At least 3 reasons: Dead branches from wind could fall, or whole trees could fall when ground is saturated, and lightening could strike.

Thanks Craig Carlton Dremann .

The world in a big place, and considering the immense variety of tree species in various biomes and terrain conditions, your question probably should be bounded somehow. For instance, here in the Pacific Northwest, it rains almost continuously, and with 200 ft Douglas Firs 8' in diameter, falling trees trees are a fact of life: https://www.chronline.com/stories/packwood-lake-trail-gets-facelift,176888

But in general, the danger is not from rain, it is mostly the wind. And especially wind in trees of poor health. And then, if the tree is isolated or in a stand of other trees. And vulnerability of lighting is highly location specific, but in general, it will go after the highest object in a vicinity, BUT it is looking for the path of least resistance, so unless you are holding a golf club or metal pipe over your head, it likes conductors (here in the US, the buildings have lighting rods in place to spare the structure.

Disclosure: I own stock in a lightning protection company: https://blog.nvent.com/erico-the-science-of-a-lightning-strike-and-how-to-safeguard-your-facility-with-a-lightning-protection-system/ ...

... and in high school, me and my girlfriend to shelter from the rain under a very picturesque cherry tree by the creek, and when I finally found enough nerve to attempt my first kiss ever, as our lips touched, a lightning bolt struck a metal light pole on a foot bridge - it was like being inside a flash bulb. Hmmm ... might be karma. :-)

Thanks Michael John Patrick

Dear Researcher,

Why do electrician cut the trees when they grow onto the electrical wires and poles? Do we have scientific reason..do share your views..

INRE: "Why do electrician cut the trees"

Stretch a piece of string across the room - maybe from a lamp to another lamp. Now take your arm and bring it down on top the string swiftly as hard as you can. Most likely the string will break, or the lamps will topple, and possibly both.

Thanks Michael John Patrick

Prisilla Jayanthi Gandam BTW, incidentally understanding the 'Scientific Reason' for this probably predates the evolution of Homo Sapiens ). :-)

https://4.bp.blogspot.com/-ciV_ugsuVRE/VdTSh95pelI/AAAAAAAAMpk/ajbtdkh3B50/s640/2015_08%2BSam%2BSiamang%2Bintro%2BJDL%2B3.jpg

Michael John Patrick you mean extinction of species?

Prisilla Jayanthi Gandam INRE: 'Extinction'. No, I mean the cognitive model of the dynamics of the relationships and interactions between tree limbs ( and their attributes) and long rope things (vines, ropes, cables) - like how and when they break goes way, way, way back in time since most likely we are descended from some sort of arboreal species back in the depths of time.