Human Influence on Banj Oak (Quercus leucotrichophora, A. Camus) Forests of Central Himalaya

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1 Journal of Sustainable Forestry, 33: , 2014 Copyright Taylor & Francis Group, LLC ISSN: print/ x online DOI: / Human Influence on Banj Oak (Quercus leucotrichophora, A. Camus) Forests of Central Himalaya VISHAL SINGH 1, RAJESH THADANI 1, ASHISH TEWARI 2, and JEET RAM 2 1 Centre for Ecology Development and Research, Dehradun, India 2 Department of Forestry, Kumaun University, Nainital, India The present study suggests that the impact of human-induced small-scale disturbances (lopping of branches and leaf litter removal) adversely impacts the functioning of banj oak ( Quercus leucotrichophora, A. Camus) forests of Central Himalaya. Significantly higher ( p <.001) biomass stocks, carbon sequestration rates, soil carbon, leaf area index (LAI), litter fall, and faster litter decomposition rates were observed in least human influenced (LHI) forests as compared to moderately human influenced (MHI) forests and highly human influenced (HHI) forests. Three replicate forest stands of each category were selected for the observation. The study is used as a background to suggest alternative strategies to conserve the forests, taking into account the social and economic concerns of the village community. KEYWORDS economical chronic, disturbances, Himalaya, conserve, social, INTRODUCTION The impact of human influence over forest ecosystems of the Himalaya has been a matter of debate for the past three decades (Singh, Pandey, & Tiwari, 1984; Ives, 1985; Singh & Singh, 1992; Thadani, 1999). Forest degradation in the Himalaya occurs primarily due to small-scale chronic Address correspondence to Vishal Singh, Centre for Ecology Development and Research, 41/1, Vasant Vihar, Dehradun , India. cedarhimalaya@gmail.com 373

2 374 V.Singhetal. disturbances (Singh, 1998). In contrast to acute human-induced forest disturbance (or deforestation), chronic disturbances are associated with the removal of small amounts of biomass from many different plants or trees at frequent and often regular intervals and generally leads to degradation (Thadani, 1999). Typically these disturbances are in the form of fire wood, fodder, and litter removal, and to a lesser extent extraction of various nontimber forest products (NTFPs) such as lichens, mosses, and medicinal plants. Such disturbances are continuous and persistent in nature and forest ecosystems do not get adequate time to recover (Singh, 1998) and this leads to a gradual degradation of the forest. While deforestation occurs as discrete patches at particular points in time and space and is often associated with economic causes, degradation is usually spread over an area (DeFries et al., 2007) and may lead to a less dense forest. Degradation is common in developing and less developed countries and is associated with poverty and low human development indices. Cadman (2008) defines degradation as a a reduction in the carbon stock in a natural forest, compared with its natural carbon carrying capacity, due to human activities (p. 2). Forest degradation has been included in the Reducing Emissions from Deforestation and Forest Degradation (REDD) program of United Nations Framework Convention on Climate Change (UNFCCC), though the focus still remains on deforestation (Gullison et al., 2007). Few studies have focused on the impact of degradation on the carbon density within forests. Studies which claim that degradation can be assessed using combination of optical and remote sensing techniques, including high resolution images, have typically focused only on selective logging in rainforests (Asner, 2005) which is not representative of the low intensity degradation as it occurs in the Himalayas and many other parts of the developing world. Due to a ban on green tree felling in many parts of the Indian Himalaya since the early 1980s, whole tree felling has declined considerably. Nevertheless, extraction of wood and leaves by the local population through lopping (or branch pruning) continues unabated across the landscape. This leads to a lowering of productivity and ecosystem carbon without bringing about a measurable loss in the forest area. Traditional agricultural practices of the Central Himalaya are heavily reliant on forests for inputs of nutrient and biomass (Singh & Singh, 1991). Approximately 75% of fuel and fodder requirement of mountain villages are met through biomass from forests (Sharma, Gairola, Ghildiyal, & Suyal, 2009). The focus of this article is on human influence in Quercus leucotrichophora (syn. Q. incana) forests of the Central Himalaya. Locally known as banj or ban oak, this is a valuable keystone species with great societal relevance (Ramakrishnan, 2001). Banj is among the main forest-forming species in the densely populated midaltitudinal zones of the Central Himalaya and provides a variety of ecosystem services. High calorific value of banj wood

3 Human Influence on Banj Oak Forests 375 makes it an excellent fuel, and its leaves are palatable and the major source of cattle fodder in the winter and dry seasons (Thadani, 1999). This oak restranslocates low amounts of nutrients prior to leaf senescence, and the nutrient rich leaf litter decomposes quickly and helps produce an excellent compost fertilizer which is widely used by local farmers and results in the removal of a large quantities of leaf litter across the landscape (Thadani, 1999). An undisturbed banj forest sequesters carbon at the rate of 4 to 5 Mg ha 1 yr 1 (Tewari et al., 2008), but this is likely to be greatly reduced in lopped forests (Thadani, 1999). Study Area MATERIALS AND METHODS The study was conducted in the Almora district of the Central Himalaya situated between N and E. Nine sites with varying degree of human disturbances were selected in the oak zone for detailed study between 1,800 2,100 m elevation. The sites are located in the lower temperate zone of the Himalayan region. The area has a monsoonal climate and annual precipitation was 1,209 mm in 2007 and 955 mm in The mean maximum temperature varies from 14.5 C (January) to 27.9 C (May) and the mean minimum temperature from 4.9 C (February) to 20.1 C (July). Selection Criteria for Disturbance Regimes Sites were selected between 1,800 2,100 m altitude (a zone densely populated and cropped in the Central Himalaya). In order to stratify sampling, each site was assigned one of three disturbance categories viz., least human influenced (LHI) forests, moderately human influenced (MHI) forests, and highly human influenced (HHI) forest. Three sites of each influence type were selected for the study. Ten subplots (total 90 subplots across the study) of 100 m 2 were selected. The sites were classified by ocular estimation based on criteria followed by Thadani (1999). The disturbance parameters were canopy cover, understory growth, forest floor status, and grazing trails (Table 1). Soil Carbon Soil samples were collected by digging to 100 cm depth three pits on each forest site. Soil carbon was measured at 10 cm intervals to a depth of 100 cm. The Walkley-Black titration method (Jackson, 1967) was used to measure soil carbon concentration.

4 376 V.Singhetal. TABLE 1 Criteria Used to Visually Estimate the Disturbance Regimes Disturbance category Oak canopy Understory Litter removal Grazing trails Least human influenced (LHI) Moderately human influenced (MHI) Highly human influenced (HHI) No apparent lopping Some lopping but tree form intact Heavy lopping, pole-like tree morphology, or cut down to stump height Present Present Bushy understory with pruned appearance No apparent litter removal High, only 10 to 20% leaves left on the ground Ground totally swept bare No grazing trails Grazing trails visible Grazing trails easily visible Leaf Area Index Undisturbed Himalayan forests at these altitudes typically have a closed canopy. A reduction in leaf area index (LAI) is an indicator of lopping, as of the pruning of branches reduces canopy foliage. LAI (Cutini et al., 1998) measurements in each site were taken at 15 random points in each season (winter, spring, summer, and autumn) using a plant canopy imager (CII 110, CID Bio-Science, Camas, WA, USA). Litter Fall, Litter Removal, and Litter Decomposition For estimating leaf litter fall of banj oak, five litter traps of 1 m 1m were placed randomly at each forest site. Traps were made of 2 mm mesh nylon suspended from galvanized wires supported by four sticks 25 cm deep to avoid litter from being swept away by wind. Leaf litter was collected at monthly intervals. The litter was then hand sorted out into three main categories viz., (a) leaf litter, (b) wood litter, and (c) miscellaneous wood litter (small twigs, bark, and acorns). The litter was dried to constant weight in an oven at 80 C, and then weighed. For estimating rates of litter decomposition, banj oak litter was collected in March April from all nine sites following Upadhayay (1987). The fresh fallen leaves were stored and oven dried to a constant weight at 40 C. Five grams of dried leaves were placed in cm 2 nylon mesh bags (0.5 mm mesh) and closed firmly by inserting metal pins as described by Khulbe (1992). Fifty-four bags were prepared, 18 for each disturbance regime (LHI, MHI, and HHI), 6 per site. Extra bags were also prepared for each site to replace any lost/damaged. The bags were placed in the forest after scraping off the fresh leaf litter from the forest floor. Bags were in contact with

5 Human Influence on Banj Oak Forests 377 semi-decomposed leaf litter (duff layer). Three litter bags from each of the nine sites were picked at bimonthly intervals, and brought to the laboratory. The residual organic matter was separated from the bags, cleaned from the attached soil particles, and oven dried for 48 hr at 80 C to constant weight. Percent organic matter disappearance was calculated on dry weight basis. Litter removal was estimated by weighing different sizes of head loads to calculate an average weight of one head load. To estimate the total litter removal, numbers of head loads being removed from the forests were counted at exit points of the forests in different months. Biomass and Carbon Sequestration Rates The tree biomass was estimated by measuring DBH (diameter at breast height) and using allometric equations developed by Rawat and Singh (1988). The biomass of different components (bole, branch, twig foliage, stump root, lateral root, and fine root) of trees was calculated from the DBH measurements. For biomass estimation, measurements of diameter were taken at the same point on marked trees in permanent plots in October 2007 and repeated again in October Change in biomass ( B = B 2 B 1 ) was taken as annual biomass accumulation, where B 1 = biomass of 1st yr, B 2 = biomass of 2nd yr, and B is the difference. The sum of B values for different components was taken for accretion of biomass in trees. Fifty percent of the B was used to measure the carbon of the trees and the difference between the carbon content of Yr 1 and Yr 2 was taken as the sequestration rate (Brown, Gillespie, & Lugo, 1989; Singh, Tewari, Kushwaha, & Dadhwal, 2011). Soil Carbon RESULTS The total soil carbon in LHI (189.2 ± 9.6 Mg ha 1 ) forest was significantly higher (p <.001) than the MHI and HHI forests (156.5 ± 2.6 and ± 1.9 Mg ha 1, respectively). As would be expected, soil carbon decreased with an increase in depth. The variation in soil carbon was greater in surface layers (0 60 cm) between sites with difference disturbance levels. Variation was low in deeper layers (Figure 1). Leaf Area Index Significant variation (p <.001) across the human influence is observed in all four seasons. Due to the lower lopping or branch pruning, leaf area index values were greater for the LHI forest, ranging between

6 378 V.Singhetal. FIGURE 1 Variation in total soil carbon across different human influence regimes (values of F-test are significant at p <.001). FIGURE 2 Seasonal variations in leaf area indexes across different human influence regimes (values of F-test are significant at p <.001) ± 0.06 (spring) to 3.79 ± 0.16 (autumn). Low LAI as a result of high lopping was recorded in HHI forest and varied from 0.31 ± 0.07 (spring) to 0.44 ± 0.15 (autumn). Strong seasonal influence was apparent and highest LAI values were recorded in autumn (September November; Figure 2).

7 Human Influence on Banj Oak Forests 379 FIGURE 3 Monthly variations in leaf litter fall across different human influence regimes (values of F-test are significant at p <.001). Leaf Litter Fall, Removal, and Decomposition Rates As would be expected given the higher canopy cover, leaf litter fall was maximum in LHI forest (6.18 ± 0.11 Mg ha 1 yr 1 ), followed by MHI forest (4.36 ± 0.09 Mg ha 1 yr 1 ), and lowest in HHI forests (1.8 ± 0.02 Mg ha 1 yr 1 ). Maximum litter fall was recorded in the month of April for the LHI forest, and in March for MHI forests and HHI forest (Figure 3). Litter removal was maximum in March and April in all categories. The quantity of litter removal showed significant variation (p >.001) across different human influence categories. Litter removal from MHI forest was higher (1.73 ± 0.0 Mg ha 1 yr 1 ), followed by LHI forest (1.21 ± 0.01 Mg ha 1 yr 1 ) and HHI forest (1.05 ± 0.02 Mg ha 1 yr 1 ; Figure 4). Litter decomposition rate varied significantly among months (p <.001) as well as among human influence categories. Faster litter decomposition rates were observed from LHI forest (78.67 ± 0.9% at the end of 1 yr), followed by MHI forest (61.92 ± 0.7%) and slowest (45.99 ± 0.8%) in HHI forest (Figure 5). Biomass Stocks and Carbon Sequestration Rates Highly significant (p <.001) variation in total biomass was observed between the disturbances regimes. The undisturbed site had the highest carbon sequestration rate, 5.00 Mg C ha 1 yr 1, whereas the degraded sites showed

8 380 V.Singhetal. FIGURE 4 Monthly leaf litter removal in different human influence regimes (values of F-test are significant at p <.001). FIGURE 5 Litter decomposition rates with the increase in number of days (values of F-test are significant at p <.001). the lowest carbon sequestration (1.04 Mg C ha 1 yr 1 ). Results of the carbon sequestration rates were within range to those obtained in earlier studies (Tables 2 and 3).

9 Human Influence on Banj Oak Forests 381 TABLE 2 Effect of Human Influence on Biomass Stocks and Carbon Sequestration Rates LHIF MHIF HHIF Parameters Biomass (Mg ha 1 ) Yr Biomass (Mg ha 1 ) Yr Carbon sequestration (Mg ha 1 yr 1 ) Note. LHIF = least human influenced forest; MHIF = moderately human influenced forest; HHIF = highly human influenced forest. TABLE 3 Comparisons of Carbon Sequestration Rates of Different Forest Species in Himalaya (Singh et al., ;KTGAL 2 ; Singh, ; Sah, ) Previous studies in Himalaya Carbon sequestration rate (Mg ha 1 yr 1 ) Mixed Quercus leucotrichophora forest Quercus semecarpifolia forest Mixed Quercus floribunda forest Young Shorea robusta forest Old Cedrus deodara forest Mixed Pinus roxburghii forest Pure Pinus roxburghii forest Present study LHI forest 5.0 ± 0.5 MHI forest 2.6 ± 0.1 HHI forest 1.0 ± 0.1 Note. LHI = least human influenced; MHI = moderately human influenced; HHI = highly human influenced. DISCUSSION There is a strong relationship between the fate of the canopy and to the processes that take place in shaping the physical, chemical, and hydrological properties of the forest (Post, Emaneul, Zinke, & Sangenberger, 1982). The most evident consequence of high lopping is reduced canopy cover which is reflected in low LAI in moderately and highly human influenced forests. As a consequence of high lopping, the area of individual tree canopies is condensed leading to a decline in leaf production and leaf litter fall. The highest leaf litter removal was observed in MHI forest (1.73 Mg ha 1 yr 1 ) and minimum litter removal was observed in HHI forest (1.05 Mg ha 1 yr 1 ) where leaf fall is also lowest as severe lopping reduces the ability of the tree to produce new leaves. In terms of percentage, however, about 40% of the litter was removed from the moderately impacted (MHI) sites while in the highly influenced (HHI) sites about 60% of the leaf fall was being collected. Even in the relatively undisturbed LHI sites, about 20% of

10 382 V.Singhetal. the litter was being collected. As MHI and HHI sites dominate across the landscape, litter removal at this elevational zone would be close to half of the total litter fall. This is a huge amount of transfer of carbon and nutrients from the forest ecosystem to agricultural ecosystems. Lopping of branches leads to a sparse canopy and low litter fall and hence litter is not only less available but collection becomes time consuming and inefficient. Oaks, like many other midelevational Himalayan trees, lose most of their leaves in the spring. The period between March and May has the heaviest litter fall; and consequently the highest litter collection by local people also takes place in the same period. This leads to a short residence time of litter on the ground. This results in low in situ decomposition and impairs the return of nutrients to the ground (Bargali, Singh, & Joshi, 1993). An important consequence of litter removal is the sweeping away of banj oak acorns (which mature and are dispersed in December January but germinate only around June) and desiccation due to exposure to the sun of most of the acorns that remain. Banj acorns are sensitive to direct sunlight and even a few days of exposure is sufficient to cause them to lose viability. This leads to greatly reduced oak germination while pine seeds, which thrive on bare mineral soil, show increased germination rates. Additionally, litter removal disturbs the habitat of many invertebrates and microorganisms which would otherwise help breakdown this litter (Swift, Heal, & Anderson, 1979) and conserve moisture, which plays an important role in decomposition of leaf litter (Pastor & Post, 1988). It is evident from this study that an increase in human influence leads to reduced moisture in the forest floor (Table 4). This occurs due to higher direct evaporation of water from the surficial layers as well as evapotranspiration from shallow rooted shrubs and herbs which deplete water in the upper soil layers. Apart from the microorganisms and moisture which help in decomposition, temperature also plays a significant role. The amount of litter present on the ground also helps to maintain the diurnal temperature and moisture of the forest floor which also helps in litter decomposition rates (Stevenson, 1982). Highest litter decomposition occurred in the LHI forest TABLE 4 Forest Soil Moisture Percent of Forests Under Different Human Influence Soil moisture percent (0 30 cm depth) Least human influenced forest ± ± ± 0.23 Moderately human influenced forest ± ± ± 0.35 Highly human influenced forests ± ± ± 0.32 Note. ValuesoftheF-test are significant at p <.001.

11 Human Influence on Banj Oak Forests 383 and least in HHI forest where loss of moisture and litter removal was high. The litter decomposition rates of the LHI forest were close to the previously obtained values from Central Himalayan forests (Upadhayay & Singh, 1989). Litter removal by local communities for composting is one of the important reasons behind the large decrease in soil organic carbon concentration (Whiteside & Smith, 1941) observed in the soils of the study. Less attention has been paid to the loss of organic matter and C release due to small-scale disturbances like litter removal and grazing. A significant amount of banj oak leaves are removed as fodder and leaf litter. These impact the carbon and nutrient cycles. Minimum soil carbon was observed in the HHI forest where lopping was high, litter fall was less, and litter removal was considerable in relation to litter fall. Proper management practices (low lopping and sustainable litter removal) in forests may restore soil carbon over a period of time. As a consequence of high lopping for fuelwood and fodder, the photosynthetic capacity of the MHI forests and HHI was significantly lower, thereby negatively impacting biomass production. Decreased nutrients due to heavy litter removal also act as limiting factor to the growth of the trees. Raikwal (2009) studied the impact of human influence on Banj oak forests using similar methodology and observed that the density of banj oak declined sharply with increasing human influence. The presence of chir pine (Pinus roxburghii) was higher in highly influenced forests. These trees are rarely lopped as the leaves are of little use and fuelwood is inferior to that of banj. The lopping of banj oak trees and removal of litter is thought to be the main mechanism of replacement of oak by pine in the Central Himalaya (Thadani, 1999). CONCLUSIONS The problems of Himalayan forests are complex and entwined between socioeconomic and ecological concerns. Hill agriculture is heavily dependent on the forest ecosystem for nutrient and energy inputs and it is pointless to talk about forest conservation in isolation without considering croplands. Across much of the landscape, about half of the total litter fall from banj oak forests is collected and used to make compost fertilizer for agricultural terraces. Firewood and cattle fodder from forests sustain local livelihood systems. The pruning of oak trees greatly opens the forest canopy leading to its degradation and a loss of associated biodiversity. The solutions to forest management need to be holistic and take into consideration environmental sustainability, economic demands, and social values. Interventions such as plantations of fast growing fodder grasses such as Pennisetum purpureum and Thysanolaena species in common lands and degraded areas, along with protection of these areas can yield green fodder between Mg ha 1 yr 1 (Integrated Fodder

12 384 V.Singhetal. and Livestock Development Project [IFLDP], 2011). Introduction of biogas plants and energy efficient cook stoves, along with promotion of cooking gas and electricity, will curb lopping of branches and provide clean energy, while also reducing womens drudgery by reduction in time spent in collection of firewood, and enhance health as traditional cooking practices produce high concentrations of particulate matter and harmful emissions (Smith et al., 2009). Providing alternates to fuelwood and fodder can reduce and reverse forest degradation. In disturbed areas, the loss of litter reduces greatly oak germination and dibbling of oak seeds to shallow depths (1 2 inches) has been recommended to ensure adequate regeneration of banj oak (Thadani, 2008). Recommendations from the study carried out in six countries under the project, Kyoto: Think Global, Act Local, suggests that one of the most effective ways to tackle the problem of forest degradation is through involvement of local communities in forest management. Incentivizing communities for conservation of forests through mechanism such as REDD+ of UNFCCC will result in enhanced ownership over the forest and economic upliftment of the forest dependent population of Central Himalaya. REFERENCES Asner, G. P., Knapp, D. E., Broadbent, E.N., Oliveira, O. J. C., Keller, M., & Silva, J. N. (2005). Selective logging in the Brazilian Amazon. Science, 310(5747), Bargali S. S., Singh, R. P., & Joshi, M. (1993). Changes in soil characteristics in Eucalyptus plantation replacing natural broad leaved forests. Journal of Vegetation Science, 4(1), Brown, S., Gillespie, A., & Lugo, A.E. (1989). Biomass estimation methods for tropical forests with applications to forest inventory data. Forest Science, 35(4), Cadman, S. (2008, October). Defining degradation for an effective mechanism to reduce emissions from deforestation and forest degradation (REDD). Paper presented at the SBSTA Workshop on Forest Degradation, Bonn, Germany. Cutini, A., Matteucci, G., & Mugnozza, G. S. (1998). Estimating of leaf area index with the Li-Cor LAI 2000 in deciduous forests. Forest Ecology and Management, 105(1 3), DeFries, R., Achard, F., Brown, S., Herold, M., Murdiyarso, D., Schlamadinger, B., & de Souza, C., Jr. (2007). Earth observations for estimating greenhouse gas emissions from deforestation in developing countries. Environment Science and Policy, 10(4), Gullison, R. E., Frumhoff, P. C., Canadell, J. G., Field, C. B., Nepstad, D. C., Hayhoe, K.,...Nobre, C. (2007). Tropical forests and climate policy. Science, 316(5827), Integrated Fodder and Livestock Development Project (IFLDP). (2011). Project report: Dehradun, India: Centre for Ecology, Development and Research (CEDAR).

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