Wood is affected by humidity. Wood expands and contracts as the moisture in the air changes. If I make a wood piece here in the New Mexican desert and send it east it will most likely expand because of the moisure in the east. Vice versa - a piece made on the east coast and ships west will likely shrivel a bit, dry out, and crack. So extra care is needed in understanding wood and it's environment.

"RH" - relative humidity is at a stable range at between 45 and 55 percent. Wood exposed to high humidity levels for a prolonged period of time may experience mold growth, insect infestation, and most certainly pop at glued edges. Screws can shift too! If a dramatic change occurs in the RH it is possible that wood may experience shrinkage damage and warping. Woods in dry climates need periodic oiling or other barrier method to help hold the mositure. Here in New Mexico we'll go through a whole spring and summer at 10% humidity..... or less!

But the reason why wood does thrive is because it is very adaptable - you just need to understand where it's been, where it's going ... and what therapy (oil, wax, polish) it needs along the way :-)