Stand-Level Variation Drives Canopy Water Storage by Non-vascular Epiphytes Across a Temperate-Boreal Ecotone

Epiphytes, including bryophytes and lichens, can significantly change the water interception and storage capacities of forest canopies. However, despite some understanding of this role, empirical evaluations of canopy and bole community water storage capacity by epiphytes are still quite limited. Epiphyte communities are shaped by both microclimate and host plant identity, and so the canopy and bole community storage capacity might also be expected to vary across similar spatial scales. We estimated canopy and bole community cover and biomass of bryophytes and lichens from ground-based surveys across a temperate-boreal ecotone in continental North America (Minnesota). Multiple forest types were studied at each site, to separate stand level and latitudinal effects. Biomass was converted into potential canopy and bole community storage on the basis of water-holding capacity measurements of dominant taxa. Bole biomass and potential water storage was a much larger contributor than outer canopy. Biomass and water storage capacity varied greatly, ranging from 9 to >900kg ha–1 and 0.003 to 0.38 mm, respectively. These values are lower than most reported results for temperate forests, which have emphasized coastal and old-growth forests. Variation was greatest within sites and appeared to reflect the strong effects of host tree identity on epiphyte communities, with conifer-dominated plots hosting more lichen-dominated epiphyte communities with lower potential water storage capacity. These results point to the challenges of estimating and incorporating epiphyte contributions to canopy hydrology from stand metrics. Further work is also needed to improve estimates of canopy epiphytes, including crustose lichens.

ALLOMETRIC MODELS FOR ESTIMATING ABOVEGROUND BIOMASS AND BIOMASS ALLOCATION OF CAPIXINGUI TREES (Croton floribundus Spreng.) IN AN AGRISILVICULTURAL SYSTEM

ABSTRACT The objective of this study was to select allometric models to estimate total and pooled aboveground biomass of 4.5-year-old capixingui trees established in an agrisilvicultural system. Aboveground biomass distribution of capixingui was also evaluated. Single- (diameter at breast height [DBH] or crown diameter or stem diameter as the independent variable) and double-entry (DBH or crown diameter or stem diameter and total height as independent variables) models were studied. The estimated total biomass was 17.3 t.ha-1, corresponding to 86.6 kg per tree. All models showed a good fit to the data (R2ad > 0.85) for bole, branches, and total biomass. DBH-based models presented the best residual distribution. Model lnW = b0 + b1* lnDBH can be recommended for aboveground biomass estimation. Lower coefficients were obtained for leaves (R2ad > 82%). Biomass distribution followed the order: bole>branches>leaves. Bole biomass percentage decreased with increasing DBH of the trees, whereas branch biomass increased.

Changes in biomass and production over 53 years in a coastal Piceasitchensis –Tsugaheterophylla forest approaching maturity

Using periodic remeasurements of tagged trees in nine 0.4-ha sample plots in a Piceasitchensis (Bong.) Carr. – Tsugaheterophylla (Raf.) Sarg. forest at Cascade Hand Experimental Forest, Oregon, we calculated that biomass of bolewood increased from 570 Mg•ha−1 at age 85 years to 760 Mg•ha−1 at age 138 years. Net primary production of bolewood declined from 11 to about 6 Mg•ha−1•year−1, and mortality loss increased from 2 to about 6 Mg•ha−1•year−1. Values for 37-year-old plots in the same area were 210–360 Mg•ha−1•year−1 bole biomass, 7–20 Mg•ha−1•year−1 bolewood production, and 0–2 Mg•ha−1•year−1 mortality loss. Indications are that bolewood production and biomass were lower in the older plots when they were 37 years old. In the older plots, biomass did not increase between ages 120 and 138. Of the photosynthate potentially available for bolewood production, some replaces biomass lost via mortality and some is allocated to maintenance (respiration plus allocation to fine roots). We estimate that one-quarter to one-half of the production is lost by mortality, and that mortality loss may thus be an important factor limiting forest biomass accumulation.

Analysis of Forest Land-use and Vegetation in a Part of Central Himalaya, Using Aerial Photographs

The forest canopy, biomass, and basal tree-trunk cover, of an area of about 200,000 ha, comprising 10 subcatchments in the Indian Central Himalaya, were mapped by employing aerial photographs and non-destructive field sampling. This method provides basic information on the current forest land-use and biomass for enlightened environmental planning and conservation. Regression equations developed to describe predictive relationships between crown-cover and basal tree-trunk cover; biomass and crown-cover; basal tree-trunk cover and bole biomass; and basal tree-trunk cover and total above-ground biomass, for different forests occurring in the area, should prove of value for future ecological studies in the Central Himalaya.

Forest turnover and the dynamics of bole wood litter in subalpine balsam fir forest

A chronosequence of three stands of balsam fir was sampled in 1974 and 1982; during these 8 years, recruitment was absent so mortality alone accounted for an 18–30% decrease in live tree density. In a mature 78-year-old stand, the mass of bole wood on the forest floor was 1.4 kg•m−2 compared with an estimated aboveground live and dead bole biomass of 17.2 kg•m−2. During 5 years of repetitive sampling, annual bole input to the forest floor was episodic and variable in time and space, ranging from 3 to 365 g•m−2•year−1. A mass balance model was used to characterize the changes in wood litter on the forest floor. If most of the live trees die within a short period of time, bole input would occur in a pulse event and cause a peak in wood litter mass, which would then decline over time (and with stand maturation) as decomposition prevails. The assumption of steady-state conditions for wood litter is not valid; rather the mass of wood litter will wax and wane through time. Over a landscape, spatial patterns in the abundance of wood litter reflect a stand's history; old mature stands would have little wood litter while young regenerating stands would have large amounts. A maximum value for wood litter would be found in a stand located immediately behind a fir wave. Natural disturbances from wind and avalanches lead to contrasting patterns with high and low wood litter values, respectively. About 41% of forest turnover in the balsam fir zone is initiated from natural disturbance and fir waves.

Estimation of biomass and nutrient storage in a Himalayan moist temperate forest

Aboveground tree biomass, estimated for three relatively protected oak forest sites in the Kumaun Himalaya using allometric equations based on circumference at breast height and density, ranged from 197.2 to 322.8 t•ha−1. Average leaf, twig, branch, and bole biomass proportions were 6.9, 11.6, 29.1, and 52.4%, respectively. Nutrients stored in the aboveground tree biomass on slightly acidic, fairly deep, residual sandy loams averaged (kilograms per hectare): ash, 7962.5; Ca, 4946.6; Mg, 831.9; N, 2270.7.