Dryland biomes cover two-fifths of Earth's land surface, but their forest area is poorly know... more Dryland biomes cover two-fifths of Earth's land surface, but their forest area is poorly known. Here, we report an estimate of global forest extent in dryland biomes, based on analyzing more than 210,000 0.5-hectare sample plots through a photo-interpretation approach using large databases of satellite imagery at (i) very high spatial resolution and (ii) very high temporal resolution, which are available through the Google Earth platform. We show that in 2015, 1327 million hectares of drylands had more than 10% tree-cover, and 1079 million hectares comprised forest. Our estimate is 40 to 47% higher than previous estimates, corresponding to 467 million hectares of forest that have never been reported before. This increases current estimates of global forest cover by at least 9%.
The Amazon Basin has experienced more variable climate over the last decade, with a severe and wi... more The Amazon Basin has experienced more variable climate over the last decade, with a severe and widespread drought in 2005 causing large basin-wide losses of biomass. A drought of similar climatological magnitude occurred again in 2010; however, there has been no basin-wide ground-based evaluation of effects on vegetation. We examine to what extent the 2010 drought affected forest dynamics using ground-based observations of mortality and growth from an extensive forest plot network. We find that during the 2010 drought interval, forests did not gain biomass (net change: À0.43 Mg ha À1 , confidence interval (CI): À1.11, 0.19, n = 97), regardless of whether forests experienced precipitation deficit anomalies. This contrasted with a long-term biomass sink during the baseline pre-2010 drought period (1998 to pre-2010) of 1.33 Mg ha À1 yr À1 (CI: 0.90, 1.74, p < 0.01). The resulting net impact of the 2010 drought (i.e., reversal of the baseline net sink) was À1.95 Mg ha À1 yr À1 (CI:À2.77, À1.18; p < 0.001). This net biomass impact was driven by an increase in biomass mortality (1.45 Mg ha À1 yr À1 CI: 0.66, 2.25, p < 0.001) and a decline in biomass productivity (À0.50 Mg ha À1 yr À1 , CI:À0.78, À0.31; p < 0.001).
To what extent does species-specific variation in gut passage time (GPT), habitat use and mobilit... more To what extent does species-specific variation in gut passage time (GPT), habitat use and mobility of three key avian frugivores synergistically affect the distribution of Xymalos monospora seeds within and among isolated forest fragments?
Historically the atmospheric and meteorological communities are separate worlds, with their own d... more Historically the atmospheric and meteorological communities are separate worlds, with their own data formats and tools for data handling, which makes sharing of these data with the geospatial communities difficult and cumbersome. These information sources are becoming of increasing interest outside of these communities at present, because of the continuously improving spatial and temporal resolution of e.g. model and satellite data and the interest in historical datasets. New user communities that use geographically based datasets in a cross-domain manner are emerging. This development is supported by the progress made in Geographical Information System (GIS) software. The current GIS software is not yet ready for the wealth of atmospheric data, although the faint outlines of new generation software are already visible: support of HDF, NetCDF and an increased understanding of temporal issues are only a few of the hints. To aid in this trend, the ADAGUC project aims to reduce the need for scientists to invent their own converter tools. Selected space borne atmospheric datasets will be made accessible for GIS software. Both the geospatial and the atmospheric user communities are involved intensively in the project, to obtain a high fitness for use. The deliverables of this project are: Open Source conversion tools, selected atmospheric datasets in a GIS-friendly format and a web service to demonstrate the usability of the above to the geospatial and atmospheric community. Dissemination of the results is pursued through publications, workshops and (inter)national cooperation. * [email protected]; phone +31 317 481552; fax: +31 317 419000; http://adaguc.knmi.nl
In common with all domains of remote sensing, residues indicative of past human activity can only... more In common with all domains of remote sensing, residues indicative of past human activity can only be detected if they exhibit some form of identifiable contrast with their surroundings. Unlike many other domains these residues do not exhibit consistent spectral signatures. Archaeological spectral responses are commonly expressed as subtle deviations from their surrounding matrix. This is true for crop marks, soil marks and thermal anomalies. The challenge is to collect imagery when the contrast between archaeological residues and ...
While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly to... more While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few 'hyperdominant' species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only E1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region.
Dryland biomes cover two-fifths of Earth's land surface, but their forest area is poorly know... more Dryland biomes cover two-fifths of Earth's land surface, but their forest area is poorly known. Here, we report an estimate of global forest extent in dryland biomes, based on analyzing more than 210,000 0.5-hectare sample plots through a photo-interpretation approach using large databases of satellite imagery at (i) very high spatial resolution and (ii) very high temporal resolution, which are available through the Google Earth platform. We show that in 2015, 1327 million hectares of drylands had more than 10% tree-cover, and 1079 million hectares comprised forest. Our estimate is 40 to 47% higher than previous estimates, corresponding to 467 million hectares of forest that have never been reported before. This increases current estimates of global forest cover by at least 9%.
The Amazon Basin has experienced more variable climate over the last decade, with a severe and wi... more The Amazon Basin has experienced more variable climate over the last decade, with a severe and widespread drought in 2005 causing large basin-wide losses of biomass. A drought of similar climatological magnitude occurred again in 2010; however, there has been no basin-wide ground-based evaluation of effects on vegetation. We examine to what extent the 2010 drought affected forest dynamics using ground-based observations of mortality and growth from an extensive forest plot network. We find that during the 2010 drought interval, forests did not gain biomass (net change: À0.43 Mg ha À1 , confidence interval (CI): À1.11, 0.19, n = 97), regardless of whether forests experienced precipitation deficit anomalies. This contrasted with a long-term biomass sink during the baseline pre-2010 drought period (1998 to pre-2010) of 1.33 Mg ha À1 yr À1 (CI: 0.90, 1.74, p < 0.01). The resulting net impact of the 2010 drought (i.e., reversal of the baseline net sink) was À1.95 Mg ha À1 yr À1 (CI:À2.77, À1.18; p < 0.001). This net biomass impact was driven by an increase in biomass mortality (1.45 Mg ha À1 yr À1 CI: 0.66, 2.25, p < 0.001) and a decline in biomass productivity (À0.50 Mg ha À1 yr À1 , CI:À0.78, À0.31; p < 0.001).
To what extent does species-specific variation in gut passage time (GPT), habitat use and mobilit... more To what extent does species-specific variation in gut passage time (GPT), habitat use and mobility of three key avian frugivores synergistically affect the distribution of Xymalos monospora seeds within and among isolated forest fragments?
Historically the atmospheric and meteorological communities are separate worlds, with their own d... more Historically the atmospheric and meteorological communities are separate worlds, with their own data formats and tools for data handling, which makes sharing of these data with the geospatial communities difficult and cumbersome. These information sources are becoming of increasing interest outside of these communities at present, because of the continuously improving spatial and temporal resolution of e.g. model and satellite data and the interest in historical datasets. New user communities that use geographically based datasets in a cross-domain manner are emerging. This development is supported by the progress made in Geographical Information System (GIS) software. The current GIS software is not yet ready for the wealth of atmospheric data, although the faint outlines of new generation software are already visible: support of HDF, NetCDF and an increased understanding of temporal issues are only a few of the hints. To aid in this trend, the ADAGUC project aims to reduce the need for scientists to invent their own converter tools. Selected space borne atmospheric datasets will be made accessible for GIS software. Both the geospatial and the atmospheric user communities are involved intensively in the project, to obtain a high fitness for use. The deliverables of this project are: Open Source conversion tools, selected atmospheric datasets in a GIS-friendly format and a web service to demonstrate the usability of the above to the geospatial and atmospheric community. Dissemination of the results is pursued through publications, workshops and (inter)national cooperation. * [email protected]; phone +31 317 481552; fax: +31 317 419000; http://adaguc.knmi.nl
In common with all domains of remote sensing, residues indicative of past human activity can only... more In common with all domains of remote sensing, residues indicative of past human activity can only be detected if they exhibit some form of identifiable contrast with their surroundings. Unlike many other domains these residues do not exhibit consistent spectral signatures. Archaeological spectral responses are commonly expressed as subtle deviations from their surrounding matrix. This is true for crop marks, soil marks and thermal anomalies. The challenge is to collect imagery when the contrast between archaeological residues and ...
While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly to... more While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few 'hyperdominant' species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only E1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region.
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Papers by Nikée Groot