Influence of Human Pressure on Forest Resources and Productivity at Stand and Tree Scales: The Case Study of Yunnan Pine in SW China.

This paper examines human impact on stands and individual trees of growing near the small mountain villages of Pianshui and Yangjuan in southwestern Sichuan Province, China. In an effort to assess whether use of these forests was sustainable, we examined the effects of human use in two ways. First, we directly measured the effect of cutting branches, for fuel and fodder, on tree growth.

Is the Returning Farmland to Forest Program a Success? Three Case Studies from Sichuan.

China's or "Returning Farmland to Forest" (RFFP) program has been widely praised as the world's largest and most successful payment for ecosystem services program, as well as a major contributor to China's dramatic increase in forest cover from perhaps as low as 8% in 1960 to about 21% today. By compensating rural households for the conversion of marginal farmland to forestland and financing the afforestation of barren mountainsides, the program, in addition to expanding forestland, aims to reduce soil erosion and alleviate poverty. This paper presents qualitative and quantitative studies conducted on the local implementation of RFFP in three diverse townships in Sichuan.

Defining how aging Pseudotsuga and Abies compensate for multiple stresses through multi-criteria assessment of a functional-structural model.

Many hypotheses have been advanced about factors that control tree longevity. We use a simulation model with multi-criteria optimization and Pareto optimality to determine branch morphologies in the Pinaceae that minimize the effect of growth limitations due to water stress while simultaneously maximizing carbohydrate gain. Two distinct branch morphologies in the Pareto optimal space resemble Pseudotsuga menziesii (Mirb.

Actual and potential transpiration and carbon assimilation in an irrigated poplar plantation.

We examined the tradeoffs between stand-level water use and carbon uptake that result when biomass production of trees in plantations is maximized by removing nutrient and water limitations. A Populus trichocarpa Torr. x P.

Tree water storage and its diurnal dynamics related to sap flow and changes in stem volume in old-growth Douglas-fir trees.

Diurnal and seasonal tree water storage was studied in three large Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees at the Wind River Canopy Crane Research site. Changes in water storage were based on measurements of sap flow and changes in stem volume and tissue water content at different heights in the stem and branches.

Boundary layer conductance, leaf temperature and transpiration of Abies amabilis branches.

We used three methods to measure boundary layer conductance to heat transfer (g(bH)) and water vapor transfer (g(bV)) in foliated branches of Abies amabilis Dougl. ex J. Forbes, a subalpine forest tree that produces clumped shoot morphology on sun-formed branches.

Variation in specific needle area of old-growth Douglas-fir in relation to needle age, within-crown position and epicormic shoot production.

Variation in specific needle area (SNA; cm2 projected fresh needle area g-1 oven-dried needle weight) was investigated in relation to needle age, within-crown position and epicormic shoot production in 450-year-old Douglas-fir (Pseudotsuga menziesii Mirb. (Franco) var. menziesii) trees.

The effects of light acclimation during and after foliage expansion on photosynthesis ofAbies amabilis foliage within the canopy.

Variation in the photosynthetic function ofAbies amabilis foliage within a canopy was examined and related to three different processes that affect foliage function: foliage aging, sun-shade acclimation that occurred while foliage was expanding, and reacclimation after expansion was complete. Foliage produced in the sun had higher photosynthesis at light saturation (A , μmol·m·s), dark respiration (μmol·m·s), nitrogen content (g·m), chlorophyll content (g·m), and chlorophylla:b ratio, and a lower chlorophyll to nitrogen ratio (chl:N), than foliage produced in the shade. As sun foliage becomes shaded, it becomes physiologically similar to shade foliage, even though it still retains a sun morphology.

Models of water flux through forest stands: critical leaf and stand parameters.

The basis for estimating water flux through forest stands is described using models. By means of the Penman-Monteith equation, transpiration is described in relation to the degree of coupling between the canopy and the surrounding air. Models of canopy and aerodynamic conductance are available, but more mechanistic models of stomatal conductance, and further development of turbulence theory, are needed along with improved estimates of leaf area index, leaf area distribution, and seasonal dynamics.