assignment怎么写：屋顶花园的植被形式分析
植被的形式和植被被支持的时间周期将根据内部因素和外部因素而变化(Liu & Minor, 2005)。由于使用的基质非常低，这里将支持的大多数植被都是多肉植物。多肉植物能够很好地承受极端天气条件(Axter, 2008)。在气候破坏的情况下，多肉植物品种比任何其他植物更经济的再植。此外，除了最低限度的灌溉外，这些植物需要低维护。
这里将使用土壤替代介质。这是生长基质。虽然这是一个人工生成的生长基质，但它是有机的，因此被认为是安全的建筑使用(跟上生态屋顶背后的理念)。所需的土壤替代介质的深度在50毫米到一米之间。需求将根据建筑物的屋顶及其承重能力而有所不同。以基督教青年会大楼为例，在决定最终的实施方案之前，必须对数据进行研究。
在屋顶花园的情况下，存在一个过滤织物层。这种薄而耐用的织物可以看作是排水的顶层——将排水的粗集料从上面的介质层中分离出来。过滤织物也被称为根尖岩分离织物(Vanwoert et al, 2005)。根尖分离织物将渗透到根部，确保根部能够充分利用整个深度。过滤作用将确保底层的细颗粒不进入排水系统。排水堵塞是屋顶花园业主需要投资维护的一个主要原因，这在这里得到了缓解。此外，根状结构是一种不会随时间退化的结构。它是一种无纺布，也经过机械强化以确保获得足够的水介电常数，同时作为引入的生长介质的支撑层。
有一层用于排水。排水层的目的是确保给植物生长的基质的多余的水将被适当地排掉。排水厚度应在20毫米或以下。这里的一个主要缺点是排水层需要维护，以减轻堵塞或任何不必要的堵塞。过滤水的使用将确保排水层的有效工作。保湿元件也可以用来减少排水，以阻止水分流失。灌溉用水的量也可以根据季节的温度来控制。
assignment怎么写：屋顶花园的植被形式分析
The form of vegetation and the time period in which the vegetation will be supported will vary based on internal actors and external factors (Liu & Minor, 2005). Given the very low millimetres level of substrate used, the most vegetation that will be supported here is of the succulent type. The succulent type of vegetation will be able to stand extreme weather conditions very well (Axter, 2008). In case of weather damage, the succulent variety of plants is more economical to replant compared to any other. In addition, low maintenance is needed for these plants except for a minimal form of irrigation.
A soil substitution medium would be used here. This is the growth substrate. Although this is an artificially generated growth substrate, it is organic in nature and hence is considered to be safe for the use in construction (keeping up with the philosophy behind the eco roofing). The soil substitution medium required would be anywhere from 50 mm to a meter in depth. The need will vary based on the building roof and its weight capacity. In the case of the YMCA building, the data have to be studied before deciding on the final implementation.
A filter fabric layer is present in the case of the roof garden. This thin yet durable fabric can be seen as the top layer of the drainage – separating the coarser aggregate of the drainage from the media layers above. The filter fabric is also called the rooflite separation fabric (Vanwoert et al, 2005). The rooflite separation fabric would be permeable for the roots, ensuring that the roots will be able to make use of the entire depth. The filtering action will ensure that the fine particles in the base layer do not move into the drainage. Drainage clogging is a major reason that roof garden owners need to invest in maintenance and this is alleviated here. Furthermore, the rooflite fabric is one that does not degrade over time. It is a non-woven fabric and also has been mechanically strengthened to ensure adequate water permittivity achieved and at the same time functioning as a support layer for the growing medium that has been introduced.
A layer exists for the drainage. The purpose of the drainage layer is to ensure that the excess water to the substrate that allows the plants to grow will be drained off properly. The drainage thickness should be somewhere between 20 mm or less. One major disadvantage here is that the drainage layer will require maintenance in order to mitigate blockage or any unwanted clogging. The use of filtered water will ensure the drainage layer works efficiently. Moisture retaining elements could also be used to minimize drainage in order to stop the loss of water. The amount of water being sent out in irrigation can also be controlled based on the temperature of the season.
