Response of water yield to silvicultural treatments in a temperate forest in northern Mexico

Forest management modifies tree cover, directly influencing various ecosystem services, such as water regulation. Evapotranspiration, water interception, surface runoff, stemflow, and throughfall are among those processes that depend on tree cover. The objective of this study was to evaluate the changes in water yield, defined as the difference between precipitation and evapotranspiration, after the application of silvicultural treatments in a temperate forest ecosystem in northern Mexico. Fifteen experimental plots were established in which the following treatments were applied: intensive management (clearcutting), semi-intensive management (selection, tree cutting of 59-61% of basal area), conservative management (selection, tree cutting of 29-31% of basal area), and no treatment (control group). Incident precipitation, throughfall, stemflow, net precipitation, interception, and surface runoff were analyzed. Results show that conservative management treatments increase water yield between 2 to 3.6 mm per m-2 ha-1 of tree basal area removed. Water flow distribution, in relation to the incident precipitation, ranged from 72.3 to 91.8% for throughfall, 0.2 to 0.4% for stemflow, 72.7 to 91.8% for net precipitation, 8.19 to 27.42% for interception or evaporation, and 0.54 to 1.93% for surface runoff. The conservative management treatment was the most viable alternative for increasing water yield without compromising timber harvesting and loss of soil due to hydric erosion.

65 years of museum-based mammal research in Mexico: from taxonomy to worldwide information networks

Biological collections have become a key tool for biodiversity research. They are repositories of germplasm and data on modified or extinct natural populations, providing valuable information for understanding anthropogenic impacts on the natural world. We appraised the scientific value of the three mammal collections maintained by the Instituto Politécnico Nacional of Mexico (IPN): Escuela Nacional de Ciencias Biológicas (ENCB), CIIDIR Durango (CRD), and CIIDIR Oaxaca (OAXMA). We evaluated their specimen inventory, geographic coverage, and scientific importance for mammalogy. We assessed their physical conditions and provided insights into their future as data sources for understanding natural changes in the 21st century. We measured the scientific importance of the collections in terms of the number of specimens and taxa held and their geographic coverage. We also quantified research projects, publications, theses, and dissertations that have used at least one specimen, associated data, or materials deposited in these collections. We assessed their physical conditions by comparison with the standards set by the American Society of Mammalogists. As of 2018, these collections held a total of 61,560 cataloged specimens (ENCB 44,275; CRD 12,163; OAXMA 5,122), the largest repository of Mexican mammals in the Americas. All the orders, 86 % of the genera, and 69% (342) of the species of terrestrial mammals known to inhabit Mexico are represented in these collections. Specimens from all the Mexican States are included, with CRD focusing mostly on the northern part of the country, ENCB on central and southeastern Mexico, and OAXMA on the southeast. Materials from these collections have been used for at least 285 peer-reviewed publications, 91 research projects, and 107 theses and dissertations. CRD keeps >9,000 tissue samples, while OAXMA keeps >300 tissue samples plus 1,139 echolocation recordings of 24 bat species. All collections meet most curatorial standards of specimen preservation and availability and are being actively used in research projects. Nonetheless, we believe a sound institutional policy is necessary for the IPN mammal collections to successfully face the 21st-century challenges, particularly for ensuring the availability of usable data for the scientific community, digitizing the holdings, and designing and implementing a long-term preservation strategy.