Variation of seed mass and its effects on germination in Polylepis australis: implications for seed collection

Abstract

South American Polylepis mountain forests are recognised as being one of the most endangered forest ecosystems in the world. Reforestation measures have been strongly recommended but may be hampered due to the very low seed germination reported for several Polylepis species. In order to facilitate reforestation we analysed the influence of seed mass on germination probability for Polylepis australis seeds in the Co ´rdoba mountains (central Argentina). We collected seeds from 43 trees distributed throughout five woodland fragments located within two regions differing in size, topographical position, and altitude (1,900 m a.s.l. and 2,200 m a.s.l.). Seeds of Polylepis australis exhibited a great variation in terms of mass and percent seed germination among individual trees and among geographical regions. The results of logistic regression showed that germination probability was highly correlated with seed mass. However, the explained deviance significantly increased by including the region, the woodland fragment and especially the individual tree in addition to seed mass in the regression models. We conclude that selecting seeds on the basis of mass is an appropriate way to enhance germination prospects for reforestation projects. However, no absolute mass values are applicable in this context as the highest germination probabilities were reached at varying seed mass values depending on geographical region, woodland fragment or individual tree. We suggest collecting the relatively heaviest available seeds, even though the absolute seed mass may be low.

The performance of Polylepis australis trees along their entire altitudinal range: implications of climate change for their conservation

“…Seeds of four (2700 m a.s.l.) to five individual trees (all other altitudes) were randomly selected and weighed individually to the nearest 0.1 mg. As the results of a former study (Seltmann et al ., 2007) revealed that lighter P. australis seeds often lack embryos, seeds were divided evenly into two seed mass classes: light and heavy seeds. Replicates of three Petri dishes, each containing 30 -35 seeds, were taken from these two fractions.…”

“…Germination of P. australis seeds was tested in a climate chamber with a warm white light source at temperatures of 20 ° C/10 ° C (12 h of light/12 h of darkness), which are known to reflect optimum temperatures (Seltmann et al ., 2007). Seeds were laid on filter paper and kept moist with deionized water for 50 days, after which time the germination rate reached zero.…”

Seed characteristics and germination limitations in the highly invasive Fallopia japonica s.l. (Polygonaceae)

“…1). Even though seed weight was previously addressed to be important for a successful germination (Kidson and Westoby 2000;Seltmann et al 2007;Van Mo¨lken et al 2005), its importance for Fallopia japonica s.l. has to be discussed.…”

Using Knowledge of Plant Persistence Traits to Optimize Strategies for Post-Mine Ecological Restoration on the Peruvian Altiplano

“…Research in Andean ecosystems has shown that plants may have limited recruitment due to the production of nonviable seed (Enrico et al 2004). The lack of viability of the seed has been related to water stress, constant frost, and a lack of nutrients such as nitrogen (Enrico et al 2004;Kessler 2006), which all lead to the production of sterile seeds (Renison et al 2004;Seltmann et al 2007). This is a possible explanation for the fact that we recorded only 3 individual Polylepis in the germination trial, which would not be enough to support a restoration project using soil redeployment as the main method.…”