问：求两个关于园林树木的国外参考文献答：Temporal and spatial variation in garden and street trees in six eastern Australian cities Original Research ArticleLandscape and Urban Planning, Volume 101, Issue 3, 15 June 2011, Pages 244-252J.B. Kirkpatrick, G.D. Daniels, A. DavisonLitterfall and nutrient return in five tree