A fig tree in a Sydney park will become a living memorial to a young paramedic killed in the line of duty as his grieving loved ones mark his sacrifice.

The family of Steven Tougher - who died on the job in April - gathered in Koshigaya Park at Campbelltown, in the city's southwest, on Thursday to celebrate his life and compassion for others.

They planted a Port Jackson fig tree, which his father said was symbolic of his open and loving personality.

Mr Tougher, 29, was allegedly attacked during his meal break outside a McDonald's outlet in southwest Sydney on April 14. He died in hospital from stab wounds.

It was the first on-duty death of a paramedic in three decades, devastating his family, colleagues and heavily pregnant wife Madison.

Mr Tougher's sister Jess and parents Jeff and Jill were at the service.

Jeff Tougher said his son made the ultimate sacrifice for his community and the tree represented his character.

"It's a wonderful symbol with its large outreaching branches, symbolic of Steven's arms ... and Steven's big heart and ever-empowering sense of compassion," he said.

The emotional father said he hoped families would gather under the tree and reflect on what happened to his son.

Flowers and cards from the paramedic's funeral were processed as mulch and spread around the newly-planted tree, "taking that positive energy and enriching the soil to grow that love", Jeff Tougher said.

NSW Health Minister Ryan Park said the death should never be considered "part and parcel" of what paramedics did.

"Steven made an incredible contribution and would have continued to make a contribution," he said.

"Today and every day, we remember him."

NSW Ambulance commissioner Dominic Morgan said the paramedic's death had impacted the entire organisation, particularly those who had responded to the incident.

"To be standing here today planting a tree that will more than likely outlive every single one of us today is a beautiful tribute to a beautiful man," he said.

Dr Morgan described the 29-year-old as a "young man of limitless potential, taken too soon".

"Every single one of his colleagues has spoken so positively about his larger than life personality, his sense of humour but also a strong sense of natural justice," he said.

NSW laws were amended last year to strengthen safeguards for frontline emergency and health workers after Mr Tougher's family called for protections after his death.

The changes, which came into effect in October, mean offenders can face up to 14 years behind bars for assaulting a frontline worker.

Jordan James Fineanganofo, 22, was arrested and charged with murdering Mr Tougher. He remains before the courts.