Environmental Engineering Reference
In-Depth Information
periodically from adjacent chir pine forests. Ecological literature during last few
decades from the central Himalaya is full of the concerns that fi re adapted chir pine
(
Pinus roxburghii
) is replacing ecologically and socially valuable Indian white oak
(
Qurecus leucotrichophora
), because the latter is subjected to various degree of
anthropogenic disturbances like lopping, browsing, and recurrent forest fi res (Singh
et al.
1984
,
1997
; Singh
1998
; Semwal and Mehta
1996
; Semwal et al. 2003). Fire
causes extensive damages to nearby degraded white oak especially on dry south fac-
ing slopes and has resulted into encroachment of
P. roxurghii
in oak forests (Singh
et al.
1984
; Singh and Singh
1992
). Fire in chir pine forests occur at 3-5 years inter-
vals and usually eliminate seedlings and saplings of other co-occurring species
(Tewari
1982
; Semwal and Mehta
1996
). Chir pine being fi re adapted successional
species colonizes the burnt sites (Singh and Singh
1992
). However, it has been
observed that in oak-pine transition zones, fi re damages during certain years have
resulted in vigorous regeneration of white oak in several moist chir pine occupied
sites (Garkoti personal observations). Owing to high social value local people prefer
oak compared to chir pine and thus protect regenerating oak from fi re and animal
grazing in order to ensure sustainable supplies of goods and services from white oak
forests. Although replacement of white oak by pine after disturbance is common in
central Himalaya as well as natural because the pine is a successional species and
the same has been widely reported by various ecologists (Singh and Singh
1992
),
there is no published record in ecological literature that describes the reverse.
Material and Methods
Study Area
The forest sites studied were located at 29° 20
′
11.6° N 80° 01
′
05.2° E (oak I) and at
29° 19
26° E (oak II) at 1,849 m and 1,653 m amsl, respectively.
Vegetation and soil characteristics of the study sites are presented in Table
1
. Previously
both the sites were under pine forest with a few scattered oak trees. The climate is tem-
perate with an annual average rainfall 1,430 mm. In all the aspects in ridge sites pine
occurs even above the present study site elevations. Monsoon rains in this part of
Himalaya occur from late June/early July to the middle of September. The year is divis-
ible into three main seasons: cool and usually dry winters (October-March), warm and
dry summer (April-June), and warm humid rainy season (July-September).
′
06.9° N 80° 01
′
Methods
Present study was conducted in two representative oak regeneration sites in the
central Himalaya. Both the oak regeneration sites were located in oak-pine transi-
tion zone and were surrounded by old growth pine forests. Following Misra (
1968
)
each regenerating stand was sampled by using ten, 10 m × 10 m randomly placed
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