Patterns of Phenological Characteristics of Important Tree species of Kumaun Himalaya

Phenology is one of the simplest and most effective study to understanding the role of climate change in recent scenario. A number of biotic and abiotic drivers controlled the timing and duration of various phenophases in same or different species. Temperature, rainfall and photoperiod are key drivers which adversely affect the phenology of woody plant. The study sites were conducted at 413 and 2345 m elevation in Nainital forest division of Kumaun Himalaya. The phenological study were carried out on Shores robusta, Mallotus philippinensis, Pinus roxburghii, Myrica esculenta, Quercus leucotrichophora and Rhododendron arboreum. The phenological observations were made at 15 days interval for low activity period and weekly in the periods of high activity. Phenological records were made for four phenophases, viz., leafing, leaf drop, flowering and seed fall. The leaf fall in S. robusta started from March 2nd week and was complete by the end of April. In M. philippinensis the fruiting commenced from the beginning of December and seed fall was complete by the 3rd week of April. In M. esculenta male flowers appear from August end and flowering was complete by October end. In R. arboreum seed dispersal started from February end and all the capsules had opened by mid-March. It is apparent from the present study that the phenological events of species controlled/shifted due to climatic irregularities and temperaturerise and these phenomena showed worldwide. Microclimatic condition also responsible for controlling/shifting the phenological patterns of same or different species. CONTACT Amit Mittal amitforestry26@gmail.com Graphic Era Hill University, Bhimtal Campus, Nainital, Uttarakhand263126,


Introduction
The entire Himalaya region is highly vulnerable to the impacts of global warming and forest ecosystem can be seriously impacted in these changes. Phenological events of the plants are good indicators of climate differences. 1,2 Phenology involves precise documentation of timing and duration of different phenological events at species level, their interrelations and possible causal links between environmental variables and phenology. 3 The various phenological events such as leafexpansion, abscission, flowering, bud-burst, fruiting, seed dispersal and germination of Himalayan species all take place in due season. 3,4 Phenological studies are as important to understand the species interactions and community function because each phenological events of each species occurs in its own calendar slot. 5 Fruiting must wait upon flowering; seed dispersal cannot precede fruiting even an individual flower undergoes a sequence of events. 4,6 A number of studies in different parts of the world indicate that global warming of last three decades has advanced by a few days several spring time activities such as leaf production flowering and fruiting in plants. 7,8 The observed change may be a positive sign because species are apparently adapting to changing climatic conditions, or they may be negative sign because they show that climate change is indeed impacting living systems. 9 A number of studies have convincingly demonstrated that plants are already responding to climate change with earlier leafing, flowering and leaf drop. [10][11][12] It is an important component for predicting how species will respond to global warming and increasing drought stress in recent scenario of changing climatic patterns. 13 The most significant ways by which trees can react and cope with rapid environmental change could be adjustments of phenological pattern, allowing trees to persist in their environment. 14,15 Phenological phases are closely linked with temperature, rainfall and photoperiod and adversely affect the pattern of phenology in same or different species on a small region. A number of evidences have been reported by various researches that phenophases of several species changed by changing climatic patterns. The present work focuses on the documentation of the phenological events and compared with earlier studies to find the shift the phenophases in last three decades and effect of climate change on phenological events ofsal, chir-pine and banj oak dominated forests in Nainital forest division of Kumaun Himalaya.

Material and Methods
The study sites were selected across an altitudinal transect located between 413 and 2345 m elevation (between 29 0 18/ and 29 0 24/ N and 79 0 19/ and 79 0 30/ E) in sal, chir-pine and banj oak dominated forests in Nainital forest division of Kumaun Himalaya. In the sal dominated forest Shorea Robusta Rox (Sal) and Mallotus philippinensis (Lam.) Muell. Arg (Rohini) in chir-pine dominated forest Pinus roxburghiisarg (Chirpine) and Myrica esculenta Thumb (Kaphal) and in Oak dominated forest Quercus leucotrichophora A.camus (Banj Oak) and Rhododendron arboreum Wall (Buransh) were selected for detailed phenological observation (Table 1). In sal forest the average annual precipitation was 1201 mm and mean annual temperature was 23.4 0 C with mean minimum temperature was 7.5 0 C in the months of December and mean maximum temperature was 35.5 0 C in the months of June.
In oak and pine forest average annual precipitation was 2258 mm of which two third occurred during rainy season (mid-June to mid-September. Mean annual temperature was 15.2 0 C with mean minimum temperature was 4.6 0 C in the months of January and mean maximum temperature was 25.9 0 C in the months of June.

Shorea Robusta
Across all the sites the leaf fall in S. robusta started from March 2 nd week and was complete by the end of April. Flower bud break started from March 2 nd week and flowering was in <10% trees after 2-3 days of flower bud break. Flowering had peaked in the 4 th week of March (75% trees had flowered). New leafing started after one week of floral bud opening and by the April end trees had maximum new leafing (95%). However, in seedlings and saplings it continued till July end. Seed fall started from June first week and almost all fruits had fallen after the torrential rain in the third week of June ( Fig. 1 and 2).

Mallotus Philippinensis
In this species the leaf fall started in the 2 nd week of June and was complete in August 2 nd week. New leaves started appearing from May 3 rd week and leafing was completed in August 1 st week. However, in saplings and seedlings new leaves appeared after July during August and September.
Flowering started from September end and was completed in the mid of November. Fruiting commenced from the beginning of December and seed fall was complete by the 3 rd week of April ( Fig.1 and 2).

Pinus Roxburghii
Needle bud enlargement started from February end and was complete by the 2 nd week of March. Needles had attained their maximum length ranging between 14.3cm to 17.1cm by May end. Leaf fall started from March last week and was over by May 2 nd week. Seed dispersal commenced from April 2 nd week and was completed by June 2 nd week ( Fig. 1 and 2).

Myrica Esculenta
Leafing started from April 2 nd week and was completed by May end when >95% trees and saplings had leafed. Leaf fall started from June 2 nd week and continued till 2 nd week of July. Seed fall was observed from April end and was completed by 3 rd week of May only occasional trees had fruits. Only a few trees (10%) of M. esculenta had seeds, and it may be concluded that year as a lean seed year. Male flowers appear from August end and flowering was complete by October end. Maximum flowering was observed between August end and September 2 nd week when 80% trees had flowers ( Fig.1 and 2).

Quercus Leucotrichophora
Seed fall commenced from 2 nd week of November and seed fall was complete (85%) by January end. Bud bursting started from February end and was completed by March end across all the sites. Leafing started in the 1 st week of March and was completed in the 1 st week of April in trees. Leaf fall started simultaneously with bud bursting and continued till April end. Acorn appeared from March 1 st week and continued to appear till 2 nd week of April. Seedlings and saplings showed late bud opening, leafing and leaf fall compared to matured trees. Bud bursting was earlier at the disturbed sites ( Fig.1 and 2).

Rhododendron Arboreum
Flower bud bursting and flowering started from 1 st week of February (<5% trees had flowers). However, occasional trees started flowering from February 1 st week. Flowering peaked in 1 st week of April (>75% tree had flowered) and was completed by the end of May. New leaves appear after the completion of flowering from May 3 rd week and was completed by the end of rainy season. Leaf fall took place round the year but was maximum during the summer months (May-June). Seed dispersal started from February end and all the capsules had opened by mid-March. Leaf longevity of this species is more than 16 months ( Fig.1 and 2).  We compared the timing of phenological events of present study with the earlier studies of. 17,18 In S. robusta when we compared the timing of flowering initiation and completion with earlier studies, we do not find any significant shifts in timing of these phenological events. 17,18 There was no perceptible change in the initiation of leaf drop and leaf fall completion in comparison. 18 However, the period of leaf flushing has become small by approximately a month in comparison to earlier studies (Table 2). In M. phillippinensis the period of leafing has been reduced by approximately 4-6 week. The period of leaf drop and leaf flushing were similar to. 17 In P. roxburghii the time of flowering initiation has become earlier by 4-6 weeks. Similarly, commencement of needle drop was also earlier by 4-5 weeks in comparison to earlier studies ( Table 2). In M. esculenta the timing of flowering initiation and completion showed no change in comparison to earlier studies. Leaf flushing initiation was earlier by 4 weeks in both the years whereas leaf drop initiation was delayed by 2 week and completion was same incomparison to earlier studies ( Table 2). In Q. leucotrichophora there appear to be no major changes in the timing of flowering and new leaf flushing; however, the period of leaf drop has become extended by 2-3 weeks in comparison to earlier studies (Table 2). In R. arboreum it has reported flowering initiation in January extending up to April. 17 Earlier researcher has given more restricted period of flowering February-March for the species. 18 In our study flowering commenced from January II week and continued up to May II week in both the years showing more extended flowering period. The period of leaf drop also shows an extended period coupled with leaf flushing (Table 2).

Conclusion
It is apparent from the present study that due to climatic irregularities and temperaturerise the role of temperature would become paramount in controlling/ shifting of the phenological events. Many species shifted their flowering time across the worldwide. Global warming could be a primary cause for these changes some other factors also responsible for these changes such as precipitation pattern, soil and water stress, moisture condition and photo period that would be useful to better understand spatial patterns in the sensitivity of phenological responses to temperature. Microclimatic condition also responsible for controlling/shifting the phenological patterns of same or different species. Hence, more detailed investigations at the local level are required to examine the influence of these events in future studies.