After the riots, hundreds (possibly thousands) of Vancouver residents took to the streets to clean up their city (and help track down the idiots who destroyed it). This was their city. They were going to keep it clean.
At the height of the protests in Egypt, thousands took the time to keep the streets clean amongst the government chaos. They felt they had control now. They felt that it was their city.
A sense of ownership is a remarkable thing. We take actions to protect the things we feel a sense of ownership over (we don't want the cognitive dissonance that comes with wasting our time, making a wrong decision, losing money etc..).
A sense of ownership is the feeling that individuals believe they crossed the boundary and made enough contributions to have a respectable claim to ownership. Each contribution is an investment in the community's future success. It's also combined with knowing they have control and influence over what happens.
Ownership isn't a binary value. Your community members don't either feel or not. It's an increasing scale. Some members feel a stronger sense of ownership than others.
Too many organizations prohibit their community members from feeling a sense of ownership. They don't allow members to get involved. They don't share control. They don't have an insider group. They plan and do things without ever asking members what they want, they don't even provide a way for members to get more involved.
It's a shame. A sense of ownership is self-sustaining and guarantees your community will succeed in the medium-term.