scholarly journals Caatinga Vegetation Dynamics under Various Grazing Intensities by Steers in the Semi-Arid Northeast, Brazil

1999 ◽  
Vol 52 (3) ◽  
pp. 241 ◽  
Author(s):  
Severino G. De Albuquerque
Phytotaxa ◽  
2017 ◽  
Vol 331 (2) ◽  
pp. 289 ◽  
Author(s):  
JACIELE DE OLIVEIRA DANTAS ◽  
ELAINE SANTOS ALVES ◽  
ROBERT LÜCKING ◽  
MARCELA EUGENIA DA SILVA CÁCERES

Three new lichenized fungal species in the family Graphidaceae are described from Northeast Brazil. Graphis alba has lirellae with a conspicuous white cover, eventually becoming striate, small, (sub-)muriform ascospores, and stictic acid. Halegrapha redonographoides features somewhat pseudostromatic ascomata with immersed lirellae, a completely carbonized excipulum, and small, submuriform ascospores, in combination with a norstictic acid chemistry. Thelotrema pachysporoides has an ecorticate, white thallus and produces brown, 7–13-septate, 25–35 × 7–10 µm large ascospores. The new species were found in an isolated remnant of Caatinga vegetation, at Fazenda Santa Maria da Lage, Poço Verde, Sergipe state, with additional material of one of the species also detected in the state of Tocantins.


2021 ◽  
Vol 41 (2) ◽  
Author(s):  
Antonio Rodrigues Ximenes Neto ◽  
Paulo Roberto Silva Pessoa ◽  
Lidriana de Souza Pinheiro ◽  
Jáder Onofre de Morais

Author(s):  
Ivanilson de Souza Maia ◽  
Dárlio Inácio Alves Teixeira ◽  
Vigínia Maria Cavalari Henriques ◽  
Maulori Curié Cabral

Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 76
Author(s):  
Ioannis N. Daliakopoulos ◽  
Ioanna Panagea ◽  
Luca Brocca ◽  
Erik van den Elsen

Under arid conditions, where water availability is the limiting factor for plant survival, water balance models can be used to explain vegetation dynamics. [...]


Author(s):  
Raquel Barbosa da Silva ◽  
Edvaldo Vieira Silva‐Júnior ◽  
Larissa Maria Barreto de Medeiros Trigueiros ◽  
Rayza Helen Graciano dos Santos ◽  
Jailane de Souza Aquino ◽  
...  

2000 ◽  
Vol 55 (9-10) ◽  
pp. 688-692 ◽  
Author(s):  
Antonio F. M. Oliveira ◽  
Antonio Salatino

Abstract The epicuticular waxes of leaves of four species (Aspidospermci pyrifolium, Capparis yco, Maytenus rigida and Ziziphus joazeiro) from the Caatinga, (a semi-arid ecosystem of Northeast Brazil) and four species (Aristolochia esperanzae, Didymopanax vinosum, Strychnos pseudoquina and Tocoyena formosa) from the Cerrado, (a savanna ecosystem covering one third of the Brazilian territory), were analyzed. Six species contained a high content (above 60 μg.cm-2) of wax, four of them from the Caatinga. Triterpenoids and n-alkanes were the most frequent and abundant constituents found in the species from both habitats. The distribution of n-alkanes predominated by homologues with 27, 29, 31 and 33 carbon atoms, displayed no consistent differences between species from the two habitats. Lupeol, β-amyrin, epifriedelinol and ursolic acid were the triterpenoids found. Triterpenoids clearly predominate over alkanes in the waxes from the Cerrado species. The waxes of two evergreen species from the Caatinga yielded n-alkanes as predominant constituents. A comparison of foliar epicuticular waxes of native plants from ecosystems with different hydric constraints is discussed.


2020 ◽  
Vol 12 (12) ◽  
pp. 5214 ◽  
Author(s):  
Hao Wang ◽  
Fei Yao ◽  
Huasheng Zhu ◽  
Yuanyuan Zhao

Vegetation coverage is a key variable in terrestrial ecosystem monitoring and climate change research and is closely related to soil erosion and land desertification. In this article, we aimed to resolve two key scientific issues: (1) quantifying the spatial-temporal vegetation dynamics in the Otindag Sandy Land (OSL); and (2) identifying the relative importance of climate factors and human activities in impacting vegetation dynamics. Based on correlation analysis, simple regression analysis, and the partial derivative formula method, we examined the spatiotemporal variation of vegetation coverage in the OSL, belonging to the arid and semiarid region of northern China, and their interaction with climate-human factors. The results showed that the vegetation coverage of the area showed a downward trend with a rate of −0.0006/a during 2001–2017, and gradually decreased from east to west. Precipitation was the main climate factor controlling the overall distribution pattern of vegetation coverage, while the human factors had a more severe impact on the vegetation coverage than the climate factors in such a short period, and the overall impact was negative. Among the human factors, population pressure, urbanization, industrialization, pastoral production activities, and residents’ lifestyles had a negative impact. However, ecological restoration polices alleviated the contradiction between human development and vegetation deterioration. The results of this article provide a scientific basis for restoring grassland systems in arid and semi-arid areas


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