The Importance Of Mapping Forest Resources

Purabi Saikia, an associate professor with the Department of Botany at Banaras Hindu University, is one of 18 scientists to win the Vigyan Yuva-Shanti Swarup Bhatnagar – a government honour recognising young scientists under the age of 45 who have made “exceptional contributions” to their field of study. A total of 33 scientists were awarded the Rashtriya Vigyan Puraskar – a national award recognising the contributions of outstanding researchers in the fields of science, technology and innovation – under various categories.

A plant ecologist by specialisation, Saikia’s range of study is wide – from making assessments in plant diversity and composition to devising ecosystem-based disaster risk reduction strategies. Before joining Banaras Hindu University earlier this year, Saikia spent 12 years at the Central University of Jharkhand, teaching with the Department of Environmental Sciences.

Saikia was conferred with the Vigyan Yuva-Shanti Swarup Bhatnagar award, a category of the Rashtriya Vigyan Puraskar, on August 22 by the President. According to the award citation, her research publications “have potential for field applications and are also important as scientific evidence for policy planning.” Saikia spoke to Mongabay India about the importance of mapping forest resources and long-term monitoring of ecosystems. Edited excerpts below:

Mongabay: What research questions motivate and interest you?

Purabi Saikia: After completing my M.Sc. in botany from Guwahati University in Assam, where I specialised in plant ecology, I joined the lab of Professor M.L. Khan at the North Eastern Regional Institute of Science and Technology. There, I did my Ph.D. in forestry, with a specialisation in forest ecology.

After I joined Dr. Khan’s lab in 2007, I was offered the role of a senior research fellow in a research project sponsored by the Department of Biotechnology, which was about mapping plant resources and doing their quantitative assessment in northeast India. The project concerned all eight states in northeast India, but I worked with Dr. Khan in Arunachal Pradesh.

Being a part of this project was a turning point in my life. I was one of two women in my Ph.D. cohort and the only woman working on this project. Till I worked with Dr. Khan, teachers would not let the women participate in field studies, because the perception was that fieldwork was not for women. But Dr. Khan had a different mentality and he encouraged me a lot.

It’s during my Ph.D. that I became very interested in mapping forest resources and I was able to identify more than 350 species in the study area in Arunachal Pradesh. The kind of exposure I got through this project made me want to do more in this field.

Mongabay: What’s the significance of mapping forest resources, and how can it inform decision-making when it comes to land use?

Purabi Saikia: In my research, I design a plot for study, go into the forest, and identify individual species and their numbers. I also check the circumference or the girth of a tree 1.75 metres above the ground, which helps determine its age.

There are times when you find a species has a large number of old and mature trees, but not many saplings or seedlings. If the circumference of the tree’s trunk is big, it means the tree is old. If the tree is approaching the end of its lifecycle, and it dies in the next 10 to 15 years, how will it maintain its representation in a certain area without seedlings and saplings? The lack of seedlings and saplings means there’s a certain constraint in regeneration. There may be some condition which is not allowing the seed to germinate, or maybe pollinators are not reaching the area. It could be for a variety of reasons. One important aspect of this type of study is understanding the regeneration potential of existing plant and tree species in a certain area.

Plants are the basis of life, and they’re the only species that can recycle carbon dioxide to use them in photosynthesis. But not every plant species is equally good at capturing carbon dioxide for photosynthesis. Around 13% of tree species make up a majority of carbon dioxide in carbon sinks. If those 13% are lost over time, then what will happen? It’s important to locate these species, identify the distribution, and understand what the suitable habitats are to do more advanced research. Knowledge of forest resources can also help prioritise which species to include in plantations, such as in a botanical garden. That priority can be set based on this quantitative assessment.

Every plant species has a different ability to withstand environmental stress, and some of the recent PhD research which I am supervising identifies tree species which can optimise air pollution. We found 12 predominant, commonly-occurring tree species and ranked them according to their ability to trap air pollution, which can help with urban planning.

Mongabay: A lot of your work relies on remote sensing. How is remote sensing helping us understand forest composition and ecologies better? What are its limitations and how can errors be avoided?

Purabi Saikia: In hilly terrains, where there are 90-degree slopes, it’s not always possible to go and collect data of vegetation present, and remote sensing can help capture that information. It’s possible to interpret the image and determine the composition of the vegetation.

Using topographical sheets to identify a location and then go into the forest is a very difficult task, and remote sensing through satellite data can give you that precise information and location in real time. Ground truthing is expensive, involves a lot of human labour, and is also prone to error.

There are limitations to remote sensing too. Remote sensing uses optical data which is colour coded. In classical optical remote sensing, vegetation is represented by red colour and the red colour captures the concentration of chlorophyll. Since the image is reflecting concentrations of chlorophyll, sometimes it is difficult to tell if it is agriculture, tea garden, plantations, or a forest. It can only give you a sense of green cover.

But remote sensing has advanced a lot. ISRO and NASA are collaborating and have recently launched a joint mission on Synthetic Aperture Radar remote sensing, which uses microwaves to detect physical properties. I was also part of a mission on hyperspectral remote sensing, which using multiple spectra to generate an image.

Remote sensing is a new field and advancements are ongoing. When optical remote sensing is unable to provide the desired information, we sometimes combine it with other remote sensing methods, like hyperspectral or microwave, to get more detailed information.

Mongabay: Emerging research shows that climate change is negatively affecting the carbon sequestration and storage potential of forests. What have you observed in your own research about the changes forest ecosystems are undergoing due to climate change?

Purabi Saikia: My research does not specialise in the impacts of climate change, but while I was doing my Ph.D. in Aquilaria malaccensis, I noticed some changes. Every plant species produces a seed once in a year, with flowering occurring at a single time. Each plant and tree has its own flowering season and everything from when new leaves will grow to when the plant will mature is fixed in its lifecycle. This is based on the seasons.

Every plant has different nutritional needs. Sal leaves are small compared to leaves from teak trees, and teak trees need more water to give new leaves. When there’s a little rainfall and moisture in the soil, sal leaves can start to grow, even in February. Teak, on the other hand, will wait for the onset of the monsoon because it needs more water.

When doing my Ph.D. research, I observed that some plants were flowering in two seasons. That means the plant is finding suitable conditions to flower twice in a year, once in March and again in September. But March and September are totally different seasons, and the plant’s behaviour is a symptom of climatic changes that are occurring. These phenological changes are one of the indicators of climate change.

I’ve also done studies in high altitudes where some changes have become apparent. Tropical, subtropical, temperate and alpine zones have different climatic conditions. Beyond a certain altitude, called the timberline, you won’t find large trees as you do in lower altitudes. In alpine zones, it’s a constraining environment so plant and tree growth are stunted, and we prefer to refer to this growth as vegetation, not forest. What we’re observing is that due to changes in rainfall and temperature, these zones are shifting. Tropical zones are invading sub-tropical zones, sub-tropical zones are invading temperate zones and so on.

But the alpine zone cannot travel any higher. What will happen to the species existing above the timberline when its territory is being appropriated? We are seeing that these species are disappearing because of these changes.

Mongabay: Another focus area of yours is Long Term Ecological Monitoring. What are the challenges in carrying out this type of research?

Purabi Saikia: I’m part of the Long Term Ecological Monitoring Observatory (LTEO) programme under by the Ministry of Environment, Forests and Climate Change, which is being led by Dr R. Sukumar of the Indian Institute of Science (Bengaluru).

LTEO is a very difficult task. In a country where a majority of the population depends on agriculture and forest resources for their livelihood, there cannot be a forest that is completely devoid of human intervention. When there’s a high dependency on forest resources, finding an undisturbed area for long-term monitoring of 30 or 40 years can be difficult. Even forest departments don’t have the capacity to guard these areas continuously, especially when there are other pressing issues like poaching and illegal wildlife trade happening. It’s also difficult to find funding for these projects.

This project is going on in each ecozone of India, and the project was allotted Rs. 374 lakhs. Though it sounds like a large number, divided by all the groups it amounts to little compared to the expenditure involved. While long term monitoring is common globally, it’s still very new in India.

Fortunately, Dr. Sukumar chose our group to conduct long term monitoring of forests in the Central and Eastern Himalayan ecozones. In this project, we’re looking at what microclimatic changes are occurring in a given plot, using a wide variety of tools, including weather stations, to track this information. In the Eastern Himalayan zone, we are identifying a plot at an altitudinal gradient, while in central India we have found a sal and teak ecotone zone, which is a transitional zone between two ranges.

The type of monitoring includes observing weather conditions, making observations about each shrub and tree species, recording every stage of growth and generally tracking all components needed to understand forest dynamics.

(Published under Creative Commons from Mongabay-India. Read the original article here)