Below are sentences containing some vocabulary that you will need to understand the texts in this unit. Examine the words in bold and try to determine their meaning from the context in which they are used. These ten bold words will be assessed in the final exam and end of unit quizzes. When you are ready, take the practice quiz below and check your answers.
Dendrochronology is a hundred-year old discipline which not only studies the dating of trees based on patterns in their rings but also gives scientists detailed records of climate and environmental conditions hundreds, even thousands of years ago.
The limiting factors principle implies that a tree’s rate of growth is constrained by the resource which is most limited.
In trees that grow in a tropical climate, the cambium cells grow at a steady unchanging rate. So the rings that indicate the age of the trees cannot be clearly distinguished.
Trees that grow in temperate climates show a difference in growth between the seasons.
In spring and summer, cambium cells become progressively larger whereas in autumn and winter they progressively become smaller.
Some scientists think that the existence of the divergence problem means tree ring data are not suitable for reconstructing past climate trends. However, trees in other regions, where there is sufficient water for growth, are not affected by this divergence.
Therefore, for trees to give us information about past climate through their rings, they need to grow in difficult conditions which include significant variations in temperature and drought.
With advances in technology, the width of the rings can be measured using computer software and a scanner. Wide rings show healthy growth while narrow ones show weak growth.