*Article* **Assessment of Night-Time Lighting for Global Terrestrial Protected and Wilderness Areas**

#### **Liangxian Fan 1,2, Jianjun Zhao 1,2,\*, Yeqiao Wang 3,\*, Zhoupeng Ren 4, Hongyan Zhang 1,2 and Xiaoyi Guo 1,2**


Received: 1 October 2019; Accepted: 15 November 2019; Published: 18 November 2019

**Abstract:** Protected areas (PAs) play an important role in biodiversity conservation and ecosystem integrity. However, human development has threatened and a ffected the function and e ffectiveness of PAs. The Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) night-time stable light (NTL) data have proven to be an e ffective indicator of the intensity and change of human-induced urban development over a long time span and at a larger spatial scale. We used the NTL data from 1992 to 2013 to characterize the human-induced urban development and studied the spatial and temporal variation of the NTL of global terrestrial PAs. We selected seven types of PAs defined by the International Union for Conversation of Nature (IUCN), including strict nature reserve (Ia), wilderness area (Ib), national park (II), natural monument or feature (III), habitat/species managemen<sup>t</sup> area (IV), protected landscape/seascape (V), and protected area with sustainable use of natural resources (VI). We evaluated the NTL digital number (DN) in PAs and their surrounding bu ffer zones, i.e., 0–1 km, 1–5 km, 5–10 km, 10–25 km, 25–50 km, and 50–100 km. The results revealed the level, growth rate, trend, and distribution pattern of NTL in PAs. Within PAs, areas of types V and Ib had the highest and lowest NTL levels, respectively. In the surrounding 1–100 km bu ffer zones, type V PAs also had the highest NTL level, but type VI PAs had the lowest NTL level. The NTL level in the areas surrounding PAs was higher than that within PAs. Types Ia and III PAs showed the highest and lowest NTL growth rate from 1992 to 2013, respectively, both inside and outside of PAs. The NTL distributions surrounding the Ib and VI PAs were di fferent from other types. The areas close to Ib and VI boundaries, i.e., in the 0–25 km bu ffer zones, showed lower NTL levels, for which the highest NTL level was observed within the 25–100 km bu ffer zone. However, other types of PAs showed the opposite NTL patterns. The NTL level was lower in the distant bu ffer zones, and the lowest night light was within the 1–25 km bu ffer zones. Globally, 6.9% of PAs are being a ffected by NTL. Conditions of wilderness areas, e.g., high latitude regions, Tibetan Plateau, Amazon, and Caribbean, are the least a ffected by NTL. The PAs in Europe, Asia, and North America are more affected by NTL than South America, Africa, and Oceania.

**Keywords:** Protected areas; Night-time light; Global lightscape assessment; Human disturbance
