Keyword(s):  
Species Richness ◽  
Water Retention ◽  
The State ◽  
Soil Water Retention ◽  
High Importance ◽  
Soil Carbon Pool ◽  
Grassland Plants ◽  
Wet Grassland ◽  
Wet Grasslands ◽  
Plant Families

A systematic survey was carried out on wet grasslands found over Histosols at Upper Tibagi River basin, between Ponta Grossa and Palmeira municipalities, in the state of Paraná, Brazil, place of high importance because of soil water retention capability and soil carbon pool composition. We provide a checklist containing 146 species, 96 genera and 42 plant families for the area. Families with higher species richness were Asteraceae (27 species; 21 genera), Poaceae (24; 16) and Cyperaceae (18; 6). Four species were classified as endangered or rare, and one as exotic. The specific richness in wet grassland environments at the state of Paraná underlines the need for conservation efforts encompassing these formations.

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