Estimate of Leaf Area Index in an Old-Growth Mixed Broadleaved-Korean Pine Forest in Northeastern China

Leaf area index (LAI) is an important variable in the study of forest ecosystem processes, but very few studies are designed to monitor LAI and the seasonal variability in a mixed forest using non-destructive sampling. In this study, first, true LAI from May 1st and November 15th was estimated by making several calibrations to LAI as measured from the WinSCANOPY 2006 Plant Canopy Analyzer. These calibrations include a foliage element (shoot, that is considered to be a collection of needles) clumping index measured directly from the optical instrument, TRAC (Tracing Radiation and Architecture of Canopies); a needle-to-shoot area ratio obtained from shoot samples; and a woody-to-total area ratio. Second, by periodically combining true LAI (May 1st) with the seasonality of LAI for deciduous and coniferous species throughout the leaf-expansion season (from May to August), we estimated LAI of each investigation period in the leaf-expansion season. Third, by combining true LAI (November 15th) with litter trap data (both deciduous and coniferous species), we estimated LAI of each investigation period during the leaf-fall season (from September to mid-November). Finally, LAI for the entire canopy then was derived from the initial leaf expansion to the leaf fall. The results showed that LAI reached its peak with a value of 6.53 m2 m−2 (a corresponding value of 3.83 m2 m−2 from optical instrument) in early August, and the mean LAI was 4.97 m2 m−2 from May to November using the proposed method. The optical instrument method underestimated LAI by an average of 41.64% (SD = 6.54) throughout the whole study period compared to that estimated by the proposed method. The result of the present work implied that our method would be suitable for measuring LAI, for detecting the seasonality of LAI in a mixed forest, and for measuring LAI seasonality for each species

Spatial and temporal dimensions of landscape fragmentation across the Brazilian Amazon

The Brazilian Amazon in the past decades has been suffering severe landscape alteration, mainly due to anthropogenic activities, such as road building and land clearing for agriculture. Using a high-resolution time series of land cover maps (classified as mature forest, non-forest, secondary forest) spanning from 1984 through 2011, and four uncorrelated fragmentation metrics (edge density, clumpiness index, area-weighted mean patch size and shape index), we examined the temporal and spatial dynamics of forest fragmentation in three study areas across the Brazilian Amazon (Manaus, Santarém and Machadinho d’Oeste), inside and outside conservation units. Moreover, we compared the impacts on the landscape of: (1) different land uses (e.g. cattle ranching, crop production), (2) occupation processes (spontaneous vs. planned settlements) and (3) implementation of conservation units. By 2010/2011, municipalities located along the Arc of Deforestation had more than 55% of the remaining mature forest strictly confined to conservation units. Further, the planned settlement showed a higher rate of forest loss, a more persistent increase in deforested areas and a higher relative incidence of deforestation inside conservation units. Distinct agricultural activities did not lead to significantly different landscape structures; the accessibility of the municipality showed greater influence in the degree of degradation of the landscapes. Even with a high proportion of the landscapes covered by conservation units, which showed a strong inhibitory effect on forest fragmentation, we show that dynamic agriculturally driven economic activities, in municipalities with extensive road development, led to more regularly shaped, heavily fragmented landscapes, with higher densities of forest edge

CUTICULAR WATER PERMEANCE OF EUROPEAN TREES AND SHRUBS GROWN IN POLLUTED AND UNPOLLUTED ATMOSPHERES, AND ITS RELATION TO STOMATAL RESPONSE TO HUMIDITY IN BEECH (FAGUS-SYLVATICA L)

Cuticular water permeance (P) of astomatous adaxial surfaces of intact leaves was determined in Acer pseudoplatanus L., Betula pubescens Ehrh., Corylus avellana L., Fagus sylvatica L. and Prunus avium L. Water evaporating from the stomata-bearing abaxial leaf surface could not reach the moisture analyzer and the values of P presented here are therefore free from errors that often arise from unintentional inclusion of residual stomatal transpiration. Plants were exposed from before bud-break for several months to 20-50 ppb SO2 (Fagus), a combination of 50-60 ppb SO2 and 50-60 ppb NO2 (Betula), 300-400 ppb NO (Acer, Corylus, Fagus), regular ozone episodes of up to 120 ppb (Fagus, Prunus), or an elevated level of CO2 (600 ppm for 2 yr; Acer, Fagus). Permeances were in the range 0.6-2.9 x 10(-5) m s-1 and were unaffected by most treatments. In Prunus, P increased slightly but significantly in the NO treatment. In Corylus and Fagus, P was sometimes found to be reduced by fumigation with NO, but not always. Betula leaves grown under elevated SO2 and NO2 showed higher values of P only if they were visibly damaged. Minimum conductances (g(min) estimated from water loss rates of both sides of detached hypostomatous leaves were higher than P, and were more strongly affected by treatments. In these cases, the most probable explanation is some damage to stomatal function resulting in a reduced ability to close after leaf excision. Effects of growing conditions and time of year on P were found, which allowed a hypothetical interaction between P and stomatal sensitivity to air humidity to be tested in beech. No unambiguous indication of such a relationship was found

Relationships between demography and gene flow and their importance for the conservation of tree populations in tropical forests under selective felling regimes

Determining how tropical tree populations subject to selective felling (logging) pressure may be conserved is a crucial issue for forest management and studying this issue requires a comprehensive understanding of the relationships between population demography and gene flow. We used a simulation model, SELVA, to study (1) the relative impact of demographic factors (juvenile mortality, felling regime) and genetic factors (selfing, number and location of fathers, mating success) on long-term genetic diversity; and (2) the impact of different felling regimes on population size versus genetic diversity. Impact was measured by means of model sensitivity analyses. Juvenile mortality had the highest impact on the number of alleles and genotypes, and on the genetic distance between the original and final populations. Selfing had the greatest impact on observed heterozygote frequency and fixation index. Other factors and interactions had only minor effects. Overall, felling had a greater impact on population size than on genetic diversity. Interestingly, populations under relatively low felling pressure even had a somewhat lower fixation index than undisturbed populations (no felling). We conclude that demographic processes such as juvenile mortality should be modelled thoroughly to obtain reliable long-term predictions of genetic diversity. Mortality in selfed and outcrossed progenies should be modelled explicitly by taking inbreeding depression into account. The modelling of selfing based on population rate appeared to be oversimplifying and should account for inter-tree variation. Forest management should pay particular attention to the regeneration capacities of felled species