g'day robbie,

from my expereince i would say the jacaranda has suffered some damage
and in these cases they often never turn into a good solid tree, you
could try by selecting the upright that represents the strongest
growth but where this growth i will assume is coming from a damaged
area that could be a week link for alter on in life. also there may be
better native trees to do the same job.

as for the alder i don't know much about them but are they an exotic?
sounds like it may be suffering due to dry conditions maybe? again
replace with a native more suitable tree.

the hybrid grevillea can handle pruning to shape so go to it removing
growth may give more flowers then attract more birds.



snipped
With peace and brightest of blessings,

len

--
"Be Content With What You Have And
May You Find Serenity and Tranquillity In
A World That You May Not Understand."

http://www.users.bigpond.com/gardenlen1