Guy Geudens

The role of fine and coarse roots in shallow slope stability and soil erosion control with a focus on root system architecture: a review

The contribution of plant root systems to slope stability and soil erosion control has received a lot of attention in recent years. The plant root system is an intricate and adaptive object, and understanding the details of soil–root interaction is a difficult task. Although the morphology of a root system greatly influences its soil-fixing efficiency, limited architectural work has been done in the context of slope stabilization and erosion control, and hence it remains unknown exactly which characteristics are important. Many of the published research methods are tedious and time-consuming. This review deals with the underlying mechanisms of shallow slope stabilization and erosion control by roots, especially as determined by their architectural characteristics. The effect of soil properties as well as the relative importance of different root sizes and of woody versus non-woody species are briefly discussed. Empirically and intuitively, architectural features seem to determine the effect of root systems on erosion phenomena and an effort is therefore made here to link both aspects. Still, the research to underpin this relationship is poorly developed. A variety of methods are available for detailed root system architectural measurement and analysis. Although, generally time-consuming, a full 3D architectural description followed by analysis in software such as AMAPmod offers the possibility to extract relevant information on almost any root system architectural characteristic. Combining several methods of measurement and analysis in a complementary way may be a useful option, especially in a context of modelling.

Patterns of throughfall deposition along a transect in forest edges of silver birch and Corsican pine

In two adjacent forest stands in Flanders, one dominated by Corsican pine (Pinus nigra subsp. laricio Maire) and another dominated by silver birch (Betula pendula Roth), throughfall deposition was monitored along a transect per- pendicular to the forest edge exposed to the prevailing wind direction. Throughfall deposition of Na + ,K + ,C a 2+ ,M g 2+ , NH4 + ,N O3 - ,C l - , and SO4 2- was examined on forest edge patterns expressed in the depth of influence of the edge effect (forest edge distance) and the level of enhancement at the edge (forest edge enhancement). In addition, an integrated forest edge enhancement factor was computed that incorporates these two parameters. Our results show that the edge effects on throughfall deposition of Na + ,C l - , the sum of so-called base cations, the sum of potentially acidifying ions, and the sum of inorganic nitrogen (NH4 + +N O3 - ) are more pronounced in the pine stand. The edge zone of the pine stand receives as a result of the edge effect 9.4 times more extra potentially acidifying ions and 12.7 times more extra inorganic nitrogen than the birch stand. We conclude that an appropriate design or conversion of the edge structure, from high-density Corsi- can pine plantations into lower density deciduous forests, can reduce the input of acidifying and eutrophying pollutants in the forest edge.

Nutrient cycling in two continuous cover scenarios for forest conversion of pine plantations on sandy soil. I. Nutrient cycling via aboveground tree biomass.

Conversion of coniferous pine plantations into mixed-species forests on sandy soils is an important concern for forest and nature management in Europe. However, little is know of the effect of the applied sylvicultural strategy on biogeochemical cycling throughout the conversion process. This study examined the aboveground biomass production and nutrient (N, P, K, Ca, and Mg) cycling in terms of litterfall, immobilization in stems and branches, canopy exchange, and yearly root uptake in two scenarios of continuous cover forestry a decade after the first intervention for converting a homogeneous Scots pine (Pinus sylvestris L.) forest. Four regeneration types were studied: silver birch (Betula pendula L.) and pine after a shelterwood cutting and birch and pine after a group cutting. In conclusion, it can be stated that both the tree species and the conversion scenario influence the circulation of nutrients through the forest ecosystem: cycling of N, P, and K is determined by the tree species as well as the...

Long-term dynamics in a planted conifer forest with spontaneous ingrowth of broad-leaved trees

ABSTRACT Question: What are the age structure and growth trends in a 160-year old not-managed Pinus sylvestris plantation with spontaneous development of Quercus robur and can recruitment of Q. robur be related to the radial growth pattern of the P. sylvestris overstorey? Location: Mattemburgh forest reserve, The Netherlands. Methods: Throughout the forest, we sampled 103 oaks and 102 pines with an increment corer. Tree ring widths were measured and cross-dated to produce mean ring width series. With these data we determined tree ages, investigated growth trends and identified growth releases and suppressions. Results: Q. robur is uneven-aged: some individuals recruited around 1925, but most reached coring height in the 1940s. The latter recruitment period related to a transition from stressed to released growth of the overstorey pines, growth releases of the oldest Q. robur and occurrence of P. sylvestris regeneration. No further recruitment has taken place since 1950. Conclusions: This study demonstrates that an old pine plantation can develop spontaneously into well-structured pine forest with an understorey of oak and pine. However, understorey recruitment in these forest types is not a continuous process and in this case a single allogenic canopy disturbance triggered its establishment. Nomenclature: Lambinon et al. (1998).

Scots pine in Belgium and the Netherlands

El Pino silvestre es la especie forestal mas importante en los Paises Bajos (39 % de la superficie forestal), y una de las tres principales coniferas en Belgica (10 % de la superficie forestal). Los objetivos de la gestion para el Pino silvestre han cambiado mucho durante el siglo XX: desde la produccion de apeas de minas hasta los anos setenta, hasta la gestion multifuncional de los bosques al final del siglo. Se discuten los tipos naturales de bosques con Pino silvestre en los Paises Bajos y Belgica. En Belgica el Pino silvestre no se considera indigena. Se describe la sucesion forestal con Pino silvestre, principalmente desde brezales degradados o arenas transportadas por el viento hasta los ecosistemas forestales. Normalmente, el Pino silvestre desempena un papel importante en el comienzo de esta sucesion, pero decrece cuando las especies de frondosas se convierten en dominantes en el dosel arboreo en la etapas sucesionales posteriores. La selvicultura ha cambiado mucho, a traves de la sucesion forestal y por el cambio en los objetivos de gestion. Los iniciales monocultivos plantados se reemplazan con estructuras forestales mas diversas a menudo utilizando la regeneracion natural. Las cortas a hecho se realizan cada vez menos, llevando a cabo muchas intervenciones en una escala pequena. La edad del rodal aumenta y el dosel cada vez se abre mas a traves de las claras, hasta que se elimina todo el dosel. La calidad del sitio tambien esta cambiando, principalmente por la acidificacion y los aportes de nitrogeno por la contaminacion. Mientras que la superficie de Pino silvestre disminuye gradualmente, la biodiversidad originalmente baja en los rodales jovenes esta aumentando en las zonas que permanecen con Pino silvestre.

Comparison of Ceramic and Polytetrafluoroethene/Quartz Suction Cups for Sampling Inorganic Ions in Soil Solution

Abstract Because the widely used ceramic cups are reported to release, adsorb, and filter dissolved nutrients from soil solution samples, inert cups made of poly(tetrafluoroethene) (PTFE) are frequently proposed as a more reliable alternative. A ceramic and a PTFE/quartz cup were compared with each other in this laboratory study. The PTFE/quartz cup was the most suited for pH measurements. Because only the ceramic cup samples both ammonium and nitrate in a satisfactory way, this cup type is recommended for nitrogen (N) balance studies. In most cases, the ceramic cup also performed better in sampling cations [sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+)] than the PTFE/quartz cup. Both cup types seemed inadequate to sample soil solution for aluminum (Al3+) determinations. The ceramic cups released chloride (Cl−) at low ion concentrations, but sulfate (SO4 2−) concentrations remained almost unaltered in the sample as compared to the solution outside the cup. In contrast, Cl− and SO4 2− were retained by the PTFE/quartz cups. The overall conclusion of this study is that PTFE/quartz cups have no clear advantages over the more widely used ceramic cups for use in ecological studies dealing with dissolved inorganic ions in the soil solution.