Editing Test:SRCCL/Chapter-1 (section)

==== Status and trends in the global land system: A. Trends in area, production and trade, and drivers of change. The map shows the global pattern of land systems (combination of maps Nachtergaele (2008); Ellis et al. (2010); Potapov et al. (2017); FAO’s Animal Production and Health Division (2018); livestock low/high relates to low or high […] ====

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Status and trends in the global land system: '''A''' . Trends in area, production and trade, and drivers of change. The map shows the global pattern of land systems (combination of maps Nachtergaele (2008) <sup>[[#fn:r177|177]]</sup> ; Ellis et al. (2010) <sup>[[#fn:r178|178]]</sup> ; Potapov et al. (2017) <sup>[[#fn:r179|179]]</sup> ; FAO’s Animal Production and Health Division (2018); livestock low/high relates to low or high livestock density, respectively). The inlay figures show, for the globe and seven world regions, from left to right: (a) Cropland, permanent pastures and forest (used and unused) areas, standardised to total land area, (b) production in dry matter per year per total land area, (c) trade in dry matter in percent of total domestic production, all for 1961 to 2014 (data from FAOSTAT (2018) <sup>[[#fn:r180|180]]</sup> and FAO (1963) <sup>[[#fn:r181|181]]</sup> for forest area 1961). (d) drivers of cropland for food production between 1994 and 2011 (Alexander et al. 2015 <sup>[[#fn:r182|182]]</sup> ). See panel “global” for legend. “Plant Produc., Animal P.”: changes in consumption of plant-based products and animal-products, respectively. '''B''' .Selected land-use pressures and impacts. The map shows the ratio between impacts on biomass stocks of land-cover conversions and of land management (changes that occur with land-cover types; only changes larger than 30 gC m <sup>–2</sup> displayed; Erb et al. 2017 <sup>[[#fn:r183|183]]</sup> ), compared to the biomass stocks of the potential vegetation (vegetation that would prevail in the absence of land use, but with current climate). The inlay figures show, from left to right (e) the global Human Appropriation of Net Primary production (HANPP) in the year 2005, in gC m <sup>–2</sup> yr <sup>–1</sup> (Krausmann et al. 2013 <sup>[[#fn:r184|184]]</sup> ). The sum of the three components represents the NPP of the potential vegetation and consist of: (i) NPP <sub>eco</sub> , i.e. the amount of NPP remaining in ecosystem after harvest, (ii) HANPP <sub>harv</sub> , i.e. NPP harvested or killed during harvest, and (iii) HANPP <sub>luc</sub> , i.e. NPP foregone due to land-use change. The sum of NPP <sub>eco</sub> and HANPP <sub>harv</sub> is the NPP of the actual vegetation (Haberl et al. 2014 <sup>[[#fn:r185|185]]</sup> ; Krausmann et al. 2013 <sup>[[#fn:r186|186]]</sup> ). The two central inlay figures show changes in land-use intensity, standardised to 2014, related to (f) cropland (yields, fertilisation, irrigated area) and (g) forestry harvest per forest area, and grazers and monogastric livestock density per agricultural area (FAOSTAT 2018). (h) Cumulative CO <sub>2</sub> fluxes between land and the atmosphere between 2000 and 2014. LUC: annual CO <sub>2</sub> land use flux due to changes in land cover and forest management; Sink <sub>land</sub> : the annual CO <sub>2</sub> land sink caused mainly by the indirect anthropogenic effects of environmental change (e.g, climate change and the fertilising effects of rising CO <sub>2</sub> and N concentrations), excluding impacts of land-use change (Le Quéré et al. 2018 <sup>[[#fn:r187|187]]</sup> ) (Section 2.3)

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While most pastureland expansion replaced natural grasslands, cropland expansion replaced mainly forests (Ramankutty et al. 2018 <sup>[[#fn:r188|188]]</sup> ; Ordway et al. 2017 <sup>[[#fn:r189|189]]</sup> ; Richards and Friess 2016 <sup>[[#fn:r190|190]]</sup> ). Noteworthy large conversions occurred in tropical dry woodlands and savannahs, for example, in the Brazilian Cerrado (Lehmann and Parr 2016 <sup>[[#fn:r191|191]]</sup> ; Strassburg et al. 2017 <sup>[[#fn:r192|192]]</sup> ), the South American Caatinga and Chaco regions (Parr et al. 2014 <sup>[[#fn:r193|193]]</sup> ; Lehmann and Parr 2016 <sup>[[#fn:r194|194]]</sup> ) or African savannahs (Ryan et al. 2016 <sup>[[#fn:r195|195]]</sup> ). More than half of the original 4.3–12.6 million km <sup>2</sup> global wetlands (Erb et al. 2016a <sup>[[#fn:r196|196]]</sup> ; Davidson 2014 <sup>[[#fn:r197|197]]</sup> ; Dixon et al. 2016 <sup>[[#fn:r198|198]]</sup> ) have been drained; since 1970 the wetland extent index, developed by aggregating data field-site time series that report changes in local inland wetland area, indicates a decline of more than 30% (Darrah et al. 2019 <sup>[[#fn:r199|199]]</sup> ) (Figure 1.1 and Section 4.2.1). Likewise, one-third of the estimated global area that in a non-used state would be covered in forests (Erb et al. 2017 <sup>[[#fn:r200|200]]</sup> ) has been converted to agriculture.

Global forest area declined by 3% since 1990 (about –5% since 1960) and continues to do so (FAO 2015a <sup>[[#fn:r201|201]]</sup> ; Keenan et al. 2015 <sup>[[#fn:r202|202]]</sup> ; MacDicken et al. 2015 <sup>[[#fn:r203|203]]</sup> ; FAO 1963; Figure 1.1 <sup>[[#fn:r204|204]]</sup> ), but uncertainties are large. ''Low agreement'' relates to the concomitant trend of global tree cover. Some remote-sensing based assessments show global net-losses of forest or tree cover (Li et al. 2016 <sup>[[#fn:r205|205]]</sup> ; Nowosad et al. 2018 <sup>[[#fn:r206|206]]</sup> ; Hansen et al. 2013 <sup>[[#fn:r207|207]]</sup> ); others indicate a net gain (Song et al. 2018 <sup>[[#fn:r208|208]]</sup> ). Tree-cover gains would be in line with observed and modelled increases in photosynthetic active tissues (‘greening’; Chen et al. 2019 <sup>[[#fn:r209|209]]</sup> ; Zhu et al. 2016 <sup>[[#fn:r210|210]]</sup> ; Zhao et al. 2018 <sup>[[#fn:r211|211]]</sup> ; de Jong et al. 2013 <sup>[[#fn:r212|212]]</sup> ; Pugh et al. 2019 <sup>[[#fn:r213|213]]</sup> ; De Kauwe et al. 2016 <sup>[[#fn:r214|214]]</sup> ; Kolby Smith et al. 2015 <sup>[[#fn:r215|215]]</sup> ) (Box 2.3 in Chapter 2), but ''confidence'' remains ''low'' whether gross forest or tree-cover gains are as large, or larger, than losses. This uncertainty, together with poor information on forest management, affects estimates and attribution of the land carbon sink (Sections 2.3, 4.3 and 4.6). Discrepancies are caused by different classification schemes and applied thresholds (e.g., minimum tree height and tree-cover thresholds used to define a forest), the divergence of forest and tree cover, and differences in methods and spatiotemporal resolution (Keenan et al. 2015 <sup>[[#fn:r216|216]]</sup> ; Schepaschenko et al. 2015 <sup>[[#fn:r217|217]]</sup> ; Bastin et al. 2017 <sup>[[#fn:r218|218]]</sup> ; Sloan and Sayer 2015 <sup>[[#fn:r219|219]]</sup> ; Chazdon et al. 2016a <sup>[[#fn:r220|220]]</sup> ; Achard et al. 2014 <sup>[[#fn:r221|221]]</sup> ). However, there is ''robust evidence''  and ''high agreement'' that a net loss of forest and tree cover prevails in the tropics and a net gain, mainly of secondary, semi-natural and planted forests, in the temperate and boreal zones.

The observed regional and global historical land-use trends result in regionally distinct patterns of C fluxes between land and the atmosphere (Figure 1.3B). They are also associated with declines in biodiversity, far above background rates (Ceballos et al. 2015 <sup>[[#fn:r222|222]]</sup> ; De Vos et al. 2015 <sup>[[#fn:r223|223]]</sup> ; Pimm et al. 2014 <sup>[[#fn:r224|224]]</sup> ; Newbold et al. 2015 <sup>[[#fn:r225|225]]</sup> ; Maxwell et al. 2016 <sup>[[#fn:r226|226]]</sup> ; Marques et al. 2019 <sup>[[#fn:r227|227]]</sup> ). Biodiversity losses from past global land-use change have been estimated to be about 8–14%, depending on the biodiversity indicator applied (Newbold et al. 2015 <sup>[[#fn:r228|228]]</sup> ; Wilting et al. 2017 <sup>[[#fn:r229|229]]</sup> ; Gossner et al. 2016 <sup>[[#fn:r230|230]]</sup> ; Newbold et al. 2018 <sup>[[#fn:r231|231]]</sup> ; Paillet et al. 2010 <sup>[[#fn:r232|232]]</sup> ). In future, climate warming has been projected to accelerate losses of species diversity rapidly (Settele et al. 2014 <sup>[[#fn:r|]]</sup> 233; Urban et al. 2016 <sup>[[#fn:r234|234]]</sup> ; Scholes et al. 2018 <sup>[[#fn:r235|235]]</sup> ; Fischer et al. 2018 <sup>[[#fn:r236|236]]</sup> ; Hoegh-Guldberg et al. 2018 <sup>[[#fn:r237|237]]</sup> ). The concomitance of land-use and climate change pressures render ecosystem restoration a key challenge (Anderson-Teixeira 2018 <sup>[[#fn:r238|238]]</sup> ; Yang et al. 2019 <sup>[[#fn:r240|240]]</sup> ) (Sections 4.8 and 4.9).

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