Jesús Fernández-Moya

Variability in Mediterranean annual grassland diversity driven by small-scale changes in fertility and radiation

Using the small-scale gradients in light and fertility imposed by the presence of trees on Mediterranean open oak woodlands, we studied differences in the ecology, floristic diversity and species composition of an annual grassland, and modeled plant relationships with soil properties and radiation using generalized linear models. The strong intra-annual variability in the annual grassland greatly affected overall floristic diversity estimates. Therefore, sampling at least twice during the annual growing period was important to avoid underestimating floristic composition. As has been found in previous studies, different groups of grasses were clearly shaped as a response to the ecological gradient created by the influence of the tree. However, when analyzing specific relationships, only a few individual species directly responded to the studied soil and light availability factors analyzed. Among them, those species considered ‘ruderal’ such as Carduus tenuiflorus, Echium plantagineum, Lolium rigidum, Rumex bucephalophorus, and Tolpis barbata showed a clear response to some nutrients and to light availability but displayed no relationship to N soil content. Our results suggest that individual species are responding to a combination of ecological factors. Therefore, some of the generally accepted assumptions regarding the ecology of specific taxa may not be as straightforward as traditionally considered.

Soil fertility characterisation of teak (Tectona grandis L.f.) plantations in Central America

Teak (Tectona grandis L.f.) is an important species in the worldwide quality tropical hardwood sector, which has gained significance in Central America since the first large plantations were established in the 1980s. The present work is a descriptive study that aims to: (1) analyse and characterise the general soil patterns which may be influencing teak plantations in Central America; (2) assess differences between countries and sub-regions; (3) create a global framework to help contextualise the soil fertility analyses conducted at sub-regional or farm level, and (4) determine the main problems associated with soil fertility in the region. Soil fertility was measured at 684 sites in Costa Rica, Guatemala and Panama. Although teak is considered to be a species with high soil nutrient requirements, and high fertility is usually assumed in teak plantations, the results show that this species has been planted in a wide variety of soils, including many with serious fertility problems (e.g. Ultisols and perhaps Oxisols) or with added difficulties due to their physical properties (e.g. Vertisols). The present analysis reveals a general K deficiency in the Central American teak plantations, where P deficiency and acidity toxicity are also relatively common problems. These soil fertility problems probably stem from poor site selection by forest managers in the 80s and 90s. Hence, although soil fertility is carefully evaluated when most teak plantations are established today, managers have to deal with soil fertility deficiencies in many sites where teak was established some years ago.

High resolution forest inventory of pure and mixed stands at regional level combining National Forest Inventory field plots, Landsat, and low density lidar

ABSTRACT Many countries have employed recently developed technologies, such as airborne lidar, to capture nationwide three-dimensional information over the past few years. In Spain, a huge volume of lidar information is available for the majority of the territory in the Spanish National Plan of Aerial Orthophotography. In this article, a multi-source approach is taken, integrating available databases, such as nationwide lidar flights, Landsat imagery and permanent field plots from the Spanish National Forest Inventory, with good results in the generation of wall-to-wall forest inventories. Volume and basal area errors are similar to those obtained by other authors (using specific lidar flights and field plots) for similar species. Errors in stem number estimates are larger than the values found in the literature as a consequence of the great influence of variable-radius plots, as used in the Spanish National Forest Inventory, on this variable.

An Operational Framework for Land Cover Classification in the Context of REDD+ Mechanisms. A Case Study from Costa Rica

REDD+ implementation requires robust, consistent, accurate and transparent national land cover historical data and monitoring systems. Satellite imagery is the only data source with enough periodicity to provide consistent land cover information in a cost-effective way. The main aim of this paper is the creation of an operational framework for monitoring land cover dynamics based on Landsat imagery and open-source software. The methodology integrates the entire land cover and land cover change mapping processes to produce a consistent series of Land Cover maps. The consistency of the time series is achieved through the application of a single trained machine learning algorithm to radiometrically normalized imagery using iteratively re-weighted multivariate alteration detection (IR-MAD) across all dates of the historical period. As a result, seven individual Land Cover maps of Costa Rica were produced from 1985/1986 to 2013/2014. Post-classification land cover change detection was performed to evaluate the land cover dynamics in Costa Rica. The validation of the land cover maps showed an overall accuracy of 87% for the 2013/2014 map, 93% for the 2000/2001 map and 89% for the 1985/1986 map. Land cover changes between forest and non-forest classes were validated for the period between 2001 and 2011, obtaining an overall accuracy of 86%. Forest age-classes were generated through a multi-temporal analysis of the maps. By linking deforestation dynamics with forest age, a more accurate discussion of the carbon emissions along the time series can be presented.

N-P-K fertilisation of teak (Tectona grandis) plantations: a case study in Costa Rica

The global importance of short rotation, intensively managed planted forests has increased over recent years due to the growing need for timber and other goods. In this kind of system, nutrient management is a key issue and fertilisation plays a double role: a) improving productivity and b) compensating nutrient output in order to attain sustainability and maintain productivity for further rotations. The need to replace nutrients, taken up by the growing forest or removed during timber extraction, has long been recognised (Rennie 1955). However, Fölster & Khanna (1997) stated that conventional forest management has shown a general lack of concern with regard to this problem. Several authors have recommended the application of fertiliser to sustain productivity in short-cycle plantations (FSC 2004, Rennie 1955, Gonçalves et al. 1997, Worrel & Hampson 1997). This is especially important in tropical forests where nutrient dynamics and tree growth take place more rapidly than temperate zones. Teak (Tectona grandis) is an important species worldwide in the quality tropical N-P-K FERTILISATION OF TEAK (TECTONA GRANDIS) PLANTATIONS: A CASE STUDY IN COSTA RICA