Nutrient return to the forest floor through litter and throughfall under 7 forest species after conversion from Norway spruce

in Forest Ecology & Management (in press), (0),

Tree species can influence nutrient return to the forest floor and nutrient cycling through the amount and chemical composition of throughfall and litter. We compared foliar nutrient concentrations ... [more ▼]

Tree species can influence nutrient return to the forest floor and nutrient cycling through the amount and chemical composition of throughfall and litter. We compared foliar nutrient concentrations, litter production, nutrient return and soil chemistry under 7 tree species planted on the same site after two generations of a Norway spruce (Picea abies (L.) Karst.) monoculture. Common alder (Alnus glutinosa (L.) Gaertn.), european beech (Fagus sylvatica L.), pedunculate oak (Quercus robur L.), silver birch (Betula pendula Roth.), goat willow (Salix caprea L.) and rowan (Sorbus aucuparia L.) were planted within an experimental catchment on poor acid soil in south-eastern Belgium. Measurements were performed during one year, 11 years after planting. This study demonstrated that Ca, Mg, K and N concentrations in foliage and leaf litter are tree-species specific. Fresh foliage and foliar litter N concentrations were highest in alder and willow, while Ca, Mg and K concentrations were highest in rowan. Litter Ca concentrations were approximately twice in rowan than those of all other species. Differences in nutrient concentrations between foliage and leaf litter depended both on the element concerned and on tree species. The total average litterfall biomass ranged from 615 kg ha−1 year−1 under oak to 3122 kg ha−1 year−1 under rowan. Foliar litterfall represented above 85% for beech, spruce and oak, 70% for alder and willow and ca. 55% for birch and rowan. Reproductive parts formed 44% of total litterfall biomass under rowan. Ca, Mg, K and N return via throughfall, foliar litter and reproductive parts were higher under accompanying tree species (alder, birch, willow, rowan) than under the main commercial tree species (oak, beech, spruce). Total N return was in the order of 50 kg ha−1 year−1 under accompanying species, 33 kg ha−1 year−1 under spruce and near 20 kg ha−1 year−1 under beech and oak. Under rowan, total Ca, Mg, and K return to the forest floor through throughfall deposition, litterfall of leaves and reproductive parts amounted to 47, 9 and 66 kg ha−1 year−1, respectively. Compared to spruce, forest floor pHH20 has increased by 0.4 unit under birch and rowan, and exchangeable Ca2+, Mg2+, K+ have increased about threefold under rowan. Planting rowan as accompanying species may therefore represent an interesting management option for improving forest floor chemistry on nutrient poor sites through Ca, Mg, and K nutrient return. [less ▲]

Enrichment of logging gaps with moabi (Baillonella toxisperma Pierre) in a Central African rain forest

in Forest Ecology & Management (2009)

Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we ... [more ▼]

Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we present the results of an experimental enrichment planting with moabi (Baillonella toxisperma Pierre), a valuable and important timber species harvested in Central Africa. Although forest gaps are generally considered as favourable for the regeneration of this species, a survey conducted in a forest concession in southeastern Cameroon provided an estimate of only 12.7 seedlings ha 1, suggesting that the species was, in fact, poorly represented in logging gaps within the study area. To further investigate the dynamics of the moabi in logging gaps, 795 seeds were sown in 15 logging gaps and 410 nursery-raised seedlings were planted in 15 other gaps. A biannual monitoring program over a 30-month period showed a lower survival rate for seedlings from sowing (75.9%) compared to that of nursery-raised seedlings (95.3%). Planted seedlings reached on average 229.3 cm whereas seedlings from sowing were 167.5 cmtall, with the observed difference roughly corresponding to the average height of the nursery-raised seedlings at the time they were introduced to the logging gaps. After 30 months, the diameters of planted seedlings (16.8 mm) were also greater than those of the directly sown individuals (12.5 mm). Forest gap characteristics significantly influenced the growth of the plants. Factors accounting for the differences were total solar radiation, the soil content of coarse sand, the topographic position of the gap, the vegetation cover and the density of Macaranga spp. Whilst total solar radiation had a positive influence on growth, the remaining factors had impacted growth negatively. A streamlined technique was tested by planting 7 seedlings in 250 gaps. Without additional site maintenance, 29.3% of the moabi seedlings emerged naturally from the competing vegetation after 24 months. With biannual maintenance some 89.4% of seedlings became successfully established. Clearance operations had no significant influence on the height of plants whilst plant diameter was greater in cleared gaps. The total cost of the enrichment technique was 5.5 EUR per gap without maintenance and 7.5 EUR per gap with a single maintenance measure. Whilst long-term monitoring is needed, this study suggests a high survival rate of moabi introduced in logging gaps, and a growth rate 10 times higher than previously reported under canopy cover. These findings, combined with the low costs of the enrichment technique, support the use of silvicultural measures in logging gaps to restore the forest. [less ▲]

Biomass production of 17 poplar clones in a short-rotation coppice culture and its relation to soil characteristics.

in Forest Ecology & Management (2004), 187(2), 295-309