Packham told the BBC: "The aim of the petition was to get our Royal Family to think about taking some more dramatic action when it comes to conservation of both the environment and of wildlife at a crucial time given we are in an environment and biodiversity crisis."
Marland raised his fears in a debate over proposed changes to laws governing animals in the UK.
He mentioned Packham's plan, which he said asked the Queen to "rewild her entire estate so that we can have bears and wolves back on it".
Speaking in the House of Lords, Marland said: "Imagine going out of Balmoral with your corgis and being confronted by a bear and a wolf".
Packham, a well-known face on British television, is among those being considered for a place on a committee to discuss the Animal Welfare (Sentience) Bill, which would recognise animals feelings in law.
The UK Govt recently extended the legislation to cover animals such as octopuses and lobsters after a recent study found they had feelings.
Marland said he was "terrified" that Packham could have a say in UK law.
"I mean, what sort of people are we listening to?" he asked.
"There are so many holes in this and there is such a lack of clarity that I thoroughly despair for the countryside in the future."
