Preliminary Studies On Plants Selection For Green Roofs In North Of China

Investigation on the green roofs in Beijing as the represent of North of China showed that there are no more than the others besides the stonecrops and grasses that were applied on the extensive green roofs.Selection of the more suitable plants for the entensive and semi-extensive green roofs of North of China was carried out in order to improve the biodiversity and the sustainable development of eco-roofs. Except for Sedum species,selecting other perennial herb species and ground covers with dought tolerance,aesthetic effect,longevity,limit transpiration and minimum maintenance were the emphasis for research.Some exotic green roof plants or rock plants,especially from north-east of North American and indigenous plants were collected under the direction of climate similarity principle.53 survival plants were evaluated for the drought resistence after 71 of them were test for the hardness.Plant establishment,growth,drought tolerance,and hardiness of some plant species and cultivars were evaluated on simulated roof platforms at the BJFU Horticulture farm and several green roofs as at the same time.The experiment results showed that:Most suitable species included Sedum spectabile,Sedum kamtsehaticum var.ellacombianum,Rhodiola dumulosa,which require little maintenance;suitable species are Sedum acre,Sedum spurium 'Coccineum',Sedum sexangulare,Sedum album 'Coralarpe', Sedum reflexum,Sedum sarmentosum,Sedum spurium 'Splendens',Sedum hybridum,Sedum spurium 'Voodoo',which need more watering and thicker media depth.The non-succulent plant species are divided into three classes on the basis of the adaptability: Allium senescens,Allium nutans,Allium mongolicum,Filifolium sibiricum,Arenaria juncea, Caryopteris×clandonensis,Saponaria officinalis,Allium giganteum,Aquilegia viridiflora and Veronica prostrata 'Mrs.Holt' were included in the first class,which require shallower substrates and minimal lever of installation;Festuca valesiac,Thymus mongolicus,Thymus longicaulis,Thymus pulegioides, Thymus seipyllum,Thymus vulgaris,Thymus hybrid,Polygonatum odoratum,Phyla canescens,Potentilla anserine,Potentilla betonicifolia,Achillea sibirca,Elachanthemum intrieatum,Nepata tenuifolia, Capparis spinosa,Dianthus plumarius,Eryngium foetidum,Allium strictum,Rudbeckia hirta,Iris lacteal var.chinensis,America maritima,Saponariao cymoideswere are included in the second class, which require shallow substrates and lower lever of installation.Lonicera japonica,Parthenocissus quinquefolia,Rosa chinenses,Euonymus fortunei,Euonymus japonicus,Spiraea×bumalda 'Golden Mound',Rosa multiflora,Ligustrum lucidum,Berberis thumbergii cv.atropurpurea,Tradescantia rdflexa, Fragaia ananassa,Hemerocallis fulva and Ajania pacifica were included in the third class,which required thick substrates and low lever of installation.