Earth is changing rapidly and so are many plant species’ ranges. Here, we synthesize eco-evolutionary patterns found in plant range studies and how knowledge of species ranges can inform our understanding of species conservation in the face of global change. We discuss whether general biogeographic “rules” are reliable and how they can be used to develop adaptive conservation strategies of native plant species across their ranges. Rules considered include (1) factors that set species range limits and promote range shifts; (2) the impact of biotic interactions on species range limits; (3) patterns of abundance and adaptive properties across species ranges; (4) patterns of gene flow and their implications for genetic rescue, and (5) the relationship between range size and conservation risk. We conclude by summarizing and evaluating potential species range rules to inform future conservation and management decisions. We also outline areas of research to better understand the adaptive capacity of plants under environmental change and the properties that govern species ranges. We advise conservationists to extend their work to specifically consider peripheral and novel populations, with a particular emphasis on small ranges. Finally, we call for a global effort to identify, synthesize, and analyze prevailing patterns or rules in ecology to help speed conservation efforts.

Vernal pools are temporary wetlands that can form during a rainy season, often in Mediterranean climates, and serve as ideal testing grounds to understand species detection using eDNA and how biological communities may shift across time and spatial and environmental heterogeneity. Most vernal pools exhibit high plant and animal diversity and endemism, but due to their ephemeral nature, they are understudied, especially their microorganisms. Habitat destruction and fragmentation creates an urgent need to monitor their biodiversity, but traditional species surveys require time and taxonomic expertise. We conducted a community science‐enabled examination of soil environmental DNA (eDNA) in California's Great Central Valley and assessed the capacity of eDNA to aid biomonitoring. We used metabarcoding of 16S, ITS1, CO1, 18S, and ITS2 marker regions to quantify and compare differences in pool communities across two sampling periods (during years with disparate precipitation) and to estimate variation among pools and inundation zones (vernal pool bottom, transitional edge, and grassland upland). We found differences in beta diversity among sampling periods, pools, and inundation zones; alpha diversity was mainly affected by sampling period and zone, but this differed by marker. Numerous taxonomic families varied in abundance and composition among samples, yet vernal pool communities remained distinct from upland grass communities, even between sampling periods differing by 1 year. Turnover in ecologically co‐occurring taxon pairs varied by over 90% between sampling periods in all metabarcodes but plants, which were more stable. Finally, we confirmed substantial concordance between eDNA and traditional inventories of the reserve's plants and presented a case in which we detected one endangered plant species, Colusa grass (Neostapfia colusana), in advance of its emergence. This initial study adds hundreds of new taxon records for California vernal pools and discusses benefits and challenges of using eDNA for biomonitoring within stressful, temporary, or otherwise challenging ecosystems.