Does a heavy fruit crop reduce the tree ring increment? Results from a 12-year study in a subalpine zone

Abstract

Life history theory posits that an increased investment in reproduction should result in decreased vegetative investment. Switching resources from growth to reproduction are also expected in species experiencing selection pressure for high variation of seed crops. In this study, we tested whether the reproductive effort of trees, measured as the number of fruits produced, is related to their radial growth increment. We examined a population of Sorbus aucuparia, a fleshy-fruited tree species with highly variable interannual individual fruit production growing in the subalpine zone and under strong selection pressure from pre-dispersal seed predators. We used 12-year data to test the relationship between fruit crop and radial growth increments in current, previous and subsequent years, and found no trade-off between growth and reproduction. For almost all trees, there was no correlation between fruit crop and radial growth increment in the same year or next year. Only a few trees showed a positive correlation between fruit crop and previous-year growth. In the statistics, we took advantage of the high variability of individual fruit crops in high production years. In four heavy crop years, we compared the radial growth increments of trees with heavy crops with those of trees with low fruit crops. Current and next-year radial growth did not differ between trees with low and high fruit crops. In all those years, however, trees having heavy fruit crops had higher previous-year growth increments. We suggest that the harsh subalpine weather conditions account for the lack of a trade-off between growth and reproduction in the studied population.

Climate drivers of seed production in Picea engelmannii and response to warming temperatures in the southern Rocky Mountains

“…Widespread negative correlations between radial growth and reproduction in trees support this assumption (Koenig & Knops ). The lack of evidence for visible trade‐offs in this study is not unprecedented however (Speer ; Knops, Koenig & Carmen ; Żywiec & Zielonka ). Our failure to identify expected trade‐offs may be attributed to within‐plant resource variability.…”

Interannual variation in tree seed production in a primeval temperate forest: does masting prevail?

“…This pattern should be expressed as either (1) a negative correlation between seed production in one year relative to the next and/or (2) low tree growth (measured as radial wood increment) in bumper crop years (Silvertown 1980;Sork et al 1993;Kelly 1994;Knops 1998, 2000;Kelly and Sork 2002;Monks and Kelly 2006). Although such correlations have been found in several species at the population level (review in Kelly and Sork 2002), including Q. robur in England (Crawley and Long 1995) and P. abies in Norway (Selås et al 2002), the predicted relationship between reproduction and growth at the individual level (studied only in about 10 species; Monks and Kelly 2006) is not always found (Seifert andMüller-Starck 2009-P. abies, _ Zywiec andZielonka 2013) or it appears not to be causally related (Knops et al 2007). We have no data from BNP on variation in tree growth rates to check the postulated growth/reproduction trade-offs, but the predicted negative relationship between the current and the next year seed production was found only in P. abies.…”

Irregular Shelterwood Cuttings Promote Viability of European Yew Population Growing in a Managed Forest: A Case Study from the Starohorské Mountains, Slovakia

“…In other tree species, a negative relationship between fruit production and radial growth was shown (e.g., in beech) [65,66]. On the contrary, radial growth in the year of seed formation and the year after did not differ between trees with low and high seed crops for rowan [67].…”