Climate ’causes leaves to narrow’
A team of Australian researchers studies specimens from the wild and from herbarium collections stretching back more than 120 years.
Analysis of the herbarium samples found that leaf width had decreased by two millimetres.
The findings of the study, described as the first of its kind, appear in the Royal Society journal Biology Letters.
Lead author, Greg Guerin, from the University of Adelaide, said the team chose narrow-leaf hopbush (Dodonaea viscosa subsp. angustissima) as it appeared to display different leaf characteristics in different climates.
“We followed this up by examining exciting herbarium collections before beginning to gather [field] data,” he told BBC News.
The researchers looked at more than 250 herbarium specimens collected from one region: Flinders Ranges, southern Australia’s largest mountain range.
Dr Guerin observed: “Historical herbarium collections provide immediate access to wide sampling throughout a geographic region and through time.
“You just can’t replicate that kind of sampling, covering hundreds of kilometres… from one region over 130 years.”
To support this data, the team gathered 274 field samples from a mountain, collecting specimens at every 50m drop in altitude.
“This gave us information on variation within populations and the local influence of altitude on leaf shape and size,” Dr Guerin explained.
The analysis revealed a two-millimetre decrease in leaf width over 127 years across the region.
Between 1950 and 2005, the team added, there had been a 1.5C (2.7F) increase in the maximum temperatures in the region but there had been little change in rainfall patterns