Snowdon getting 'warmer and wetter' says 15-year survey
Wales' tallest mountain is being changed by rising temperatures, pollution and land management, a survey has revealed.
Results show higher spring and summer temperatures, and wetter and less cold winters on the 1,085m (3,560ft) peak.
There is less acid rain, but habitats are not recovering overnight, and other pollutants are affecting vegetation.
Snowdon is the only site in Wales to take part in the UK-wide Environmental Change Network (ECN) survey.
The ECN investigates how the environment changes over time, and on Snowdon the study is jointly funded by the Welsh government and Countryside Council for Wales (CCW).
The conclusions say a direct result of the UK's drive to cut sulphur dioxide emissions is that there is less acid rain on Snowdon.
The survey notes, however that habitats do not recover overnight and ongoing pollution - "from nitrogen oxides, mainly from vehicle exhausts, and ozone, mainly from industry" - are still having a negative impact on vegetation.
A CCW spokesman said that in some cases this meant native plants were losing out to plants which would not normally grow on the mountain.
This winter has been one of the mildest on record on the mountain, but the survey notes there has been plenty of snow over the last couple of winters.
Diverse plant life
The bigger picture - over the 15-year survey period - suggests the climate has changed slightly on Snowdon.
Spring and summer temperatures have risen, and winters have become wetter and less cold.
More butterflies than ever have been recorded due to the trend for warmer weather. "They are well known indicators of environmental change", said the spokesman.
Land use has also changed over the last 10 years including a big fall in the number of sheep grazing the land.
This has led to an increase in the amount of heather and purple-moor grass, and less grassy areas, "leading to a more diverse mix of plant life which is good news for wildlife".
"As our monitoring work progresses, Snowdon ECN will continue to track changes in the climate, in airborne pollution and land management," said one of the report's authors Dylan Lloyd.
"This will reveal valuable information about the impact of changes on Snowdon's natural habitats."
Mr Lloyd added that being part of a broader network of ECN sites across the UK strengthened the findings.
"We can differentiate short-term variation from long-term patterns of change, making ECN sites invaluable to investigate the health of the ecosystems we rely on," he added.
The findings of the report will be presented and discussed at the CCW Terrestrial Natura 2000 monitoring workshop in Aberystwyth on Tuesday and Wednesday.