TY  - JOUR
U1  - Wissenschaftlicher Artikel
A1  - Anadon‐Rosell, Alba
A1  - Talavera, Marc
A1  - Ninot, Josep M.
A1  - Carrillo, Empar
A1  - Batllori, Enric
ED  - Bullock, James
T1  - Seed production and dispersal limit treeline advance in the Pyrenees
JF  - Journal of Vegetation Science
N2  - Abstract

Aims
Pinus uncinata is the major treeline‐forming species in the Pyrenees. Yet, the role of its reproduction and dispersal as drivers of treeline dynamics remains unknown. Here we quantify seed production, dispersal and germination changes along the elevation gradient to assess whether they may constrain the foreseen treeline advance in the Pyrenees.


Location
Central Pyrenees, Catalonia, NE Spain.


Methods
We established four plots along an elevation gradient from the closed subalpine forest to the krummholz zone at five study sites. In each plot, we collected cones from five to six trees, measured their length, and triggered their opening in the laboratory to count the number of empty seeds and the number and weight of full seeds. We used the collected seeds in a germination experiment under controlled conditions in growth chambers. Additionally, we installed seed traps along the forest–alpine grassland transition to measure seed rain for three consecutive years in three of the study sites.


Results
The number of full seeds per cone decreased along the elevation gradient and was correlated with cone length. However, the proportion of full seeds per cone and their weight did not differ between elevation positions. Seed rain decreased drastically with elevation and no seeds arrived into the alpine grassland traps consistently across study years. Although germination success did not significantly differ between elevation provenances (i.e., elevation position of origin), we found significant differences in germination dynamics between study sites and between elevation provenances within sites.


Conclusions
Our results indicate that whereas the viability of Pinus uncinata seeds is not limited by elevation, seed production and dispersal are constraining the ongoing rates of treeline advance in the Pyrenees.
KW  - -
KW  - alpine
KW  - Pinus uncinata
KW  - reproductive ecology
KW  - seed germination
KW  - seed rain
KW  - treeline ecotone
Y1  - 2020
UN  - https://nbn-resolving.org/urn:nbn:de:gbv:9-opus-40452
SN  - 1654-1103
SS  - 1654-1103
U6  - https://doi.org/10.1111/jvs.12849
DO  - https://doi.org/10.1111/jvs.12849
SP  - n/a
EP  - n/a
PB  - Wiley
CY  - Hoboken, New Jersey
ER  -