Onset of summer flowering in a ‘Sky Island’ is driven by monsoon moisture

Abstract

Summary• Temperatures for the southwestern USA are predicted to increase in coming decades, especially during the summer season; however, little is known about how summer precipitation patterns may change. We aimed to better understand how nonsucculent plants of a water-limited gradient encompassing xeric desert to mesic mountain-top may respond to changes in summer conditions.• We used a species-rich 26-yr flowering record to determine species' relationships with precipitation and temperature in months coincident with and previous to flowering.• The onset of summer flowering was strongly influenced by the amount and timing of July precipitation, regardless of elevation or life form, suggesting the critical importance of soil moisture in triggering summer flowering in this region.• Future changes in the timing or consistency of the early monsoon will probably impact directly on the onset of flowering for many species in this region. In addition, a key implication of predicted increasing temperatures is a decrease in available soil moisture. At all elevations, many species may be expected to flower later in the summer under the decreased soil moisture conditions associated with warmer temperatures. However, impacts on summer flowering may be greater at higher elevations, because of the greater sensitivity of mesic plants to water stress.

Phenological asynchrony in plant–butterfly interactions associated with climate: a community‐wide perspective

“…Previous studies have reported that precipitation is a relevant phenological cue for the emergence of butterflies (Stefanescu et al ) and hoverflies (Graham‐Taylor et al , but see Iler et al ). Flowering time has also shown to be sensitive to precipitation in a number of ecosystems, including Mediterranean environments (Crimmins et al , Peñuelas et al , 2013). Our results showing the importance of aridity in explaining asynchrony are thus not surprising.…”

Standardized phenology monitoring methods to track plant and animal activity for science and resource management applications

“…Instead of recording the date of phenological events directly, status monitoring involves evaluating phenophase status (e.g., the presence or absence of leaves, flowers, or fruits for plants, and mating, feeding, or movement for animals) during a series of repeated observations over the course of a season (e.g., Frankie et al 1974; Inouye and McGuire 1991; Borchert 1994; Sparks et al 2005; Morellato et al 2010; Crimmins et al 2011) (Fig. 1).…”

“…These studies have primarily documented advances in spring plant and animal activity, though changes in summer and autumn events have also been documented (Vitasse et al 2009; Ibanez et al 2010; Crimmins et al 2011; Fridley 2012). Together, these analyses underscore the value of phenology data as an indicator of plant, animal, and ecosystem response to climate change (IPCC 2007).…”

Phenological niches and the future of invaded ecosystems with climate change

“…These patterns are based on findings in North American prairie systems; however, far more work is needed additionally to understand if this period is occupied by invaders in other systems or is possibly too stressful. This represents an area where predictions are difficult for several reasons: (i) understanding and modelling how species respond to moisture has proven far more difficult than modelling temperature responses (Crimmins et al 2011; Wolkovich et al 2013), (ii) work to date suggests that phenological responses to drought are highly variable between different species (Jentsch et al 2009; Prieto et al 2009), and (iii) projections of how precipitation and droughts will shift in the future are some of the most uncertain of all climate change forecasts (Knutti and Sedlacek 2013). …”