cAgaves dominate vegetation in the southernmost stretch.
duce vegetatively by producing shoots and rhizomes, or sexually by producing seed-bearing fruits in the stalk after successful pollination (Arizaga and Ezcurra, 1995, 2002), but when pollinators fail to appear, agaves may produce aerial bulbils in the flowering stalk (Arizaga and Ezcurra, 1995). In the Tehuacan Desert of central Mexico, about 5 percent of the plants were never pollinated and instead produced bulbils (Arizaga and Ezcurra, 2002). Monitoring the frequency of bulbil production in selected areas (Table 5-4) may provide a direct indicator of pollinator availability or pollinator service to agaves.
Current monitoring systems for commercial pollinators, chiefly Apismellifera, exist, but these fail to report or capture all of the necessary data to monitor pollinator status and function. In particular, new questionnaires directed at both the beekeepers and growers need to be developed to capture information on pollination by agricultural commodity. Several monitoring programs also exist for specific taxa or functional groups of pollinators, but many of these programs are either run by individual scientists, and are therefore limited in scale and not sustainable over the long term, or by citizen-scientist groups, and are therefore limited in precision and repeatability.
For pollinators, the ALARM project of the EU provides an excellent model for monitoring and includes development and testing of monitoring methods. In addition, some excellent models exist for a variety of taxa that