Comparing Conifers and Deciduous Trees | Botanical …
Temperature, light, and water supply have an influence on the degree and the duration of fall color. Low temperatures above freezing will favor anthocyanin formation producing bright reds in maples. However, early frost will weaken the brilliant red color. Rainy and/or overcast days tend to increase the intensity of fall colors. The best time to enjoy the autumn color would be on a clear, dry, and cool (not freezing) day.
Comparing Conifers and Deciduous Trees ..
Globally, patterns of primary productivity vary both spatially and temporally. The least productive ecosystems are those limited by and water like the deserts and the polar tundra. The most productive ecosystems are systems with high temperatures, plenty of water and lots of available soil nitrogen. Table 9l-1 describes the approximate average net primary productivity for a variety of ecosystem types.
Seasonal patterns of photosynthesis and respiration of single leaves of four understory perennial herbs in deciduous forests were investigated in relation to their leaf growth and light conditions on the forest floor. Anemone flaccida shows rapid growth of leaf area and high rates of gross photosynthesis at light saturation (Psat) in its early stage of development. Its photosynthetic activity is restricted to a brief period of high light intensity before the closure of overstory canopies. Disporum smilacinum possesses light-photosynthesis curves of the shade-leaf type throughout its whole growing period. A shading experiment has shown that this plant is low-light adapted and can utilize weak light efficiently. The light-photosynthesis curve of Syneilesis palmata shifts from the sun-leaf type to the shade-leaf type in response to the seasonal change of light regime on the forest floor. Evergreen leaves of Pyrola japonica have three year longevity, and light-photosynthesis curves of the shade-leaf type. They maintain some photosynthetic activity even in late autumn and winter.
21.12.2017 · Some Temperate Forest conifers ..
Now, another perspective. I originally wrote this post in the Pacific Northwest, a region noted for trees that are green all year round. Many trees, however, are not evergreen; they are deciduous. As you can see in this photograph from my winter home in Minnesota, they drop their leaves during the winter and go for several months at a stretch without any possibility of photosynthesis. How do deciduous trees and bushes get the energy they need to maintain life during the winter? Just as they do on a summer’s night. When their leaves are gone, deciduous trees rely on cellular respiration, disassembling the reserves of sugar (mainly in the form of starch stored in the roots) that they accumulated during the bright days of the year. They use this stored energy to drive all the diverse processes of life. A bear stores fat for the winter, a plant stores starch. And, as we will see in another post, in really cold weather both of them can reduce their demands for metabolic energy, and thus for food, dramatically.
The Temperate Deciduous Forest Food Web ..
While its trees have their leaves, a deciduous forest, like an evergreen forest, reverses its breath on a daily cycle. During the day, while photosynthesis works faster than does cellular respiration, a deciduous forest primarily breathes in carbon dioxide and exhales oxygen. During the night, when photosynthesis stops but cellular respiration continues unabated (not only in green plants but also in the myriad other organisms that compose the forest ecosystem), the forest breathes in oxygen and exhales carbon dioxide. Once the leaves are gone, however, it only breathes in oxygen. At that point, it no longer matters whether it’s day or night—the trees respire without photosynthesizing. They always take in oxygen and release carbon dioxide, just like you and I do.
Seasonality of temperate forest photosynthesis and …
To examine a possible convergence in leaf photosynthetic characteristics and leaf display responses to light environment in seedlings of three canopy and two shrub tree species in understorey of cool-temperate deciduous broadleaf forest, relationships between light environment, leaf orientation and leaf light-photosynthetic response were measured. Light capture of the seedlings (17-24 individuals with 2-12 leaves for each species) was assessed with a three dimensional geometric modeling program Y-plant. Leaf photosynthetic characteristics of the five species were found to have acclimated to the understorey light environment, i.e., low light compensation point and high apparent quantum yield. In addition, light-saturated photosynthetic rates were higher in seedlings inhabiting microsites with higher light availability. Efficiencies of light capture and carbon gain of the leaf display were evaluated by simulating the directionalities of light capture and daily photosynthesis for each seedling using hemispherical canopy photography. The results showed that most of the seedlings orientated their leaves in a way to increase the daily photosynthesis during the direct light periods (sunflecks) rather than maximize daily photosynthesis by diffuse light. Simulations also showed that daily photosynthesis would increase only 10% of that on actual leaf display when the leaves orientated to maximize the diffuse light interception. Simulations in which leaf orientations were varied showed that when the leaf display fully maximized direct light interception, the time that leaves were exposed to excessive photon flux density of >800 μmol photons m-2 s-1 were doubled. The understorey seedlings studied responded to the given light environments in a way to maximize the efficiency of acquisition and use of light during their short (approximately 3 month) seasonal growth period.