5 Conclusion
The
TLS, a new and powerful tool, was used to accurately extract the
parameters of vegetation and micro-topography during the natural
restoration of S. moorcroftiana population on the degraded land
in this study. The changes of structure of S. moorcroftianapopulation and effect of micro-topography on spatial distribution ofS. moorcroftiana population after natural restoration on an
extremely degraded land were evaluated by the field investigation and
TLS scans in the middle reaches of Yarlung Zangbo River in 2017. Since
2008, the effectiveness of natural
restoration for S. moorcroftiana population had gradually
improved in the Yarlung Zangbo River valley, Shannan city and the
vegetation coverage had reached 30% - 58% in 2017.
The dominant age structure ofS. moorcroftiana population were adults. The heights of
individual shrubs ranged from 0.43 m to 0.74 m in different
topographies, and the CPA ranged from 0.52 m2 to 4.13
m2. The west slope of approximately 25° with altitudes
of 3593-3643 m (T2) has highest individual growth. The positive
correlation between height and CPA reached the 99% confidence level
(p < 0.01).
The measured elevation and slope spanned from 3550 m to 3695 m and from
0° to 84°, respectively. The
elevation and slope exhibited significant positive correlations with
plant height (r = 0.167 and 0.145, respectively; p< 0.01). However, the distribution of S. moorcroftianapopulation decreased along increasing elevation, while the overall trend
of distribution of S. moorcroftiana population was decreasing
firstly, increasing secondly and decreasing finally with increasing
slope. There was little distribution of individuals on the west and
north. Therefore, our results showed that
the habitat conditions on the
southwest slope of approximately 20°-25° with altitudes of 3593-3643 m
most favor to the distribution and growth of S. moorcroftianapopulation in this region. In order to be able to advise managers on the
effectiveness of natural restoration in producing ecological benefits of
high value for community distribution and growth, along with optimized
strategies of ecological restoration in the restored process, it is
necessary to monitor and evaluate the structural development of
population and spatial distribution of individuals after natural
restoration.