What do you mean by "broadcast"?
And (separate question) do you want the sensors to send their data to a single "master" or do they each need to send data to all the other sensors?
Does your figure of 1000m represent the radius of a circle with the master at the centre? If not, a diagram of the location of the sensors with approximate distance measurements would be useful.
Will there be obstructions (such as trees or buildings) between a sensor and the master?
How often will the data need to be sent and about how much data (how many bytes) will there be in a data message?
I mean that all the nodes can send data to the center node (aggregator). No, not to each other. 1000 m is the maximum distance form the center node, like radius, yes. They will be set inside a forest, with trees between the center node and the sensor nodes. Data every 2 seconds.