I don't grow this specific species, but I have grown other species that belong to the same section and come from roughly similar regions as it.
First of all let's get the name correct so you have a better chance of finding the correct information on this plant.
The correct spelling is:
Den. stricklandianum
It is apparently a synonym of:
Den. catenatum
This species of
Dendrobium is in the section
Dendrobium.
It is a semi-deciduous species from what I've seen in a photo of the plant.
In other words, the leaves on your plant may be dropping naturally, especially if the leaves are from the older canes.
It is one of those
Dendrobium species that has a winter dormancy.
In the future, it would also be of great help to see a photo of your plant.