Phenological Patterns of Terrestrial Plants

Abstract

The term phenology is derived from the Greek word phaino meaning to show or to appear. Hence, phenology is defined as the study of the seasonal timing of life cycle events. For plants the seasonal timing of such events can be critical to survival and reproduction. In agriculture the most common failure of introduced crops is the inability to adjust to the seasons imposed by the new, environment (68). In the past few years, interest in the ecology and evolution of timing of life cycle events has grown. Here we review the literature on phenological patterns of germination, flowering, and fruiting (including dispersal).The phenological pattern of any life cycle event can be quantitatively defined as a statistical distribution characterized by such parameters as time of occurrence (onset, mean, mode), duration (range), synchrony (variance), and skewness. For each life cycle event we discuss each parameter for which data are available. Because parameters at one level can contribute to parameters at higher levels, parameters are sometimes related. For example, the degree of synchrony within and among individuals can determine duration at the population level. Therefore, we discuss phenological patterns at the levels of individuals, populations, species, and communities. Also, we use the word phenology in its strict sense of seasonal timing within years; and we address variation among years only when it pertains to the discussion of within-year patterns.The purpose of this review is to present hypotheses about possible evolutionary causes and consequences of different phenological patterns and to discuss the evidence for each hypothesis. We also briefly summarize information about the environmental and genetic controls of timing because these are the proximate factors that can influence the evolution of phenological patterns. We divide our review into four sections. The first three address germination, flowering, and fruiting separately. Each section covers possible selective factors, proximate environmental cues, and genetic determinants of different phenological parameters. The last section focuses on the relationships of germination, flowering, and fruiting, to the whole life cycle of the plant. Here we address possible ecological and evolutionary constraints that may direct the evolution of all life cycle events.Space prevents an exhaustive literature review, particularly of descriptive studies, so we mention representative studies and reviews that provide the reader access to additional literature. We do not address phenological patterns of leaf production (43,146) or the specific methodologies for collecting and analyzing phenological data (151, 194, 20 1). GERMINATIONThe seedling stage is the most vulnerable time in the life cycle of a plant (10 1). Mortality is often severe because small seedlings have minimal capacity for homeostatic responses or physiological retrenchment in the face of unfavorable abiotic or biotic conditions (10). Therefore, the timing of germination should be under strong selection to occu...

Diverse responses of phenology to global changes in a grassland ecosystem

“…Phenological complementarity promotes coexistence in multispecies plant communities (37,38) and is one of the main mechanisms by which species composition influences ecosystem processes such as nutrient capture and primary production (39). In Mediterranean-type ecosystems, plant growth is concentrated in a short growing season, so even small shifts in phenology can disrupt complementarity among species.…”

Pollination decays in biodiversity hotspots

“…This finding suggests that even species that may have evolved traits to increase pollination success still suffer due to competition for pollinator service. Plant species may also evolve flowering phenologies that differ from those of their coflowering competitors, thus increasing their conspecific pollen delivery (11)(12)(13). Although there is greater potential for phenological diversity in tropical (speciesrich) areas due to the potentially long growing season (10), if numerous coexisting clades are diversifying in phenology, there may still be higher competition for pollination in species-rich relative to depauperate floras, regardless of flowering time.…”

“…Pollen limitation may decrease as plants evolve traits that reduce reliance on pollinators (e.g., self-compatible breeding systems and vegetative reproduction), attract more specialized pollinators that deliver less heterospecific pollen, or reduce competition for pollinators (e.g., shifts in flowering time) (11). Studies have found that diversity in flowering phenologies and pollinator fauna is indeed higher in species-rich areas (12,13).…”

Opportunities to utilize traditional phenological knowledge to support adaptive management of social-ecological systems vulnerable to changes in climate and fire regimes

“…Phenology is the study of recurring plant, fungi, and animal life cycle stages, especially as they relate to climate and weather (Schwartz 2013). Phenological processes such as developmental stages of plant, fungi, and animal species triggered by accumulated heat, or exceedance of temperature thresholds, can also serve as indicators of seasonal variation and proxies to monitor the biological effect of climate change (Larcher 1983, Rathcke and Lacey 1985, Lantz and Turner 2003. Lantz and Turner (2003:265) introduced and defined the term, TPK, to encompass IK regarding phenology:…”