Here are a couple of more articles that may be of interest:

• "Clean territory": Urbicide in the West Bank
  Stephen Graham (Israeli Committee Against House Demolitions)
  Thursday, August 15, 2002

  Although this article focuses on Israel bulldozing houses, there is a passage about why olive groves are also destroyed: "Under the guise of 'destroying sniper hiding places' the IDF have also destroyed many fields, olive groves, factories and greenhouses, adding to the economic effects of the bombings and tightening checkpoints."

• Palestinian farmers face settler terror
  By Khalid Amayreh in the West Bank
  Thursday 14 October 2004

  According to this article, the army has had a hand in the destruction of olive groves by not doing anything about the settlers who do the actual uprooting and burning. Also in this article, an edict is mentioned whereby some influential rabbis have stated that uprooting olive trees isn't stealing, but reclaiming, because the Palestinians are on Jewish land.

• Residents of Three Villages to Block Bulldozers-Protest the Construction of the Wall. This article states that another excuse for the destruction of Palestinian olive trees is because they're in the way of the separation wall.
• UN accuses US bulldozer company of human rights violations
  Mark Willacy, ABC Online
  9 Jul 04

  This article cites a figure of over 100,000 olive and fruit trees having been destroyed by Caterpillar equipment used by the Israeli government in the past two years.