According to a 2011 survey[update], Central Park had more than 20,000 trees,[78][79][80] representing a decrease from the 26,000 trees that were recorded in the park in 1993.[81] The majority of them are native to New York City, but there are several clusters of non-native species.[82] With few exceptions, the trees in Central Park were mostly planted or placed manually. Over four million trees, shrubs, and plants representing approximately 1,500 species were planted or imported to the park.[83] In Central Park's earliest years, two plant nurseries were maintained within the park boundaries: a demolished nursery near the Arsenal, and the still-extant Conservatory Garden.[84] Central Park Conservancy later took over regular maintenance of the park's flora, allocating gardeners to one of 49 "zones" for maintenance purposes.[85]