SBSTTA Review DRAFT GBO4 – Technical Document – Chapter 5 DO NOT CITE 1 Target 5: Habitat loss and degradation 2 3 By 2020, the rate of loss of all natural habitats, including forests, is at least halved and where 4 feasible brought close to zero, and degradation and fragmentation is significantly reduced. 5 6 7 Preface 8 9 Habitat loss is the main driver of biodiversity change in terrestrial and inland water systems. 10 In particular, the conversion of natural systems including forests, woodlands and grasslands 11 to agricultural areas has diminished the area of natural systems and has often reduced 12 species richness. Various meta-analyses have shown that species abundance and species 13 richness declines after conversion in most cases, but not all species from the natural system 14 disappear and other species may colonize converted habitats (Gibson et al., 2011). 15 16 Conversion of land started from the establishment of agriculture about 10,000 years ago and 17 continues to modern times. The extent of conversion and the additional human alterations 18 of the environment have led to the notion that earth has entered the era of the 19 Anthropocene (Ellis et al., 2010, Zalasiewicz et al., 2011). Increasing human population and 20 growing wealth, leading to a growing demand of food, bioenergy, wood and fiber are the 21 primary drivers of land conversion and thus habitat loss. It is projected that more land will be 22 needed to achieve increases in production of agricultural and forestry products in the future. 23 However, increases in productivity per unit land can potentially provide a large increase in 24 global production. 25 26 The main focus of this analysis is on habitat loss in terrestrial systems, especially focusing on 27 forests. The main forest areas occur in the high northern latitudes (boreal forests), the 28 temperate zone and the tropics. Forest definitions depend on the threshold of canopy 29 closure that is used and the different forest types that are included. “Closed forests” have a 30 tree canopy density greater than 40% or 45%, “open forests and woodlands” have a tree 31 canopy density ranging between 20–45% and “non-forest ecosystems” have a tree canopy 32 density ranging between 10-25% (Laestadius et al., 2012, Potapov et al., 2008). The later 33 forest type includes savannas, grasslands and mountain ecosystems (Potapov et al., 2008) 34 and is treated in the assessment of grassland ecosystems. Closed forests cover about 18% 35 and open forests and woodlands cover about 9% of the Earth's total land area (Potapov et 36 al., 2008). 37 38 Changes in forest cover are assessed in several ways. This chapter focuses on gross forest 39 cover loss (defined as forest cover loss due to natural and human-induced disturbances), 40 gains in forest cover (due to forest regrowth or human driven reforestation and 41 afforestation) and net forest cover change. Gross forest loss is a particularly important 42 indicator in tropical forests because many are primary forests that contain high biodiversity 43 that is only very partially recovered during reforestation (Gibson et al., 2011). The primary 44 methods for determining forest cover change include remote sensing (e.g., Hansen et al. 45 2013, Potapov et al., 2011) and national reports (e.g., FA0 2010). Remote sensing provides 46 uniform regional and global evaluation of gross loss, gain and net change, but has difficulty in 47 distinguishing the causes of forest loss. This can be due to deforestation (which is a change in 1 SBSTTA Review DRAFT GBO4 – Technical Document – Chapter 5 DO NOT CITE 1 land use), logging or natural factors such as hurricanes or fire. National reports can be used 2 to estimate types of forest loss, but suffer from heterogeneity in reporting. 3 4 In addition to forest habitat, trends in grasslands are also described since they cover about 5 40% of the Earth’s surface (excluding Greenland and Antarctica) and have high biodiversity 6 values (White et al., 2000). In Europe, for example, about 50% of the endemic plant species 7 are dependent on grassland biotopes (Veen et al., 2009). Grasslands can be defined as 8 ecosystems dominated by herbaceous and shrub vegetation and maintained by fires, 9 drought, grazing and/or freezing temperatures (White et al., 2000). Non-forest ecosystems, 10 such as savannas, woodlands, shrublands and tundra, are also included in grassland 11 ecosystems. Grasslands are found on every continent; the largest amount is located in Sub- 12 Saharan Africa and Asia, while the Middle East and Central America have the least grassland 13 ecosystems (White et al., 2000). In Sub-Saharan Africa grasslands are mostly savanna 14 systems, while in Oceania and Asia grasslands are often shrubland, in Asia mostly non-woody 15 grasslands and in Europe tundra ecosystems (White et al., 2000). However, these grasslands 16 are increasingly modified due to human activities, such as cultivation, urbanization, 17 desertification, fire, livestock grazing, fragmentation and introduction of invasive species 18 (White et al., 2000). Nevertheless, uncertainties exist due to the use of various grassland 19 definitions and difficulty in monitoring by remote sensing (Verburg et al., 2011, White et al., 20 2000). Therefore the change in grassland extent is not as thoroughly described as forest 21 cover change. 22 23 Trends in aquatic habitat types, such as freshwater and coastal systems are less extensively 24 described in this chapter. Coastal systems and low-lying areas include all areas near mean 25 sea level, comprising a diversity of ecological systems including rocky coasts, beaches, 26 barriers and sand dunes, estuaries and lagoons, deltas, river mouths, wetlands and coral 27 reefs (IPCC, 2014). Generally, there is no single definition for the coast and the coastal area. 28 In relation to exposure to potential sea level rise, the LECZ (low-elevation coastal zone) has 29 been used in recent years with reference to specific area, ecosystems and population up to 30 10 m elevation (Vafeidis et al., 2011). As of 2000, the LECZ constitute 2% of the world’s land 31 area but contains 10% of world’s human population (600 million; McGranahan et al., 2007). 32 In addition, approximately 65% of the world’s cities with populations of over 5 million are 33 located in the LECZ (McGranahan et al., 2007). The extent of intact coastal ecosystems is an 34 important indicator as these systems provide a wide variety of regulating, provisioning, 35 supporting and cultural services (MA, 2005). However, they have been heavily altered and 36 influenced by human activities, resulting in tightly coupled social-ecological systems (Berkes 37 & Folke, 1998, Hopkins et al., 2012, IPCC, 2014, Vörösmarty et al., 2010). Key drivers of 38 coastal habitat loss and degradation continue to be increasing human population and land- 39 use (including pollution), sea level rise (coastal ecosystem flooding and erosion) and ocean 40 temperature change (IPCC, 2014). Given the diversity of ecological systems that comprise 41 coastal systems, there is a paucity of information available for many of these systems. As 42 many existing studies as possible were used, however explicit numbers on the extent, loss or 43 degradation are not available for all ecosystems on a global scale. Therefore only broad 44 categories of ecosystems are distinguished; changes in specific vulnerable ecosystems are 45 described in the chapter on target 10. 46 2 SBSTTA Review DRAFT GBO4 – Technical Document – Chapter 5 DO NOT CITE 1 Freshwater ecosystems most commonly refer to lakes, different types of wetlands, rivers 2 and streams, and groundwater. These systems occupy less than 1% of the Earth’s surface 3 (Strayer & Dudgeon, 2010). The global extent of freshwater wetlands has been estimated at 4 9.2 – 12.8 million km2 at the end of the 20th century (Finlayson, 2006, Lehner & Döll, 2004, 5 MA, 2005). Despite this, fresh waters support more than 10% of all known species including 6 around a third of all vertebrates (Strayer & Dudgeon, 2010). Exploitation of these systems 7 for food, energy, transport, and water supply (Vörösmarty et al., 2010), together with the 8 emerging threat from climate change (Woodward et al., 2010), has led to freshwater 9 ecosystems suffering more strongly from human activities than marine and terrestrial 10 ecosystems (Darwall et al., 2008, Dudgeon et al., 2006, Keenleyside & Tucker, Ricciardi & 11 Rasmussen, 1999). Similar to coastal ecosystems, information and data on the extent of 12 freshwater ecosystem fragmentation at the global scale are limited. 13 14 15 Are we on track to achieve the 2020 target? 16 17 1.a. Status and trends 18 19 At global level, the extent of all natural ecosystems, terrestrial and aquatic, are declining (Fig. 20 5.1), however, large regional differences exist. The causes of decline for forests, grassland, 21 coastal and freshwater systems are described below. 22 23 24 Figure 5.1. Change in land cover types from 1970 – 2010. Derived from IMAGE (Bouwman et al., 25 2006), based on FAO (2014). 26 27 1.a.i. Forests 28 29 The most recent estimates of global forest cover change, based on high-resolution satellite 30 imagery, indicate substantial forest loss (2.3 million square kilometers) and gain (0.8 million 31 square kilometers) over the period 2000 to 2012 (Fig. 5.2; Hansen et al., 2013). Gross forest 3 SBSTTA Review DRAFT GBO4 – Technical Document – Chapter 5 DO NOT CITE 1 cover loss is high in all forested biomes, but differs greatly among regions. Rates of loss in 2 terms of total area are particularly high in boreal forests and the humid tropics (Fig. 5.2.; 3 Hansen et al., 2013). There are no temporal trends in rates of gross loss except for an 4 increasing trend for tropical forests (Hansen et al., 2013).