تحميل كتاب فهم اضطراب الغابات والنمط المكاني Understanding Forest Disturbance and Spatial Pattern by RS and GIS Approaches

 

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تحميل كتاب فهم اضطراب الغابات والنمط المكاني Understanding Forest Disturbance and Spatial Pattern by RS and GIS Approaches

تحميل كتاب فهم اضطراب الغابات والنمط المكاني Understanding Forest Disturbance and Spatial Pattern by Remote Sesing and GIS Approaches ، استكمالا لسلسلة تطبيقات نظم المعلومات الجغرافية GIS والاستشعار عن بعد RS نقدم لكم في هذه المقالة The Book Understanding Forest Disturbance and Spatial Pattern by Remote Sensing and GIS Approaches ، من تأليف Michael A. Wulder & Steven E. Franklin.

Introduction the Book Understanding Forest Disturbance and Spatial Pattern by RS and GIS Approaches

Remotely Sensed Data in the Mapping of Forest Harvest Patterns

The economic value of the timber, paper, and fuel products extracted from forests has made forest harvesting one of the primary agents of forest disturbance globally. In addition to economic importance, forest harvests can have significant ecological consequences. Harvest levels have in some cases been observed to significantly affect wildlife habitat (Curtis and Taylor, 2004; Richards et al., 2002) and influence biogeochemical (Cohen et al., 1996; Hassett and Zak, 2005) and hydrological (Swank et al., 2001) cycles. This chapter summarizes a range of forest harvest practices by way of creating a framework for understanding data and method considerations specific to forest harvest detection. There are several thorough reviews of digital.

Understanding Forest Disturbance and Spatial Pattern

change detection methodology (Coppin et al., 2004; Gong and Xu, 2003; Singh, 1989). With those works as background, the focus here is on how the physical characteristics of various silvicultural operations influence data and method considerations in the change detection process. A case study involving detection of standreplacing harvests in the Pacific Northwest of the United States of America is used to illustrate the process of selecting data and methods to address a particular set of analytical and mapping needs.

SILVICULTURAL OPTIONS

Silviculture is the science of manipulating ecological processes with a goal of shaping the structure of a forest stand to meet management goals. Harvesting, in addition to often yielding merchantable forest products, is a primary tool in this manipulation. The term harvest is used here to represent the cutting of any trees, even if that cutting does not produce salable products. In this section, harvests are broken into three different kinds of cuts: regeneration harvest, thinning, and salvage. This organization of harvest operations is based on silvicultural intent; regeneration harvest is intended to stimulate growth of a new cohort of trees, thinning is intended to stimulate growth of existing trees, and salvage is regeneration neutral, focusing mainly on extracting dead or dying trees that would otherwise become unusable. Salvage harvests have also on occasion been classified as a type of thinning when undertaken to remove suppressed trees proactively (e.g., Smith et al., 1997). However, only salvage that follows another disturbance is discussed in this chapter.

Although it is true that most remotely sensed data are fundamentally quantitative and not always suited to identifying silvicultural distinctions based on long-term intentions, there are nevertheless good reasons for becoming familiar with silvicultural theory. First, the management records often used as reference data in harvest mapping projects are likely to describe harvests in silvicultural terms (e.g., Franklin et al., 2000). Also, awareness of typical harvest strategies, some of which include a number of stand entries, can facilitate interpretation of the spectral data. This is particularly true if certain assumptions based on forest type and ownership can be used to predict likely harvest strategies in a given region. This section describes differences between regeneration, thinning, and salvage cuts and discusses the role of these harvest types within specific silvicultural systems.

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