Field Notes: Nature Conservation Foundation

Day 2

Location: Candura, Valparai | Long-Term Monitoring Plot (LEMoN Program), Nature Conservation Foundation (NCF)

In the evergreen rainforests of Candura, within the Valparai plateau, we joined researchers from NCF and NCBS as they quietly mapped the life of things that fall. Leaves, twigs, seeds, bark, what most of us might walk past without noticing, are meticulously gathered, sorted, weighed, and studied to understand how forests feed themselves.

Every two weeks, the team collects leaf litter using small traps spread across a one-hectare plot. And once every four months, they turn their attention to coarse woody debris, fallen logs and branches, which are harder to carry and even harder to measure, but just as important. These pieces are tracked, classified by how decomposed they are, and some are even hauled back to camp for further analysis.

All of this is part of a long-term monitoring effort to understand how organic matter cycles through the forest. It's careful, coordinated work, part science, part storytelling, where every fallen twig helps tell us something about the health, rhythm, and resilience of the rainforest.

At the monitoring site in Candura forest, trying out controls in the photomon app with the NCF team Gopana Nanda Kumar (Nandu), Project Coordinator and  K. Srinivasan (Srini), a Senior Project Manager

Leaf Litter Monitoring

Leaf litter is collected twice a month-every two weeks-to estimate the input of decomposing organic matter from the forest canopy. Within each one-hectare LEMoN plot, the team deploys 25 uniformly distributed leaf litter traps, each measuring 50 by 50 centimeters and pegged into place. These passive traps capture everything that falls from above: leaves, fruits, seeds, flowers, and twigs (specifically those smaller than 2 cm in diameter).

After collection, the contents are transported back to a base camp. There, the material is sorted by type-leaves, twigs, fruits, seeds, and flowers. Each category is first weighed in its fresh form, then dried and weighed again to calculate dry biomass. This helps quantify the volume and nature of plant material returning to the soil and forms the basis for understanding seasonal and spatial changes in forest nutrient cycles.

Coarse Woody Debris (CWD) Monitoring

In parallel, the team monitors CWD-larger fallen branches and logs that form a vital part of forest structure and nutrient turnover. CWD sampling is conducted once every four months, given the slower rate of accumulation and the physical effort involved.

To avoid disturbing the LEMoN plot itself, the researchers lay 100-meter transects just outside the plot’s boundaries, one on each side, at a distance of approximately two meters from the edge. These transects follow the plot’s square, 100m x 100m layout, which is itself divided into 100 ten-by-ten meter grid cells for spatial clarity.

As the team walks along these transects, they document all wood pieces with a diameter greater than 2 centimeters (measured at the point of decay, known as Diameter at Decay Height or DDH) that intersect the line. Each piece is measured for length and diameter, and assigned a decomposition class—BC-1 (least decayed), BC-2, or BC-3 (most decayed)-based on field protocols that evaluate texture, bark presence, and ease of breakage. While the decomposition classification is somewhat subjective, researchers make collective decisions and rely on field training to ensure consistency.

The research team segregating coarse wood debris along the transect, taking paper measurements in rain-wet notebooks.

When pieces are small enough to transport, they are cut into half-meter segments, sorted into up to 15 clearly labeled bags according to decomposition class and size. These are weighed using a hanging balance at the site. For each decomposition class, the team creates a pile and selects up to 30 representative samples (or fewer, if availability is limited) to take back to camp. There, the wood is cut into smaller sections, weighed again, dried, and measured for volume. This enables the calculation of wood density for each decay class.

These density figures are then used to extrapolate the biomass of larger logs that were recorded but not collected. By factoring in the frequency of tree species and distribution patterns, the team refines its biomass calculations, accounting for differences in wood density and decay rates across species and decomposition classes.

The first round of CWD sampling was the most laborious, involving setup of all transects and the processing of a large backlog of fallen wood. Since then, the volume of new debris has decreased, allowing the team to cover transects more quickly. Still, the work remains time-intensive: setting up transects, selecting and carrying logs to weighing stations, ensuring proper bagging, and managing high coordination demands across team members.

Accuracy matters. Both diameter and length are measured with a margin of error of plus or minus 0.05 cm. The process also demands seamless coordination, especially when managing the categorisation and bagging of dozens of wood samples across multiple decomposition categories. Despite training and field guides, decomposition classification can vary between observers, requiring team discussions and consensus calls in the field.

Each round of CWD monitoring provides a critical dataset to understand how deadwood decomposes and contributes to soil fertility, supporting fungi, insects, and other forest life. Combined with leaf litter data, it allows researchers to model nutrient flow and ecosystem health with a fine-grained understanding of seasonal dynamics and spatial distribution.

Together, these two methods, leaf litter collection and CWD monitoring, offer a robust picture of organic matter turnover in evergreen forest ecosystems. They help map how the forest sustains itself, how carbon is stored and cycled, and how natural decay processes underpin long-term ecological resilience.

A Forest Measured in Grids: Annual Tree Census

Within rainforests, trees that have survived centuries are silent witnesses to shifting climates, animal migrations, and human interventions. They store carbon, and lend crucial information on forest evolution, biomass accumulation, other forms of life, and the shifting dynamics of natural ecosystems over time. 

As part of the LeMoN initiative, old trees that have belonged to the forest for hundreds of years, are the subject of a rigorous study. This work may look tedious; measuring tree girths, setting up plots, tagging saplings, but each data point adds to a larger understanding of how forests grow, regenerate, and respond to all forms of stress.

A one hectare plot is divided into 100 grids of 10×10 meters, numbered in a zigzag pattern to ensure spatial continuity. Within these squares, every tree above a baseline girth of 10 cm (measured at breast height) is included in a tree census. A theodolite typically used in civil engineering for angular and leveling measurements is employed to establish accurate grid intersections. The use of such equipment mitigates the limitations associated with GPS-based technologies, which often suffer from signal issues in densely canopied environments. Even a five meter inaccuracy is an error margin substantial enough to compromise the ecological integrity of data. 

Each qualifying tree is assigned a unique identification code, coupled with its corresponding grid number, thereby enabling two dimensional referencing from plot-level to individual tree level. Tree species name is concurrently recorded to facilitate species-specific growth and mortality analyses. This indexing is essential for re-identification and ensures that measurements can be reliably replicated across survey years.

How the trees are measured 

Two points are marked on each tree for girth measurement: one, closer to the ground for annual censuses, another 20-30 centimeters higher fitted with dendrobands. These are metallic bands that record girth expansion every quarter. Height is tracked once every four years with a laser Rangefinder, which calculates height by projecting a laser beam from eye level to the apex of the tree. New recruits- trees that cross the 10 cm threshold are added each year, ensuring regeneration patterns are captured in the dataset.

This whole process relies on paper sheets carried into the field, where every entry, species name, girth, height is carefully logged manually under all weather conditions.

Experiment on Organic Materials for Weed Suppression

As part of an ongoing inquiry into sustainable and low-input methods of weed management, a small-scale field experiment is testing the potential of organic residues and waste by-products as mulching materials. The goal is to evaluate their ability to suppress weed regeneration, particularly of a persistent local species, Vadelia, without reliance on chemical herbicides or intensive manual labor.

This experiment does not end with  first observations. Its findings will rely on continuous monitoring of the 2 × 2 meter plots, tracking how Vadelia responds to each organic material over time. This site became the first station for field testing the photo-monitoring tool we built with NCF. 

Lessons from the Field 

We followed the NCF team on their monitoring routines to 3 recently restored sites in the Candura forest where saplings had just been planted and the first round of invasives  cleared. This is how it plays out on the field: Two people walk to each station which is usually marked with colored stone. The photographer stands at the stone, points the camera toward the forest and frames the shot. A second person stands in the camera’s field of vision as a frame of reference. The goal is to align the new image with a reference(ghost) image, the very first one captured at that station.

Over time, these photos are visually compared to track changes in canopy cover, understory, species diversity, and overall density of vegetation. Observations are made in relation to the human figure in the frame: the canopy rising above head height, deeper shade falling around the person (indicating denser growth), or invasive species visibly taller in comparison to the person These visual cues, simple yet telling, form the basis of photo monitoring and help distinguish positive change from setbacks.

As we tested the photomon app with K. Srinivasan (Srini), a Senior Project Manager at NCF, we discussed practical aspects such as aspect ratio and capturing images in both landscape and portrait modes. Since field staff often rely on familiarity with the terrain rather than maps or GPS points, displaying the  five closest monitoring stations on the app  could make their trip significantly more efficient. To minimize errors such as selecting the wrong station ID, particularly when different team members are involved in monitoring, the app could automatically suggest the correct station ID, either through GPS coordinates or by matching the selected ghost image.

In dense rainforest understory, aligning the live photo with the ghost image overlay is rarely straightforward. Trees shift, branches fall, the sky changes. Therefore alignment is anchored on the human figure in the ghost image. During monsoons, fast-growing weeds and shrubs can obscure stone landmarks, making it a game of hide and seek with the forest, where deception is high and visibility is low.

Alongside photo monitoring, sapling survival and growth are also tracked systematically. Sapling survival is recorded twice a year, with each sapling marked alive or dead. Over the past two to three years, survival has ranged from 60–80% in most Candura sites, though in some cases it has dropped to as low as 20%. Mortality is often linked to extended dry spells, browsing by animals, human disturbance, or broader climate variability. To strengthen these assessments, survival data is cross-checked with weather records from the base camp and with observations from camera traps, helping build a more complete picture of the ecological pressures at play.

On Losing Biomass and Big Trees Preservation

There’s fewer bigger trees than 20 years ago. All eyes point to climate change. But there are numerous hypotheses around what factors directly contribute to big tree mortality and if they can be controlled.

Big trees take between 100 and 200 years to grow. The biomass contained in one such tree is roughly equivalent to that of a thousand smaller ones. Losing it is not merely a numbers problem, it is a biomass problem.

Dr. T R Shankar Raman (Scientist, NCF) explained that losing even one or two large trees in a hectare represents a major setback in terms of both biomass and canopy cover. True restoration then must also include protecting the giants that took centuries to stand tall. 

In some parts of the world, trees survive for thousands of years, like the conifers of the White Mountains or the deodars of the Himalayas. Rainforests are more dynamic and rarely host such ancient individuals, but even here, large trees can live for 300–500 years. 

Drone Technology for Preservation

Drone technology is a useful method to identify and protect these trees. By measuring canopy extent and ground cover, drones can help quantify how much of a forest’s structure depends on its largest members.

While we can't control the larger impacts of climate change, we can begin to identify landscape-level vulnerabilities that make some areas more prone to tree loss. One hypothesis being explored is whether large trees closer to forest roads are more vulnerable in Valparai. These trees are often more exposed to sunlight, dry out more quickly, face higher temperatures, and during storms, experience stronger winds especially along open corridors. Validating these anecdotes and assumptions could inform local policy changes, like closing down the forest road to reduce risk. Such landscape insights through flying drones could make forests more resilient, even in the face of bigger changes.

Drones are proving to be valuable tools both for restoration and for studying forests. In restoration projects, they can track how the canopy expands over time, measure tree height, and assess the extent of ground cover by monitoring canopy closure.  This simple metric becomes a powerful signal of progress, pointing to healthy growth and recovery in restored sites. 

Beyond restoration, drones also help researchers detect the effects of climate change, examine whether large trees are disproportionately affected compared to smaller ones, and estimate crown damage with greater accuracy and consistency. In the Amazon, researchers have established temperature thresholds for hundreds of tree species. Beyond a certain point, the leaves essentially cook in the sun, stopping photosynthesis and eventually the plant’s death. When these observations are combined with climate data, they provide critical insights into the drivers of change and offer direction for conservation strategies. This kind of  monitoring is highly intensive, but with robust data pipelines to collect and process the information, it can become a repeatable annual exercise.

Elephant and Invasive Interactions

Tea swamps play a crucial role for elephants, gaur, and many other wildlife species moving through Valparai, which is dominated by tea plantations covering about 80% of the area.

Elephant sighting with Ganesh Raghunathan, Senior Programme Manager, NCF

Ludwigia peruviana, an invasive plant with small yellow flowers, has been rapidly spreading in these swamps over the last decade, choking them completely. And it's possible that the places they are spreading more, are also increased hotspots of conflict with elephants, because they are losing forage. This hypothesis has not yet been tested, largely because the complexity of Valparai’s landscape  makes manual mapping impractical.

By mapping invasive species and identifying high-density patches, drones could guide targeted removal efforts. Today, drone applications in Valparai focus mainly on preserving tea foliage, with little attention to swamp health or its role in wildlife movement.

Together, these approaches point toward a new way of understanding and caring for forests. From testing new tools to observing ecological studies firsthand, Day 2 underscored the value of combining technology, design thinking, and field rigour when building tools for conservation.