Age‐Related Changes in Tree Growth and Physiology

Abstract

Trees pass through specific developmental phases as they age, including juvenile to adult, and vegetative to reproductive phases. The timing of these transitions is regulated genetically but is also highly influenced by the environment. Tree species have evolved different strategies and life histories that affect how they age – for example some pioneer species are fast growing and become sexually mature at younger ages but have shorter life spans. Trees do not have a strictly programmed senescence, and their life span is influenced by factors including challenges associated with increasing size, and ability to cope with environmental stress such as water availability, rot fungi, insects and disease pressure. Some long‐lived tree species escape threats in exceptionally dry environments, while others use clonal reproduction through sprouts from stumps or roots to enable the same genotype to persist for thousands of years. On longer timescales, tree species migrate across landscapes to suitable environments.

Key Concepts

  • Forest tree species display a range of strategies and life histories that affect their life span and ageing and can be described in terms of forest succession concepts.
  • Trees undergo juvenile to adult transitions that can be reflected in distinct differences in morphology of leaves, changes in physiology or changes in the anatomy and biochemical makeup of wood.
  • Trees also undergo a period of vegetative growth before becoming sexually mature and competent to make reproductive structures (flowers in angiosperm trees or strobili in gymnosperm trees).
  • Trees do not have a genetically programmed life span or senescence. Life span is affected by limitations imposed by size and abiotic and biotic factors.
  • In some species, while the original tree stem may die, clonal sprouts can form, allowing the same genotype to live for thousands of years.
  • Over long timescales, tree species migrate to accommodate changes in climate over time.

Keywords: climate change; forests; forest mortality; tree physiology; tree development

Figure 1. Forest succession can lead to mortality. On this slope near Rabbit Ears Pass in Colorado, spruce (green trees) can be seen encroaching into an aspen stand (yellow trees). In the absence of disturbance such as fire, the longer lived shade‐tolerant spruce can establish under the aspen, eventually overtopping and replacing the stand. Photo credit: Barry Lilly, US Forest Service.
Figure 2. Extreme changes in maturation in longleaf pine. Longleaf pine frequently establishes in sites after fire and can grow for many years in a ‘grass’ stage, which helps protect the apical and cambial meristems from fire (a). After establishing a root system that can support rapid growth, seedlings switch to elongative growth to achieve the mature form (b). Photo credit: John Kush, Auburn University.
Figure 3. Life span of individual stems in aspen is affected by fungal rots. (a) A fruiting body of Phellinus tremulae, a shelf fungus and the cause of white trunk rot in aspen. (b) White trunk rot can cause death through direct damage to living sap wood and can weaken stems by decaying the heartwood, leading to susceptibility to mechanical breakage by wind or snow. An interesting ecological benefit – woodpeckers prefer making their nest cavities in aspen with decay. Photo credits: Jim Worrall, USDA Forest Service.
Figure 4. Survival strategies for long‐lived tree species. (a) Populus euphratica growing in Inner Mongolia, China. In contrast to most trees within the genus Populus, individual stems of P. euphratica can persist for several hundred years and live in an extremely dry environment. While presenting obvious challenges, the dry environment may be the key in reducing the danger of parasitic and rot‐causing fungi that can limit life span. (b) Pinus longaeva growing in the white mountains of California. (a,b) Photo credit: Suzanne Gerttula, US Forest Service. (c) Populus tremuloides clone near Lake Tahoe, California. Aspen (P. tremuloides) can propagate by ‘root suckering’, where new shoots arise from roots of established trees. The young trees in the foreground are clonal shoots extending into a meadow from the roots of older trees. In this way, aspen can incrementally pioneer new sites or else re‐establish quickly after disturbances including fire. Large aspen clones can occupy dozens of hectares and live for thousands of years. (c) Photo credit: Andrew Groover, US Forest Service.
Figure 5. Tree populations and species migrate over time in response to changes in climate. (a) The migration of single‐leaf piñon pine (Pinus monophylla) in the Pacific Southwest of the United States since the Last Glacial Maximum, moving from refugial regions in the current Mojave and Sonoran Desert. Data points correspond to the locations of and approximate dates of arrival (years before present) of expansion northward to its current distribution limit north of Reno, Nevada. Modified from Grayson 2011 © University of California Press. (b) Topography, water availability and other local factors influence migration patterns over the landscape. In this location in the Toquima Range of central Nevada, single‐leaf piñon (arrows indicate individual piñon trees) is moving downslope to take advantage of higher water availability, as well as upslope as warming temperatures open ecological windows at higher elevations. Photo credit: Connie Millar, US Forest Service.
close

References

Aitken SN and Bemmels JB (2016) Time to get moving: assisted gene flow of forest trees. Evolutionary Applications 9: 271–290.

Ally D, Ritland K and Otto SP (2010) Aging in a long‐lived clonal tree. PLoS Biology 8: e1000454.

Augspurger CK and Bartlett EA (2003) Differences in leaf phenology between juvenile and adult trees in a temperate deciduous forest. Tree Physiology 23: 517–525.

Aukerman MJ and Sakai H (2003) Regulation of flowering time and floral organ identity by a microRNA and its APETALA2‐like target genes. The Plant Cell 15: 2730–2741.

Bentz BJ, Hood SM, Hansen EM, Vandygriff JC and Mock KE (2017) Defense traits in the long‐lived Great Basin bristlecone pine and resistance to the native herbivore mountain pine beetle. New Phytologist 213: 611–624.

Bond BJ (2000) Age‐related changes in photosynthesis of woody plants. Trends in Plant Science 5: 349–353.

Borchert R (1976) The Concept of Juvenility in Woody Plants: International Society for Horticultural Science (ISHS), pp. 21–36. Belgium: Leuven.

Critchfield WB (1960) Leaf dimorphism in Populus trichocarpa. American Journal of Botany 47: 699–711.

DeWoody J, Rowe CA, Hipkins VD and Mock KE (2008) Pando lives: molecular genetic evidence of a giant aspen clone in central Utah. Western North American Naturalist 68: 493–497.

Grayson DK (2011) The Great Basin: A Natural Prehistory. Berkeley and Los Angeles, CA: University of California Press.

Koch GW, Sillett SC, Jennings GM and Davis SD (2004) The limits to tree height. Nature 428: 851–854.

Krasnow KD and Stephens SL (2015) Evolving paradigms of aspen ecology and management: impacts of stand condition and fire severity on vegetation dynamics. Ecosphere 6 (1): 1–16.

Lanner RM (2002) Why do trees live so long? Ageing Research Reviews 1: 653–671.

Ledig FT, Rehfeldt GE, Sáenz‐Romero C and Flores‐López C (2010) Projections of suitable habitat for rare species under global warming scenarios. American Journal of Botany 97: 970–987.

McDowell NG, Fisher RA, Xu C, et al. (2013) Evaluating theories of drought‐induced vegetation mortality using a multimodel–experiment framework. New Phytologist 200: 304–321.

Mock KE, Rowe CA, Hooten MB, Dewoody J and Hipkins VD (2008) Clonal dynamics in western North American aspen (Populus tremuloides). Molecular Ecology 17: 4827–4844.

Munné‐Bosch S (2008) Do perennials really senesce? Trends in Plant Science 13: 216–220.

Sanderson LA, Mclaughlin JA and Antunes PM (2012) The last great forest: a review of the status of invasive species in the North American boreal forest. Forestry 85: 329–340.

Stetller RF, Bradshaw HDJ, Heilman PE and Hinckley TM (1996) Biology of Populus and Its Implications for Management and Conservation. Ottawa, CA: National Research Council of Canada Research Press.

Varner JM, Gordon DB, Putz FE and Hiers JK (2005) Restoring first to long‐unburned Pinus palustris ecosystems: novel fire effects and consequences for long‐unburned ecosystems. Restoration Ecology 13: 536–544.

Wang J‐W, Park MY, Wang L‐J, et al. (2011) MiRNA control of vegetative phase change in trees. PLoS Genetics 7: e1002012.

Wendling I, Trueman SJ and Xavier A (2014) Maturation and related aspects in clonal forestry – Part I: concepts, regulation and consequences of phase change. New Forests 45: 449–471.

Wu G, Park MY, Conway SR, et al. (2009) The sequential action of miR156 and miR172 regulates developmental timing in Arabidopsis. Cell 138: 750–759.

Xu M, Hu T, Smith MR and Poethig RS (2015) Epigenetic regulation of vegetative phase change in Arabidopsis. The Plant Cell 28 (1): 28–41.

Yang L, Xu M, Koo Y, He J and Poethig RS (2013) Sugar promotes vegetative phase change in Arabidopsis thaliana by repressing the expression of MIR156A and MIR156C. eLife 2: e00260.

Zobel BJ and Sprague JR (1998) Jouvenile Wood in Forest Trees. Berlin: Springer‐Verlag.

Further Reading

Barnes BV, Zak DR, Denton SR and Spurr SH (1997) Forest Ecology, 4th edn. Ney York, NY: John Wiley and Sons, Inc.

Poethig R (2013) Vegetative phase change and shoot maturation in plants. Current Topics in Developmental Biology 105: 125–152.

Stettler R (2009) Cottonwood and the River of Time. Seattle, Washington, DC: University of Washington Press.

Thomas H (2013) Senescence, ageing and death of the whole plant. New Phytologist 197: 696–711.

Zimmermann M and Brown C (1974) Trees Structure and Function. New York: Springer‐Verlag.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Groover, Andrew(Jun 2017) Age‐Related Changes in Tree Growth and Physiology. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0023924]