Land Retirement Demonstration Project

Overview

Due to the large-scale conversion of lands in the San Joaquin Valley, local sources of native plant seed are exceeding scarce (click here to view an online PowerPoint presentation about this topic).

In response to this lack of native seed availability, the Valley Flora Propagation Center (VFPC) was established in order to serve a variety of essential functions:

• to augment available commercial sources of native seed
• to substantially amplify the number of San Joaquin Valley species that are available for use in local restoration activities
• to serve as a "laboratory", where the various species can be screened for their potential applicability in restoration settings
• to provide a setting that is suited for outreach and volunteer-centered activities.

Seed production activities were conducted at a native plant field nursery (Figure 1), located approximately 4.8 kilometers (3 mi) southwest of Tranquillity, California, and a seed processing facility located in Fresno, California. Seeds of native species were collected from numerous sites in the western San Joaquin Valley and planted in the nursery for seven consecutive growing seasons (2001-2008), in order to increase available seed supplies through field propagation.

The Native Plant Field Nursery

The nursery and associated seed collecting and seed processing activities expanded significantly throughout the course of the project. The original nursery, established in 2001, occupied ca. 0.8 ha (2 ac), of which approximately 0.6 ha (1.5 ac) was planted. In the second year (2002-03 growing season), the nursery was relocated to a better site (i.e., slightly better soils and improved access to irrigation), and was expanded to approximately 1.6 ha (4 ac), with weed control measures applied to an additional 0.8 ha (2 ac) in order to prepare that area for future nursery expansion.

During the third year (2003-04 growing season), the Nursery expanded again. During this time ca. 0.2 ha (0.5 ac) of the area that was prepared during the previous year was put into production. Also, an additional 1.6 ha (4 ac) to the east of the nursery were established as a "mechanized nursery", in which eight species were grown in single-species blocks (0. 2 ha; 0.5 ac). In contrast to the "main" portion of the nursery, which was reliant on extensive hand labor, cultivation and harvesting in the mechanized nursery emphasized machine-based technologies (e.g., the tractor, sprayer, and mechanical seed harvester). During the 2004-05 growing season, the nursery was slightly reduced in area: the main nursery was reduced to ca. 1.6 ha (4 ac) and the mechanized nursery was reduced to ca. 1.4 ha (3.5 ac). For the 2005-06 growing season, the main nursery was reduced slightly to ca. 1.1 ha (2.7 ac), and the mechanized nursery was not maintained. The nursery was maintained at ca. 1.1 ha during the 2006-07 and 2007-08 growing seasons.

The number of species in cultivation at the nursery rose steadily over the first four growing seasons. Eighteen species were cultivated during the first year, 31 species in 2002-03, 67 species in 2003-04, and 84 species in 2004-05. The peak number of species (85) planted was during the 2005-06 growing season. Due to changes in funding and allocation of staff time, 50 species were cultivated during the 2006-07 growing season and 63 species during the 2007-08 growing season.

Seed Collecting

Seed collecting activities (Figure 2) expanded dramatically over the course of the project. In the first year of seed collection (2000-01) seed was collected from just 7 locations. In subsequent years, a significant amount of effort was expended on locating additional seed collecting sites. By 2007, we had identified 41 local collecting sites (i.e., within 80.5 km (50 mi) of the nursery) that support a total of 158 native species, and we have collected seed from 125 of the species. A list of the species that we have documented within an 80.5 km radius of the nursery is available here.

Seed Processing

In order to be able to accommodate (i.e., dry, clean, and store) the seed from the nursery and from additional seed collecting, an approximately 140 square meter (1500 sq ft) facility was leased from 2003 through 2008. A variety of seed processing equipment was purchased and/or constructed, and a dust collection system was installed.