By measuring the height of a tortoise a scientist is gathering QUANTITATIVE DATA.
Explanation:
There are two basic types of data that can be gathered during scientific investigation, these are qualitative data and quantitative data. Qualitative data are those data that are descriptive in nature, this type of data can not be represented with numbers. One good example of qualitative data is the colour of a substance. For instance: A WHITE rat.
Quantitative data on the other hand are those information that can be recorded in number form. For instance, the height of the tortoise in this question can be measured and the value obtained can be recorded in number form.
Primary succession starts with bare rock which is broken down by either lichen or moss to make soil while secondary succession starts with developed soil
