Landscape work at rental property - Repair or improvement?

The lawn of our rental property was inundated with sticker burrs/grass burrs when we bought it. After fighting the stickers for 2 years, our landscaper strongly recommended complete scraping of the property and re-sodding - which we agreed to. We installed a sprinkler system during the sod replacement project. While the heavy equipment was on-site, we also paid him to remove and replace trees which did not survive the deep freeze from the prior year.  

 

Are these expenses considered repairs or improvements?