There are entire chapters dedicated to this at textbooks of plant eco-physiology. Also you can find a good deal of publications, specially about studies at the tropics on journals like plant physiology, and experimental botany.
Dear Arbeen, The climate change indicator caan come from " Symbiotic relationships" such as Pollination of cross pollinated species through aa specific insect or Season of Honey collection. the Forest department experience of collection of Neem flower based honey is moving towards winter months such as March/April whereas it was April /MAy in earlier months.
There is a lot of information concerning tree phenology and climate change in the following publication: Sofiev, M. and Bergmann, K-C (Eds.) (2012) Allergenic Pollen
A Review of the Production, Release, Distribution and Health Impacts. Springer. ISBN 978-94-007-4880-4
Annette Menzel in Global Change Biology, International Journal of Biometeorology and Nature or Science.
Also, Victoria Jato
and Athanasios Damialis (Trees and Atmospheric Environment).
These (and many more of course) have dealt with reproductive attributes of trees and other plants.
Overall, but also in my country, Greece, most woody species seem to start earlier the flowering and pollen emission, transport and production, with increased temperature, lower altitudes and southern directions.