Date of Graduation

7-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biology (PhD)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Stephenson, Steven L.

Committee Member

Stahle, David W.

Second Committee Member

Smith, Kimberly G.

Third Committee Member

James, Douglas A.

Keywords

Biological sciences; Earth sciences; Dendroclimatology; Forest displacement; Fungal diversity; Invasive species; Socioeconomic impact

Abstract

Various studies have suggested that chir pine (Pinus roxburghii) is replacing banj oak (Quercus leucotrichophora) in the Central Himalaya. Five sites with three different types of forests (banj oak, chir pine and mixed oak-pine) were sampled to compare the diversity of their vegetation and to assess the impact of this ongoing conversion on biodiversity. Soil samples collected from oak and pine forests were analyzed and compared. In addition, dendrochronology was used to obtain age estimates of chir pine and to understand the growth response of this species to precipitation. Also, samples of ectomycorrhizal fungi were collected in the form of fruiting bodies and root tips of banj oak and chir pine for DNA analysis, to identify the species associated with these forest types. Since these forests are heavily exploited by local people, Social surveys were carried out to understand the dependency of the local people on these forests and their awareness and opinions relating to the current situation of the banj oak degradation, its consequences for them and the reasons behind it.

Analysis of tree rings of chir pine indicated a positive cool season precipitation response in earlywood and a negative response to warm season precipitation in latewood, which indicate that an increase in summer rainfall associated with anthropogenic climate change could adversely affect the chir pine. Banj oak does not form reliable annual rings, so we do not have any information regarding the potential impact of climate variability or change on banj oak growth.

Overall, banj oak forests were found to be richer in terms of soil fertility, tree and shrub diversity as compared to the chir pine forests. Tree ring data suggested that the mixed forest at Jakholi site was actually an oak forest that got encroached upon by the chir pine. Based on the observations, data and results obtained during this study, it can be concluded that the banj oak forests are declining and chir pine is displacing banj oak in the Central Himalaya.

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