Data/hora: 23/09/2024 05:04:46

Biblioteca(s): 	Embrapa Florestas.	
Data corrente: 	22/09/2008	
Data da última atualização: 	22/09/2008	
Autoria: 	JOUQUET, P.; BOTTINELLI, N.; ZANGERLÉ, A.; BRUNET, D.; HALLAIRE, V.; DUC, T. T.	
Título: 	Relevance and limit of the Biogenic and Physicogenic classification. A multivariable fingerprinting approach to discriminate the origin of soil aggregates.	
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: 	To maintain or rehabilitate soil quality requires understanding the biotic and abiotic processes
involved in the dynamic of soil structure. Soil aggregates have been proposed as structural units
within the soil that control the dynamic of soil organic matter (SOM) and nutrient cycling.
Earthworms, as ecosystem engineers, contribute greatly to the creation of macro-aggregates.
However, A major obstacle to the quantification of the influence of earthworms on soil and
ecosystem functioning is an almost complete ignorance on the dynamic of casts once formed.
Indeed, there is plenty of studies dealing with the formation and structural stability of casts, while
very few is known about the mechanisms involved in cast desegregation. As a consequence,
the quantification of earthworm activity in the field is assessed through the classification of soil
aggregates into ?biogenic? and ?physicogenic? aggregates according to their shapes: biogenic
aggregates are rounded shape macro-aggregates that are clearly visually identified as casts or
old casts, while physicogenic aggregates are angular to subangular blocky macroaggregates
that are not produced by soil macrofauna activity. This pragmatic approach has been efficiently
used to discriminate the influence of ecosystem engineers in soil functioning. However, these
studies relied on the assumption that a visual estimation is enough to discriminate aggregates
made by soil engineers or that, in other words, biogenic aggregates keep their visual signature
until they become physicogenic?like aggregates. One can therefore suggest that in addition to
be imprecise, this approach is probably also non-reproducible (i.e., experimentally dependant)
when we are faced to aggregates collected in situ.
Using a multivariable fingerprinting approach, we discussed the limit and relevance of the
classification into biogenic and physicogenic aggregates through visual identification. We used
different physical and chemical analyses to go further in the identification of soil biogenic
aggregates and to differentiate them even after the loss of their specific visual aspect. The
studied variables were chosen according to the criteria that are usually used in the literature to
discriminate biogenic and physicogenic aggregates: (i) the aspect (i.e., the magnitude of the
rounded shape), (ii) the physical (soil structural stability), (iii) chemical (12,13C and 14,15N
content); and (iv) spectral signature (Near Infrared Reflectance Spetrometry: NIRS).	
Categoria do assunto: 	--	
Registro original: 	Embrapa Florestas (CNPF)	
Exemplares: 	CNPF - (43658-1) - UPE - PL - -- - CD0305 -  -  - DIS