Grassland afforestation impact on primary productivity a remote sensing approach
Question: How is the magnitude and seasonality of carbon uptake affected by the replacement of native grasslands by eucalyptus plantations? Location: Río de la Plata Grasslands in Argentina and Uruguay. Methods: A total of 115 paired sites of fast-growing Eucalyptus grandis plantations and adjacent grasslands were used to characterize the magnitude and seasonality of [1] radiation interception by canopies and [2] above-ground net primary productivity based on a time series of MODIS-derived normalized difference vegetation index [NDVI]. The response of NDVI to precipitation was explored across temporal scales. Results: NDVI in afforested vs. grassland plots presented higher annual averages [1.3-fold], lower seasonal ranges [average relative range of 0.11 vs. 0.29] and delayed growing seasons [2-month shift]. Temporally, NDVI was positively associated with precipitation input, showing a correlation with longer periods of precipitation accumulation in tree plantations compared to grasslands [greather than 7 vs. 2-3 months]. Estimated average annual above-ground net primary productivity [ANPP] almost quadrupled as a consequence of replacing grasslands by tree plantations [&4 vs. &17Â Mg dry matter. ha-1.·yr-1], and this difference was evidenced throughout the whole study period. Conclusions: Afforested grasslands intercept more radiation and have higher and more stable ANPP throughout the year, probably as a result of major changes in leaf phenology and root distribution patterns, which in turn allowed better access to water. Changes in carbon uptake can influence climate/biosphere feedbacks and should be considered in land-use planning, especially when grassland afforestation is recommended as a tool to mitigate global warming.
| Main Authors: | , , , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Subjects: | ANPP, LAND-USE CHANGE, MODIS, NDVI, RIO DE LA PLATA GRASSLANDS, TREE PLANTATIONS, EUCALYPTUS, EUCALYPTUS GRANDIS, |
| Online Access: | http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=46940 |
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