Evidence for the widespread occurrence of ancient forests on cliffs

Abstract

Aim The objective of this work was to determine if the existence of ancient forests on cliffs was specific to the Niagara Escarpment, Canada, or part of a globally widespread pattern. Location Sixty‐five cliff sites were visited in five countries in the temperate climatic zone, and trees were sampled for age and growth rate on forty‐six of these. Methods Two hundred and twenty‐four core samples or cross‐sections were taken from trees on cliffs that varied in height, aspect, rock‐type, and exposure. General observations were also made of regeneration of the tree species forming the mature canopy, and other habitat conditions. Results The evidence shows that ancient slow‐growing forest occurs on most cliffs. Age and growth rate distributions were similar at all treed sites. Small‐statured Thuja, Juniperus, or Taxus stems with age estimates in excess of 1000 years were found in the United States, the United Kingdom and France, and small Pinus and Quercus stems nearly 400 years in Germany. There was a high rate of recurrence of plants in the genera Polypodium, Asplenium, Cystopteris, Campanula, Rosa, Prunus, Hedera, and Sorbus. Most of the sites appear to be habitats of completely natural origin. Conclusions We conclude that ancient natural forest is a normal feature of cliffs, at least in the temperate zone.

Population ecology of yew (Taxus baccata L.) in the Central Apennines: spatial patterns and their relevance for conservation strategies

“…In terms of regeneration, it is interesting to note that nearly flat terrain hampers yew establishment by favoring the accumulation of beech litter (Ellenberg 1988;Dovčiak 2002;Dhar et al 2007). At our study sites, yew also occurs in particularly rugged locations, with individuals that are relatively small but with signs of old age, which they may have acquired thanks to lack of human impacts and other disturbance factors (see Larson et al 2000).…”

“…This limit is apparently surpassed on mountains of northern Iran (Lesani 1999), and in the Hosta Reserve, a protected forest on the Russian coast of the Black Sea, where yew height may reach 40 m (Earle 2001). Yew is also supposed to live for more than a millennium (Bebber and Corona 1986;Larson et al 2000;Molisch 1938), although in reality dendrochronological studies to date have proved a maximum longevity of about five centuries (Biondi 1992). As a long-lived, shade-tolerant species, yew is favored by lack of disturbance (such as wildfire), and is adapted to a range of edaphic conditions (Brzeziecki and Kienast 1994;Thomas and Polwart 2003).…”

Occurrence of phi thickenings is correlated with gymnosperm systematics

“…We became interested in phi thickenings because of the observations of these structures in Thuja occidentalis and Juniperus virginiana (Cupressaceae) while studying the distribution of these species on cliffs in the Northern Hemisphere (Larson et al 2000b).…”

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“…Probablemente esto se debe tanto al esfuerzo que supone como a la inaccesibilidad de sus poblaciones. Recientes estudios demográficos detallados están demostrando tanto una gran longevidad (LARSON et al, 2000;GARCÍA et al, 2002;FORBIS & DOAK, 2004) como una inusual estabilidad demográfica y resiliencia en especies localizadas en estos hábitats (MORRIS & DOAK, 1998;PICÓ & RIBA, 2002;GARCÍA, 2003), lo que en parte ayuda a entender la antigüedad de muchas de estas especies relictas, y en parte permite albergar esperanzas sobre su capacidad para persistir en el futuro si su hábitat no se altera.…”