Warming alarmists see no good coming out of rising CO2 and the current climate optimum, and their warnings extend to forests as well. So in love with their theory of global warming, they cannot see the forests as they are, and as documented in numerous research studies.

Claim: Forest growth is diminished by higher CO2 and warmer summers.

Fact: CO2 increases have improved forest health.

Claim: Forest areas will be hard-hit by future droughts.

Fact: No trend in droughts is discernible.

Claim: Warmer temperatures increase damage from pests and pathogens.

Fact: Enhanced CO2 is making forests more resilient to diseases and infestations.

Claim: Old growth forests will not sequester CO2 as young forests do.

Fact: Rising CO2 has given new life even to aging forests.

Basic Vegetation Biology (from Bill Illis here)

Almost ALL C3 pathway vegetation (trees, bushes, wheat, rice and 95% of all plants) are CO2-starved except in extremely high rainfall environments like tropical rain-forests. They need to keep their CO2-absorbing stomata more open to get the CO2 they need but this also leads to more loss of water through evapotranspiration.

As rainfall gets lower and lower, the 95% of plants that are C3 suffer more and more until they cannot even grow anymore. In low rainfall and low CO2, these plants are done, and the C4 pathway grasses take over. The C4 grasses are more efficient at absorbing CO2 so do not require as much rainfall. Even 10 inches per year is enough.

But take anywhere on the planet where grasses are dominant, it is because rainfall is too low for trees and bushes, combined with CO2 being too low.

Now ramp-up CO2 and the trees do better in these regions. In fact, they do better absolutely everywhere. Now ramp-up precipitation as well, as should happen in a warmer world, and we have forests everywhere and they grow better everywhere.

Go back to the little ice age, when temperatures were lower and precipitation was lower and CO2 was lower, all plants grew at a lower rate and C3 crops like vegetables, wheat and rice probably failed regularly and people died of starvation.

In the ice ages, when all these numbers were even far lower, our ancestors lived off the grassland herbivores because there were no trees or bushes and no fruit, nuts, wheat, or berries to be found. But there were lots of grass-eating herbivores like the Auroch which was the ancestor of today’s cattle. Our ice age ancestors were mainly meat-eaters.

Forests are Increasingly Healthy

Physiological and ecological factors influencing recent trends in United States forest health responses to climate change

Craig Loehle, Craig Idso, T. Bently Wigley

Highlights

• We review information on US forest health in response to climate change.

• We found that trees are tolerant of rising temperatures and have responded to rising carbon dioxide.

• No long-term trends in US drought have been found in the literature.

• CO2 tends to inhibit forest pests and pathogens.

• Projections of forest response to climate change are highly variable.

Abstract:

The health of United States forests is of concern for biodiversity conservation, ecosystem services, forest commercial values, and other reasons. Climate change, rising concentrations of CO2 and some pollutants could plausibly have affected forest health and growth rates over the past 150 years and may affect forests in the future. Multiple factors must be considered when assessing present and future forest health. Factors undergoing change include temperature, precipitation (including flood and drought), CO2 concentration, N deposition, and air pollutants. Secondary effects include alteration of pest and pathogen dynamics by climate change.

We provide a review of these factors as they relate to forest health and climate change. We find that plants can shift their optimum temperature for photosynthesis, especially in the presence of elevated CO2, which also increases plant productivity. No clear national trend to date has been reported for flood or drought or their effects on forests except for a current drought in the US Southwest. Additionally, elevated CO2 increases water use efficiency and protects plants from drought. Pollutants can reduce plant growth but concentrations of major pollutants such as ozone have declined modestly. Ozone damage in particular is lessened by rising CO2. No clear trend has been reported for pathogen or insect damage but experiments suggest that in many cases rising CO2 enhances plant resistance to both agents.

There is strong evidence from the United States and globally that forest growth has been increasing over recent decades to the past 100+ years. Future prospects for forests are not clear because different models produce divergent forecasts. However, forest growth models that incorporate more realistic physiological responses to rising CO2 are more likely to show future enhanced growth. Overall, our review suggests that United States forest health has improved over recent decades and is not likely to be impaired in at least the next few decades.

Carbon Sequestration

On the specific issue of aging forests losing their ability to absorb CO2, extensive research is reviewed at CO2 Science (here)

As important as are these facts about trees, however, there’s an even more important fact that comes into play in the case of forests and their ability to sequester carbon over long periods of time. This little-acknowledged piece of information is the fact that it is the forest itself – conceptualized as a huge super-organism, if you will – that is the unit of primary importance when it comes to determining the ultimate amount of carbon that can be sequestered on a unit area of land. And it when it comes to elucidating this concept, it seems that a lot of climate alarmists and political opportunists can’t seem to see the forest for the trees that comprise it.

That this difference in perspective can have enormous consequences was demonstrated quite clearly by Cary et al. (2001), who noted that most models of forest carbon sequestration wrongly assume that “age-related growth trends of individual trees and even-aged, monospecific stands can be extended to natural forests.” When they compared the predictions of such models against real-world data gathered from northern Rocky Mountain subalpine forests that ranged in age from 67 to 458 years, for example, they found that aboveground net primary productivity in 200-year-old natural stands was almost twice as great as that of modeled stands, and that the difference between the two increased linearly throughout the entire sampled age range.

The answer is rather simple. For any tree of age 250 years or more, the greater portion of its life (at least two-thirds of it) was spent in an atmosphere of much-reduced CO2 content. Up until 1920, for example, the air’s CO2 concentration had never been above 300 ppm throughout the entire lives of such trees, whereas it is currently 400 ppm or 33% higher. And for older trees, even greater portions of their lives were spent in air of even lower CO2 concentration. Hence, the “intervention” that has given new life to old trees and allows them to “live long and prosper,” would appear to be the aerial fertilization effect produced by the flooding of the air with the CO2 that resulted from the Industrial Revolution and that is currently being maintained by its ever-expanding aftermath (Idso, 1995).

Based on these many observations, as well as the results of the study of Greenep et al. (2003) – which strongly suggested, in their words, that “the capacity for enhanced photosynthesis in trees growing in elevated CO2 is unlikely to be lost in subsequent generations” – it would appear that earth’s forests will remain strong sinks for atmospheric carbon far beyond the date at which the world’s climate alarmists have proclaimed they would have given back to the atmosphere most of the carbon they had removed from it over their existence to that point in time. And subsequent reports have validated this assessment.

Summary

No doubt that forests are threatened by the human race, but it has nothing to do with CO2, which trees love. Urban and agricultural encroachments can and do cause loss of forest habitats. Pests and pathogens come and go in cycles, and their impacts can be mitigated by proper forest management.

The 2015 Global Forest Resources Assessment was encouraged by the reduced rate of deforestation and the increasing quality and extent of forest management practices in many countries.

Too bad so much effort and funding is wasted on IPCC circuses.

Footnote:

For More on the Link between Forests and Precipitation see Here Comes the Rain Again