Modeling susceptibility to deforestation of remaining ecosystems in North Central Mexico with logistic regression

Determining underlying factors that foster deforestation and delineating forest areas by levels of susceptibility are of the main challenges when defining policies for forest management and planning at regional scale. The susceptibility to deforestation of remaining forest ecosystems (shrubland, temperate forest and rainforest) was conducted in the state of San Luis Potosi, located in north central Mexico. Spatial analysis techniques were used to detect the deforested areas in the study area during 1993-2007. Logistic regression was used to relate explanatory variables (such as social, investment, forest production, biophysical and proximity factors) with susceptibility to deforestation to construct predictive models with two focuses: general and by biogeographical zone.In all models, deforestation has positive correlation with distance to rainfed agriculture, and negative correlation with slope, distance to roads and distance to towns. Other variables were significant in some cases, but in others they had dual relationships, which varied in each biogeographical zone. The results show that the remaining rainforest of Huastecaregion is highly susceptible to deforestation. Both approaches show that more than 70% of the current rainforest area has high and very high levels of susceptibility to deforestation. The values represent a serious concern with global warming whether tree carbon is released to atmosphere. However, after some considerations, encouraging forest environmental services appears to be the best alternative to achieve sustainable forest management.     

Sp?tfr?ste und Massenwechsel vonTortrix viridana L.Lep. Tortr.)

Ohne Zusammenfassung     

Fodder production responses to pruning height and fodder quality of some trees and shrubs in a forest-savanna transition zone in southwestern Nigeria

Seasonal fodder production responses of five shrubs (Centrosema arenarium, Desmodium strigillosum, Desmodium velutinum, Phyllodium pulchellum, and Tadehagi triquetrum)and five trees (Albizia gummifera, Berlinia grandiflora, Albizia niopoides, Bauhinia monandra, and Inga edulis) to pruning heights ranging from 15 to 75 cm were evaluated during the main-wet, minor-wet, and dry seasons of 1993 and 1994 in the forest-savanna transition zone of West Africa. Fodder from the main-wet season was analysed for nitrogen (N) and phosphorus (P), and dry matter degradation characteristics after 6, 12, 24, 48, 72 and 96 h of incubation in rumen-fistulated N'Dama steers. In the minor-wet season, fodder production of all species increased in response to increasing pruning height with the exception of P. pulchellum and A. gummifera. Highest fodder production was attained at a pruning height of 45 cm for the Desmodium species, 50 cm for P. pulchellum, and 75 cm for the rest of the species. Concentrations of N and P varied significantly among the species; for N the ranges were 28.7–38.8 g kg^–1 (shrubs) and 25.3–44.5 g kg^–1 (trees), while for P the ranges were 3.26–7.04 g mg^–1 (shrubs) and 3.58–6.76 g mg^–1 (trees). Dry matter degradation characteristics differed significantly among shrubs and trees; ranges for shrubs were: soluble fraction (a), 128–185; degradable fraction (b), 664–703; potential degradability (PD), 793–857, as g kg^–1; rate of degradation (c), 0.0241–0.0308 as % h^–1 while for trees ranges were: (a), 139–160; (b), 651–826; (PD), 824–970, as g kg^–1; (c), 0.0143–0.0227 as % h^–1. Based on fodder production and quality, C. arenarium, D. strigillosum, D. velutinum, B. monandra, I. edulis, and A. niopoides were the most promising species for the development of animal agroforestry technologies in the west African forest-savanna transition zone and similar environments in the tropics.This revised version was published online in November 2005 with corrections to the Cover Date.     

Screening of 18 agroforestry species for highly acid and aluminum toxic soils of the humid tropics

A screening trial involving 18 agroforestry species were initiated on highly acidic and Al toxic soils of Nkoemvone, Southern Cameroon, with the objective of identifying fast growing species that can be suitable for improving short fallows. Selected growth parameters evaluated were plant height, stem and crown diameter, number of stems at 3, 12 and 20 months after planting (MAP), and biomass yield at the first pruning (20 MAP). Then 9 months regrowths were evaluated for the same parameters. Outstanding height and stem diameter were observed for Indigofera zollingeriana, Inga edulis, Grewia mollis and Pterocarpus santalinoides. They reached between 6 and 9 m height and between 8 and 10 cm diameter. The best height was correlated to the best stem diameter for I. zollingeriana (8.7, 8.6), I. edulis (7.7, 10.1) and P. santalinoides (6.4, 10.3). The same four species developed a crown of more than 5 m diameter and easily out competed weed in the alley. G. mollis, Glyphea brewis, Dactiladenia barteri and I. zollingeriana had a shrubby architecture; G. mollis had up to 17 stem before the first pruning. Inga edulis and G. mollisproduced the highest total biomass, with respectively 61 and 39 t/ha dry matter. Other species with more than 20 t/ha total mass were I. zollingeriana, P. santalinoides, and Xylia xylocarpa. The first pruning stimulated shoot development, and the response of the species was similar to before the first pruning. Therefore I. edulis, P. santalinoides, G mollis and I. zollingeriana had the best growth performances and can be recommended for introduction in short fallows provided their contribution to soil fertility processes is assessed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Observations on the rooting patterns of some agroforestry trees in an arid region of north-western India

The present study deals with root architecture of 6-year-old trees of 9 indigenous and 3 exotic species growing in arid climate of north-western India. Observations, made on excavated root systems (3 tree replicates of each species) showed large variation in horizontal and vertical spread of roots. In Morus alba, Melia azedarach and Populus deltoides, the roots were confined to 80 cm, while in Prosopis cineraria, Acacia nilotica and Eucalyptus tereticornis, roots penetrated more deeply to 233 cm. The number of total roots ranged from 103 in Acacia catechu to 1932 in Eucalyptus tereticornis, and 62 to 80% of the roots were less than 2 mm in diameter. The primary roots were more horizontal than the secondary roots. The total root biomass varied from 2.2 kg in Acacia catechu to 30.6 kg^–1 tree in Populus deltoides, and top 30 cm soil contained 42 to 78% of the total biomass. The implications of the results are discussed in the context of the ecological niche of the species, and its usefulness in agroforestry systems.     

Evaluating changes in switchgrass physiology,biomass, and light-use efficiency under artificial shade to estimate yields if intercropped with Pinus taeda L.

There is growing interest in using switchgrass (Panicum virgatum L.) as a biofuel intercrop in forestry systems. However, there are limited data on the longevity of intercropped bioenergy crops, particularly with respect to light availability as the overstory tree canopy matures. Therefore, we conducted a greenhouse study to determine the effects of shading on switchgrass growth. Four treatments, each with different photosynthetically active radiation (PAR) levels, were investigated inside the greenhouse: control (no shade cloth, 49 % of full sunlight), low (under 36 % shade cloth), medium (under 52 % shade cloth), and heavy shade (under 78 % shade cloth). We determined the effect of shading from March to October 2011 on individually potted, multi-tillered switchgrass transplants cut to a stubble height of 10 cm. In the greenhouse, there was a reduction in tiller number, tiller height, gas exchange rates (photosynthesis and stomatal conductance), leaf area, above- and belowground biomass and light-use efficiency with increasing shade. Total (above- and belowground) biomass in the control measured 374 ± 22 compared to 9 ± 2 g pot^?1 under heavy shade (11 % of full sunlight). Corresponding light-use efficiencies were 3.7 ± 0.2 and 1.4 ± 0.2 g MJ^?1, respectively. We also compared PAR levels and associated aboveground switchgrass biomass from inside the greenhouse to PAR levels in the inter-row regions of a range of loblolly pine (Pinus taeda L.) stands from across the southeastern United States (U.S.) to estimate when light may limit the growth of intercropped species under field conditions. Results from the light environment of loblolly pine plantations in the field suggest that switchgrass biomass will be significantly reduced at a loblolly pine leaf area index between 1.95 and 2.25, which occurs on average between ages 6 and 8 years across the U.S. Southeast in intensively managed pine plantations. These leaf area indices correspond to a 60–65 % reduction in PAR from open sky.     

A molecular toolkit for population genetic investigations of the ash dieback pathogen Hymenoscyphus pseudoalbidus

The recently described ascomycete fungus Hymenoscyphus pseudoalbidus (anamorph: Chalara fraxinea) causes the current dieback of ash (Fraxinus excelsior) in large parts of Europe. The origin of this species and its relation to the native cryptic species Hymenoscyphus albidus are still enigmatic. The spatiotemporal pattern of the epidemic is typical for an introduced invasive species. However, the presence of two cryptic species indicates that hybridization or mutation might have been involved in driving speciation in this case. In this study, we present a set of 18 polymorphic microsatellite markers to study these processes in more detail on a population genetic level. Markers were designed such that they can be amplified in three individual multiplex PCRs and analysed in two fragment analysis runs. We thoroughly tested the marker set for pairwise linkage among loci, selective neutrality and Mendelian inheritance. Additionally, the markers were applied on two large collections of isolates derived from study sites in Germany. Population genetic calculations suggested a low yet significant level of differentiation, a large genotypic diversity and a limited genetic diversity within populations. Furthermore, we present additional data concerning the phylogenetic relation between H. albidus and H. pseudoalbidus, which seems to be more distantly related to each other than expected previously.     

Nutrient and heavy metals in decaying harvest residue needles on drained blanket peat forests

Harvest residue decomposition can significantly contribute to nutrient and heavy metal exports to receiving water courses. This study monitors the nutrient and heavy metal dynamics in decaying Sitka spruce and lodgepole pine harvest residue needles on Atlantic blanket peat forests in the west of Ireland. Using the litterbag method, harvest residue was placed both within and between furrows in two uncut forest and two clear-cut sites. On the clear-cut sites, the litterbags were positioned outside the harvest residue piles (i.e. brash windrows). Over the 2-year monitoring period, the needles decomposed slower at the clear-cut sites than the uncut forest sites, with mass losses of 46–55 and 58–77 %, respectively. Approximately 20 % less phosphorous (P) was released from the decaying needles at the clear-cut sites, while nitrogen (N) was released only at the uncut sites. Tree species was a significant factor contributing to nutrient and heavy metal release and accumulation patterns, with higher concentrations of aluminium (Al), nickel (Ni), cadmium (Cd) and zinc (Zn) in the decaying spruce needles than in pine. Conversely, the spruce needles showed accelerated depletion of calcium (Ca) and magnesium (Mg) relative to the pine. The harvest residue needle positioning (inside furrow/between furrows) and the site soil characteristics contributed significantly to Al transformations in spruce needles and iron (Fe) in both spruce and pine needles, with more accumulation occurring inside the furrows where Al and Fe contents of the peat were high. Manganese (Mn) was released from the needles in three of the four sites with a total release of over 90 % within 2 years. In the remaining site, where the Mn content of the peat was high, an accumulation of Mn in the needles was observed. The decomposition of needles on blanket peat catchments may be a significant source of P to receiving water courses, owing to their fast release of P, but not a likely source for N export.     

Kebon tatangkalan: a disappearing agroforest in the Upper Citarum Watershed,West Java,Indonesia

A comprehensive study was carried out on a typical indigenous agroforestry system, called kebon tatangkalan, in the changing agricultural landscape of the Upper Citarum Watershed, West Java, Indonesia. The main objectives of the study are to elucidate the structural patterns, multidimensional functions, and dynamics of this multi-layered agroforest. The study has identified 12 groups of different plant assemblages indicating that this type of agroforest contributes considerably to the heterogeneity of the agricultural landscape in the study area. Multivariate analysis suggests that elevation and slope are the biophysical factors that correlate most significantly with the distribution of plant species in kebon tatangkalan. The presence of this man-made vegetation is currently declining from the landscape due to population growth and rapid regional economic development. Serious effort to revitalize this traditional agroforest is needed to prevent its disappearance. Introduction of highly productive species and establishment of integrated policies in regional land-use planning and management are measures that should be taken into account in preserving this traditional agroforestry system.     

Agroforestry diffusion and secondary forest regeneration in the Brazilian Amazon: further findings from the Rondônia Agroforestry Pilot Project (1992–2002)

In July 1992 the Rondônia Agroforestry Pilot Project (RAPP) was launched in two agricultural municipalities (Nova União and Alto Paraiso) in the western Brazilian Amazon State of Rondônia. The purpose of the RAPP was to assess the conditions under which colonist farmers in the western Amazon would integrate agroforestry plantings into their small-scale farming systems and to assess the performance of those plantings over time. An experimental group consisting of 50 small-scale farmers was selected to participate. Plots were designed to accommodate between 3 and 25 different species, each producing one or more commodities with local market potential (hardwood, fruits, nuts, latexes, oils). Farmers planted seedlings typically on a 1-ha plot, located and designed by each farmer with the advice of a professional Brazilian extensionist. During the first phase of the project (1992–1998), the growth performance of the seedlings and changes in household characteristics were monitored on an annual basis. By 2002, 32 (64.0%) of the original 50 agroforest plots were found in place. This paper updates the research findings based on a 2002 follow-up visit to these 32 farms. In addition to growth performance, the authors’ found that 17.95% of the farms in the neighboring control group had planted trees and other agroforest crops between 1992 and 2002, compared to only 5.38% of farms outside the project area, suggesting spontaneous diffusion. The authors also found a potentially synergistic relationship between agroforestry and secondary forest regeneration with the use of satellite image analysis. The experience of the RAPP indicates that colonist farmers in Amazonia can be successful managers of agroforest plots with minimal external inputs over the long-term (10 years).