Natural and Anthropogenic Impacts on Forest Structure: A Case Study of Uttarakhand State

1.1. Geographical Location of Study Area

Uttarakhand is the 27^th state of Republic of India which lies between 28⁰ 44' & 31⁰ 28' N Latitude and 77⁰ 35' & 81⁰ 01' E longitude. It was carved out of Uttar Pradesh on 9th November 2000 and was divided into two divisions of Garhwal and Kumaon with total of 13 districts namely Pithoragarh, Bageshwar, Champawat, Nainital, Pithoragarh, Udham Singh Nagar, Dehradun, Haridwar, Tehri Garhwal, Uttarkashi, Chamoli, Pauri Garhwal, Rudraprayag. It has a total geographical area of 53,483 km², of which large area is mountainous with under snow cover and steep slopes. It shares an international boundary with Nepal in the East and China in the North. In the West, it touches state Himachal Pradesh, and in the South, Uttar Pradesh. The human population of the state is 101.167 lakhs (2011census) out of which approximately 70 percent lives in rural areas. There are four major river systems viz. Ganga, Yamuna, Ramganga and Sharda originating from the state along with their tributaries serving as the prime source of water for drinking, irrigation and hydropower. A brief statistics of Uttarakhand state is mentioned in Table 1.

1.2. Classification of Study Area

The major wealth of the state is its rich biodiversity forests. Based on altitude different climate zones are classified as warm temperate (900 m-1800 m), cool temperate (1800 m-2400 m), cold zones (2400 m-3000 m), alpine zone (3000 m-4000 m), glacier zone (4000 m-4800 m), and frozen zone (above 4800 m). The average annual rainfall is about 1550 mm. Based on land elevation, the State is classified as terrain region (less than 300 m above msl), lower hilly region (300-600 m), upper hilly region (600- 2400 m) high altitude region (2400-4500 m) and upper high altitude region (above 4500 m). Udham Singh Nagar and Haridwar are the only plain districts in the State. The state comprises of five lithotectonically and physiographically distinct subdivisions namely, the Outer Himalaya (comprising the Tarai and Bhabhar), Sub-Himalayan belt of the Siwalik, the Lesser Himalaya, the Greater Himalaya and the Trans-Himalaya or Tethys. Human habitation is found up to an altitude of 3500 m above msl; however, the zone between 1200 - 2000 m, largely falling in the Lesser Himalaya (1500 - 2500 m above msl), is densely populated.

1.3. Climate and Soil of Uttarakhand

In the mountainous regions of Uttarakhand the climate is cold, humid and temperate type but it varies with the altitude. The valleys are hot in summer and much colder in winter. So overall Uttarakhand has a temperate climate except in the plain areas where the climate is tropical. The state has different types of soil ranging from low to medium fertile in status. The major soil groups in the state are brown hill soil, mountain meadow soil, sub-mountain soils, and red loamy soils. Most of the soils in the high altitude region are acidic in nature. The Tarai soils are mostly rich, clayey loams, mixed with humus considered best for the cultivation of rice and sugarcane.

5.1. Climate Change

The major factor that controls the ecology of a region is climate (Faisal, 2008). Slight change in climate can significantly alter the growth, abundance, survival, composition, productivity, diversity and distribution of species in an ecosystem (Leemans & Eickhout, 2004). Forest ecosystems are one of the most vulnerable ecosystems to any change in the climate (IPCC, 2001). An indication of climate change is the abrupt fluctuation in the meteorological data. Fig. 2 shows 4-year record of monthly averaged surface temperature observations (Hourly) over the 2010-2014 period for the right bank of Alaknanda river Chauras campus, HNB Garhwal University (30°22”N 78°78” E, 560 metres) has been examined to reveal surface temperature trend in Garhwal region. Similarly, monthly averaged surface temperatures derived from the NCEP reanalysis have been examined over the same time period for the Garhwal region (30°22”N 78°78” E). Considerable variation of temperatures from year to year has been observed in both data sets. Trends in annual mean temperature anomalies showed an increase in surface temperature in this region of Garhwal region during past four years. Based on mean monthly and annual surface air temperature records at the Chauras campus, HNB Garhwal University, gradual warming of the order of 0.2 °C (± 0.022) per year has been observed as per NCEP reanalysis data. However, Annual surface temperature at Chauras campus, HNB Garhwal University has been observed 1.58 ± 1.22 °C averaged during 2010 and -0.08 ± 0.47 °C averaged during 2013. Similarly, in a study Mishra (2014) conducted analysis of 100 years of temperature and rainfall data and observed that the Uttarakhand region has recorded a declining rainfall trend during the 1911-1970 period and after 1970 onward, this trend has become steeper. Furthermore, temperature trend of the region shows an increase in warming with year which was more prominent during the last decade (Fig. 3).

Due to increase in temperatures, rapid deforestation, habitat destruction, change in vegetation, scarcity of water and corridor fragmentation may lead extinction of wild flora and fauna (Negi et al. 2012). The abrupt changes in climatic conditions of Uttarakhand are directly or indirectly affecting the vegetation growth and regeneration of important forest species. The regeneration of many species is dependent on the monsoon rainfall mainly the dominant Sal, Banj Oak and Telonj oak in the forests. The variation in rainfall and temperature may lead to changes in phenological events such as flowering, fruiting, budding, coloration etc. of many species, particularly the dominant oaks. In the Himalayan mountains early flowering of several members of Rosaceae (e.g., Pyrus, Prunus spp.) and Rhododendrons are considered the impact of global warming (Khanduri et al. 2008; Negi et al., 2012). Early bud break in Betula utilis has been recorded in 2010 as compared to earlier years (Rai et al., 2010). One of the major consequence of Global warming is the shifting of vegetation from lower elevation to higher elevation and therefore alpine ecosystems are more are very susceptible to the adverse effects of climate change. The species surviving at this region will have no space for their upward movement. (Kumar et al. 2012). Disturbed and fragmented forests and monoculture forests are considered to be more vulnerable to climate change (Rosenzweig 1995; Jandl et al. 2007).

5.2. Natural Calamities

The frequency of natural calamities in Uttarakhand has increased in last few years mostly heavy rainfall, landslide, earthquakes, cloudburst and avalanche (Table 2). These all are directly or indirectly indicating the impact of climate change. The problems of landslides, subsidence and erosion are quite common in the Uttarakhand due to the contribution of several factors like geological movements, structure, lithology, soil cover, vegetal cover; weather and climatic changes. The problem of landslide is majorly linked to the nature of earthquakes in the region. In the state the frequency of earthquakes per year has been increased in last decade. The other natural calamity i.e. heavy rainfall also shows high frequency of occurrence in 2013, 2014 and 2015. In past few years the problem of cloud burst in Uttarakhand has also caused very severe damage to living and non living thing. Overall all the natural calamities in the state have severely affected the forest ecology directly or indirectly.

5.3. Forest Fires

Forest fires in the Uttarakhand state has been a common phenomenon which is increasing more frequently in the decade due to rising temperatures. Forest fires generally occur in two phases; late March and early April when the accumulation of fresh litter can burn, and May-June, when high temperatures, low humidity, extreme dryness becomes favourable. Uttarakhand forests are made up of many species of trees; including chir pine, blue pine, ban oak, sal, sissoo, eucalyptus, etc. The most fire prone zone is the banj oak at the higher altitudes and the chir pine zone, which occupies 17% of the total forest area, and its transition zone with sal (11% of the total forest area) at the lower altitude, a zone with the maximum habitation. Controlled forest fires help in removing and dried litter and allow new growth to come up. However, uncontrolled forest fires, especially summer fires, cause severe damage to the forest biodiversity. Low precipitation during summer season reduces moisture level in the forest making it more susceptible to catch fire and spread quickly over large area of the forest land. It has been observed that forest fires occur mainly due to lightening but in case of Uttarakhand occurrences due to lightening is less as compared to anthropogenic occurrence. All fires in the chir pine forests of Uttarakhand are man-made intentional or accidental. Of the total forest fires incidences in Uttarakhand, 63% were intentional and remaining 37% were accidental (Tiwari et al., 1986, 1987). Table 3 is explaining that a large fraction of area is affected every year due to forest fires and correspondingly a good amount of economic loss is seen in Uttarakhand. Some other effects of forest fires are change in species composition, loss of micro flora and fauna, loss of seeds, loss of habitat of particular species, change in microclimate, migration of species, soil desiccation, soil erosion resulting in landslides and invasion by exotic species.

5.4. Encroachment on Forest Areas and Illicit Felling

Increasing population leading to poverty is the major factor for stimulating forestland encroachment. In Uttarakhand state large population is below poverty level and most of them encroach forests for shelter, food and a range of subsistence products like fuel wood, food, fodder, timber etc. Forest encroachment results in forest degradation which further results in land degradation and leads to agricultural stagnation and even a lowering of productivity, which in turn promotes further encroachment and completes the vicious cycle. As per the report given by FSI, 2015, the total forest area encroached in Uttarakhand state as on 31 March 2015 is 9646.607 Ha. In the total, Kumaun divison contribute 8318.3 Ha. and Garhwal divison 1323.2 Ha. While the contribution from protected areas includes Rajaji National Park 2.988 Ha, Corbett Tiger reserve 1.980Ha and Nanda Devi Biosphere Reserve 0.117 Ha. To control encroachment effective legal restrictions should be forced in the state.

Fig. 4 shows trend of illicit felling of trees in the state since 2001. Illicit felling is one of the important causes for forest degradation in Uttarakhand. Many strategies are implemented by government against illicit felling but still there is a large volume of illicit felling conducted in the forest.

5.5. Diversion of Forest Land

To support the increasing population development is required and therefore diversions of forest for various activities are practised at large scale. The diversion of forest land in Uttarakhand from 09.11.2000 to 31.03.2015 under Forest (Conservation) Act, 1980 is 39087.8443 ha. This total diversion includes Irrigation Projects (65.9383 ha), Hydro Power projects (2225.0711 ha), Mining (7375.9770ha), Road construction (6375.4835 ha), Communication (2157.2326 ha), Drinking water scheme (196.4014 ha), other scheme (20691.7404 ha). A large area of forest in state is converted into other forms which has created a huge impact on biodiversity.