Impact of progressive and retrogressive land use changes on ecosystem multifunctionality: Implications for land restoration in the Indian Eastern Himalayan region.

Land use change, anthropogenic exploitation and climate change have impacted the flow of services in the Himalayan region. The dominant land uses in the region including natural forest, degraded forest, rubber (Hevea brasiliensis) plantations, Areca catechu plantations, Areca agroforestry and Piper agroforestry were considered for the study. A progressive shift in land use was defined as the conversion and restoration of a less productive system like degraded land to plantations or agroforestry systems. A land use shift was considered retrogressive when it entails the establishment of plantations after clearing natural forests or anthropogenic disturbance of natural forests resulting in forest degradation. The objectives of the current study were to estimate changes in soil properties, stand structure, tree biomass, fine root production and carbon storage following a progressive and retrogressive shift in land usage. The aboveground biomass (105.9 Mg ha-1) was highest in the natural forest, followed by Areca agroforestry (100.2 Mg ha-1) and least in the degraded forest (55.3 Mg ha-1). The aboveground biomass carbon (47.1 Mg ha-1) of Areca agroforestry was comparable with that of natural forest (51.3 Mg ha-1). The highest proportion of passive carbon concentrations was observed under Areca agroforestry, whereas the lowest (4.13 g kg-1) was found under Areca plantations in the 0-25 cm soil depth. With the progressive shift in land use from degraded forest to agroforestry, SOC stocks increased by 27.6 % and 3 % under Piper and Areca agroforests, respectively. SOC stocks decreased by 8.5 % with a shift in land use from natural forests to Areca plantations. The production of fine roots was maximum in the Areca agroforest (13.2 Mg ha-1) and lowest under rubber plantations (4.2 Mg ha-1). The results show that progressive shifts from degraded forest to agroforestry can considerably increase carbon stocks, plant species diversity and multifunctionality than shifts to monoculture plantations thereby supporting improved biodiversity and mitigation of climate change.

Modelling habitat suitability for Moringa oleifera and Moringa stenopetala under current and future climate change scenarios.

Moringa oleifera Lam and Moringa stenopetala (Baker f.) Cufod are being widely promoted as multipurpose trees across the tropics for their nutritional, medicinal and soil health benefits. Different parts of these species are edible, have therapeutic values and their seeds are used for water purification. Although the two species are similar in many ways, they have contrasting distributions. However, their current promotion is not guided by adequate knowledge of the suitability of the target areas. Information is also scanty on the suitability of habitats for these species under the current and future climate change scenarios. Therefore, the objective of this study was to predict the habitat suitability of M. oleifera and M. stenopetala under current and future climate change scenarios using an ensemble of models assuming four shared socio-economic pathways, namely, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 for 2050 and 2070. The results suggest that areas that are highly suitable for M. oleifera will increase by 0.1% and 3.2% under SSP1-2.6 to SSP5-8.5 by 2050, respectively. By 2070, the area suitable for M. oleifera would likely decrease by 5.4 and 10.6% under SSP1-2.6 and SSP5-8.5 scenarios, respectively. The habitat that is highly suitable for M. stenopetala was predicted to increase by 85-98% under SSP3-7.0 and SSP5-8.5 scenarios by 2050 and by 2070, while suitable areas could increase by up to 143.6% under SSP5-8.5. The most influential bioclimatic variables for both species were mean diurnal temperature range, mean temperature of driest quarter, precipitation of wettest month, and isothermality. Additionally, soil pH, elevation and water holding capacity were influential variables in the distribution of M. oleifera, while soil pH, soil salinity and slope were influential in M. stenopetala distribution. This study has provided baseline information on the current distribution and possible future habitat suitability, which will be helpful to guide formulation of good policies and practices for promoting Moringa species outside their current range.

Determinants of phytolith occluded carbon in bamboo stands across forest types in the eastern Indian Himalayas.

Phytoliths are known to play a significant role in the global carbon cycle by sequestering atmospheric carbon dioxide as phytolith-occluded carbon (PhytOC) for a long time. Given the resistant nature of phytolith to decomposition, PhytOC can represent up to 82 % of total carbon in some soil and sediments even after 2000 years of litter decomposition. Hence, forests with high PhytOC sequestration rates could play a critical role in increasing terrestrial carbon storage. In this study, we quantified the variation in PhytOC concentrations in bamboo leaves, branches and culms with forest types in the Eastern Indian Himalayas as bamboos are efficient accumulator of phytolith and PhytOC due to their fast growth and high biomass accumulation rates. Using nine different machine learning techniques, we also investigated the determinants of PhytOC production in bamboo stands in the study area in India. The results revealed that the PhytOC concentrations in bamboo stands were in the order of leaf (3.0 g kg-1) > culm (1.0 g kg-1) > branch (0.2 g kg-1) across forest types. The highest PhytOC stock (53.8 kg ha-1) was found in bamboo stands in the subtropical pine forests (1900-3500 m elevation), while the lowest (28.0 kg ha-1) was in the tropical evergreen forests (<900 m elevation). Machine learning techniques established a positive correlation of PhytOC content in leaf and total PhytOC content with soil available phosphorus, elevation, total nitrogen, exchangeable potassium, atmospheric humidity, SOC content, CEC and pH. Numerical evaluation criteria and graphic methods identified artificial neural network (ANN) and support vector regression as the superior techniques with a root mean square error value of 0.52 kg ha-1 and 0.59 kg ha-1 respectively. The results of these two models were found to be better among all the nine machine learning algorithms used. The high PhytOC storage in the bamboo stands in the Indian Himalayan region suggests that forest management could secure a stable carbon sink on a millennial scale.

Post-fire restoration of land under shifting cultivation: A case study of pineapple agroforestry in the Sub-Himalayan region.

Access to the knowledge associated with traditional and/or indigenous land-use systems can help develop adaptive strategies, more productive systems and, design sustainable development models and technologies. This article describes the evolution of traditional pineapple (Ananas comosus) agroforestry systems (PAFS) developed by the ethnic Hmar communities as a strategy for the restoration of land under slash-and-burn agriculture in the Sub-Himalayan region. We critically examine the social and ecological perspectives on rural livelihoods and environmental management, and documented the native tree species managed under different age groups of PAFS. We also interviewed farm managers to gain insights into the traditional farming practices and the uses and services of the different multipurpose tree species (MPTs) along with their traditional management. The study showed that PAFS are an integral part of the rural landscape in the study region exemplifying unique agroforestry systems that have evolved as a strategy to improve land under slash-and-burn on hilly landscapes. PAFS are post-fire sedentary systems evolving as a by-product of shifting agriculture. The system combines pineapple crops with remnant fallow vegetation and subsequent plantations of cash-oriented MPTs in the same farmland. MPTs such as the critically endangered Aquilaria malaccensis and the economically important tree bean (Parkia timoriana), which is no longer found in the wild are largely conserved in the PAFS. Our study demonstrates that PAFS can play a vital role in post-fire restoration of land under slash-and-burn agriculture, which is still practiced among many tribes in the Indian Eastern Himalayas.

Assessing tree diversity and carbon storage during land use transitioning from shifting cultivation to indigenous agroforestry systems: Implications for REDD+ initiatives.

Indigenous agroforestry systems are important reservoirs of biodiversity, and ecosystem services with a potential contribution for conservation of biodiversity while sustaining the livelihood of the rural populace. Pineapple (Ananas comosus) agroforestry systems (PAFS) form an essential constituent of the rural landscape in the Indian Eastern Himalayas and other parts of Asia. The traditional PAFS management in southern Assam is unique in that it involves shifting cultivation transitioning from native forests to a PAFS. Scarcity of information on the functioning and services in terms of species diversity and carbon storage potential in the traditional PAFS has restricted the opportunities for consideration under the nature-based solutions of climate action including REDD+. Therefore, the present study assessed the tree diversity and ecosystem carbon storage in a chronosequence from swidden agriculture through different phases of PAFS establishment. The result demonstrated that basal area in the PAFS increased with age. The most dominant species in the native forests was Palaquium polyanthum, while agricultural land use and PAFS aged <5, 11-15 and > 15 years old were dominated by Gmelina arborea, Albizia procera, Areca catechu and Hevea brasiliensis, respectively. The highest value of Shannon-Wiener diversity index (H) was recorded in native forests (2.71), and lowest in 5-10 years old PAFS. The ecosystem carbon storage declined from 261.43 Mg ha-1 in native forests to 181.07 Mg ha-1 in <5-years old PAFS. In <5 years old PAFS, the ecosystem carbon storage was 30 % lower than the native forest; while at >15 years it was merely 5 % less than the native forests. The traditional PAFS maintains a steady ecosystem carbon stock while reducing land use related carbon emission and providing additional co-benefits to the communities. Therefore, the traditional PAFS constitute a good opportunity for REDD+.

Variations in soil organic carbon content with chronosequence, soil depth and aggregate size under shifting cultivation.

Shifting cultivation is a globally important form of agriculture covering over 280 million hectares in the tropics, but it has often been blamed for deforestation and forest degradation. In North East India (NEI) it has been practiced for millennia and it is an important element of the cultural identity of indigenous communities. It is often practiced on slopping lands with fragile soils (mostly Acrisols), which are prone to rapid degradation with cultivation. The shortened fallow cycle as practised currently is ecologically unsustainable and economically not viable. This study aimed to quantify (i) changes in soil bulk density, aggregate stability and compaction in relation to chronosequence and soil depth, (ii) changes in the proportion of macro, meso, and micro aggregates and associated soil organic carbon (SOC) content in relation to soil depth and fallow chronosequence, and (iii) determine the minimum fallow length that achieves SOC stocks comparable with adjacent intact forest land. The proportion of soil macro-aggregates and meso-aggregates significantly varied with land-use and soil depth as well as their interactive effects. Across all soil depths, forest land had the highest proportion of macro-aggregates (75.6%), while the currently cultivated land had the least proportion (51.1%). The SOC contents in macro-aggregates increased with fallow age and decreased with soil depth; the highest (1.95%) being in the top 10 cm soil of 20 years old fallows and the lowest (0.39%) in 21-30 cm depth of 5 years old fallows. Multivariate analysis identified bulk density and porosity as the most important variables to discriminate between land use practices. The analysis provided evidence for significant changes in soil compaction, aggregate stability and SOC content with the transition from undisturbed forest to slash-and-burn cultivation and fallow phases. It is concluded that a minimum of 20 years of fallow period is required to achieve SOC content and C stocks comparable with intact forest land.

Water stable aggregates and the associated active and recalcitrant carbon in soil under rubber plantation.

Rehabilitation of the degraded soil is imperative to minimize the effects of soil degradation. It is in this context that stable soil aggregates, essential to providing physical protection to the organic residues, are important indicators of soil restoration or degradation. Thus, the present study was aimed at determining the soil aggregate stability and associated carbon fractions under rubber (Hevea brasiliensis) plantations. The study was conducted on 10, 15, 25, and 34-year-old rubber plantation established on Imperata grassland. Soil samples were collected from 0 to 10, 10-20, 20-50, 50-100 cm depths from different aged rubber plantation and native forest (NF) using a soil core of 5.6 cm inner diameter. Soil aggregates from each depth were separated by the wet-sieving technique, and grouped into three fraction size classes: macro-aggregates (>2 mm), meso-aggregates (0.25-2 mm), and micro-aggregates (<0.25 mm), and analyzed for carbon concentrations. The results showed that macro-aggregates dominated soil under different plantation ages and decreased with an increase in soil depth. The Mean Weight Diameter (MWD) and the Geometric Mean Diameter (GMD) increased with an increase in the age of the plantation and decreased with increase in soil depth. The MWD was the highest in the forest soil (5.8 mm) and the lowest (3.0 mm) under 10-year-old rubber plantation. The highest GMD was found under 34-year-old rubber plantation (2.1 mm) and the lowest under 10-year (1.4 mm) plantation. The SOC concentration under the recalcitrant pool increased with the increase in plantation age, and the highest amount was observed under 34-year old plantation. The increase in aggregate stability, recalcitrant carbon pool, and SOC stock with age chronosequence suggests the ecological role of mature rubber plantations in soil rehabilitation by minimizing the process of soil degradation.

Net ecosystem productivity and carbon dynamics of the traditionally managed Imperata grasslands of North East India.

There have been few comprehensive descriptions of how fire management and harvesting affect the carbon dynamics of grasslands. Grasslands dominated by the invasive weed Imperata cylindrica are considered as environmental threats causing low land productivity throughout the moist tropical regions in Asia. Imperata grasslands in North East India are unique in that they are traditionally managed and culturally important in the rural landscapes. Given the importance of fire in the management of Imperata grassland, we aimed to assess (i) the seasonal pattern of biomass production, (ii) the eventual pathways for the produced biomass, partitioned between in situ decomposition, harvesting and combustion, and (iii) the effect of customary fire management on the ecosystem carbon cycle. Comparatively high biomass production was recorded during pre-monsoon (154 g m-2 month-1) and monsoon (214 g m-2 month-1) compared to the post-monsoon (91 g m-2 month-1) season, and this is attributed to nutrient return into the soil immediately after fire in February. Post fire effects might have killed roots and rhizomes leading to high belowground litter production 30-35 g m-2 during March to August. High autotrophic respiration was recorded during March-July, which was related to high belowground biomass production (35-70 g m-2) during that time. Burning removed all the surface litter in March and this appeared to hinder surface decomposition and result in low heterotrophic respiration. Annual total biomass carbon production was estimated at 886 g C m-2. Annual harvest of biomass (estimated at 577 g C m-2) was the major pathway for carbon fluxes from the system. Net ecosystem production (NEP) of Imperata grassland was estimated at 91 g C m-2 yr-1 indicating that these grasslands are a net sink of CO2, although this is greatly influenced by weather and fire management.

Managing India's small landholder farms for food security and achieving the "4 per Thousand" target.

The "4 per Thousand" initiative was launched at the 21st Conference of Parties (COP21) in December 2015 to address global climate change through the aspirational goal of increasing soil organic carbon (SOC) stock of the world to 40-cm depth by an average annual rate of 4%. Small landholders (SLHs), often faced with difficult bio-physical and socio-economic conditions, are the principal managers of soil in India. There are 117 million SLHs representing 85% of the total operational holdings, cultivating over 72 million ha of land, and meeting 50-60% of India's food requirement. The agricultural soils of SLHs are strongly depleted of SOC and nutrient reserves. Therefore, the challenge of feeding 1.7 billion people in India by 2050 will depend on increasing the current productivity levels by restoring the depleted soils of SLHs. According to our estimates, soils of SLHs currently contain 1370-1770 Tg C and, which can be increased to 2460-2650 Tg C by 2050 through large-scale adoption of best management practices (BMPs) including balanced application of nutrients, compost, agroforestry, and conservation agriculture. A wide spread adoption of these practices can enhance C sequestration by 70-130 Tg CO2e per annum and produce 410-440 million Mg of food grains accounting for 80-85% of the total requirement by 2050. In this paper we propose strategies for achieving the dual objectives of advancing food security, the "4 per Thousand" target and mitigating climate change in India.

Fired Bricks: CO2 Emission and Food Insecurity.

Fired bricks are used for construction purposes over the millennia, going back to the Indus Valley Civilization. The traditional brick-making process involves removal of agriculturally productive topsoil rich in clay and soil organic matter contents. In addition to the removal of the fertile topsoil and accelerated degradation by other processes, the traditional clay brick making process also emits CO2 and other gases into the atmosphere. Therefore, the present study aims to assess the impact of brick making in India on: (i) the magnitude of annual CO2 emission and (ii) the loss of agricultural production. Currently, 0.7 Mha (million hectare) of agricultural land is under brick kilns that produce ≈250 billion bricks annually. It is estimated that soil organic carbon lost through the firing process of 250 billion bricks is 5.58-6.12 Tg (teragram) (20.48-22.46 Tg CO2), and in conjunction with clay burning and coal combustion the process releases 40.65-42.64 Tg CO2 into the atmosphere per annum. Brick kiln also impacts quality of the exposed subsoil, and may also reduce 60-90% agronomic yield. Therefore, brick making from topsoil exacerbates food and nutritional insecurity by degrading soil quality, and increases risks of climate change through increase in gaseous emissions.

Impact of land use changes on the storage of soil organic carbon in active and recalcitrant pools in a humid tropical region of India.

Quantifying soil organic carbon (SOC) dynamics is important in understanding changes in soil properties and carbon (C) fluxes. However, SOC measures all C fractions and it is not adequate to distinguish between the active C (AC) and recalcitrant or passive C (PC) fractions. It has been suggested that PC pools are the main drivers of long term soil C sink management. Therefore, the present study was undertaken with the objective of determining whether or not SOC fractions vary with land use changes under a humid tropical climate in the North East India. A chronosequence study was established consisting of natural forest, Imperata cylindrica grassland and 6, 15, 27 and 34yr old rubber (Hevea brasiliensis) plantations to determine changes in the different fractions of SOC and total SOC stock. SOC stocks significantly varied with soil depth in each land use practice. SOC stocks increased from 106Mgha-1 under 6yr to 130Mgha-1 under 34yr old rubber plantations. The SOC stocks under 34yr old plantations were 20% higher than that under I. cylindrica grassland, but 34% lower than SOC stocks recorded under natural forest soil. The proportion of AC pools decreased with increase in plantation age, AC pools being 59% of SOC stock in 6yr old stands and 33% of SOC stocks in 34yr old plantations. In contrast, the proportion of PC pools increased from 41% of SOC stock in 6yr old plantation to 67% of SOC in 34yr old plantation. In the 50-100cm soil depth, the PC pool under 27-34yr old plantations was comparable with that under natural forest but much higher than in I. cylindrica grassland. Therefore, it is concluded that old rubber plantations can play a significant role in long term soil C sink management.

Vegetative and reproductive phenology of a floodplain tree species Barringtonia acutangula from North East India.

Vegetative and reproductive phenology of Barringtonia acutangula, a floodplain tree species was studied at Chatla floodplain, Assam North East India with the aim to investigate vegetative and reproductive phenology under stressful environment of seasonal submergence and to assess the impact of environmental variables (temperature and precipitation) on tree phenophases. Quantitative assessment was made at 15 day interval for all the phenophases (leaf initiation, leaf-fall, flowering and fruiting) by tagging 40 (forty) trees over aperiod of two years (2012-14).To test seasonal influence on the phenology of Barringtonia acutangula different phenophases were correlated with environmental variables and statistical spearman's rank correlation coefficient was employed. Aridity index was computed that delineate influence of rainfall and temperature together on any phenophases. Leaf initiation showed positively significant correlation with temperature (r(s) = 0.601, p = < .05) during the year 2012-2013 whereas it was significantly correlated with rainfall (r(s) = 0.583, p = < .05) and aridity index (r(s) = 0.583, p = < .05) during the year 2013-2014. Leaf-fall was significant negatively correlated with temperature (r(s) = -0.623, p = < .05), rainfall (r(s) = -0.730, p = < .01) and aridity index (r(s) = -0.730, p = < .01) for both the studied years. Flowering was significantly influenced by temperature (r(s) = 0.639, p = < .05), rainfall (r(s) = 0.890, p = < .01) and aridity index (r(s) = 0.890, p = < .01) while in one month lag flowering was significantly correlated with rainfall (r(s) = 0.678, p = < .01) in 2012-13. Fruiting was also positively significant with temperature (r(s) = 0.795, P < .05), rainfall (r(s) = 0.835, P < .01) and aridity index (r(s) = 0.835, P < .01) for both the years. During one month lag period fruiting was positively correlated with temperature, rainfall and aridity index in both the years. Temperature, rainfall and aridity index were major determinants of the various vegetative and reproductive phenology of B. acutangula and any changes in these variables in future due to climate change, might have profound effect on phenophases of this tree species.

Fuel wood properties of some oak tree species of Manipur, India.

Five indigenous oak tree species, i.e., Castanopsis indica (Roxb. ex Lindl.) A.DC., Lithocarpus fenestratus (Roxb.) Rehder, Lithocarpus pachyphyllus (Kurz) Rehder, Lithocarpus polystachyus (Wall. ex A.DC.) Rehder and Quercus serrata Murray were estimated for their wood properties such as calorific value, density, moisture content and ash content from a sub-tropical forest of Haraothel hill, Senapati District, Manipur. Wood biomass components were found to have higher calorific value (kJ g(-)) than bark components. The calorific values for tree species were found highest in L. pachyphyllus (17.99 kJ g(-1)) followed by C. indica (17.98 kJ g1), L. fenestratus (17.96 kJ g"), L. polystachyus (17.80 kJ g(-1)) and Q. serrata (17.49 kJ g(-1)). Calorific values for bole bark, bole wood and branch bark were found significantly different (F > 3.48 at p = 0.05) in five oak tree species. Percentage of ash on dry weight basis was found to be highest in Q. serrata (4.73%) and lowest in C. indica (2.19%). Ash content of tree components gives a singnificant factor in determining fuelwood value index (FVI). Of all the five oak tree species, Q. serrata exhibited highest value of wood density (0.78 g cm-) and lowest was observed in C. indica (0.63 g cm(-3)). There was significant correlation between wood density (p<0.05), ash content (p<0.01) with calorific value in oak tree species. Fuelwood value index (FVI) was in the following order: C. indica (1109.70) > L. pachyphyllus (898.41)> L. polystachyus (879.02)> L. fenestratus (824.61)> Q. serrata (792.50). Thus, the present study suggests that C. indica may be considered as a fuelwood oak tree species in Manipur.

Ethnopedology and soil quality of bamboo (Bambusa sp.) based agroforestry system.

It is widely recognized that farmers' hold important knowledge of folk soil classification for agricultural land for its uses, yet little has been studied for traditional agroforestry systems. This article explores the ethnopedology of bamboo (Bambusa sp.) based agroforestry system in North East India, and establishes the relationship of soil quality index (SQI) with bamboo productivity. The study revealed four basic folk soil (mati) types: kalo (black soil), lal (red soil), pathal (stony soil) and balu (sandy soil). Of these, lal mati soil was the most predominant soil type (~ 40%) in bamboo-based agroforestry system. Soil physio-chemical parameters were studied to validate the farmers' soil hierarchal classification and also to correlate with productivity of the bamboo stand. Farmers' hierarchal folk soil classification was consistent with the laboratory scientific analysis. Culm production (i.e. measure of productivity of bamboo) was the highest (27culmsclump(-1)) in kalo mati (black soil) and the lowest (19culmsclump(-1)) in balu mati (sandy soil). Linear correlation of individual soil quality parameter with bamboo productivity explained 16 to 49% of the variability. A multiple correlation of the best fitted linear soil quality parameter (soil organic carbon or SOC, water holding capacity or WHC, total nitrogen) with productivity improved explanatory power to 53%. Development of SQI from ten relevant soil quality parameters and its correlation with bamboo productivity explained the 64% of the variation and therefore, suggest SQI as the best determinant of bamboo yield. Data presented indicate that the kalo mati (black soil) is sustainable or sustainable with high input. However, the other three folk soil types (red, stony and sandy soil) are also sustainable but for other land uses. Therefore, ethnopedological studies may move beyond routine laboratory analysis and incorporate SQI for assessing the sustainability of land uses managed by the farmers'. Additional research is required to incorporate principal component analysis for improving the SQI and site potential assessment. It is also important to evaluate the minimum data set (MDS) required for SQI and productivity assessment in agroforestry systems.

Comparative study on growth performance of two shade trees in tea agroforestry system.

An attempt was made to study the stem growth of two native dominant shade tree species in terms of annual girth increment in three dominant girth size categories for two years in tea agroforestry system of Barak Valley, Assam. Fifty two sampling plots of 0.1 ha size were established and all trees exceeding 10 cm girth over bark at breast height (1.37 m) were uniquely identified, tagged, and annually measured for girth increment, using metal tape during December 2010-12. Albizia lebbeck and A. odoratissima were dominant shade tree species registering 82% of appearance of the individuals studied. The girth class was categorized into six different categories where 30-50 cm, 50-70 cm and 70-90 cm were dominating girth classes and selected for increment study. Mean annual girth increment ranged from 1.41 cm in Albizia odoratissima (50-70 cm girth class) to 2.97 cm in Albizia lebbeck (70-90 cm girth class) for the first year and 1.70 cm in Albizia odoratissima (50-70 cm girth class) to 3.09 cm in Albizia lebbeck (70-90 cm girth class) for the second year. Albizia lebbeck exhibited better growth in all prominent girth classes as compared to Albizia odoratissima during the observation period. The two shade tree species showed similar trend of growth in both the years of observation and significant difference in girth increment.

Vegetative and reproductive phenology of some multipurpose tree species in the homegardens of Barak Valley, northeast India.

Traditional homegardens are an important component of the farming systems in many rural communities and have been highlighted considerably due to their sustainability and role in the conservation of biodiversity. However, the functional aspect of the homegardens, which includes the phenological behavior of the dominant tree species in such agroforestry systems, has been undermined till date, and there is a lack of adequate data on this aspect of the traditional homegardens. As a step in this direction the present study was carried out to determine the phenological behavior of important multipurpose trees in the homegardens of the village of Dargakona, Assam, northeast India. The study revealed the dominance of periodic growth deciduous species from a total of 25 tree species selected for phenological observation. The diversity of multipurpose trees in the homegardens is represented by different plant functional types with different phenological behavior which showed significant changes in their responses to inter-annual climatic variations. The diversity of tree species with different phenological behavior has implications for the temporal partitioning of resources, especially during periods of scarcity, thereby resulting in efficient utilization of resources such as water. Also the diverse phenological behavior plays an important role in regulating the food supply for the herbivore population and the year-round availability of products, and such information can be useful in the selection of species for integration into other agroforestry systems which can be sustainable in the long run.

Diversity and utilization of tree species in Meitei homegardens of Barak Valley, Assam.

An inventory of tree diversity in traditional homegardens of Meitei community was conducted in a Bontarapur village in Cachar district of Barak Valley, Assam. Meitei homegarden locally called Ingkhol exhibits a wide diversity in size, shape, location and composition. Seventy one tree species were enumerated from 50 homegardens belonging to 60 genus and 35 families. Among the families encountered, Rutaceae was the dominant family (4 genus and 7 species) followed by Meliaceae (5 genus and 5 species), Arecaceae (4 genus and 4 species) and Moraceae (3 genus and 5 species). Total 7946 tree individuals were recorded, with the density of 831 No ha(-1) of and total basal area of 9.54 m2 ha(-1). Areco catechu was the dominant species with the maximum number of individuals. Other dominant trees include Mangifera indica, Artocarpus heterophyllus, Citrus grandis, Parkia timoriana, Syzygium cumini and Psidium guajava. Being a cash crop, the intensification of betel nut has been preferred in many homegardens. Homegardens form an important component of land use of Meitei community which fulfills the socio-cultural and economic needs of the family and helps in conserving plant diversity through utilization.

Analysis of vegetation in an Imperata grassland of Barak valley, Assam.

Imperata grassland at Dorgakona, Barak valley, North Eastern India was analyzed for species composition and diversity pattern in relation to traditional management practices. 19 families were in the burnt and unburnt plots of the study site with Poaceae as the most dominant one. 29 species occurred in the burnt plot and 28 in the unburnt plot. Most of the species were common in both the plots. The pattern of frequency diagrams indicated that the vegetation was homogeneous. Imperata cylindrica, a rhizomatous grass was the dominant species based on density (318.75 and 304.18 nos. m(-2)), basal cover (158.22 and 148.34 cm2 m(-2)) and Importance value index (IVI) (132.64 and 138.74) for the burnt and unburnt plots respectively. Borreria pusilla was the co-dominant species constituting Imperata-Borreria assemblage of the studied grassland. It was observed that B. pusilla (162.25 nos. m(-2) and 50.37 nos. m(-2), I. cylindrica (318.75 nos. m(-2) and 304.18 nos. m(-2)) and Setaria glauca (24.70 nos. m(-2) and 16.46 nos. m(-2) were benefited from burning as shown by the values sequentially placed for burnt and unburnt plots. Certain grasses like Chrysopogon aciculatus and Sacciolepis indica were restricted to burnt plot while Oxalis corniculata showed its presence to unburnt plot. Grasses dominated the grassland as revealed by their contribution to the mean percentage cover of 72% in burnt plot and 76% in umburnt plot. The dominance-diversity curves in the study site approaches a log normal series distribution suggesting that the resources are shared by the constituent species. Seasonal pattern in diversity index suggested definite influence of climatic seasonality on species diversity; rainy season was conducive for maximum diversity (1.40 and 1.38 in the burnt and unburnt plots, respectively). Dominance increased with concentration of fewer species (0.0021 in burnt plot and 0.0055 in unbumt plot) in summer and behaves inversely to index of diversity. This study showed that the traditional management practices benefits the farmers as it promote grassland regeneration with I. cylindrica as the dominant grass.