For most charities, trustee roles are unpaid. They can require a significant time commitment (a trustee of a charity with who I am involved recently suggested four days per month). And they typically involve meetings in a specific geographic location.
While such requirements mean that these roles may be accessible to those with sufficient free time, income, independence, etc., they can become inaccessible to the most marginalised members of society (and of our communities).

As "8 Ways People of Color are Tokenized in Nonprofits" explains, "many POC simply can’t afford the low pay of nonprofit life". This undoubtedly applies to members of other marginalised groups too. And must apply equally, if not even more so, for unpaid roles! 
Furthermore, a board of trustees that lacks diversity may not appear (or actually be) welcoming (or safe) for those who do not share common characteristics.
So how do we ensure that our boards are truly representative? How can we make trustee roles more accessible to members of marginalised groups., who might otherwise be under represented - in order to achieve greater diversity and inclusion?
Photograph by Ibex73 (Own work) [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons