user16187: The question is this one.
I think that the question is perfectly in scope on Sustainability.SE, but on Biology.SE the community is broader and more technical, and I'd receive a better response there. I'm not sure on how to deal with these cases. Ideally, I'd copy it and not migrate it, but I don't think it's possible.   

user3340: In general cross posting is discouraged. If your question lies in an interdisciplinary area and you would want different kind of opinions then you should fashion the question differently for different kind of forums. In simple words - do not copy and paste, but modify the basic question based on the philosophy of different sites. 
Having said that, I wish to point out that your question, as it is posted in Sustainability.SE, would be considered too broad here because you are asking too many questions and giving too little background information. 
Not many users would be familiar with geological and climatic condition of Northern Italy. You should state all necessary parameters. You should also clarify what you mean by first few years. 
Then you can identify the right tree based on the whatever seems like the best for the given parameters. 

16187: <p>The question is <a href="https://sustainability.stackexchange.com/questions/4539/how-do-trees-absorb-carbon-dioxide">this one</a>.<br>
I think that the question is perfectly in scope on Sustainability.SE, but on Biology.SE the community is broader and more technical, and I'd receive a better response there. I'm not sure on how to deal with these cases. Ideally, I'd <em>copy</em> it and not <em>migrate</em> it, but I don't think it's possible.   </p>
 3340: <p>In general cross posting is discouraged. If your question lies in an interdisciplinary area and you would want different kind of opinions then you should fashion the question differently for different kind of forums. In simple words - do not copy and paste, but modify the basic question based on the philosophy of different sites. </p>

<p>Having said that, I wish to point out that your question, as it is posted in Sustainability.SE, would be considered too broad here because you are asking too many questions and giving too little background information. </p>

<p>Not many users would be familiar with geological and climatic condition of Northern Italy. You should state all necessary parameters. You should also clarify what you mean by first few years. </p>

<p>Then you can identify the right tree based on the whatever seems like the best for the given parameters. </p>
