Supplement 3. Matlab code calculating the variance of Y for different time lags, used to analyze the BBS data.

File List varY_lag.m (MD5: ac6cef05a4f087a2f14fc91ab62d0cd4) Description varY_lag.m is a matlab script that calculates the variance of Y over increasing timelags. The main output is the y_lag matrix of calculated variances, with columns denoting time lag and rows - size group. The code receives as output a very specific data structure: a STRUCT vector of sites, each site containing a STRUCT vector of species (+some metadata, i.e., all the lags and species at that site), each species having it's time series at this site. the time series is represented by a matrix with the first row denoting years and the second row denoting population size at that year. For example, sites(3).species(10).ts=[1970 1971; 10 15] means that at site3 for species 10, in 1970 there were 10 individuals and in 1971 there were 15. Some metadata are sites.all_lags (all available lags for this site) and sites.tot_abundance (which species are available at the site?). The grouping requires entering the minimum edges of each group. For example, if group_min = [1 31], the variance would be calculated separately for two groups, one with initial size 1-30, the other 30 and beyond.