His films have won significant Indian and international awards, and In Which Annie Gives It Those Ones acquired cult status in the years after it was made.
Starting in 1995, Krishen began studying trees[14] and spending time in the jungles of Panchmarhi in Madhya Pradesh, with the help of a forester friend.
[15] Krishen taught himself field botany and began identifying and photographing Delhi's trees, extensively exploring the city's green habitat.
The following year, he took over as Project Director of the gardens of the Calico Museum in Ahmedabad, and most recently, leads a team of horticulturists and landscape architects to restore an extensive set of sand dunes in Jaipur city, Rajasthan.
Krishen's book Trees of Delhi: A Field Guide, published by Dorling Kindersley/Penguin Group in 2006, met with popular and critical acclaim, and became a best-seller in India.