A natural resource is a material that occurs in nature and can be used for economic benefit. (ex. coal, minerals, soil)
The way in which humans are altering the envrionment is one of the main reasons why pathogens move from one species to another. The emergence of hemorrhagic fever in Argentina is an example of how human change to the environment has caused a cross-species transfer.
The vascular cambium produces secondary phloem and xylem tissue.
<span>Vascular cambium, a plant tissue located between the xylem and the phloem in
the stem of a vascular plant. It is also the source of both secondary xylem growth
and the secondary phloem growth. Vascular
cambium is usually found on dicots and gymnosperms not on monocots which
usually lack secondary growth. It does not transport water, dissolved food or
minerals by plants. </span>
<span>Vascular cambia are cylinders of unspecialized meristem cells which
divide to make new cells which
specialize to form secondary vascular tissues.</span>
