Is a tree in a forest the same as one outside it? The belief that it is,allays the con-science of government backed afforestation programmes where dense forests are often razed for mines,and multiple saplings are commissioned in alternate locations that are usually outside forest boundaries.
conservation have on the other hand painted out that this isn't the same because a loss of section of forest means destroying an ecosystem that can't be easily substituted for. To account for these losses more minutely, lucy hutyra, a bio geochemist and ecologist at the boston university, massachusetts, U.S., has been analyzing the terrestrial carbon sink.
Storehouses of carbon
This is made up of the billoins of square kilometers of forest in the world that are major storehouses of carbon. In net, forests store more carbondioxide than they release and an estimated 30% of carbon emissions from emitting fossil fuels are observed by the forest, making them a terrestrial carbon sink.
Trees absorb carbon-dioxide(CO2), release oxygen by way of photo synthesis, and store carbon in their trunks. When they shed, soil microbes work to decompose the leaves and other organic matter that releases the trapped carbon-dioxide. A major prong of countries climate change strategy, including India's is to increase the terrestrial sink area.
Consequence of loss
Hutyra, who has been researching the consequences of forest loss, examined if the same species of tree had different patterns of carbon-dioxide storage when located at the forest edge or further away.
The text book assumption was that trees at the forest edges release and store carbon at similar rates as forest interiors, but hutyra and her colleagues report this isn't true.
In two paper published in the peer reviewed global change biology,and nature communications, hutyra's team found edge trees grew faster than their country cousins deep in the forest, and the soil in urban areas can hoard more carbon dioxide than previously thought.
Differential growth
Using data from the U.S. Department of agriculture's forest Inventory and analysis program - which monitor tree size , growth, and land use across the country-Hutyra's team looked at more than 48000 forest plots in northeast united states. They found trees on the edges grow nearly twice as fast as interior trees- those roughly 100 feet away from the edge.
"This is likely because the trees on the edge don't have competition with interior forest, so they get more light," says Luca Morreale, a PhD candidate in hutyra's Lab, in a press statement
Solid behavior
In another related study, Hutyra found differences even in the way soil in forest and outside released carbon dioxide. Warmer temperature at the edge of the forest caused leaves and organic matter to decompose faster, as it forced soil microorganisms to work harder and release more carbon dioxide than their cooler, more shaded peers in the forest interior. But in urban forests, where the ground was significantly hotter and drier, those soils stopped releasing as much carbon, they note in a press statement from Boston University.
Those these studies were specific to Massachusetts. There are implications for India too. Conservationist have noted that the plantation outside forest don't capture carbon efficiently and don't make up for biodiversity losses.
Indian context
The India state of forest Report(2021) released in January found that nearly 28% of the forest cover is outside the recorded forest area. About 12% of the forest classified as 'very dense' is also outside the recorded areas. Following a trend and noted in previous editions of the forest surveys, the increase in fore
st cover between 2019 and 2021 we led by growth outside the recorded area and the sharpest increase was in so called 'open forest' where any patch over a hectare and having a canopy density more than 10% count as 'forest'. This brings in man-made plantations of cash crops such as tea and coffee plantation and man go orchards and even tree lined avenues in densely build-up cities were being classified as 'forest'.
Role of plantations
Ecologists M.Madhusudan and T.R. Shankar raman note: " In one stroke, just between the 1999 AND THE 2001, This redefinition helped raise India's forest cover by over 38000 sq.km. They highlight research in the western ghats that finds plantation deplete ground water, have higher surface water runoff, poorer to trees in natural forest. They also report that carbon stocks in plantations such as teak and eucalyptus were 30% to 50% lower than in natural evergreen forests and were generally less stable and resilient. The biggest loss, however, was the species dependent on forest from insects to primates were ripped apart from their natural habitats and plantations, which were mostly mono cultures, rarely had the capacity to support a rich, bio diverse system
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