Dendrochronology and Climate Change

Dendrochronology and Climate Change

Mostafa Jafari (Islamic Republic of Iran Meteorological Organization, Iran)
Copyright: © 2015 |Pages: 14
DOI: 10.4018/978-1-4666-5888-2.ch285
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Introduction

Importance of Global Warming and its’ effects on natural resources, plants, animal and in general on human life are among subjects that received attention of scientists and politicians in recent years. To both understand the present climate and to predict future climate change, it is necessary to have both theory and empirical observation. Any study of climate change involves the construction (or reconstruction) of time series of climate data. How these climate data vary across time provides a measure (either quantitative or qualitative) of climate change. Types of climate data include temperature, precipitation (rainfall), wind, humidity, evapotranspiration, pressure and solar irradiance (aric, 2008). Climate change assessments and evaluation should be done by using recorded observation data as well as prepared and provided proxy data (Jafari, 2010). Plant ecophysiological study has very important role to recognize climate changes (Jafari, 2007). Trees and also woods can be used as archive of past events. Water, environment humidity and temperature are main factors of plant growth. Majority of plant and forest ecosystems on the earth are formed under these two main factors. Whatever amount of humidity and required water are available and also favorable temperature for plant growth cause plant community reach higher plants and trees and forest ecosystems would develop. In fact plants are important climate indicators. Trees are not an exception. Investigation of quantity and quality of these growths could help to consider past climatic conditions. Tree ring widths can be measure and record to produce time series (Figure 1).

Figure 1.

Tree ring densities (TGTC, 2008)

Trees growing in temperate climatic region are under seasonal changes. In spring and summer time plants grow better than unpleasant seasons like fall and winter. The outermost layer of a tree is composed of bark. Bark itself is composed of two tissues: an innermost layer of live phloem, and an outer layer of periderm (the bark 'proper'), which has an outermost layer of waterproofing cork (phellum) which protects the wood to some degree from insects, etc (Figure 2). The cork has its own cambium (phellogen) between the phloem and cork layer. Only the outermost layer of a tree is alive (essentially only the phellogen, phloem, cambium, and maturing xylem of the current year's growth). Consequently, the majority of the trunk does not require gaseous exchange. The bark is punctuated by lenticels, a sort of giant stoma, which allows the thin outermost living layers of the trunk to 'breathe' (Anonymous, 2008a),

Figure 2.

Wood anatomy (Anonymous, 2008a)

Wood is secondary xylem produced by growth of the vascular cambium tissue. Sapwood is xylem that conveys water and dissolved minerals from the roots to the rest of the tree. The darker heartwood is older xylem that has been infiltrated by gums and resins and has lost its ability to conduct water. Each growth layer is distinguished by early wood (springwood), composed of large thin-walled cells produced during the spring when water is usually abundant, and the denser latewood (summerwood), and composed of small cells with thick walls. Growth rings vary in width as a result of differing climatic conditions; in temperate climates, a ring is equivalent to one year's growth. Certain conducting cells form rays that carry water and dissolved substances radially across the xylem. Bark comprises the tissues outside the vascular cambium, including secondary phloem (which transports food made in the leaves to the rest of the tree), cork-producing cells (cork cambium), and cork cells. The outer bark, composed of dead tissue, protects the inner region from injury, disease, and desiccation (Encyclopedia Britannica, 2006). A big trunk of a harvested tree can be use as an archive of data and may provide its life long time series (Figure 3)(Jafari, 2010).

Figure 3.

A big trunk of Fagus orientalis L. in Hyrcanian forest research site (Asalem, Gilan province)(Jafari, 2010)

Key Terms in this Chapter

Proxy Data: Climate change assessments and evaluation should be done by using recorded observation data as well as prepared and provided proxy data. Paleoclimatologists (climatologists who study past – or paleo – climates) use the term “proxy” to describe a way that climate change is recorded in nature, within geological materials such as ocean or lake sediments, tree-rings, coral growth-bands, ice-cores, and cave deposits.

Climate Change: Global Warming, climate change and climate variability are a definition of deviation of climatic factors from its normal trends mainly impacted by human activities. Global Warming and its’ effects on natural resources, plants, animal and in general on human life are among subjects that received attention of scientists and politicians in recent years.

Tree Rings: Trees growing in temperate climatic region are under seasonal changes. In spring and summer time plants grow better than unpleasant seasons like fall and winter. Each growth layer is distinguished by early wood (springwood), composed of large thin-walled cells produced during the spring when water is usually abundant, and the denser latewood (summerwood), and composed of small cells with thick walls.

Dendrochronology: Dendrochronology was developed about 1913, and is a (climate change) method to study tree ring widths in terms of time. The word dendrochronology is compose of: dendro (using trees, or more specifically the growth rings of trees), chrono (time, or more specifically events in past time), and logy (the study of). Dendrochronology as an able and certified study method could be implying in a wide range of applications.

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