Document Type

Thesis

Degree

Master of Science

Major

Biology

Date of Defense

11-27-2017

Graduate Advisor

Dr. Robert J. Marquis

Committee

Dr. Peter F. Stevens

Dr. Robbie Hart

Abstract

The authors of more than 97% of the scientific publications on climate change agree that global temperature has increased in the last six decades and is caused by human beings via emission of greenhouse gases in the atmosphere. This phenomenon has altered natural ecosystem functions, causing many species to shift to a more suitable habitat. Throughout the world, because of recent climate warming, many forms of range shift associated with climate warming has occurred. While animals can move as warming happens, plants being stationary organisms cannot move, so the difference in the distribution of different plant life stages is an indication that plants are responding to climate change effects. The genus Juniperus is the most diverse genus in the Cupressaceae, the cypress family. Species of Juniperus are found in many varied climatic conditions throughout the world. Junipers in Bhutan are high altitude plant species and extensively harvested for incense manufacturing and construction purposes. The current study analyzed the elevational distribution of J. recurva and J. squamata in Bhutan along six transects, two in each of the eastern, central and western portions of Bhutan. The range of J. squamata is found to be shifting at the leading edge (upper elevation). The distribution of seedlings is on average 83 m higher than that of adults at the leading edge. No differences were found in distribution at lower elevations or in the middle. J. recurva, in contrast, does not show comparable evidence of a range shift. The harvesting of J. recurva was found to be greater than that for J. squamata, and the intensity of harvest is positively linked to the proximity of the nearest road from sampling points. Thus, humans appear to be having an indirect effect on the distribution of J. squamata, via changes in climate, and a direct effect on the abundance of J. recurva, via harvesting of adults.

KEYWORDS: Global warming, range shift, J. recurva, J. squamata, harvesting intensity

Share

COinS