High-resolution planet satellite imagery and multi-temporal surveys to predict risk of tree mortality in tropical eucalypt forestry.

Global high-resolution imagery is a well-assimilated technology in forest mapping. The release of the Norway's International Climate & Forests Initiative (NICFI) Planet tropical basemaps time-series starting in 2015 at a 4.77-m resolution represents a unique opportunity to forecast climate change consequences such as drought episodes. Using multi-temporal ground surveys over 144 plots and publicly available high-resolution Planet dove time-series imagery we evaluate forest mortality patterns driven by imaging spectroscopy methods in Mato Grosso (Brazil) over an area planted with eucalypts severely affected by the 2019 drought. Changes in vegetation indexes before and after the 2019 drought were modelled using the effective logistic regression modelling to explain variation in tree mortality between the surveys, the dependent variable. We aimed to straightforwardly model tree mortality using change vectors in Planet's image mosaics co-registering in time with the observed tree mortality measurements in the field. The results showed differences in Normalized Difference Vegetation Index (NDVI) as the most significant predictor variable under the effective logistic regression modelling performed. The efficacy of 80.98% in concordance pairs correctly classified represented 0.81 of area under the Receiver Operating Curve (ROC). The release of the 2015-2020 Planet imagery in the tropics at 4.77-m resolution represents a valuable dataset to better understand previous natural disturbances and a powerful technology to detect in advance, and monthly after September 2020, eucalypt areas prone to harmful and increasingly frequent water-stress episodes.

Intensive silviculture enhances biomass accumulation and tree diversity recovery in tropical forest restoration.

Maximizing initial aboveground woody biomass (AGB) accumulation in order to obtain early payments for carbon stocking is essential for the financial viability of reforestation programs fostered by climate mitigation efforts. Intensive silviculture, i.e., silviculture traditionally used in commercial forestry to maximize productivity and gains, has recently been advocated as a promising approach to enhance AGB accumulation in restoration plantations. However, this approach may hamper natural forest regeneration and ecological succession due to high competition between colonizing plants and planted trees. We investigated the impacts of different silvicultural treatments applied to restoration plantations with 20 native tree species on AGB accumulation and spontaneous regeneration of native woody species in an experiment set up in the Atlantic Forest of Brazil. Intensive silviculture demonstrated a remarkable potential to enhance AGB accumulation in restoration plantations by increasing up to three times the AGB of tree stands (from ~25 to 75 Mg/ha in the 12th year). Intensive fertilization/weed control enhanced AGB accumulation, while higher tree density and the proportion of pioneers did not have a significant effect on AGB over the time. In spite of higher costs (cost increase of 13-19%), the cost-effectiveness for AGB accumulation of intensive silviculture was comparable to that of traditional silviculture applied to restoration (US$50-100/Mg AGB for 3 × 2 m spacing). Contrary to our expectations, we did not find a trade-off between AGB accumulation by planted trees and the spontaneous regeneration of tree species, since intensive silviculture enhanced the regeneration of both planted (total of 12 species) and colonizing woody species (total of 30 species) in the plantation understory. Specifically, a strong association was found between AGB stocks and the abundance and richness of colonizing species, a vast majority of which (90% of species and 95% of individuals) were dispersed by animals. We report a case of positive correlation between AGB stocking and woody species regeneration in the restoration of the Atlantic Forest. Fostering the establishment and maintenance of restoration tree plantations can, in some cases, be a win-win strategy for climate mitigation and biodiversity conservation in human-modified tropical landscapes.

Trade-offs between carbon stocks and timber recovery in tropical forests are mediated by logging intensity.

Forest degradation accounts for ~70% of total carbon losses from tropical forests. Substantial emissions are from selective logging, a land-use activity that decreases forest carbon density. To maintain carbon values in selectively logged forests, climate change mitigation policies and government agencies promote the adoption of reduced-impact logging (RIL) practices. However, whether RIL will maintain both carbon and timber values in managed tropical forests over time remains uncertain. In this study, we quantify the recovery of timber stocks and aboveground carbon at an experimental site where forests were subjected to different intensities of RIL (4, 8, and 16 trees/ha). Our census data span 20 years postlogging and 17 years after the liberation of future crop trees from competition in a tropical forest on the Guiana Shield, a globally important forest carbon reservoir. We model recovery of timber and carbon with a breakpoint regression that allowed us to capture elevated tree mortality immediately after logging. Recovery rates of timber and carbon were governed by the presence of residual trees (i.e., trees that persisted through the first harvest). The liberation treatment stimulated faster recovery of timber albeit at a carbon cost. Model results suggest a threshold logging intensity beyond which forests managed for timber and carbon derive few benefits from RIL, with recruitment and residual growth not sufficient to offset losses. Inclusion of the breakpoint at which carbon and timber gains outpaced postlogging mortality led to high predictive accuracy, including out-of-sample R2 values >90%, and enabled inference on demographic changes postlogging. Our modeling framework is broadly applicable to studies that aim to quantify impacts of logging on forest recovery. Overall, we demonstrate that initial mortality drives variation in recovery rates, that the second harvest depends on old growth wood, and that timber intensification lowers carbon stocks.

Effects of donor plant age and explants on in vitro culture of Cedrela montanaMoritz ex Turcz

Para evaluar el potencial organogénico de Cedrela montanaMoritz ex Turcz, se colectaron explantes de árboles maduros (10-20 años) y juveniles (7-18 meses). Los primeros incluyeron yemas,hojas y nudos de brotes juveniles (ubicados hacia la parte basal deltronco) y rejuvenecidos (obtenidos a partir de estacas). Los segundoshojas, peciolos, nudos, entrenudos y nudos de brotes elongados invitro. Los nudos de árboles juveniles presentaron el mayor potencialorganogénico, ya que el 45,8% de los explantes presentaron elongaciónde yemas axilares y el 56,2% enraizamiento en medio sin reguladoresde crecimiento. El 51% de los brotes elongados formaron brotesadventicios con 0.5 μM NAA y 0.5 μM BA, el 30% con 0.5 μM NAAy 1 μM BA, y el 30% con 1 μM BA; y el 20% raíces con 0,5 μM NAA.La formación de raíces se vio estimulada con la adición de carbónactivado (5 gL-1) en el medio. El 80% de las plántulas regeneradas apartir de nudos y el 72,5% de las provenientes de brotes generadosin vitro se aclimataron exitosamente. Por el contrario, explantesde árboles maduros presentaron baja respuesta organogénica.Elongación de yemas axilares fue registrada solamente en 10.7% delos nudos de brotes juveniles y en 6.7% de aquellos provenientes debrotes rejuvenecidos. En conclusión, la edad de la planta donadoray el tipo de explante influyen sobre el potencial organogénico de C.montana. Este estudio contribuyó al conocimiento de la respuesta deesta especie bajo condiciones in vitro...

To evaluate the organogenic potential ofCedrela montana Moritz ex Turcz, explants from mature(10-20 year-old) and juvenile (7-18 month-old) treeswere collected. The first grouping included buds, leaves,and nodes derived from juvenile basal offshoots andrejuvenated shoots from cuttings. The second, includedleaves, petioles, nodes, internodes and nodes of in vitroelongated shoots. The highest organogenic potential wasobserved in nodes from juvenile trees: 45.8% of explantspresented axillary bud elongation, while 56.2% presentedrooting in a growth regulator free culture medium. Fiftyonepercent of elongated shoots produced adventitiousshoots with 0.5 μM NAA and 0.5 μM BA; 30% with0.5 μM NAA and 1 μM BA; and 30% with 1 μM BA.Twenty percent presented roots with 0.5 μM NAA. Rootformation was stimulated in a medium supplementedwith activated charcoal (5 gL-1). The acclimatizationof eighty percent of plantlets regenerated from nodes,and of 72.5% in vitro generated shoots was successful.On the contrary, mature trees material presented loworganogenic response. Axillary bud elongation wasrecorded just in 10.7% of explants from juvenile shootsand in 6.7% of explants from rejuvenated shoots. Inconclusion the age of donor plant and type of explantaffect the organogenic potential of C. montana. Thisstudy contributes to the understanding of this species’response under in vitro conditions...

Para avaliar o potencial organogênico da Cedrela montanaMoritz ex Turcz, explantes derivados de árvores adultas (10-20 anos)e jovens (7-18 meses) foram coletados. O primeiro incluiu brotos,folhas, e nós derivados de brotações jovens (localizado na direçãoda parte basal do tronco) e rejuvenescida (obtido a partir de estacas).O segundo incluía folhas, pecíolos, nós, entrenós e nós de brotosalongados in vitro. Maior potencial organogênico foi observado emnós de árvores jovens, em que o alongamento de brotos foi obtidoem 45,8% dos explantes e o enraizamento atingiu 56,2% em meiosem reguladores de crescimento. Brotos adventícios foram induzidasem 51% dos rebentos gerados in vitro com 0.5 μM NAA e 0.5 μM BA;30% de indução ocorreu com 0.5 μM NAA e 1 μM BA; 30% com 1μM BA. Raízes adventícias foram induzidas em 20% dos rebentoscom 0,5 μM NAA. Formação de raízes foi estimulada com carvão ativado(5 gL-1) no meio. 80% das plântulas regeneradas a partir de nós e 72,5%das plântulas a partir de brotações obtidas in vitro foram aclimatizadascom sucesso. Em contraste, explantes derivados de árvores adultasapresentou resposta organogênica baixo. Alongamento de brotos degemas axilares foi registrado somente em 10,7% dos nós de brotaçõesjovens e 6,7% das brotações ejuvenescidas. Em conclusão a idade daplanta doadora e o tipo de explante afeta o potencial de organogênesein vitro da C. montana. Este estudo contribuiu para o conhecimento daresposta desta espécie sob condições in vitro...