Livestock tracks transform resource distribution on terracette landscapes of the Loess Plateau

Abstract

Abstract. Striking networks of livestock tracks, or terracettes, molded to the contours are a common feature on hilly rangelands of the semiarid Loess Plateau, one of the regions with the most severe soil erosion in the world. The formation of livestock tracks results in modified micro-topography and ecological processes and leads to strong patterns in spatial distribution of vegetation, water, and nutrients. We investigated the spatial pattern of the topo-edaphic, hydrological, biogeochemical, and biological attributes of these terracette landscapes and explored their potential implications to ecosystem functions. The results showed strong spatial heterogeneity in topo-edaphic and biological structure of these landscapes, organized with three segments of a basic landscape unit-track, shoulder, and interslope. The above-and below-ground biomass and soil nutrients concentrated in the shoulder segment forming a "band of fertility". The network of livestock tracks likely reduced surface runoff and erosion by intercepting runoff and facilitate infiltration, while posing little risk of increasing shallow slope failures given the structure of loess soil. There appears a positive feedback loop for maintaining the structure of terracette landscapes. Trampling by goats maintains the tracks, which leads to spatial heterogeneity in biophysical structure and processes. The network of tracks enabled the goats to travel and graze in ways that reduce energy expenditure and increase foraging efficiency, which leads to strongly preferential use of the tracks by the goats. There are also evidence of a possible process resemble a slope parallel retreat at a micro-scale, which may result in upslope movement of the terracettes. There may be important functional differences between landscapes with and without networks of livestock tracks, in regulating water runoff and soil erosion, forage production, and soil carbon storage. These functional differences may have significant implications to land use policies and practices aiming at soil and water conservation and socioecological sustainability of the Loess Plateau.

Positive impacts of livestock and wild ungulate routes on functioning of dryland ecosystems

“…Similar route patterns have been reported for other drylands around the world, such as in China (Jin et al., 2016 , 2019 ; Sun et al., 2020 ), Kyrgyzstan (Liu & Watanabe, 2013 ), Spain (Ries, 2010 ; Ries et al., 2013 ), and the USA (Corrao et al., 2015 , 2016 ; Ganskopp et al., 2000 ; Trimble & Mendel, 1995 ). Also, despite not specifically indicated, livestock routes have apparently formed in Iran (see Rahmanian et al., 2019 ).…”

“…For example, in Israel, animal routes occur between the dry subhumid region in the north of the country, through the central, semiarid, and arid zones, to the hyper-arid region in the south of the country (Figure 2). Similar route patterns have been reported for other drylands around the world, such as in China (Jin et al, 2016(Jin et al, , 2019Sun et al, 2020), Kyrgyzstan (Liu & Watanabe, 2013), Spain (Ries, 2010;Ries et al, 2013), and the USA (Corrao et al, 2015(Corrao et al, , 2016Ganskopp et al, 2000;Trimble & Mendel, 1995). Also, despite not specifically indicated, livestock routes have apparently formed in Iran (see Rahmanian et al, 2019).…”

Detection of terracettes in semi‐arid rangelands using Fourier‐based image analysis of very‐high‐resolution satellite imagery

“…Terraced landscapes, both man (Tarolli et al ., 2014) and animal made (Thornes, 2007), introduce alterations in topography that in turn alter the hydrological processes of the area (Torresani et al ., 2019). A dramatic example of altered hillslope topography are rangeland terracettes found on treeless, grass‐covered hillslopes around the world (Buckhouse and Krueger, 1981; Watanabe, 1994; Walsh et al ., 2001; Kück and Lewis, 2002; Corrao et al ., 2015; Jin et al ., 2016). These step‐like, microtopographic features are characterized by repetitious benches (also referred to as treads), and risers that are rarely greater than 0.5 m in height and depth (Ward, 2003) and can be found on slopes 9–60° with feature lengths from 3 to >300 m (Corrao et al ., 2016).…”

“…Two primary mechanisms have been hypothesized for the formation of terracettes: ungulate traffic and localized solifluction. Ungulates and more specifically livestock may be the dominant geomorphic agent in semi‐arid systems, including cattle (Walsh et al ., 2001), goat (Jin et al ., 2016), sheep and yak (Watanabe, 1994), while solifluction may be the primary mechanism in humid and alpine regions (Buckhouse and Krueger, 1981; Bielecki and Mueller, 2002; Kück and Lewis, 2002). With ungulate traffic, terracette bench and riser show altered vegetative cover and soil compaction displaying strong spatial patterns (Stavi et al ., 2008; Jin et al ., 2016) that are observable in imagery of sub‐metric resolution.…”

“…Ungulates and more specifically livestock may be the dominant geomorphic agent in semi‐arid systems, including cattle (Walsh et al ., 2001), goat (Jin et al ., 2016), sheep and yak (Watanabe, 1994), while solifluction may be the primary mechanism in humid and alpine regions (Buckhouse and Krueger, 1981; Bielecki and Mueller, 2002; Kück and Lewis, 2002). With ungulate traffic, terracette bench and riser show altered vegetative cover and soil compaction displaying strong spatial patterns (Stavi et al ., 2008; Jin et al ., 2016) that are observable in imagery of sub‐metric resolution. Just as the sharp contrast in elevation was used in the detection of terraces, the abrupt change in imagery pixel intensity values between bench and riser may be utilized to detect terracettes, especially if they occur in networks of periodic benches and risers that are roughly parallel to each other and the contour of the hillslope.…”