Gopal S. Singh

Diversity of deciduousness and phenological traits of key Indian dry tropical forest trees

Abstract• In seasonally dry tropical forests deciduousness (leaflessness) is an important strategy of trees to survive in water stress period during summer. Deciduousness is a reflection of interacted effect of seasonal drought, tree characteristics and soil moisture conditions.• The present study aims to document the diversity in leaf pheno-phases in terms of duration of deciduousness (which is reciprocal to growing season length), wood density, leaf mass per area (LMA) and leaf strategy index in 24 important tree species growing in the Vindhyan dry tropical forest in India.• On the basis of phenological observations, the tree species were categorized into two main groups: leaf exchanging species exhibiting overlapping periods of leaf fall and leaf flush, and deciduous species whose timings of leaf flush and leaf fall differ resulting in a time lag (deciduousness) between the completion of leaf fall and initiation of leaf flush. Presence of wide range of deciduousness duration (from ca. a week to 7 months) among dry tropical trees indicates large variations in their growing season length. In the tree species studied, as the duration of deciduousness increased, leaf flushing period decreased significantly but leaf fall period showed little variation.• Differing deciduousness in tree species exhibited substantial differences in their leafing (vegetative growth) pattern, as reflected by ratio of durations of leaf flush to leaf fall (leaf strategy index). Across different species, duration of deciduousness was significantly positively correlated with leaf strategy index, and significantly negatively correlated with both wood density and LMA.• Wide variations in deciduousness, leaf strategy index, wood density and LMA in the 24 species investigated indicate considerable functional diversity in tree species growing in Vindhyan dry tropical region. Variation in seasonal duration of deciduousness among species is reflections of differences in tree functional traits like stem wood density, leaf strategy index and LMA.Résumé• Dans les forêts sèches tropicales saisonnières, la défoliation est une stratégie importante des arbres pour survivre dans les périodes de stress hydrique durant l’été. La défoliation est un reflet de l’interaction entre la sécheresse saisonnière, les caractéristiques des arbres et les conditions d’humidité du sol.• La présente étude vise à documenter la diversité des phénophases des feuilles en termes, de durée de la défoliation (qui est réciproque à la durée de la saison de croissance), de densité du bois, de masse foliaire par unité de surface (LMA) et d’indice de stratégie des feuilles chez 24 importantes espèces d’arbres poussant dans la forêt sèche tropicale de Vindhyan en Inde.• Sur la base d’observations phénologiques, les espèces d’arbres ont été classées en deux groupes principaux : espèces présentant des périodes de chevauchement de la chute des feuilles et de la feuillaison et espèces décidues dont les rythmes de feuillaison et de chute des feuilles diffèrent d’où un décalage dans le temps entre la fin de la chute des feuilles et l’initiation de la feuillaison. La présence d’une large variation de la durée de défoliation (environ d’une semaine à 7 mois) parmi les arbres tropicaux secs indique de grandes variations dans la longueur de leur saison de croissance. Chez les espèces d’arbres étudiées, comme la durée de défoliation augmente, la période de feuillaison diminue significativement, mais la période de chute des feuilles montre peu de variations.• Différentes défoliation chez les espèces ont montré des différences importantes dans leur modèle de croissance végétative, comme en témoignent les taux des durées de feuillaison par rapport à la chute des feuilles (indice de stratégie de la feuille). A travers les différentes espèces, la durée de défoliationétait significativement positivement corrélée avec l’indice de stratégie de la feuille, et significativement corrélée négativement avec la densité du bois et LMA.• Des écarts importants de défoliation, d’indice de stratégie de la feuille, de densité du bois et LMA, chez les 24 espèces étudiées montrent une diversité fonctionnelle considérable chez les espèces poussant dans la région tropicale sèche de Vindhyan. Les variations saisonnières entre espèces de la durée de défoliation sont les reflets de différences dans des caractéristiques fonctionnelles comme la densité du bois des tiges, l’indice de stratégie de feuilles et LMA.

Soil Seed Bank Dynamics: History and Ecological Significance in Sustainability of Different Ecosystems

The existence and potential importance of the soil seed bank have been recognized by ecologists and evolutionary biologists since the dawn of modern biology, from Darwin (1859) to Mall and Singh (2011) and Hong et al. (2012). The earlier studies of soil seed banks began in 1859 with Darwin, when he observed the emergence of seedlings using soil samples from the bottom of a lake. However, the first paper published as a scientific research report was written by Putersen in 1882, studying the occurrence of seeds at different soil depths (Roberts 1981). Very early ecologists started to investigate the nature and the density of living seeds in the soil and the soil seed bank (Darwin 1859; Chippindale and Milton 1934; Nordhagen 1937; Bannister 1966; Barclay-Estrup and Gimingham 1975), and in modern times to determine the significance of soil seeds in the regeneration of different plant communities (Thompson and Grime 1979; Roberts 1981; Mallik et al. 1984; Simpson et al. 1989; Thompson et al. 1997; Miller and Cummins 2001; Lemenih and Teketay 2006; Tessema et al. 2011b; Mall and Singh 2001; Hong et al. 2012) and the similarity between the soil seed bank and aboveground vegetation (Tessema et al. 2011b). A soil seed bank, which begins at dispersal and ends with the germination or death of the seed (Walck et al. 2005), is a reserve of mature viable seeds located on the soil surface or buried in the soil (Roberts 1981) that provides a memory of past vegetation and represents the structure of future populations (Fisher et al. 2009). Seeds are a crucial and integral part of an ecosystem that show the past history of standing vegetation and its future deviation. An understanding of the population dynamics of buried viable seeds is of practical importance in conservation of different communities and weed management in agriculture (Fenner 1985; Fenner and Thompson 2005). The balance between trees and grasses, however, is often highly disturbed as a consequence of heavy grazing and poor management (Pugnaire and Lazaro 2000). This study aimed to gain a better understanding of soil seed bank dynamics in different ecosystems of the world. All plants establish themselves by the expansion and subsequent fragmentation of vegetative parts such as tillers, rhizomes, or runners by the successful establishment of a soil seed bank or bulbils (Freedman et al. 1982). During the past decade, there has been a rapid increase of the number of studies assessing seed density and species richness and the composition of soil seed banks in a wide range of plant communities (Thompson et al. 1997). In India, the soil seed bank has been estimated in humid tropical forest (Chandrashekara and Ramakrishnan 1993), grasslands, irrigated and dry land agro-ecosystems (Srivastava 2002), tropical dry forest (Khare 2006), jhum cultivation (Saxena and Ramakrishnan 1984; Sahoo 1996), Himalayan moist temperate forest (Viswanth et al. 2006), and wastelands and roadsides (Yadav and Tripathi 1981).

Trichoderma asperellum T42 Reprograms Tobacco for Enhanced Nitrogen Utilization Efficiency and Plant Growth When Fed with N Nutrients

Trichoderma spp., are saprophytic fungi that can improve plant growth through increased nutrient acquisition and change in the root architecture. In the present study, we demonstrate that Trichoderma asperellum T42 mediate enhancement in host biomass, total nitrogen content, nitric oxide (NO) production and cytosolic Ca2+ accumulation in tobacco. T42 inoculation enhanced lateral root, root hair length, root hair density and root/shoot dry mass in tobacco under deprived nutrients condition. Interestingly, these growth attributes were further elevated in presence of T42 and supplementation of NO3- and NH4+ nutrients to tobacco at 40 and 70 days, particularly in NO3- supplementation, whereas no significant increment was observed in nia30 mutant. In addition, NO production was more in tobacco roots in T42 inoculated plants fed with NO3- nutrient confirming NO generation was dependent on NR pathway. NO3- dependent NO production contributed to increase in lateral root initiation, Ca2+ accumulation and activities of nitrate transporters (NRTs) in tobacco. Higher activities of several NRT genes in response to T42 and N nutrients and suppression of ammonium transporter (AMT1) suggested that induction of high affinity NRTs help NO3- acquisition through roots of tobacco. Among the NRTs NRT2.1 and NRT2.2 were more up-regulated compared to the other NRTs. Addition of sodium nitroprusside (SNP), relative to those supplied with NO3-/NH4+ nutrition and T42 treated plants singly, and with application of NO inhibitor, cPTIO, confirmed the altered NO fluorescence intensity in tobacco roots. Our findings suggest that T42 promoted plant growth significantly ant N content in the tobacco plants grown under N nutrients, notably higher in NO3-, providing insight of the strategy for not only tobacco but probably for other crops as well to adapt to fluctuating nitrate availability in soil.

Ecosystem services: A bridging concept of ecology and economics

Nature is bountiful to all living organisms on Earth including human beings. Human, throughout the life, obtained various benefits from ecosystem for the sustenance on planet Earth. Ecosystem service is a linking concept between ecology and econom- ics recently paying attention worldwide. Economic and social development critically depends on the natural capital although at the environmental cost but need bridging of nature components. In the current scenario, due to increasing anthropogenic interferences ecosystem is under great threat. It is time to include ecosystem services agenda in the framework of policy to human and sustainable development.

Functional Attributes of Tribal People of Western Himalaya: Need for Indigenous Knowledge Based Sustainable Planning

Abstract Since the dawn of civilization, both sexes have played a significant role in the evaluation of mankind. In the tribal society of western Himalaya, people have been playing an integrated role in terms of ecosystem functioning. Nonetheless, women have been playing a key role in the upliftment of social, cultural, economic and political values since age-old in the mountainous region. The distinct allocation of activities of men and women has evolved locally for productive and functional usages and it has been inheriting since generations. The status of both sexes is exclusively dependent up on functional attributes of the people concerned. However, the position of women in the study area is, by and large, equal to men; women work 14-16 hours a day and enjoy their life. They never feel bore in harsh and inhospitable geo-climatic conditions but they have molded themselves to contribute optimally through conducive functioning at different subsystem levels. Lack of developmental policies and programmes focusing on cultural domain and centering around agriculture-animal-forest-domestic based interactive subsystems/sectors are endangering the indigenous society of the region. Therefore, developmental approach should be centered on interactive subsystem levels derived from indigenous knowledge oriented packages rather than introduced alien packages.