Data/hora: 12/06/2024 05:52:52

Biblioteca(s): 	Embrapa Florestas.	
Data corrente: 	15/09/2008	
Data da última atualização: 	15/09/2008	
Autoria: 	AIRA, M.; TATO, A.; DOMÍNGUEZ, J.	
Título: 	Colonization of the western bracken fern (Pteridium aquilinum (L.) Kuhn) in a pine forest and its effects on nutrient cycling and soil microbial activity.	
Ano de publicação: 	2008	
Fonte/Imprenta: 	In: INTERNATIONAL COLLOQUIUM ON SOIL ZOOLOGY, 15; INTERNATIONAL COLLOQUIUM ON APTERYGOTA, 12., 2008, Curitiba. Biodiversity, conservation and sustainabele management of soil animal: abstracts. Colombo: Embrapa Florestas. Editors: George Gardner Brown; Klaus Dieter Sautter; Renato Marques; Amarildo Pasini. 1 CD-ROM.	
Idioma: 	Inglês	
Conteúdo: 	Bracken (Pteridium aquilinum) is a conspicuous fern that forms large clonal colonies in a variety
of habitats. It is an aggressive colonizer of disturbed and other successional habitats of the
temperate forests, especially after fire events. It is allelopathic, inhibiting the growth of other
plant species, and this together with its rhizome growing strategy make bracken a major
competitor for other plants . Bracken produces a pharmacopeia of toxic compounds that renders
the plants toxic to most animals, both vertebrates and invertebrates, producing a substantial
annual amount of litter that decompose very slowly. Little is known on the effects of bracken
colonization in soil chemical and microbiological properties. Here we studied these effects during
a whole season (from nascent to senescent) in a pine forest (Pinus pinaster). To do this, we
selected islands of ferns differing in size (large, medium and small) since island size has important
effects on ecosystem level properties. We took paired composite samples of soil on every fern
island and the surrounding pine forest soil (2 m apart) and analyzed them for nutrient content (C,
N and P) and microbial activity measured as basal respiration.
Organic matter content decreased slightly through time in pine forest soil, but it increased in fern
soil, due to leaves deposition. Mineral nitrogen (N-NH4+ and N-NO3-) showed higher contents
in pine soil, which increased from summer to autumn and decreased in winter (pine soil),
conversely to fern soil. Dissolved organic nitrogen contents increased linearly with island size,
decreasing from summer to autumn and increasing again in winter (fern soil), and in pine soil
DON contents keep their values between summer and autumn. Dissolved organic carbon, as
DON, increased with island size, with higher contents in pine than in fern soil, decreasing from
summer to autumn, and increasing again in winter. Despite of higher nutrient content of pine
soil, microbial activity was consistently higher in fern than in pine soil. Microbial activity peaked
in autumn, with similar values in summer and winter, being the autumn increase higher in fern
than in pine soil.
Our results showed that the bracken fern improved soil microbial activity and also promoted a
strong N and C mineralization, due to low contents of both organic and inorganic N and organic
C indicating a low stability of soil system compared to soil below pines	
Categoria do assunto: 	--	
Registro original: 	Embrapa Florestas (CNPF)	
Exemplares: 	CNPF - (43553-1) - UPE - PL - -- - CD0305 -  -  - DIS