With mistiming of annuals and shrubs a possibility, here’s what we have planned as a fall-back. 1 and 4 are for sure, 2 and 3 are interchangeable depending on if shrub/annual flowers are mistimed or not:
1. Continue searching for alternate sites. At each possible site, walk transect sampling first 25 shrubs (of both Ambrosia and Larrea) touching transect. For each, record presence/absence of annuals under shrub, and rate shrub progression and annual progression on a scale of 1-5 (shrub: 0=shrub brown and no buds, 1=few buds present, 2=buds present and minimal flowering, 3=peak flower, 4=flowers starting to wilt or some seeds present, 5=seeding, annual: 0=emerging, 1=small buds present, 2=flowers forming but not open yet, 3=peak flowering, 4=flowers beginning to wilt, 5=seeding).
2. Check sites frequently and wait for site that has overlapping shrub and annual flowering period to conduct survey and manipulation.
3. If shrubs and annuals mistimed, use transplanted annuals (common, native, from surrounding area) in sunken pots instead. Match number of flowers to actual annual density under shrubs to keep as natural as possible.
4. Once annuals done flowering, but shrubs still in flower, buy flats of showy annual species (native). Put out as proposed at equal densities under shrubs and in open and do video/in situ trials etc.