Why are the leaves on my diksona antartica brown and dry?

Is the plant indoors? Eek edit: getting my ferns wrong, no it probably isn't!

Have you been watering it?...it needs the sides keeping moist too; sprayed regularly.

Dicksonia Antarticas are an outside plant, in a shady (if poss) part of the garden.They need to be watered reguarly,I use a full watering can per fern straight into the crown slowly un til you see the water running out of the "trunk".They need to be protected during the Winter( where I live anyway) I sack bag the trunk and push as much hay or straw into the crown as poss,that will be be where next years fronds will come from

Dicksonia Antarticas com form wet forest. thay likespray all over. keep water neer for humid

It is coming to the end of its season. You probably don't want to water it too much this time of year, it can turn cold very quickly. If the soil is damp and the trunk moist and we get a frost you may lose it. I have a 6 ft one in my garden which has started to go brown on the leaves. If they go really brown, chop them off as they die off, then do as above and protect for the Winter. Keep the crown dry as the new fronds will start to uncurl next year from there. They have a natural fleecy protection, but use fleece over the crown as this tends to let water run off it.