An increase in canopy cover leads to masting in Quercus ilex

Abstract

Masting is the intermittent and synchronous production of large crops, but its relation to tree growth remains elusive despite the ecological relevance of mast seeding. The production of huge fruit crops has been linked to the accumulation and consumption of resources as nutrients and carbohydrates, but no conclusive assessment has supported this assumption. To evaluate if masting takes place once trees' canopies reach maximum foliage, changes in canopy cover were measured in Quercus ilex susbp. ballota stands before and after a masting event using the normalized difference vegetation index (NDVI). The results on the whole underline that masting in Q. ilex occurred once maximum levels of NDVI and canopy cover were reached. After the masting event, NDVI dropped, leaf shedding increased and trees produced shorter shoots, narrower tree rings and fewer acorns than before the masting event. These findings support our contention that an increase in canopy cover precedes masting.

Temporal trends in the enhanced vegetation index and spring weather predict seed production in Mediterranean oaks

“…When taking into account the EVI temporal dynamics and SPEI, however, the negative autocorrelation at lag 1 was not significant (Table 2), which indicates the relatively small importance of these endogenous cycles in comparison with the paramount role of the current year's weather conditions. The BFAST analyses, in contrast to Camarero et al (2010), did not indicate that leaf area decreased due to crown selfthinning after a masting episode. The lack of such an effect in our oak stands could be due to several reasons: (i) the low number of acorns produced in these moderately young forests (coppiced stands of ca.…”

“…This latter hypothesis predicts that plant resources are depleted to sustain the masting episode, so that flowering and seed production are expected to be very low or absent in the next growing season, causing a negative autocorrelation between consecutive seed crops (Koenig and Knops 2000). The consequences of resource depletion after a masting episode may include signs such as a reduction in the leaf area due to self-thinning (Camarero et al 2010) or a decrease of nitrogen and phosphorous concentrations in branches (Sala et al 2012).…”

“…These indices have thus been widely used to monitor the functional traits involved in the carbon cycle (Garbulsky et al 2008) and also as annual integrators of carbon uptake in forests (Garbulsky et al 2013). Few studies, however, have yet applied remotely sensed vegetation indices to predict seed crop production in forest ecosystems, particularly in masting species (but see Camarero et al 2010). In this sense, a successful methodology to predict seed crops would allow managers to better plan management actions in the near future (e.g.…”

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

“…There are numerous examples of a negative relationship between reproduction and growth in the same or next year (Eis et al 1965;Tappeiner 1969;Gross 1972;Koenig and Knops 1998;Nicotra 1999;Silvertown and Dodd 1999;Monks and Kelly 2006;Han et al 2008;Ishihara and Kikuzawa 2009;Camarero et al 2010;Drobyshev et al 2010), but also examples of no relationship (Willson 1986;Cremer 1992;Yasumura et al 2006;Knops et al 2007) and even of a positive relationship (Reekie and Bazzaz 1987;Despland and Houle 1997).…”

Detecting tree water deficit by very low altitude remote sensing

“…Moreover, other studies have used the NDVI for tree species identification on monoculture plots (Carleer & Wolff 2004). In addition, Camarero et al (2010) used variations in NDVI to detect an increase in canopy cover preceding mast years for Quercus ilex. For drought monitoring, this vegetation index is of particular interest (Peng et al 2012, Volcani et al 2005.…”