National Forest Inventory England 2021

The National Forest Inventory (NFI) woodland map covers all forest and woodland area over 0.5 hectare with a minimum of 20% canopy cover, or the potential to achieve it, and a minimum width of 20 metres. This includes areas of new planting, clearfell, windblow and restock. The woodland map excludes all 'tarmac' roads and active railways, and forest roads, rivers and powerlines where the gap in the woodland is greater than 20 meters wide. All woodland (both urban and rural), regardless of ownership, is 0.5 hectare or greater in extent, with the exception of Assumed woodland or Low density areas that can be 0.1 hectare or greater in extent. Also, in the case of woodland areas that cross the countries borders, the minimum size restriction does not apply if the overall area complies with the minimum size. Woodland less than 0.5 hectare in extent, with the expectation of the areas above, will not be described within the dataset but will be included in a separate sample survey of small woodland and tree features.

The woodland map is updated on an annual basis and the changes in the woodland boundaries use the Ordnance Survey MasterMap® (OSMM) as a reference where appropriated. The changes in the canopy cover have been identified on:

• Sentinel 2 imagery taken during spring/summer 2021 or colour aerial orthophotographic imagery available at the time of the assessment;
• New planting information for the financial year 2020/2021, from grant schemes and the sub-compartment database covering the estate of Forestry England;

Woodland areas, greater than 0.5 hectares, are classified as an interpreted forest type (IFT) from aerial photography and satellite imagery. Non-woodland areas, open areas greater than 0.5 hectare completely surrounded by woodland are described according to open area types.

IFT categories are Conifer, Broadleaved, Mixed mainly conifer, Mixed mainly broadleaved, Coppice, Coppice with standards, Shrub, Young trees, Felled, Ground prep, Cloud \ shadow, Uncertain, Low density, Assumed woodland, Failed, Windblow.

IOA categories are Open water, Grassland, Agricultural land, Urban, Road, River, Powerline, Quarry, Bare area, Windfarm, Other vegetation.

For further information regarding the interpreted forest types (IFT) and the interpreted open areas (IOA) please see NFI description of attributes available on www.forestresearch.gov.uk Attribution statement: © Forestry Commission copyright and/or database right 2023. All rights reserved.

国家森林调查（NFI）林地进行图涵盖了所有面积超过0.5公顷的森林和林地区域，其树冠覆盖率至少为20%，或具有实现这一覆盖率的可能性，且宽度至少为20米。这包括新种植区、皆伐区、风折区和补植区。林地地图排除了所有‘柏油’道路和活跃的铁路，以及森林道路、河流和电力线路，在这些地方，林地间的空隙宽度超过20米。所有林地（无论是城市还是乡村），无论所有权如何，面积均至少为0.5公顷，除非是假想林地或低密度区域，其面积可以是0.1公顷或更大。此外，对于跨越国家边界的林地区域，如果整体面积符合最小面积限制，则不适用最小尺寸限制。面积小于0.5公顷的林地，在不影响上述区域的前提下，将不会在数据集中描述，但将被纳入单独的小林地和树木特征样本调查中。

林地地图每年更新一次，林地边界的变化在适当的情况下以军械调查主图®（OSMM）为参考。树冠覆盖率的变化已在以下方面被识别：
• 2021年春季/夏季拍摄的哨兵2号图像或评估时的彩色航空正射影像；
• 2020/2021财年的新种植信息，来自资助计划和国有林英格兰地产的子区数据库。

面积超过0.5公顷的林地被归类为从航空摄影和卫星图像中解读出的森林类型（IFT）。非林地区域，即完全被林地包围的开放区域，面积超过0.5公顷，其描述根据开放区域类型进行。

IFT类别包括针叶林、阔叶林、主要针叶林混合、主要阔叶林混合、疏林、疏林带标准树、灌木、幼树、砍伐、土地准备、云/阴影、不确定、低密度、假想林地、失败、风折。

IOA类别包括开阔水域、草地、农业用地、城市、道路、河流、电力线路、采石场、裸地、风力农场、其他植被。

有关解读森林类型（IFT）和解读开放区域（IOA）的更多信息，请参阅国家森林调查（NFI）在www.forestresearch.gov.uk上的属性描述。

版权声明：© 林业委员会版权和/或数据库权利2023。版权所有。