Effects of climate on reproductive investment in a masting species: assessment of climatic predictors and underlying mechanisms

Abstract

Summary 1.Mechanisms by which climatic factors drive reproductive investment and phenology in masting species are not completely understood. Climatic conditions may act as a proximate cue, stimulating the onset of reproduction and indirectly increasing fitness through benefits associated with synchronous reproduction among individuals. Alternatively, climatic conditions may directly influence individual-level allocation to reproduction and reproductive success through effects occurring independently of synchronous reproduction. We previously showed that masting in a ponderosa pine (Pinus ponderosa) population was strongly influenced by spring mean temperature 2 years before seed cone maturation (T i-2 ). However, recent work shows that the difference in temperature between previous growing seasons (DT) is more predictive of reproductive investment in long-lived tree species. 2. Here, we compared four candidate models that predict seed cone production in P. ponderosa based upon different climatic factors (including T i-2 and DT models). After determining the best climatic predictor, we tested for a potential mechanism by which climate might directly influence seed cone production independent of benefits via synchrony, namely effects of temperature on trade-offs between current and past reproduction (determined by underlying resource availability). 3. We found that T i-2 (rather than DT) was the best predictor of seed cone production. We further show that this same climatic factor exerts a direct fitness benefit to individuals by reducing the strength of trade-offs between current and past reproductive efforts. 4. Synthesis. We demonstrate that a single climatic factor provides fitness benefits to individuals directly, by weakening reproductive trade-offs, and indirectly through the benefits associated with synchrony and masting. This suggests a mechanism for the origin and maintenance of masting: individuals initially respond to climatic cues that directly enhance reproduction (e.g. lower reproductive costs through weakened trade-offs) and this dynamic, expressed across multiple individuals, reinforces these benefits through the economies of scale associated with synchrony and masting.

Anticipating fire‐mediated impacts of climate change using a demographic framework

“…The timing of mast years relative to fire occurrence is important in determining postfire regeneration density (Larson & Franklin, ; Peters, MacDonald, & Dale, ). Seed production and masting have been linked to climate signals for many tree species and often depend on the occurrence of specific seasonal conditions (Buechling et al., ; Mooney et al., ; Moreira, Abdala‐Roberts, Linhart, & Mooney, ; Roland, Schmidt, & Johnstone, ). Current warming trends have been linked to both increased (Buechling et al., ) and decreased (Redmond, Forcella, & Barger, ) seed production, making it difficult to generalize climate‐change impacts.…”

Parameterisation and validation of a resource budget model for masting using spatiotemporal flowering data of individual trees

“…; Moreira et al . ; Pérez‐Ramos et al . ), the temperature difference in the two previous seasons (Kelly et al .…”

Linking songbird nest predation to seedling density: Sugar maple masting as a resource pulse in a forest food web

“…Tree masting appears to be largely controlled by weather conditions (Moreira, Abdala‐Roberts, Linhart, & Mooney, ; Pucek et al., ; Schauber et al., ; Smaill, Clinton, Allen, & Davis, ) and their effects on reproductive bud initiation, seed maturation (Houle, ), and pollen availability (Pensendorfer, Koenig, Pearse, Knops, & Funk, ). In several tree species, masting can be synchronized over hundreds of square kilometers (Koenig & Knops, , , ) and, in turn, spatially synchronized prey–predator–alternative prey relationships can be detected at scales up to ~1,000 km (Haynes et al., ).…”