## 3 Analysis and Discussion
### Semi-Arid Lands
#### 3.1.1 Ecological Restoration in the Western US  
Western US semi-arid lands comprise diverse rangeland ecosystems and are often dominated by shrublands at lower elevations and in mountain valleys; these ecosystems face unique threats due to their floristic composition and past disturbances that have degraded vegetation and soils [29] (Figure 3). Of key concern are sagebrush (_Artemisia_ spp. Nutt.)-dominated ecosystems where agricultural expansion, improper livestock grazing  
Figure 2: Spatial representation of global and Continental United States (CONUS) semi-arid lands map.  
management, wildfires, invasive species, and climate change have resulted in considerable reductions since the 1850s [30].  
The United States Geological Survey (USGS) in collaboration with the Bureau of Land Management (BLM) launched the Rangeland Condition Monitoring Assessment and Projection (RCMAP) dataset to quantify the percent cover of rangeland components (bare ground, herbaceous, annual herbaceous, litter, shrub, and sagebrush across the western US. Through RCMAP, 2.9 million km\({}^{2}\) were mapped with the following main results: bare ground 45.5%, shrub 15.2%, sagebrush 4.3%, big sagebrush 2.9%, herbaceous 23.0%, annual herbaceous 4.2%, and litter 15.8% [31]. [PERSON] et al., (2021) [32] evaluated the trends of rangeland change between 1985 and 2018 and analyzed the relationships with climate drivers, and their results showed the percent net cover of shrubs, sagebrush, and litter significantly (\(p<0.01\)) decreased during this time period.  
To rehabilitate ecosystems affected by natural or anthropogenic disturbances, ecological landscape restoration emerges as a widely recommended solution, especially in semi-arid lands [33]. A crucial component of these restoration efforts relates to the development of drought-resistant grasses, legumes, and herbaceous plants capable of competing with invasive weeds while maintaining adequate productivity and quality. [34].  
Across the western US, several agencies oversee planning and implementing restoration practices that respond to the specific needs of a particular ecosystem. With regards to rangeland plant material development, the US Department of Agriculture (USDA), Agricultural Research Service (ARS), and Forage and Range Research Laboratory (FRRL) in Logan, Utah has led this process in the region. The FRRL has historically developed plant materials (grass, legume, and forb) that improve the resilience of rangelands and pastures to environmental and anthropogenic stresses [35]. This laboratory currently develops native and non-native plant materials to restore disturbed grasslands [36], recommending plant improvement of the native legume Utah clover (_Lotus utahensis_ [PERSON]), grasses prairie: Junegrass [_Koeleria marcantha_ (Ledeb.) [PERSON]], bluebunch wheatgrass (_Pseudorogeneria spicata_ ([PERSON]) [PERSON] [Poaceae]) and Snake River wheatgrass [(_Elymus wawawaiensis_) [PERSON] & [PERSON]]. Likewise, non-native perennial grasses such as crested wheatgrass (_Agropyron cristatum_, _Agropyron_ spp.), tall wheatgrass (_Thinopyrum poticum_ [Podp.] [PERSON]. [PERSON] & [PERSON]), intermediate wheatgrass and prairie brome grass to support sustainable grassland management [35].  
Agencies such as the BLM actively use these improved plant materials in various ecological restoration practices associated with fuel management, soil cultivation, rangeland seeding, invasive plant suppression, prescribed burns, soil stabilization, and wildlife management [37; 38]. In addition, the primary types of vegetation targeted for these interventions include pinyon-juniper (Pinus-Juniperus) woodlands, cresoote bush scrub, desert scrub, riparian woodlands, and big sagebrush shrubland; these practices aim to restore and maintain the ecological balance and resilience of these crucial ecosystems [39].