Handroanthus chrysanthus and Swietenia macrophylla are ecologically and economically significant tree species whose populations have declined due to high demand for their timber, adversely affecting their natural regeneration. This study aimed to evaluate the ecophysiological response to increased photosynthetic photon flux density (PPFD) in H. chrysanthus and S. macrophylla seedlings under Amazonian conditions. Assimilation measurements (A) were performed using a portable iFL-LCpro-SD system. The evaluation of A in response to increased PPFD ranged from 25 to 1800 μmol m -2s -1. water use efficiency (WUE) was calculated as the ratio between A and the transpiration rate (E). S. macrophylla exhibited a significantly higher maximum photosynthetic assimilation rate (A max, 9.4 ± 0.52 µmol CO 2 m -2 s -1) compared to H. chrysanthus (6.18 ± 0.17 µmol CO 2 m -2 s -1, p < 0.05), indicating greater carbon fixation efficiency. S. macrophylla showed a maximum WUE (WUE max) of 13.17 ± 0.24 µmol mmol -1 at 600 μmol m -2 s -1 PPFD, while H. chrysanthus reached its WUE max (6.16 ± 0.23 µmol mmol -1) at 750 μmol m -2 s -1 PPFD. These results suggest that S. macrophylla exhibits higher WUE under high irradiance conditions, potentially due to more efficient stomatal regulation and an optimized balance between carbon fixation and water loss via transpiration.

Pollution caused by heavy metals in soils and ecosystems is an environmental problematic that requires urgent attention due to the ecological problems that it generates. Forest species can be used to mitigate contamination because of their potential to bioaccumulate contaminating metals. Hence, the aim of this research was to identify tree species with good heavy metal bioaccumulating capacities that can contribute to mitigate pollution. The bioconcentration factor for five forest species, such as: Spanish cedar ( Cedrela odorata L.), cutanga ( Parkia multijuga Benth.), guaba or ice cream bean ( Inga edulis Mart.), guarumo ( Cecropia ficifolia Warb. ex Snethl.) and Amazon tree grape ( Pourouma cecropiifolia Mart.), commonly found in the Ecuadorian Amazon was analysed, based on the relationship between the leaves and soil concentration of the heavy metals. For heavy metal analysis in leaves and soil samples of each plant species, atomic absorption spectrometry was used. The results showed that P. cecropiifolia had the highest bioconcentration factor for lead, C. odorata for cadmium and nickel, and I. edulis had the highest potential for iron and aluminium absorption. Any kind of correlation between the concentration of each element in soil and leaves was found, which shows that the bioaccumulation capacity of the species studied does not determine the concentration of metals in the soil.

Few studies have comprehensively evaluated the effect of changing land use on the soil quality in Ecuadorian amazon region that subject to continued deforestation processes. This study evaluated the influence of different types of land use on soil quality using an integrated soil quality index (SQI) with minimum set of indicators, based on 140 soil samples from 7 land use types, in seven productive distinct landscapes in the Pastaza province, Ecuador. The land use type evaluated were: Chakra_A, Chakra_B, Chakra_C, Cattle_A, Cattle_B, Cattle_C and Forest. Land use type had significant effects on soil properties and thus on soil quality. Soil quality index was developed by using, AP, Zn, TOC, BD and LL; AP and Zn had highest weighting values (0.38), which indicated that these indicators contributed the most to final SQI. In general, the SQI decreased as soil depth increased and for each type of land use, in the surface layer (0-10cm) the uses of Chakra_A (0.46) and forest (0.44) showed the highest SQI, while for the second depth (10-30cm), Chakra_A (0.45) and Chakra_B (0.43) presented significantly higher SQIs than the other land uses. The applied SQI can be used to assess the effect of changes on land use on soil quality in other landscapes of the Ecuadorian Amazon Region.