  A recent problem in community ecology lies in defining structures behind
matrices of species interactions. The interest in this area is to quantify the
nestedness degree of the matrix after its maximal packing. In this work we
evaluate nestedness using the sum of all distances of the occupied sites to the
vertex of the matrix. We calculate the distance for two artificial matrices
with the same size and occupancy: a random matrix and a perfect nested one.
Using these two benchmarks we develop a nestedness estimator. The estimator is
applied to a set of 23 real networks of insect-plant interactions.
