Canopy Research in Nepal Himalayas: Opportunities and Challenges

Despite a rapidly expanding interdisciplinary field worldwide, forest canopies of Nepal Himalayas are yet to be explored and the national conservation strategy still has to recognize the importance to identify it as an essential domain of canopy dwelling animals and plants. In the last few decades canopy science has emerged as a new discipline with more interdisciplinary and large-scale research possibilities are coming including canopy-atmosphere interactions, structural and functional aspects of canopy on biodiversity are a few among them. Canopies are important in supporting high terrestrial diversity and providing goods and services. Diverse rural mountain societies not only depend on goods and services provided by canopy but it also provides opportunities to explore sustainable use of resources for local livelihood generation. New frontiers of forest canopy research can also provide inputs to understand the potential impacts of climate change on the changing availability of goods and services affecting rural communities of Nepal. Yet, it still remains one of the unexplored and overlooked areas in the biodiversity sector of Nepal. Here, the opportunities of canopy research in Nepal Himalayas and various challenges associated with this are reviewed.

Canopy Architecture and Cuvette Flow Patterns Influence Whole-canopy Net CO2 Exchange and Temperature in Sweet Cherry

To initiate photosynthetic studies of sweet cherry (Prunus avium L.) canopy architectures and cropping management under high light and temperature conditions (Yakima Valley, Wash.), we developed a whole-canopy research cuvette system with a variable airflow plenum that allowed different patterns of air delivery (in concentric circles around the trunk) into the cuvette. Air and leaf temperatures (Tair and Tleaf, respectively) were determined at four horizontal planes and four directional quadrants inside cuvette-enclosed canopies trained to a multiple leader/open-bush or a multiple leader/trellised palmette architecture. Air flow rate, air delivery pattern, and canopy architecture each influenced the whole-canopy temperature profile and net CO2 exchange rate (NCER) estimates based on CO2 differentials (inlet-outlet). In general, Tair and Tleaf were warmer (≈0 to 4 °C) in the palmette canopy and were negatively correlated with flow rate. The response of Tair and Tleaf to flow rate varied with canopy position and air delivery pattern. At a flow of 40 kL·min-1 (≈2 cuvette volume exchanges/min), mean Tair and Tleaf values were 2 to 3 °C warmer than ambient air temperature, and CO2 differentials were 15-20 μL·L-1. Tair and Tleaf were warmer than those in unenclosed canopies and increased with height in the canopy. Carbon differentials declined with increasing flow rate, and were greater in the palmette canopy and with a less dispersed (centralized) delivery. Dispersing inlet air delivery produced more consistent values of Tair and Tleaf in different canopy architectures. Such systematic factors must be taken into account when designing studies to compare the effects of tree architecture on whole-canopy photosynthesis.