Rangelands occupy over a third of global land area, and in many cases are in less than optimum condition as a result of past land use, catastrophic wildfire, and other disturbances, invasive species, or climate change. Often the only means of restoring these lands involves seeding desirable species, yet there are few cost effective-seeding technologies, especially for the more arid rangeland types. The inability to consistently establish desired plants from seed may indicate that seeding technologies being employed are not successful in addressing the primary sources of mortality in the progression from seed to established plant. Seed enhancement technologies allow for the physical manipulation and application of materials to the seed that can enhance germination, emergence, and/or early seedling growth. In this article, we examine some of the major limiting factors impairing seedling establishment in North America's sagebrush steppe ecosystem and propose seed enhancement technologies that may have the potential to overcome these restoration barriers. We discuss specific technologies for: (1) increasing soil water availability; (2) enhancing seedling emergence in crusting soil; (3) controlling the timing of seed germination; (4) improving plantability and emergence of small-seeded species; (5) enhancing seed coverage of broadcasted seeds; and (6) protecting seedlings from pre-emergent herbicide. Concepts and technologies in this article for restoring the sagebrush steppe ecosystem may apply generally to semiarid and arid rangelands around the globe.

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The use of native plant seeds is fundamental to large-scale rehabilitation and the re-establishment of self-sustaining ecosystems after high-impact mining activity has ceased. However, many of the biological attributes of seeds are often overlooked in large-scale rehabilitation programs. Multi-disciplinary, long-term research collaborations are required to improve seed-based mine rehabilitation. In this paper, we review the steps that BHP Western Australia Iron Ore (WAIO), a large iron ore mining company that operates in the Pilbara bioregion of north-west Western Australia, has taken over the past 9 years to ensure continuous improvement in rehabilitation procedures. We introduce the mining activities that WAIO undertake in the Pilbara, and emphasise specific examples of how research findings have led to incremental improvements in the seed management cycle, growth media management and mine rehabilitation practices. Specifically, we outline how the implementation of structured seed collection and storage programs has created the capacity to maintain high-quality seed stocks sufficient for 3–5 years of future rehabilitation. Research has documented the prevalence of seed dormancy in the flora (>70% of 105 species examined produce dormant seeds), with physical and physiological classes of dormancy most commonly encountered. We discuss the development of seed-treatments such as optimised wet-heat and dry after-ripening that have increased the germination capacity of many previously dormant seed batches. In addition, we highlight how seed enhancement technologies, such as hydro-priming with smoke-derived germination stimulants and polymer seed coating, and a greater understanding of the biological and physical limitations present in the growing environment, have vastly improved seedling emergence performance under field conditions for key framework Triodia species. Ongoing industry support (e.g. construction of a purpose-built rain manipulation shelter) has ensured research in the Pilbara will continue to unpack and resolve the complex challenges associated with seed regeneration of biodiverse native plant communities after mining.

The influence of woody vegetation and biological soil crusts on infiltration capacity is one of the several uncertainties associated with the ecohydrologic effects of woody plant encroachment into arid and semi-arid land systems. The objective of this study was to quantify the effects of Utah juniper (Juniperus osteosperma) and pinyon pine (Pinus edulis) on subcanopy and intercanopy ecohydrologic properties. We measured soil sorptivity, unsaturated hydraulic conductivity [K(h)], soil water content (SWC), and water repellency along radial line transects from under Juniperus and Pinus trees into the centre of the intercanopy space between trees. In the subcanopy, litter mounds, hydrophobic soils, and roots all appear to contribute to preferential flow to below-surface soils via wetted patches. For both Juniperus and Pinus, K(h) was significantly lower in the subcanopy than the intercanopy average; however, line transect measurements did not show distinct boundaries in K(h) between the two regions. K(h) increased by eight-fold across a gradient extending outward from near the edge of the canopy to approximately 2 times the canopy radius (CR). This suggests that the influence of these species on hydrologic properties extends significantly into the intercanopy region. Analysis of biological soil crust cover within the intercanopy showed that beyond the gradient zone, increasing structural development of biological soil crust was associated with increased K(h). Furthermore, these results indicate that the distance from the canopy and direction should be considered in the assessment and modelling of woody plant and biological soil crust influence on infiltration capacity.

The impact of pinyon‐juniper woodland encroachment on rangeland ecosystems is often associated with a reduction of streamflow and recharge and an increase in soil erosion. The objective of this study is to investigate vegetational control on seasonal soil hydrologic properties along a 15‐m transect in pinyon‐juniper woodland with biocrust. We demonstrate that the juniper tree controls soil water content (SWC) patterns directly under the canopy via interception, and beyond the canopy via shading in a preferred orientation, opposite to the prevailing wind direction. The juniper also controls the SWC and unsaturated hydraulic conductivity measured close to water saturation (K(h)) under the canopy by the creation of soil water repellency due to needle drop. We use this information to refine the hydrologic functional unit (HFU) concept into three interacting hydrologic units: canopy patches, intercanopy patches, and a transitional unit formed by intercanopy patches in the rain shadow of the juniper tree. Spatial autoregressive state‐space models show the close relationship between K(h) close to soil water saturation and SWC at medium and low levels, integrating a number of influences on hydraulic conductivity.