Measuring tree diameter is probably the easiest field work. You just need to bring the DBH meter and follow the standard operation procedure for measuring tree diameter and somebody else need to record the measurement. But it’s not as simple as that.
For the last 12 years, a team is observing and following the growth of trees in one of the last remained intact lowland forest in Sumatra. Each year, we tried to keep at least two or three same persons in the team. The growth of trees in this dynamic world is becoming an important issue particularly when related to climate change. During drought years, you will get an average 0.1 – 1 cm decrease from previous year measurement and we’re talking about 2500 trees! It seems an easy work but the sources of error are high. A fully conscientious person is needed for the job.
Working with trees in area that has been burned 12 years ago can give a mixed feeling. The open area caused by forest fire has not been recovered yet. Most of the area is still covered by ginger plants mixed with pioneer plants such as the Siam weed (Chromolaena odorata). Trees grow faster in this area which can be relieving but hold your breath….. Many Cananga trees (Cananga odorata) can grow more than 1 cm per year. The overall patterns showed that the distribution of wood density was shifted towards these fast-growing trees such as this Cananga. The fast-growing trees are usually trees with lesser wood density and therefore sequestered carbon less than the high wood density trees.
Every year we measure, watch, and wonder whether this forest can survive another decade or can still participate in carbon sequestration. Can it be? Over the years, we watch the slightly rising temperature which increase the respiration but decrease the photosynthetic rate. The cool weather years increased the growth rate of trees but this rising temperature trend is keeping us alert as it gives the overall decreasing growth rate patterns of this particular forest.