Dear Bay Weekly:     Recently published here was an article about black walnut trees, mainly about their impact on surrounding plants [Bay Gardener: Feb 11]. I thought to balance this article by adding something about the impact of the surroundings on black walnut trees.     I planted a grove of around 150 black walnut trees, and this account is based on my experience.     I have just taken a photo of my grove, although during winter they do not...