Data/hora: 07/06/2024 05:25:55

Biblioteca(s): 	Embrapa Pantanal.	
Data corrente: 	04/05/2001	
Data da última atualização: 	30/03/2017	
Autoria: 	TATE, K. R.; SCOTT, N. A.; PARSHOTAM, A.; BROWN, L.; WILDE, R. H.; GILTRAP, D. J.; TRUSTRUM, N. A.; GOMEZ, B.; ROSS, D. J.	
Título: 	A multi-scale analysis of a terrestrial carbon budget is a New Zealand a source or sink of carbon?	
Ano de publicação: 	2000	
Fonte/Imprenta: 	Agricultuire Ecosystem & Environment, v.82, n.1/3, p.229-246, 2000.	
Idioma: 	Inglês	
Conteúdo: 	Interest in national carbon (C) budgets has increased following the signing of the Kyoto Protocol as countries begin to develop source/sink C invetories. In this study, specific-site measurements, regional database, satellite observations, and models were used to test the hypothesis that New Zealand's terrestrial ecosystems are C neutral because C uptake by planted forests and scrub is roughly balanced by C losses from indigenous forests and soils. Net ecosystems C balance was estimated from the difference between net primary production (NPP) and heterotrophic soil respiration. The productivity portion of the CASA model and NOAA-AVHRR imagery were used to estimate national NPP (128 14 Mt C per year). Main sources of uncertainty were the coarse spatial scale (1 x 1 km2 grid cells), and the general lack of information on photosynthetically active radiation, light-use efficiency, and below-ground C allocation for the major vegetation types: indigenous and exotic forests, schrub, and grasslands (improved, unimproved and tussock). Total soil CO2-C production predicted from an Arrhenius-type function coupled to climate and land-cover data was 380 30 Mt C per year, suggesting that New Zeland's terrestrial ecosystems may be either (a) a net source of atmospheric CO2 or (b) roughly in C balance if ca. 252 Mt CO2-C per year (66%) can be attributed to roots. Soil moisture limitations on respiration were small, reducing the national value to 365 28 Mt C per year. Differences between NPP and heterotrophic soil respiration were -29 Mt C per year for improved pastures, 8 Mt C per year for indigenous forests, and +4 Mt C per year for planted forests; the large negative value for improved grassland may be due to under-estimation of NPP and root respiration. Soil C losses to coastal waters, as estimated from a consideration of all the major erosion processes, were ca. 3-11 Mt C per year. These national-scale estimates of ecosystems C balance were in general agreement with those based on plot-scale data for some major ecosystems including planted forests (4 Mt C per year vs 3.7 Mt C per year, respectively) and indigenous forest (-8 Mt C per year vs ca. -2.8 Mt C per year, respectively). Poor agreement for forest regenerating after land abandonment (-17 Mt C per year vs +3 Mt C per year) was probably due to an underestimate of NPP at the national scale. Overall, the results suggest that New Zealand is a net C source, despite the that some ecosystems are accumulating C. For some land-use types, using the balance between NPP and soil respiration at the national scale to estimate the net ecosystem C balance  may be too coarse, and studies of land-use changes at finer spatial scales are needed to reduce uncertainties in national-scale C balance estimates.	
Palavras-Chave: 	Model; Modelo; Primary production; Producao primaria.	
Thesagro: 	Carbono; Sensoriamento Remoto; Solo.	
Thesaurus Nal: 	carbon; remote sensing; soil.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Pantanal (CPAP)	
Exemplares: 	CPAP - (48944-1) - ADC - SP - PP - SP16234 -  - 16234 - DIS