Solution
= Solution
The left side is the flux of newborn trees through size zero. Every tree of size $s$ produces seedlings at rate $b(s)$, so total births are $\int_0^\infty b(s)n(s,t)ds$, giving the <boundary condition>.
= Solution
The left side is the flux of newborn trees through size zero. Every tree of size $s$ produces seedlings at rate $b(s)$, so total births are $\int_0^\infty b(s)n(s,t)ds$, giving the <boundary condition>.