In Kerala the populations of Alsophila nilgirensis are referred to as Cyathea walkerae by some authors (Nayar and Geeverghese 1993).

Alsophila nilgirensis is a tree fern endemic to Western Ghats. It is reported from Karnataka, Kerala, Tamil Nadu and Telangana states of India. It grows in evergreen forest habitat between 800-2,000 m elevation. This species has extent of occurrence (EOO) of 147,770 km² calculated by drawing a Minimum Convex Polygon in GeoCAT (Bachman et al. 2011) and area of occupancy (AOO) of 64 km² calculated using 2x2km grid. It is known to occur in 12 locations. Continuing decline is reported in EOO and number of locations. Although it is currently not used for any purpose, the presence of antibacterial and antifungal properties in its extracts may lead to future commercial use. The establishment and maintenance of tea plantations, widening of road networks involve clearing land, altering soil conditions, and introducing non-native species are activities that negatively impact the fern’s habitat, leading to its decline. Climate change and other factors are further threats to this species. The species is assessed here as Critically Endangered as it satisfies the thresholds of Criteria C1+2(i); small population and estimated continuing decline in population at a rate of over 25% in one generation (10 years) where each subpopulation has less than 50 mature individuals. Conservation of this species requires habitat protection and maintenance, which includes establishing protected areas such as wildlife sanctuaries and conservation reserves within the species' range to protect its natural habitat from further damage and encroachment. Further research in habitat and population trends is required.

Alsophila nilgirensis, belonging to the Cyatheaceae family, is a tree fern endemic to the Western Ghats of India. It is found across four states: Tamil Nadu, Kerala, Karnataka and Telangana. In Tamil Nadu it occurs is Palni Hills, Tirunelveli, Kanyakumari, Anamalai and Nilgiri; (Manickam and Irudayaraj 1992). In Kerala it occurs occasionally in Wayanad district (Nayar and Geevarghese 1993), Idukki district (Madhusoodanan 2015) and Malappuram district. In Karnataka it occurs in Kudremukh National Park (Tripathi 2018), Biligiri Rangaswamy Tiger Reserve (Bagath Singh and Benniamin 2023), and Pushpagiri Wildlife Sanctuary (Jesubalan 2018). In Telangana (formerly Andhra Pradesh) there is one record (Fraser-Jenkins 2017).

Alsophila nilgirensis is sparsely distributed in the Western Ghats. In Tamil Nadu, it has been documented in various localities including Palni Hills with 30 plants, Tirunelveli with 20-34 plants, Kanyakumari's Kothayar boasting 20-40 plants with significant growth, and the Nilgiris with 10-14 plants. Additionally, the Anamalai region hosts 5-8 plants near streamside areas. In Kerala, this species thrives in Idukki district with about 30-40 plants found in Devikulam, Elappara, Kanthallur, and Mannavan Shola and in Wayanad district with about 50 plants and Malappuram district with about 10 plants. Karnataka's populations include the Biligiri Rangaswamy Tiger Reserve, where 5-10 plants exhibit remarkable growth, in Kudremukh National Park which has around 1-2 plants and the Pushpagiri Wildlife Sanctuary, which has 15 well-growing plants. Notably, a small population of 2-3 plants has also been reported in Telangana. The total population is estimated as 198-256 plants, of which 108-196 are estimated to be mature. This fern's distribution, though spread across multiple regions, is characterized by its rarity and fragmented populations, indicating a fragile and localized existence.

The population is undergoing a continuing decline in mature individuals. This has been estimated as follows:

Year: Estimated number of mature individuals

2012: 253
2013: 241
2014: 229
2015: 217
2016: 204
2017: 190
2018: 175
2019:  159
2020: 142
2021: 155 (upward fluctuation observed)
2022: 152 (decline from 2021)

The total estimated decline over ten years (2012–2022) is:
(253−152)/253 × 100 = 39.9%

Alsophila nilgirensis thrives in high-altitude regions within the wet tropical biome. This species is particularly well-suited to fully shaded environments, typically found along streams and stream banks where moisture levels are consistently high. Additionally, Alsophila nilgirensis often flourishes along roadsides that are adjacent to streams, benefiting from the similar moist and shaded conditions these locations provide.

The early maturation of anthridia compared to archegonia in Alsophila nilgirensis poses a risk. When anthridia mature before archegonia, the latter fails to receive fertilization. Consequently, the anthridium, in its quest for the archegonium, swims in vain, leading to an unsuccessful reproductive encounter. 

The antimicrobial properties of Alsophila nilgirensis plant extracts, while beneficial for human health, may inadvertently harm the fern by disrupting the delicate balance of its ecosystem. Occasional cutting and removal of mature plants for decorative purposes by the local community in the Idukki district is another threat. 

The establishment and maintenance of tea plantations, widening of road networks involve clearing land, altering soil conditions, and introducing non-native species. These activities directly impact the fern’s habitat, leading to its decline. These ferns rely on the consistent flow of water for their growth and nutrient uptake. However, human activities such as dam construction, channelization, or diversion of water can alter the natural flow. Reduced water availability due to these alterations can directly impact the fern’s health. Local communities draw water from these streams for domestic, agricultural, or industrial purposes and excessive water extraction can lower the water table, affecting the fern’s root systems. As water levels drop, Alsophila nilgirensis may struggle to survive.

Chemical runoff from nearby fields, industrial discharges, or untreated sewage contaminants can harm the fern directly or indirectly. For instance, heavy metals or pesticides can accumulate in the soil, affecting the fern’s growth and overall vitality. 

Drought like conditions or reduced rainfall can be harsh for Alsophila nilgirensis. The fern relies on moisture to thrive, and prolonged drought can weaken it, affecting its overall health and reproductive capacity. As droughts become more frequent due to climate change, Alsophila nilgirensis faces an uphill battle. If its habitat experiences prolonged dry spells, the fern’s survival becomes precarious. Without adequate water, it may decline in numbers, inching closer to extinction.

The extract from the plant Alsophila nilgirensis (Holttum) R.M.Tryon exhibits both antibacterial and antifungal properties (Pradheesh et al. 2017), making this tree fern valuable for its antimicrobial activities.

Alsophila nilgirensis has been effectively multiplied and propagated through spore culture techniques in the Plant Tissue Culture Laboratory. This method plays a significant role in ex-situ conservation, ensuring the species' survival in both natural habitats and botanical gardens. The Botanical Survey of India Western Regional Centre has established an ex-situ cultivation protocol for Alsophila nilgirensis. Ex-situ conservation at the Kodaikanal Botanical Garden in Tamil Nadu represents a critical effort to preserve plant biodiversity outside their natural habitats. This conservation strategy involves cultivating and maintaining plant species in controlled environments. 

Conservation of this species requires habitat protection and maintenance, which includes establishing protected areas such as wildlife sanctuaries and conservation reserves within the species' range to protect its natural habitat from further damage and encroachment. Enforcing laws is essential to preserve A. nilgirensis suitable habitats. 

Supporting ongoing research on the ecology, genetics, and population dynamics of Alsophila nilgirensis is crucial. Regular monitoring supports adaptive conservation strategies. Educating local communities, tourists, and policymakers on the importance of conserving A. nilgirensis is vital. Awareness campaigns can promote responsibility and encourage sustainable practices. Restoring degraded areas by planting native tree ferns, including A. nilgirensis, aids in creating appropriate habitats and increasing biodiversity. 

Adapting to climate change is imperative for the conservation of A. nilgirensis and its habitat, necessitating the consideration of climate change's potential effects and the implementation of strategies to enhance habitat resilience. Strategies such as assisted migration, the establishment of climate-resilient corridors, and the adoption of adaptive management are essential.